Fundamentals of beer and hop chemistry

Beer brewing is an intricate process encompassing mixing and further elaboration of four essential raw materials, including barley malt, brewing water, hops and yeast. Particularly hops determine to a great extent typical beer qualities such as bitter taste, hoppy flavour, and foam stability. Conversely, hop-derived bitter acids account for an offending lightstruck flavour, which is formed on exposure of beer to light. These various processes are presented in detail, while due emphasis is placed on state-of-the-art hop technology, which provides brewers with efficient means to control bitterness, foam, and light-stability thereby allowing for the production of beers with consistent quality.

Supramolecular chemistry for nanomedicine

Mimicking Nature, supramolecular chemistry represents the chemistry beyond the molecule, in view that intermolecularinteractions constitute the driving force for the preparation of molecular and supramolecular assemblies, using the chemicalinformation contained in molecular building blocks. Upon molecular recognition between discrete units, chemical processessuch as self-assembly and self-organisation start operating, and are the leading processes to build up supramolecular aggregates and materials. When those materials have dimensions on thenanometric scale, a recently emerging scientific discipline is defined,Nanoscience. Nanomaterials are promising tools for many applications, and their use in biomedical and clinical applicationsdefines the so-called Nanomedicine. In this review we present a few selected examples of nanomaterials designed for therapeutical purposes, emphasizing the importance of the preparation methodology in terms of their therapeutical use.

Medicinal chemistry in the development of societies. Biodiversity and natural products

This document here has been elaborated by the IUPAC Medicinal Chemistry section and is backed by a large number of scientists, many of whom have had direct involvement and whose names appear at the end of the article. This work discusses the role that the discovery of new medicinal agents has in the development of societies as well as in the conservation of biodiversity in terms of the work carried out on natural products. Also included are several recommendations for countries which are presently in search of their own scientific and technological development in medicinal agents. The IUPAC Medicinal Chemistry section would appreciate the collaboration of the scientific societies in every country to aid in the diffusion of this document.

Implications, large and small, from chemical education research for the teaching of chemistry

Research studies in chemical education pose a communication problem for chemists. Unlike the findings from other specializations in chemistry the findings in chemical education tend to be reported in education journals that are not readily accessible to most chemists or chemistry teachers. This lecture is an attempt to remedy this gap in communication. Research studies fall into three broad categories. (i) issues related to the content of chemistry itself, that is, What content to teach? And What meaning of each topic is to be conveyed? (ii) issues related to how chemical content is taught, such as, the role of lectures, practical work, particular pedagogies, etc. and (iii) issues related to its learning, that is, learning of concepts, conceptual change, motivation, etc. Findings in each of these categories of research over the last twenty years have drawn attention to opportunities for improving the quality of chemical education in each of the levels of formal education where chemistry is taught. Sometimes the research findings seem small since they, in fact, merely diagnose the actual problem in teaching and learning. At other times, the research findings are large because they provide a solution to these problems. What remains to be done is to disseminate the findings so that appropriate teaching occurs more widely, with its consequent gains in the quality of learning. Research findings, of these small and large types will be used to illustrate the potential of research to make the practice of chemical education more effective.

Gas-phase ion chemistry of silyl cations obtained from hexamethyldisilazane

The gas-phase ion-molecule reactions of the Me3SiN(H)SiMe2+ ion, obtained by electron ionization from Me3SiN(H)SiMe3, have been studied in a Fourier transform ion cyclotron resonance spectrometer in order to understand the mechanistic details of an important chemical system presently used in film formation. This silyl cation has been observed to undergo addition reactions at electron rich centers to form stable adducts that may undergo further methane elimination in the case of alcohols and amines. The most important feature of these reactions is the fact that a metathesis type reaction can be observed in the presence of H2O, and other hydrogen labile substrates like alcohols, leading to the formation of the corresponding oxygen-containing ion, i.e. Me3SiOSiMe2+. For alcohols (ROH), facile formation of a tertiary product ion, presumably corresponding to an Me3Si-O-Si(Me)=O+-R structure with elimination of an amine reveals the strong tendency of these nitrogen-containing ions to undergo metathesis type reactions with oxygen containing substrates.

Flavonoids affect host-microbiota crosstalk through TLR modulation

Interaction between host cells and microbes is known as crosstalk. Among other mechanisms, this takes place when certain molecules of the micro-organisms are recognized by the toll-like receptors (TLRs) in the body cells, mainly in the intestinal epithelial cells and in the immune cells. TLRs belong to the pattern-recognition receptors and represent the first line of defense against pathogens, playing a pivotal role in both innate and adaptive immunity. Dysregulation in the activity of such receptors can lead to the development of chronic and severe inflammation as well as immunological disorders. Among components present in the diet, flavonoids have been suggested as antioxidant dietary factors able to modulate TLR-mediated signaling pathways. This review focuses on the molecular targets involved in the modulatory action of flavonoids on TLR-mediated signaling pathways, providing an overview of the mechanisms involved in such action. Particular flavonoids have been able to modify the composition of the microbiota, to modulate TLR gene and protein expression, and to regulate the downstream signaling molecules involved in the TLR pathway. These synergistic mechanisms suggest the role of some flavonoids in the preventive effect on certain chronic diseases.

