Crystallized frameworks with giant pores: are there limits to the possible?

In the domain of porous solids with inorganic or hybrid frameworks, the combination of mastered chemistry and of computer simulations pushes forward the limits of the classical approach and allows the full determination from powder diffraction data of architectures with cells of several hundred thousand cubic angstroms with hierarchies of giant pores and unprecedented Langmuir surfaces. The different limits induced by this new approach are analyzed.     

Fire safety improvements in the combustion toxicity area: is there a role for LC50 tests?

It is a well‐known fact that the bulk of fire fatalities can be attributed to the inhalation of toxic combustion gases. This single fact has led regulators in Europe, the US, and other industrialized countries to consider (and in some cases to adopt) requirements for testing of products with various tests for toxic potency, commonly expressed as LC₅₀. The regulators have more recently been joined by the International Organization for Standardization (ISO), which has been developing standards for LC₅₀ and related variables. All of the standards considered so far have been limited to using only bench‐scale test results. Engineers, however, have known for quite some time that the actual toxic effect from combustion gases must be viewed as a product of two factors: (a) the product's real‐scale mass loss rate; and (b) its real‐scale LC₅₀. Thus, two issues can be seen to arise: (1) are real‐scale values of LC₅₀ adequately similar to the bench‐scale ones; and (2) is the range of mass loss rates exhibited by various products small enough so that differences could be ignored and products ranked/rated solely by their LC₅₀ values? This paper examines these questions by the use of a database of experimental results covering a wide range of building products. The analysis shows that far from being the dominant factor in the fire toxicity picture, LC₅₀ is a minor constituent. For real products, LC₅₀ values simply do not vary much. Mass loss rates, however, vary tremendously. Thus, it is demonstrated that the proper strategy for controlling fire toxicity hazard is by reducing the burning rate, not by attempting to make the effluent less toxic. These findings directly indicate that regulations based on controlling the LC₅₀ cannot hope to address the proper concern of reducing fire fatalities. Copyright © 2000 John Wiley & Sons Ltd.     

Ionic liquids: the link to high-temperature molten salts?

Due to their wide thermal windows, ionic liquids can be regarded as the missing link between aqueous/organic solutions and high-temperature molten salts. They can be employed efficiently for the coating of other metals with thin layers of tantalum, aluminum, and presumably many others at reasonable temperatures by electrochemical means. The development of ionic liquids, especially air and water stable ones, has opened the door for the electrodeposition of reactive elements such as, for example, Al, Ta, and Si, which in the past were only accessible using high-temperature molten salts or, in part, organic solvents.     

Aquacultural Effluents: Directive Signals to the System Downstream?

Animals continuously release biogenic substances that vary in composition with physiological state. In aquatic systems, animals can gain insight about conditions or events upstream and alter their physiology and behavior to exploit this information. Here, we review observations on aquatic animals as diverse as snails, shrimp, fish, and frog tadpoles to probe the possibility that high-density aquaculture might generate chemical messages that cause conspecific or related individuals to reduce productive processes (growth, metamorphosis, ecdysis, reproduction) or even to sicken and die (loss of immunocompetence, anaphylaxis). The potential for ecological disruption logically is maximized under conditions that uncouple the parts of the system generating and receiving such signals—as would be the case when aquacultural effluents enter natural aquatic systems.     

Nutritional status of endurance athletes: what is the available information?

