Selective Behaviour of Honeybees in Acquiring European Propolis Plant Precursors

Honey bees harvest resins from various plant species and use them in the hive as propolis. While there have been a number of studies concerning the chemical composition of this antimicrobial product, little is known about selective behavior and bee preference when different potential plant sources of resin are available. The main objective of this paper was to investigate some aspects of behavioral patterns of honeybees in the context of resin acquisition. Samples of propolis originating from temperate zones of Europe and the supposed botanical precursors of the product were analyzed. Taxonomical markers of bud resins of two white birch species, aspen, black poplar, horse-chestnut, black alder, and Scots pine were determined through GC-MS analysis. All these trees have been reported as sources of propolis, but comparisons of the chemical composition of their bud resins with the compositions of propolis samples from seven European countries have demonstrated the presence of taxonomical markers only from black poplar, aspen, and one species of birch. This suggests selective behavior during the collection of bud resins by honeybees. To examine the causes of such selectivity, the antimicrobial properties of bud resins were determined. Horse-chestnut resins had lower antimicrobial activity than the other resins which did not differ significantly.     

Ultrastructure of oocytes of the Urostreptus atrobrunneus (Diplopoda,Spirostreptida, Spirostreptidae): A potential urban centers plague

The knowledge of the process of egg formation is indispensable for understanding the mechanisms involved in the reproduction of different species. In this context, the objective of this work was to describe the ultrastructure of the oocytes of Urostreptus atrobrunneus (Spirostreptida), a potential plague of urban centers in different locations of São Paulo State. The lack of knowledge about the morphology, physiology, and the reproductive behavior of the species have hindered an effective control of it. The oocytes of U. atrobrunneus presented three development stages: young oocyte or type I; intermediary oocyte or type II; and mature oocyte or type III. During the oocyte development, the cytoplasm become filled with several globules of protein, drops of lipids, and sphaerocrystals, and it was not observed in many organelles in the oocytes with exception of mitochondria, abundant, principally in young oocytes. The vitelline membrane is also deposited in a discontinuous form and the chorion does not present differentiation of layers. The follicular epithelium alters its shape according to the development phase of the oocyte. Part of the vitellus is from exogenous origin and part is endogenous. Before this, only two studies about the ultrastructural analysis of the female germ cells of diplopods were published. Microsc. Res. Tech. © 2012 Wiley Periodicals, Inc.     

Toward Demystifying the Mohs Hardness Scale

Today, the Mohs scale is used profusely throughout educational systems without any persuasive understanding of the fundamental principles. Why one mineral has a scratch hardness over the next culminating in a scale of 1 (chalk) to 10 (diamond) has no atomistic or structure‐sensitive basis that explains this outcome. With modern computationally based atomistic and multiscale models, there is increasing promise of defining the pressure and rate‐dependent parameters that will allow a fundamental understanding of the Mohs scale. This study principally addresses the combined fracture and plasticity parameters that qualitatively affect fracture at the nanoscale. A physical model wherein the crack tip under a scratch is shielded by dislocations is supported by molecular dynamics (MD) simulations in both ductile aluminum and brittle silicon carbide. Next, this model is applied to nanoindentation data from the literature to produce a ranking of Mohs minerals based on their fundamental properties. As such, what is presented here is a first step to address the flow and fracture parameters ultimately required to provide a figure of merit for scratch hardness and thus the Mohs scale.     

Microstructure and properties of friction stir welded aluminium alloys

Aluminium alloy 7136 belongs to the Al–Zn–Mg–Cu group of aluminium alloys strengthened by precipitation. These alloys offer very good properties, i.e. high strength combined with good corrosion resistance, which makes them suitable for aerospace applications. The limited range of applications of these alloys is due to problems associated with their welding. The Al–Zn–Mg–Cu alloys are classified as non-weldable. The aim of this study was to determine the quality and properties of friction stir welded (FSW) joints of alloy 7136-T76. This article presents the results of a detailed study into the microstructure and mechanical properties of FSW welds. The paper demonstrates that the FSW method is suitable for joining Al–Zn–Mg–Cu alloys. The FSW joints are of good quality and high mechanical properties. Tests of joints created at various tool rotation speeds have shown that joints of suitable quality, in terms of microstructure and properties, can be obtained for a relatively wide range of process parameters. The tool rotation speeds applied during the welding process did not have a significant influence on the quality of the welds.     

Characterization of Glass Beads Surface Modified with Ionic Surfactants

Knowledge of the wetting characteristic of mineral surfaces is very important in enhancing the efficiency of separation of valuable minerals from gangue using froth flotation or oil agglomeration. In this paper a capillary rise technique was used to characterize the glass beads surface modified with cationic surfactant. The glass microspheres were used as model particles with a spherical shape and smooth surface to eliminate the roughness effect. The value of the contact angle for water was found to be 21.5 for unmodified beads, and 61.8, 89.7, 68.4 for 0.1, 1.0, 10 mg/g_solid of CTAB, and 39.8, 68.6, 87.9 for 0.1, 1.0, 10 mg/g_solid of DDAHCl, respectively. Data revealed that the adsorption of surfactant onto glass beads decreased the value of the electron donor component, γ-, which defines the hydrophobicity of the surface. Also, the property of the surface was investigated by flotation and oil agglomeration experiments. It was observed that particles with low value of contact angle for water and high for 1-bromonaphthalene and low value of γ- were floated with a recovery equal to 91.1 and 83.1% for CTAB and DDAHCl, respectively, and effectively agglomerated. This indicates that the capillary rise method can be successfully used to predict the wetting properties of solid particles in mineral processing.     

