Comparative study of dark patinas on granitic outcrops and buildings

Formation of dark patinas on rocky surfaces is mainly related to the deposition of gases and particles and to sulphation mechanisms. In the present study, samples of dark patinas taken from granitic outcrops and from granitic buildings were examined in an attempt to understand the mechanisms of their formation. The outcrops are located in non-polluted areas and are characterized by the absence of any extraneous material that provides calcium, such as e.g. mortar. The buildings are located in areas with low levels of pollution. The climate in the study area favours proliferation of microorganisms. Important differences between the patinas sampled from outcrops and from buildings were observed, as the former are of biological origin and the latter of anthropogenic origin. Although the levels of pollution are low in the sampling area, sulphur was present in all of the samples from urban buildings. Sulphur was not present in patinas from outcrops or in patinas from monuments that are assumed to behave as outcrops (dolmens), although the latter are also of anthropogenic origin. Finally, the patinas were found to be formed by elements accumulated on the surface and not from elements contained within the rock itself.     

Bionanofactories for Green Synthesis of Silver Nanoparticles: Toward Antimicrobial Applications

Among the various types of nanoparticles and their strategy for synthesis, the green synthesis of silver nanoparticles has gained much attention in the biomedical, cellular imaging, cosmetics, drug delivery, food, and agrochemical industries due to their unique physicochemical and biological properties. The green synthesis strategies incorporate the use of plant extracts, living organisms, or biomolecules as bioreducing and biocapping agents, also known as bionanofactories for the synthesis of nanoparticles. The use of green chemistry is ecofriendly, biocompatible, nontoxic, and cost-effective. We shed light on the recent advances in green synthesis and physicochemical properties of green silver nanoparticles by considering the outcomes from recent studies applying SEM, TEM, AFM, UV/Vis spectrophotometry, FTIR, and XRD techniques. Furthermore, we cover the antibacterial, antifungal, and antiparasitic activities of silver nanoparticles.     

Possibility of Mg- and Ca-based intermetallic compounds as new biodegradable implant materials

Mg- or Ca-based intermetallic compounds of Mg₂Ca, Mg₂Si, Ca₂Si and CaMgSi are investigated as possible new candidates for biodegradable implant materials, attempting to improve the degradation behavior compared to Mg and Ca alloys. The reactivity of Ca can be indeed reduced by the formation of compounds with Mg and Si, but its reactivity is still high for applications as an implant material. In contrast, Mg₂Si shows a higher corrosion resistance than conventional Mg alloys while retaining biodegradability. In cytotoxicity tests under the severe condition conducted in this study, both pure Mg and Mg₂Si showed relatively high cytotoxicity on preosteoblast MC3T3-E1. However, the cell viability cultured in the Mg₂Si extract medium was confirmed to be better than that in a pure Mg extract medium in all the conditions investigated with the exception of the 10% extract medium, because of the lower corrosion rate of Mg₂Si. The cytotoxicity derived from the Si ion was not significantly detected in the Mg₂Si extract medium in the concentration level of ~ 70 mg/l measured in the present study. For aiming the practical application of Mg₂Si as an implant material, however, its brittle nature must be improved.     

Superior Alignment of Human iPSC-Osteoblasts Associated with Focal Adhesion Formation Stimulated by Oriented Collagen Scaffold

Human-induced pluripotent stem cells (hiPSCs) can be applied in patient-specific cell therapy to regenerate lost tissue or organ function. Anisotropic control of the structural organization in the newly generated bone matrix is pivotal for functional reconstruction during bone tissue regeneration. Recently, we revealed that hiPSC-derived osteoblasts (hiPSC-Obs) exhibit preferential alignment and organize in highly ordered bone matrices along a bone-mimetic collagen scaffold, indicating their critical role in regulating the unidirectional cellular arrangement, as well as the structural organization of regenerated bone tissue. However, it remains unclear how hiPSCs exhibit the cell properties required for oriented tissue construction. The present study aimed to characterize the properties of hiPSCs-Obs and those of their focal adhesions (FAs), which mediate the structural relationship between cells and the matrix. Our in vitro anisotropic cell culture system revealed the superior adhesion behavior of hiPSC-Obs, which exhibited accelerated cell proliferation and better cell alignment along the collagen axis compared to normal human osteoblasts. Notably, the oriented collagen scaffold stimulated FA formation along the scaffold collagen orientation. This is the first report of the superior cell adhesion behavior of hiPSC-Obs associated with the promotion of FA assembly along an anisotropic scaffold. These findings suggest a promising role for hiPSCs in enabling anisotropic bone microstructural regeneration.     

Monocular hyper‐realistic AR head‐up display

We proposed and developed a novel monocular hyper‐realistic head dome projector for an amusement application and a novel monocular windshield augmented reality projector for augmented reality and head‐up display applications. They use monocular vision that eliminates the depth cues caused by binocular parallax information. Our developed monocular hyper‐realistic head dome projector and windshield augmented reality projector system achieved a high hyper‐reality performance with free depth perception and high visibility.     

