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Over the past 2000 years, tuberculosis (TB) has claimed more lives than any other infectious disease. In 2020 alone, TB was responsible for 1.5 million deaths worldwide, comparable to the 1.8 million deaths caused by COVID-19. The World Health Organization has stated that new TB drugs must be developed to end this pandemic. After decades of neglect in this field, a renaissance era of TB drug discovery has arrived, in which many novel candidates have entered clinical trials. However, while hundreds of molecules are reported annually as promising anti-TB agents, very few successfully progress to clinical development. In this Perspective, we critically review those anti-TB compounds published in the last 6 years that demonstrate good

Existential obsessions (EO) are an uncommon type of obsessive thought, also described as philosophical or ruminative obsessions. In Obsessive Compulsive Disorder (OCD) with postpartum onset, the clinical picture frequently counts with intrusive thoughts about infant harm and compulsions of verification.

With the rise of cluster-assembled materials, an index that is able to rank and identify stable clusters or molecules is of great interest in materials sciences and engineering. In the present work...

The progressive scaling down of the silicon-based electronics has allowed to develop devices at nanometer scale, requiring new engineering techniques guided by fundamental chemical and physical concepts. Particularly, the nanostructured cluster systems are promising materials since their physical-chemical properties are sensitive to its shape, size, and chemical components, such that completely different materials can be produced by the simple addition or removal of a single atom. These size-tunable properties can open a new area in materials science and engineering. In the present work, quantum chemical methods were used to study the chemical substitution effects caused by subvalent (aluminum) and supervalent (phosphorus) atoms in the physical-chemical properties of some small silicon clusters, which demonstrate high stability, called magic numbers. The changes in the electronic structure and chemical acceptance to the dopants were evaluated with respect to ionization potential, electronic excitation energy, stability, and reactivity parameters. Taken together, these results enable to identify the most stable silicon-doped clusters. Regarding electrophilic reactions, Si10P is the most favorable system, while for nucleophilic reactions, none of the doped clusters resulted in higher stability.

Chemical bond plays a central role in the description of the physicochemical properties of molecules and solids and it is essential to several fields in science and engineering, governing the material’s mechanical, electrical, catalytic and optoelectronic properties, among others. Due to this indisputable importance, a proper description of chemical bond is needed, commonly obtained through solving the Schrödinger equation of the system with either molecular orbital theory (molecules) or band theory (solids). However, connecting these seemingly different concepts is not a straightforward task for students and there is a gap in the available textbooks concerning this subject. This work presents a chemical content to be added in the physical chemistry undergraduate courses, in which the framework of molecular orbitals was used to qualitatively explain the standard state of the chemical elements and some properties of the resulting material, such as gas or crystalline solids. Here in Part 1, we were able to show the transition from Van der Waals clusters to metal in alkali and alkaline earth systems. In Part 2 and 3 of this three-part work, the present framework is applied to main group elements and transition metals. The original content discussed here can be adapted and incorporated in undergraduate and graduate physical chemistry and/or materials science textbooks and also serves as a conceptual guide to subsequent disciplines such as quantum chemistry, quantum mechanics and solid-state physics.

Dapsone has been receiving growing interest due to it use as a new class of corrosion inhibitors, forming copolymers with aniline, pyrrole, diphenylamine and 4-aminodiphenylamine. The present work focuses on characterizing the theoretical and experimental electronic spectra of the neutral, monoprotonated and diprotonated dapsone. The theoretical electronic spectrum was obtained through the excited state characterization via time-dependent DFT theory. NBO analysis was carried out to identify the molecular orbitals involved in the detected experimental UV bands. The detected absorption wavelength values for the neutral dapsone were 292 and 258 nm (experiment), and 286.9 and 251.7 nm (theoretical). Concerning the protonated dapsone species, it was observed that the absorbance values were strongly dependent on pH, especially at pH between 1.0 and 4.0. As the pH of the solution decreases, the experimental band at 292 nm slowly decreases and shifts to 290 nm, while the absorption at 258 nm decreases until it disappears, and a new absorption band arises at 240 nm. While, when the basicity increases, the absorption spectra of dapsone do not change, but a regular red shift is noticed, and it is continued even up to pH 14.0. The red-shifted spectra may be due to the formation of a monoanion and/or dianion, but the isosbestic points were not constant.