Double-Headed Cationic Lipopeptides: An Emerging Class of Antimicrobials

Antimicrobial peptides (AMPs) constitute a promising tool in the development of novel therapeutic agents useful in a wide range of bacterial and fungal infections. Among the modifications improving pharmacokinetic and pharmacodynamic characteristics of natural AMPs, an important role is played by lipidation. This study focuses on the newly designed and synthesized lipopeptides containing multiple Lys residues or their shorter homologues with palmitic acid (C₁₆) attached to the side chain of a residue located in the center of the peptide sequence. The approach resulted in the development of lipopeptides representing a model of surfactants with two polar headgroups. The aim of this study is to explain how variations in the length of the peptide chain or the hydrocarbon side chain of an amino acid residue modified with C₁₆, affect biological functions of lipopeptides, their self-assembling propensity, and their mode of action.     

Influence of copigment derived from Tasmannia pepper leaf on Davidson's plum anthocyanins

Davidson's plum (Davidsonia pruriens, F. Muell.), a native to Australian rainforests, large, crimson-red fruit, which superficially resembles plum, has been commercially cultivated in Australia since 1990s. The current production volume exceeds market demands therefore this study was designed to evaluate the suitability of Davidson's plum extract as a source of anthocyanin-based food colorant. The stability of the Davidson's plum extract towards heat treatment at 95 °C was higher than that of commercial mulberry colorant, but inferior to colorants derived from red cabbage and purple sweetpotato. An addition of a variety of phenolic acids significantly increased color intensity indicating the formation of copigmentation complexes. Commercial chlorogenic acid as well as extract from a native Australian herb rich in chlorogenic acid, Tasmannia pepper leaf (Tasmannia lanceolata, R. Br.), were both tested in model soft drink solutions subjected to light irradiation and heat treatment. In both cases, the addition of the copigment resulted in a lasting increase in color intensity. In conclusion, Davidson's plum extract can successfully be utilized as a source of natural food color. Extract from Tasmania pepper leaf can be used as a co-pigment for Davidson's plum anthocyanins. PRACTICAL APPLICATION: The color properties of an anthocyanin colorant derived from the native Australian fruit Davidson's plum are comparable to those of mulberry, which is currently applied as a food colorant in Australian food products. Utilization of Davidson's plum fruit as a source of natural color will allow the industry to increase the range of natural pigments and will create new opportunities for the emerging native food industry.     

Fly ash as a sorbent for boron removal from aqueous solutions: Equilibrium and thermodynamic studies

ABSTRACT

This study presents the application of fly ash from brown coal and biomass burning power plant as a sorbent for the removal of boron ions from an aqueous solution. The adsorption process efficiency depended on the parameters, such as adsorbent dosage, pH, temperature, agitation time and initial boron concentration. The experimental data fitted well with the Freundlich isotherm model and the maximum capacity was found to be 16.14 mg g^?1. The adsorption kinetics followed the pseudo-second-order model. Also, the intra-particle diffusion model parameters were calculated. Thermodynamic parameters such as change in free energy (ΔG°), enthalpy (ΔH°), entropy (ΔS°) revealed on exothermic nature of boron adsorption onto the fly ash.     

The WWOX/HIF1A Axis Downregulation Alters Glucose Metabolism and Predispose to Metabolic Disorders

Recent reports indicate that the hypoxia-induced factor (HIF1α) and the Warburg effect play an initiating role in glucotoxicity, which underlies disorders in metabolic diseases. WWOX has been identified as a HIF1α regulator. WWOX downregulation leads to an increased expression of HIF1α target genes encoding glucose transporters and glycolysis’ enzymes. It has been proven in the normoglycemic mice cells and in gestational diabetes patients. The aim of the study was to determine WWOX’s role in glucose metabolism regulation in hyperglycemia and hypoxia to confirm its importance in the development of metabolic disorders. For this purpose, the WWOX gene was silenced in human normal fibroblasts, and then cells were cultured under different sugar and oxygen levels. Thereafter, it was investigated how WWOX silencing alters the genes and proteins expression profile of glucose transporters and glycolysis pathway enzymes, and their activity. In normoxia normoglycemia, higher glycolysis genes expression, their activity, and the lactate concentration were observed in WWOX KO fibroblasts in comparison to control cells. In normoxia hyperglycemia, it was observed a decrease of insulin-dependent glucose uptake and a further increase of lactate. It likely intensifies hyperglycemia condition, which deepen the glucose toxic effect. Then, in hypoxia hyperglycemia, WWOX KO caused weaker glucose uptake and elevated lactate production. In conclusion, the WWOX/HIF1A axis downregulation alters glucose metabolism and probably predispose to metabolic disorders.