Nutritional status is a critical determinant of athletic performance. We question whether currently available studies can give adequate information on nutritional status of endurance athletes. This paper is a critical review of articles published from 1989 to 2003 that investigate nutritional status of endurance athletes. The terms, "nutrition", "diet", or "nutrient", were combined with "endurance athletes" to perform Medline and Pubmed electronic database searches. Two inclusion criteria were considered: (a) study subjects should be adults and (b) articles should report gender-specific values for total energy expenditure and intake of energy, macro and micronutrient from food. Only seven studies fulfilled inclusion criteria. In general, the conclusions of these studies are that endurance athletes have negative energy balance, low intake of carbohydrate, adequate to high intake of protein, and high intake of fat. A critical discussion of the articles' data on vitamins, minerals and trace elements adequacy is conducted using insights and methodology proposed by the newly published assessment and interpretation of Dietary Reference Intakes (DRIs). The studies evaluated give an inappropriate evaluation of the prevalence of adequacy/inadequacy of micronutrient intake among endurance athletes. In this work we indicate potential limitations of existing nutritional data, which reflects the misconceptions found in published literature on nutritional group evaluation. This review stresses the need for a comprehensive and well-conducted nutrition assessment planning to fulfill the existing gap in reliable information about micronutrient adequacy of endurance athletes.     

How effective is the addition of nanoscaled particles to alumina–magnesia refractory castables?

The addition of nanoscaled alumina and magnesia particles to the matrix of alumina–magnesia refractory castables drastically reduces the residual expansion related to the in situ spinel formation. Nonetheless, as their benefits on other relevant properties have not been reported so far, the effectiveness of such nanoengineering design for castables applied in steel ladles is still uncertain. In the present work, not only the expansion level, but also the corrosion resistance, the hot modulus of rupture and the creep deformation of different nanoparticle-containing castables were evaluated and compared with the results attained by refractory materials designed only by micrometric-scaled Al₂O₃ and MgO. Although the addition of a nanoalumina and nanomagnesia mixture ensured the best results regarding to the expansive behavior, thermo-mechanical and thermo-chemical properties, its performance was only slightly superior to the castable containing micrometric alumina and magnesia particles. Therefore, as the cost–benefit ratio is one of the main requirements for the end users, the nanotechnology use in the refractory production must be previously carefully analyzed.     

Proteins Binding to the Carbohydrate HNK-1: Common Origins?

The human natural killer (HNK-1) carbohydrate plays important roles during nervous system development, regeneration after trauma and synaptic plasticity. Four proteins have been identified as receptors for HNK-1: the laminin adhesion molecule, high-mobility group box 1 and 2 (also called amphoterin) and cadherin 2 (also called N-cadherin). Because of HNK-1′s importance, we asked whether additional receptors for HNK-1 exist and whether the four identified proteins share any similarity in their primary structures. A set of 40,000 sequences homologous to the known HNK-1 receptors was selected and used for large-scale sequence alignments and motif searches. Although there are conserved regions and highly conserved sites within each of these protein families, there was no sequence similarity or conserved sequence motifs found to be shared by all families. Since HNK-1 receptors have not been compared regarding binding constants and since it is not known whether the sulfated or non-sulfated part of HKN-1 represents the structurally crucial ligand, the receptors are more heterogeneous in primary structure than anticipated, possibly involving different receptor or ligand regions. We thus conclude that the primary protein structure may not be the sole determinant for a bona fide HNK-1 receptor, rendering receptor structure more complex than originally assumed.     

Ion-doped hydroxyapatite: An impasse or the road to follow?