Flavonoids affect host-microbiota crosstalk through TLR modulation

Interaction between host cells and microbes is known as crosstalk. Among other mechanisms, this takes place when certain molecules of the micro-organisms are recognized by the toll-like receptors (TLRs) in the body cells, mainly in the intestinal epithelial cells and in the immune cells. TLRs belong to the pattern-recognition receptors and represent the first line of defense against pathogens, playing a pivotal role in both innate and adaptive immunity. Dysregulation in the activity of such receptors can lead to the development of chronic and severe inflammation as well as immunological disorders. Among components present in the diet, flavonoids have been suggested as antioxidant dietary factors able to modulate TLR-mediated signaling pathways. This review focuses on the molecular targets involved in the modulatory action of flavonoids on TLR-mediated signaling pathways, providing an overview of the mechanisms involved in such action. Particular flavonoids have been able to modify the composition of the microbiota, to modulate TLR gene and protein expression, and to regulate the downstream signaling molecules involved in the TLR pathway. These synergistic mechanisms suggest the role of some flavonoids in the preventive effect on certain chronic diseases.

Evolution and Stellar Content of AGN Host Galaxies

In this dissertation, Active Galactic Nuclei (AGN) and their host galaxies are discussed. Together with transitional events, such as supernovae and gamma-ray bursts, AGN are the most energetic phenomena in the Universe. The dominant fraction of their luminosity originates from the center of a galaxy, where accreting gas falls into a supermassive black hole, converting gravitational energy to radiation. AGN have a wide range of observed properties: e.g. in their emission lines, radio emission, and variability. Most likely, these properties depend significantly on their orientation to our line-of-sight, and to unify AGN into physical classes it is crucial to observe their orientation-independent properties, such as the host galaxies. Furthermore, host galaxy studies are essential to understand the formation and co-evolution of galactic bulges and supermassive black holes. In this thesis, the main focus is on observationally characterizing AGN host galaxies using optical and near-infrared imaging and spectroscopy. BL Lac objects are a class of AGN characterized by rapidly variable and polarized continuum emission across the electromagnetic spectrum, and coredominated radio emission. The near-infrared properties of intermediate redshift BL Lac host galaxies are studied in Paper I. They are found to be large elliptical galaxies that are more luminous than their low redshift counterparts suggesting a strong luminosity evolution, and a contribution from a recent star formation episode. To analyze the stellar content of galaxies in more detail multicolor data, especially observations at blue wavelengths, are essential. In Paper III, optical - near-infrared colors and color gradients are derived for low redshift BL Lac host galaxies. They show bluer colors and steeper color gradients than inactive ellipticals which, most likely, are caused by a relatively young stellar population indicating a different evolutionary stage between AGN hosts and inactive ellipticals. In Paper II, near-infrared imaging of intermediate redshift radio-quiet quasar hosts is used to study their luminosity evolution. The hosts are large elliptical galaxies, but they are systematically fainter than the hosts of radio-loud quasars at similar redshifts, suggesting a link between the luminosity of the host galaxies and the radio properties of AGN. In Paper IV, the characteristics of near-infrared stellar absorption features of low redshift radio galaxies are compared with those of inactive early-type galaxies. The comparison suggests that early-type galaxies with AGN are in a different evolutionary stage than their inactive counterparts. Moreover, radio galaxies are found to contain stellar populations containing both old and intermediate age components.

"Green chemistry": os 12 princípios da química verde e sua inserção nas atividades de ensino e pesquisa

Green chemistry ¾ defined as the design, development, and application of chemical processes and products to reduce or eliminate the use and generation of substances hazardous to human health and the environment. This article summarizes the 12 principles of green chemistry, describing how they have been applied to the academic, industrial and research activities around the world.

The chemistry involved in the steam treatment of lignocellulosic materials

Pretreatment of lignocellulosic materials is essential for bioconversion because of the various physical and chemical barriers that greatly inhibit their susceptibility to bioprocesses such as hydrolysis and fermentation. The aim of this article is to review some of the most important pretreatment methods developed to date to enhance the conversion of lignocellulosics. Steam explosion, which precludes the treatment of biomass with high-pressure steam under optimal conditions, is presented as the pretreatment method of choice and its mode of action on lignocellulosics is discussed. The optimal pretreatment conditions for a given plant biomass are defined as those in which the best substrate for hydrolysis is obtained with the least amount of soluble sugars lost to side reactions such as dehydration. Therefore, pretreatment optimization results from a compromise between two opposite trends because hemicellulose recovery in acid hydrolysates can only be maximized at lower pretreatment severities, whereas the development of substrate accessibility requires more drastic pretreatment conditions in which sugar losses are inevitable. To account for this heterogeneity, the importance of several process-oriented parameters is discussed in detail, such as the pretreatment temperature, residence time into the steam reactor, use of an acid catalyst, susceptibility of the pretreated biomass to bioconversion, and process design.