Transition metal acetylacetonates have a wide range of technological applications, such as modifiers in polymers and polymerization catalysts. Since the electronic structure defines the physical-chemistry properties of these materials and ultimately their selectivity in technological applications, its characterization is of paramount importance. In this work, the general trends on the electronic structure of the transition metal acetylacetonate TM(AcAc) were estimated from qualitative and quantitative approaches. The qualitative picture, based on the ligand field theory, allowed to establish a relation between the d-orbital electron occupancy and the stability of the system, in which the Cu(AcAc)2 presents a limitrophe case, indicating moderate stability and reactivity. On the quantitative approach, the low-lying electronic states of TM(AcAc) were characterized by highly correlated methods. The thermodynamic and kinetic stabilities of TM(AcAc)n were ranked by using a stability index based on parameters of the wavefunction, namely, the excitation energy, the free energy of atomization, and the HOMO energy, showing a good agreement with the qualitative results. Besides the spectroscopic data provided for TM(AcAc)n, the combined qualitative and quantitative results can guide the choice of a specific TM(AcAc)n in applications that require higher or lower stabilities.

Ultracold environments composed by atoms or molecules offer an opportunity to study chemical reactions at the quantum-state level, for simulation of solid-state systems, as qubits in quantum computing, and for test fundamental symmetries. Those ultracold conditions formed by molecules can be obtained from cryogenic buffer gas, via supersonic expansion, followed by deceleration or from the laser cooling process. Diatomic alkaline earth monofluoride molecules have been shown as great candidates for the laser cooling process. In this sense, the present work focuses on the characterization of the low-lying doublet electronic states correlated to the first dissociation channel of the alkaline earth monofluorides diatomic molecules MF (M = Be, Mg and Ca). The developed state-of-the-art methodology was based on a qualitative analysis of the diatomic electronic structure, employing a hypothetical potential energy curve or by a simple molecular orbital diagram combined with bond order analysis. The potential energy curves, excitation and dissociation energies, and various sets of spectroscopic parameters were calculated by the MRCI/cc-pV5Z methodology. Transition probabilities for emission and radiative lifetimes among the characterized electronic states were also calculated for the (A)2Π ⟶ (X)2Σ+ electronic transition. Comparing the spectroscopy properties, we were able to indicate the CaF molecule as the best candidate molecule for laser cooling devices among the studied molecules.

The present work focuses in the characterization of the low-lying quartet electronic and spin-orbit states of diatomic borides XB, in which X is an element of group 14 (C, Si, Ge, Sn, PB). The wavefunction was obtained at the CASSCF/MRCI level with a quintuple-ζ quality basis set. Scalar relativistic effects were also taken into account. A systematic and comparative analysis of the spectroscopic properties for the title molecular series was carried out, showing that the (1)4Π→X4Σ− transition band is expected to be measurable by emission spectroscopy to the GeB, SnB and PbB molecules, as already observed for the lighter CB and SiB species.

The electronic states correlated to the first dissociation channel, around 25,500 cm−1, of the AlC and GaC molecules have been investigated by CASSCF/MRCI methodology with aug-cc-pV5Z basis set. Our work focused on the accurate description of the potential energy curves, dissociation energies, transition moment functions, radiative lifetimes, dipole moments and molecular constants. The B4Σ− electronic state has been previously detected for AlC molecule and it is probably not detectable in GaC molecule due to the predissociative character which affects all its vibrational levels. The characterization of the GaC low-lying electronic states were carried out for the first time.