Doping hydroxyapatite (HAp) with foreign ions has been increasing in popularity as a chemical approach to augment the existing and impart new properties to it. However, it is uncertain whether this approach can elicit properties strong enough to make HAp competitive for commercial applications in biomedicine and elsewhere. In particular, material properties, such as grain size, morphology, surface charge, porosity, topology and others may prove to be more effective in controlling properties of HAp than the dopant choice and concentration. This study tackles this question through a meta-analysis of the dependence of selected materials properties on dopant concentrations reported across the literature, showing that doping is a convenient way of controlling some, but not all properties in HAp and should be implemented ideally in combination with other structural and compositional factors of influence. This meta-analysis is coupled to a bibliographic analysis of the evolution of trends in terms of the type, frequency and concurrency of dopants in HAp, covering the entire Periodic Table, all 72 elements incorporated into HAp so far and the 1990 – 2019 period split into successive lustra. The study demonstrates a continuously ascending trend in popularity of certain elements, such as Sr, Ce and Se, and a continuously declining trend of others in the past two decades, including F, Y, I, Ti and most lanthanides. For the fourth period transition metals a trend of constancy was observed and for yet other elements, including Ag and Mg, a period of ascent was succeeded by a steady decline, the onset of which coincided in the case of Ag with the peak in the airing of the concerns over its cytotoxicity by the scientific community. Reasons for these trends with respect to most elements are explained and connected with trends governing broader realms of materials science. It is shown that the choice of ions as dopants in HAp is largely driven by broader trends in materials science, rendering the doped HAp a mirror to view these existing and past trends in. Theoretically, by following the historic progression of these trends, a gaze in this mirror could assist in extrapolation of future trends, which normally come at the cost extinguishing some of the existing ones. This immersion in more general developments in materials science opened the path toward drawing connections between the bibliographically assessed geopolitical trends in doped HAp and in broader aspects of the scientific community, including the growing gap between the rich and the poor pervading it. The analysis reported here is conceptually novel and could be applied to numerous other materials.     

To Remove or Not to Remove? The Challenge of Extracting the Template to Make the Cavities Available in Molecularly Imprinted Polymers (MIPs)

Template removal is a critical step in the preparation of most molecularly imprinted polymers (MIPs). The polymer network itself and the affinity of the imprinted cavities for the template make its removal hard. If there are remaining template molecules in the MIPs, less cavities will be available for rebinding, which decreases efficiency. Furthermore, if template bleeding occurs during analytical applications, errors will arise. Despite the relevance to the MIPs performance, template removal has received scarce attention and is currently the least cost-effective step of the MIP development. Attempts to reach complete template removal may involve the use of too drastic conditions in conventional extraction techniques, resulting in the damage or the collapse of the imprinted cavities. Advances in the extraction techniques in the last decade may provide optimized tools. The aim of this review is to analyze the available data on the efficiency of diverse extraction techniques for template removal, paying attention not only to the removal yield but also to MIPs performance. Such an analysis is expected to be useful for opening a way to rational approaches for template removal (minimizing the costs of solvents and time) instead of the current trial-and-error methods.     

Male Infertility in the XXI Century: Are Obesogens to Blame?

The permanent exposure to environmental contaminants promoting weight gain (i.e., obesogens) has raised serious health concerns. Evidence suggests that obesogens are one of the leading causes of the marked decline in male fertility and are key players in shaping future health outcomes, not only for those who are directly exposed to them, but also for upcoming generations. It has been hypothesized that obesogens affect male fertility. By using an interdisciplinary strategy, combining in silico, in vitro, in vivo and epidemiological findings, this review aims to contribute to the biological understanding of the molecular transformations induced by obesogens that are the basis of male infertility. Such understanding is shaped by the use of Adverse Outcomes Pathways, a new approach that may shift the paradigm of reproductive toxicology, contributing to the improvement of the diagnosis and management of the adverse effects of obesogens in male fertility.     

Elasticity or viscosity,which one is more influential on the internal structure of a core-shell morphology in ternary blends?

The goal of this research was to study the internal phase structure of core-shell morphology within a ternary blend and look into the affecting parameters. In this way, a series of SEBS/SAN/PA6 ternary blends representing core-shell morphology were prepared and effect of viscosity and elasticity of core-forming component on the phase structure of core droplets were investigated. Studies based on the scanning electron microscopy micrographs demonstrated that elasticity plays a more dominant role on the formation of single or multi-core droplets. In addition, it was inferred that absolute elasticity of core component is more influential rather than elasticity ratio of core and shell components. Furthermore, morphology of prepared samples compared with predictions of DIE and modified DIE conceptual models.     

High-Protein Weight Loss Diets and Purported Adverse Effects: Where is the Evidence?