The saccharinate anion: a versatile and fascinating ligand in coordination chemistry

The saccharinate anion, obtained by deprotonation of the N-H moiety of saccharin (o-sulfobenzimide) is a very versatile and polyfunctional ligand in coordination chemistry. In this review the different forms of metal-to-ligand interactions involving this anion and some other coordination peculiarities are briefly discussed on the basis of some selected examples.

Do general chemistry textbooks facilitate conceptual understanding?

Research in chemistry education has recognized the need for facilitating students' understanding of different concepts. In contrast, most general chemistry curricula and textbooks not only ignore the context in which science progresses but also emphasize rote learning and algorithmic strategies. A historical reconstruction of scientific progress shows that it inevitably leads to controversy and debate, which can arouse students' interest and thus facilitate understanding. The objective of this article is to review research related to the evaluation of general chemistry textbooks (based on history and philosophy of science, HPS) and suggest alternatives that can facilitate conceptual understanding.

Characterizing Propionibacterium freudenreichii ssp. shermanii JS and Lactobacillus rhamnosus LC705 as a new probiotic combination: basic properties of JS and pilot in vivo assessment of the combination

Characterizing Propionibacterium freudenreichii ssp. shermanii JS and Lactobacillus rhamnosus LC705 as a new probiotic combination: basic properties of JS and pilot in vivo assessment of the combination Each candidate probiotic strain has to have the documentation for the proper identification with current molecular tools, for the biological properties, for the safety aspects and for the health benefits in human trials if the intention is to apply the strain as health promoting culture in the commercial applications. No generalization based on species properties of an existing probiotic are valid for any novel strain, as strain specific differences appear e.g. in the resistance to GI tract conditions and in health promoting benefits (Madsen, 2006). The strain evaluation based on individual strain specific probiotic characteristics is therefore the first key action for the selection of the new probiotic candidate. The ultimate goal in the selection of the probiotic strain is to provide adequate amounts of active, living cells for the application and to guarantee that the cells are physiologically strong enough to survive and be biologically active in the adverse environmental conditions in the product and in GI tract of the host. The in vivo intervention studies are expensive and time consuming; therefore it is not rational to test all the possible candidates in vivo. Thus, the proper in vitro studies are helping to eliminate strains which are unlikely to perform well in vivo. The aims of this study were to characterize the strains of Propionibacterium freudenreichii ssp. shermanii JS and Lactobacillus rhamnosus LC705, both used for decades as cheese starter cultures, for their technological and possible probiotic functionality applied in a combined culture. The in vitro studies of Propionibacterium freudenreichii ssp. shermanii JS focused on the monitoring of the viability rates during the acid and bile treatments and on the safety aspects such as antibiotic susceptibility and adhesion. The studies with the combination of the strains JS and LC705 administered in fruit juices monitored the survival of the strains JS and LC705 during the GI transit and their effect on gut wellbeing properties measured as relief of constipation. In addition, safety parameters such as side effects and some peripheral immune parameters were assessed. Separately, the combination of P. freudenreichii ssp. shermanii JS and Lactobacillus rhamnosus LC705 was evaluated from the technological point of view as a bioprotective culture in fermented foods and wheat bread applications. In this study, the role ofP. freudenreichii ssp. shermanii JS as a candidate probiotic culture alone and in a combination with L. rhamnosus LC705 was demonstrated. Both strains were transiently recovered in high numbers in fecal samples of healthy adults during the consumption period. The good survival through the GI transit was proven for both strains with a recovery rate from 70 to 80% for the JS strain and from 40 to 60% for the LC705 strain from the daily dose of 10 log10 CFU. The good survival was shown from the consumption of fruit juices which do not provide similar matrix protection for the cells as milk based products. The strain JS did not pose

Aplicação de ciclodextrinas em processos têxteis

Cyclodextrins (CDs) are water soluble cyclic sugars with a hydrophobic nanometric cavity that permits the formation of host/guest inclusion complexes with a large variety of molecules, alternating their physical-chemical properties. In the present review CD research related to the processing of textiles is revised and discussed. CDs may function as encapsulating, dispersing and levelling agents in the dyeing and washing of textiles. Furthermore they may be anchored to polymers and textile fibers in order to impart special properties such as odor reduction, UV protection or for the controlled release of perfumes, aromas, mosquito repellents or substances with therapeutical effects.