We analyzed the behavior of third-instars of Chrysomya putoria as potential cannibals in experimental populations. Cannibalism rates were evaluated in three settings observed for 3, 6, 9, and 24 h, placing injured and uninjured larvae of C. putoria together. Our data heavily support that C. putoria larvae behave as cannibals when induced by a wound in another larva, and also after starving for 24 h. The probability of cannibalism increased as a function of time, both in no-choice and in choice experiments evidencing that time is a determining factor for cannibalism induction in C. putoria. However, the treatment combining injured with uninjured larvae showed the highest probability of cannibalism. These results suggest that C. putoria larvae may cannibalize under scarcity of food over long time or the presence of injured larvae. This study is useful to understand the behavior of C. putoria feeding on ephemeral substrates such as carrion or corpses and brings relevant and significant contribution to population ecology of blowflies and also forensic entomology.

The present work focuses on establishing a function to rank the stability of small silicon clusters to characterize their magic numbers. This function is composed by a thermodynamic descriptor, the atomization Gibbs free energy, and indirect kinetic descriptors, the highest occupied molecular orbital energy and the lowest excitation energy of each system. The silicon clusters geometries were optimized using density functional theory within a hybrid meta-GGA approximation (M06), while the electronic energy was corrected by single-point calculation using CASPT2 level of theory to obtain the molecular properties. Both methodologies were combined with polarized diffused triple zeta, 6-311++G(3df,3pd), basis set for all atoms. Some molecular properties and their combinations were considered to create the aforementioned function to represent the clusters chemical stability and their magic numbers. The chosen stability ranking function, called e3, presents results in agreement with the previous mass spectrometry experimental data identifying 4, 6, 7 and 10 as magic numbers for small silicon clusters. We believe this stability ranking function can be useful to study other intramolecular atomic and molecular clusters.

The present work focuses on establishing a function to rank the stability of small silicon clusters to characterize their magic numbers. This function is composed by a thermodynamic descriptor, the atomization Gibbs free energy, and indirect kinetic descriptors, the highest occupied molecular orbital energy and the lowest excitation energy of each system. The silicon clusters geometries were optimized using density functional theory within a hybrid meta-GGA approximation (M06), while the electronic energy was corrected by single-point calculation using CASPT2 level of theory to obtain the molecular properties. Both methodologies were combined with polarized diffused triple zeta, 6-311++G(3df,3pd), basis set for all atoms. Some molecular properties and their combinations were considered to create the aforementioned function to represent the clusters chemical stability and their magic numbers. The chosen stability ranking function, called ε

Pastilhas de Peltier são dispositivos baseados no efeito Peltier e são aplicadas para produzir efeito refrigerador ou aquecedor. Este trabalho aborda conceitos envolvidos na fabricação e funcionamento desses dispositivos tais como: histórico do efeito Peltier e desenvolvimento de placas de efeito Peltier. É feito um estudo de eficiência da refrigeração de água utilizando uma placa de efeito Peltier existente no Campus Natal – Zona Norte. Para isso, é implementada uma estrutura de refrigeração de água e são feitas medições para determinar a eficiência de sistema. Por fim, são apresentadas conclusões sobre o estudo desenvolvido Peltier’s wafers are devices based on Peltier effect and it is applied to produce a cooler or heater effect. This paper points to concepts involved in the manufacture and operation of these devices such as: history of the Peltier effect and development of Peltier wafers. It is shown the efficiency of cooling water using a Peltier wafer existing in Campus Natal – Zona Norte. For this, we implemented a set of cooling water and measurements were made to determine the efficiency of system. Finally, conclusions are presented about the measurements realized

Despite their interest for the understanding of the low-temperature behavior of biodiesel, data on the phase equilibria of biodiesels at temperatures below the cloud point are not available in the literature. To overcome this limitation, the liquid- and solid-phase compositions and fractions at temperatures below the cloud point were studied for three commercial diesels at temperatures ranging from 260 to 275 K. A thermodynamic framework able to describe these multiphase systems is presented. Two versions of the predictive UNIQUAC model along with an approach assuming complete immiscibility of the compounds in the solid phase are evaluated with success against the experimental phase equilibrium data measured in this work.