Earthworms strongly modify microbial biomass and activity triggering enzymatic activities during vermicomposting independently of the application rates of pig slurry

We studied the relationships between earthworm activity, microbial biomass and the activation and dynamics of several enzyme activities. We carried out an experiment in which low and high rates (1.5 and 3 kg respectively) of pig slurry were applied to small scale reactors with and without earthworms. We found that extracellular enzyme activity increased with rate of pig slurry. In both rates of pig slurry applied, the presence of earthworms in young layers stimulated microbial growth which decreased once earthworms left the slurry and the layers aged. This increase was related to the initial activation of the microbial enzymes studied as correlations between microbial biomass and enzymes showed, which indicated an increase of intracellular enzyme activity. In the aged slurry, the pattern of activity of the four enzymes assayed depended on the rate of pig slurry applied. Thus, in low rate reactors, enzymatic activity through layers appeared to be related to microbial biomass, but in high rate reactors the activity of enzymes was more or less continuous. Further, these differences in overall enzyme activity agree with the variation found in extracellular enzyme activity suggesting certain dependence on substrate availability.     

Chemical composition and origin of black patinas on granite

Black patinas from the surfaces of granite outcrops (including some with engravings) and granite buildings were analysed. Rock samples were also taken from areas of the same surfaces where there were no black patinas. The constituent elements of the granite rocks, elements of essentially biological origin (C, N, H) and other minor elements, including some typical from pollution, were all determined. The ratios between the concentrations of each element in the patinas and in the corresponding rock samples without patina were calculated in order to determine which elements form the patinas. The data were then examined by hierarchical cluster analysis and principal components analysis to establish the factors that determine the differences between samples. It was found that the elements that differentiate the patinas from the samples of rock without patina are those unrelated to granite, which indicates that, at least from a geochemical point of view, the rocky substrate does not affect patina formation. In all patinas analysed, the concentrations of carbon were higher than in the corresponding samples without patina; there were also relatively higher concentrations of sulphur, phosphorus, chlorine, calcium, etc. in some patinas, depending on the situation of the outcrop or monument.     

Reduction of total coliform numbers during vermicomposting is caused by short-term direct effects of earthworms on microorganisms and depends on the dose of application of pig slurry

During vermicomposting of organic waste, the interactions between epigeic earthworms and the detrital microbial community lead to decreases in the abundance of some potentially pathogenic microorganisms. Despite its importance, little is known about the mechanisms involved and the factors that affect the intensity of this effect. In the present study, we carried out three experiments to test the effect of the earthworm Eisenia fetida on total coliform numbers in pig slurry. We firstly applied low and high doses (1.5 and 3 kg, respectively) of pig slurry to small scale vermireactors with and without earthworms. We found that E. fetida significantly reduced total coliform numbers after 2 weeks, but only in the low dose vermireactors. In a subsequent feeding experiment in mesocosms, we observed that the coliform population was reduced by 98% after passage through the earthworms' guts, which suggests that digestive processes in the gut of E. fetida are the main factors involved in the decrease in total coliforms observed in the low dose vermireactors. Decreases in total coliform numbers were not related to decreases in bacterial biomass, which indicates a specific negative effect of earthworms on the coliforms. In the third experiment, we tested the indirect effect of earthworms on total coliforms by inoculating pig slurry with either 2 or 10% vermicompost. The addition of vermicompost did not affect the number of coliforms either after 15, 30 or 60 days, which supports the idea that this bacterial group is more affected by the passage through the gut of E. fetida than by interactions with the earthworm-shaped microbial community.     

Methodological aspects of the induction of biofilms for remediation of the visual impact generated by quartz mining

The opening up of mine faces causes severe alteration to the environment that must be remedied. In the case of quartz mines, the bright white colour of the mineral gives rise to a significant impact that is visible for long distances. New techniques to correct this visual impact, based on the induction of biofilms on the faces, have recently been developed in an attempt to imitate natural effects that mask the impact. Although techniques have been applied successfully in the laboratory, they must be optimized to ensure their success in the field. In the present study, the results of a randomized factorial experiment indicated that although the biofilms adhere to the faces naturally, without the use of adhesives, continued development of the film depends to a large extent on the input of nutrients. Water must also be provided with nutritional supplement to maintain the required level of moisture.     

Changes in bacterial numbers and microbial activity of pig slurry during gut transit of epigeic and anecic earthworms

In soils, organic matter decomposition and stabilization largely occur as a result of microbial activity, although when present, earthworms are important drivers of the processes through their interactions with microflora which begin during organic matter digestion by earthworms. Here, we studied the effects of gut transit on the number of bacteria and the microbial activity in pig slurry, using three epigeic (Eisenia fetida, Eisenia andrei, Eudrilus eugeniae) and one anecic (Octodrilus complanatus) species of earthworm. Bacterial counts revealed that the effect of gut transit on microbes differed depending on the earthworm species. Thus, no changes in the number of bacteria were found in the gut contents of E. fetida and E. eugeniae, whereas large decreases were recorded in those of O. complanatus and E. andrei (2.7 and 1.3 times, respectively). We suggest that, unlike in the three epigeic earthworm species, microorganisms are preferentially utilized by O. complanatus to meet its nutrient requirements, because of its limited digestive capacity. Despite the decrease in bacterial numbers, there were no differences in the gut contents of the four earthworm species or undigested pig slurry in terms of dehydrogenase activity. Therefore, we suggest that after gut transit in the four earthworm species under study the potential microbial degradation of pig slurry remains unaltered.