Results of several recent studies show that high-protein, low-carbohydrate weight loss diets indeed have their benefits. However, agencies such as the American Heart Association (AHA) have some concerns about possible health risks. The purpose of this review is to evaluate the scientific validity of AHA Nutrition Committee's statement on dietary protein and weight reduction (St. Jeor ST et al. Circulation 2001;104:1869–1874), which states: "Individuals who follow these [high-protein] diets are risk for ... potential cardiac, renal, bone, and liver abnormalities overall. Simply stated, there is no scientific evidence whatsoever that high-protein intake has adverse effects on liver function. Relative to renal function, there are no data in the scientific literature demonstrating that healthy kidneys are damaged by the increased demands of protein consumed in quantities 2–3 times above the Recommended Dietary Allowance (RDA). In contrast with the earlier hypothesis that high-protein intake promotes osteoporosis, some epidemiological studies found a positive association between protein intake and bone mineral density. Further, recent studies studies suggest, at least in the short term, that RDA for protein (0.8 g/kg) does not support normal calcium homeostasis. Finally, a negative correlation has been shown between protein intake and systolic and diastolic blood pressures in several epidemiological surveys. In conclusion, there is little if any scientific evidence supporting above mentioned statement. Certainly, such public warnings should be based on a thorough analysis of the scientific literature, not unsubstantiated fears and misrepresentations. For individuals with normal renal function, the risks are minimal and must be balanced against the real and established risk of continued obesity.     

Threat at One End of the Plant: What Travels to Inform the Other Parts?

Adaptation and response to environmental changes require dynamic and fast information distribution within the plant body. If one part of a plant is exposed to stress, attacked by other organisms or exposed to any other kind of threat, the information travels to neighboring organs and even neighboring plants and activates appropriate responses. The information flow is mediated by fast-traveling small metabolites, hormones, proteins/peptides, RNAs or volatiles. Electric and hydraulic waves also participate in signal propagation. The signaling molecules move from one cell to the neighboring cell, via the plasmodesmata, through the apoplast, within the vascular tissue or—as volatiles—through the air. A threat-specific response in a systemic tissue probably requires a combination of different traveling compounds. The propagating signals must travel over long distances and multiple barriers, and the signal intensity declines with increasing distance. This requires permanent amplification processes, feedback loops and cross-talks among the different traveling molecules and probably a short-term memory, to refresh the propagation process. Recent studies show that volatiles activate defense responses in systemic tissues but also play important roles in the maintenance of the propagation of traveling signals within the plant. The distal organs can respond immediately to the systemic signals or memorize the threat information and respond faster and stronger when they are exposed again to the same or even another threat. Transmission and storage of information is accompanied by loss of specificity about the threat that activated the process. I summarize our knowledge about the proposed long-distance traveling compounds and discuss their possible connections.     

Molecular Mechanisms of Bone Metastasis: Which Targets Came from the Bench to the Bedside?

Bone metastases ultimately result from a complex interaction between cancer cells and bone microenvironment. However, prior to the colonization of the bone, cancer cells must succeed through a series of steps that will allow them to detach from the primary tumor, enter into circulation, recognize and adhere to specific endothelium, and overcome dormancy. We now know that as important as the metastatic cascade, tumor cells prime the secondary organ microenvironment prior to their arrival, reflecting the existence of specific metastasis-initiating cells in the primary tumor and circulating osteotropic factors. The deep comprehension of the molecular mechanisms of bone metastases may allow the future development of specific anti-tumoral therapies, but so far the approved and effective therapies for bone metastatic disease are mostly based in bone-targeted agents, like bisphosphonates, denosumab and, for prostate cancer, radium-223. Bisphosphonates and denosumab have proven to be effective in blocking bone resorption and decreasing morbidity; furthermore, in the adjuvant setting, these agents can decrease bone relapse after breast cancer surgery in postmenopausal women. In this review, we will present and discuss some examples of applied knowledge from the bench to the bed side in the field of bone metastasis.