In spite of their interest to understand the low-temperature behavior of biodiesel, data on the crystallization behavior of fatty acid esters mixtures are scarce. To overcome this limitation, the melting points of seven binary mixtures of saturated and unsaturated fatty acid ethyl esters with ethyl stearate were measured by differential scanning calorimetry (DSC) and are here reported. The Predictive UNIQUAC model, developed for the prediction of cloud points of diesels and previously applied to fatty acid methyl esters, is shown to produce an excellent prediction of the experimental data measured in this work. It is shown that, alternatively, a simple ideal solution is able to describe the melting points with identical accuracy to the Predictive UNIQUAC model and may prove to be able to describe cloud points of real biodiesel.

Physical activity is a known protective factor, with benefits for both metabolic and psychological aspects of health. Our objective was to verify early and late determinants of physical activity in young adults. A total of 2063 individuals from a birth cohort in Ribeirão Preto, Brazil, were studied at the age of 23–25 years. Poisson regression was performed using three models: (1) early model considering birth weight, gestational age, maternal income, schooling and smoking; (2) late model considering individual’s gender, schooling, smoking and body mass index; and (3) combined (early + late) model. Physical activity was evaluated using the International Physical Activity Questionnaire, stratifying the individuals into active or sedentary. The general rate of sedentary behavior in the sample was 49.6%. In the early model, low birth weight (relative risk (RR) = 1.186, confidence interval (95%CI) 1.005–1.399) was a risk factor for sedentary activity. Female gender (RR = 1.379, 95%CI = 1.259–1.511) and poor schooling (RR = 1.126, 95%CI = 1.007–1.259) were associated with sedentary behavior in the late model. In the combined model, only female gender and participant’s schooling remained significant. An interaction between birth weight and individual’s schooling was found, in which sedentary behavior was more prevalent in individuals born with low birth weight only if they had higher educational levels. Variables of early development and social insertion in later life interact to determine an individual’s disposition to practice physical activities. This study may support the theoretical model ‘Similarities in the inequalities’, in which opposed perinatal backgrounds have the same impact over a health outcome in adulthood when facing unequal social achievement during the life-course.

As metodologias tradicionalmente utilizadas para quantificar o estoque de madeira demandam recursos humanos e financeiros. As redes neurais artificiais e o sensoriamento remoto tem se mostrado alternativas potenciais para a quantificacao de biomassa florestal. Diante disso, o trabalho propoe uma metodologia que utilize dados de imagens gratuitas do satelite Landsat 7 juntamente com tecnicas de inteligencia artificial para estimacao do volume de madeira em uma floresta de eucalipto na regiao de Acucena, MG. Para tal, foram selecionadas as imagens das bandas 1, 2, 3, 4, 5 e 7 da area de estudo. Treinou-se uma rede neural artificial (RNA) utilizando como variavel continua o volume (m³/ha). Como resultado obteve-se que 76,67 % dos valores estimados em nivel de parcela se encontram entre + 2% de erro, indicando um resultado promissor para estimar a producao florestal a partir de dados de imagens de baixa resolucao espacial.

Among the various methods for evaluating animal venom toxicity, the calculation of the median lethal dose (LD50) is the most widely used. Although different protocols can be used to calculate the LD50, the source of the venom and the method of extraction, as well as the strain, age, and sex of the animal model employed, should be taken into consideration. The objective of the present study was to evaluate the influence of sex and age on the toxicity of Tityus serrulatus scorpion venom in Swiss mice. Although the symptoms of envenomation were similar in male and female animals, female mice proved to be more resistant to the venom. In females, age had no impact on the susceptibility to scorpion envenomation. Male mice were more sensitive to T. serrulatus venom. Moreover, in males, age was an important parameter since sensitivity to the venom increased with age.

(Erratum)

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