ToF-SIMS Analysis of Demineralized Dentin Biomodified with Calcium Phosphate and Collagen Crosslinking: Effect on Marginal Adaptation of Class V Adhesive Restorations

This study aimed to assess the effect of biomodification before adhesive procedures on the tooth-restoration interface of class V restorations located in caries-simulated vs. sound dentin, and the quality of dentin surface by time-of-flight secondary ion mass spectrometry (ToF-SIMS). Class V cavities located on cervical dentin were prepared on the buccal surfaces of extracted human molars under the simulation of intratubular fluid flow. Two dentin types, i.e., sound and demineralized by formic-acid, were biomodified with 1% riboflavin and calcium phosphate (CaP) prior to the application of a universal adhesive (Clearfil Universal Bond) in etch and rinse or self-etch mode, and a conventional micro hybrid composite (Clearfil APX). Restorations were subjected to thermo mechanical fatigue test and percentages of continuous margins (% CM) before/after fatigue were compared. Bio modification of dentin surfaces at the molecular level was analyzed by Time-of-Flight Secondary Mass Spectometry (ToF-SIMS). % CM were still significantly higher in tooth-restoration interfaces on sound dentin. Meanwhile, biomodification with riboflavin and CaP had no detrimental effect on adhesion and in carious dentin, it improved the % CM both before and after loading. Etching carious dentin with phosphoric acid provided with the lowest results, leading even to restoration loss. The presence of molecule fragments of riboflavin and CaP were detected by ToF-SIMS, evidencing dentin biomodification. The adhesive interface involving carious dentin could be improved by the use of a collagen crosslinker and CaP prior to adhesive procedures.

A Preliminary Study of Chemical Profiles of Honey, Cerumen, and Propolis of the African Stingless Bee Meliponula ferruginea

Recently, the honey and propolis of stingless bees have been attracting growing attention because of their health-promoting properties. However, studies on these products of African Meliponini are still very scarce. In this preliminary study, we analyzed the chemical composition of honey, two cerumen, and two resin deposits (propolis) samples of Meliponula ferruginea from Tanzania. The honey of M. ferruginea was profiled by NMR and indicated different long-term stability from Apis mellifera European (Bulgarian) honey. It differed significantly in sugar and organic acids content and had a very high amount of the disaccharide trehalulose, known for its bioactivities. We suggested trehalulose to be a potential marker for African stingless bee honey analogously to the recent proposal for Meliponini honey from Asia, South America, and Australia and demonstrated its easy discrimination by 13C NMR. Propolis and cerumen were studied by GC-MS (gas chromatography-mass spectometry). The samples contained mainly terpenoids (di-and triterpenes) but demonstrated qualitative and quantitative differences. This fact was an indication that possibly M. ferruginea has no strict preferences for resins used to construct and protect their nests. The antimicrobial and anti-quorum sensing properties of the two materials were also tested. These first results demonstrated that the honey, cerumen, and propolis of African stingless bees were rich in biologically active substances and deserved further research.

Effect of ultraviolet radiation on the metabolomic profiles of potentially toxic cyanobacteria

ABSTRACT Interactions between climate change and ultraviolet radiation (UVR) have a substantial impact on aquatic ecosystems, especially on photosynthetic organisms. To counteract the damaging effects of UVR, cyanobacteria developed adaptive strategies such as the biosynthesis of secondary metabolites. This study aimed to evaluate the effects of UVR on the metabolomic profiles of potentially toxic cyanobacteria. Twelve strains were irradiated with ultraviolet A and ultraviolet B radiation and parabolic aluminized reflector lamps for 3 days, followed by liquid chromatography–tandem mass spectometry (LC-MS/MS) analysis to assess changes in metabolomic profiles. Matrices were used to generate principal component analysis biplots, and molecular networks were obtained using the Global Natural Products platform. Most strains showed significant changes in their metabolomic profiles after UVR exposure. On average, 7% of MS features were shown to be exclusive to metabolomic profiles before UVR exposure, while 9% were unique to metabolomic profiles after UVR exposure. The identified compounds included aeruginosins, spumigins, cyanopeptolins, microginins, namalides, pseudospumigins, anabaenopeptins, mycosporine-like amino acids, nodularins and microcystins. Data showed that cyanobacteria display broad metabolic plasticity upon UVR exposure, including the synthesis and differential expression of a variety of secondary metabolites. This could result in a competitive advantage, supporting cyanobacterial blooms under various UVR light exposures.

Esterification of Glycerol with Acetic Acid in Bioadditive Triacetin with Fe2O3/Activated Carbon Catalyst

Esterification and transesterification processes for biodiesel production generate glycerol which is possible to be converted into triacetin. It is an actractive bioadditive for increasing octane number of fuel. The production of this bioadditive in a biodiesel plant also increases the revenue as raw material comes from biodiesel process production as by-product.This study examines the effects of catalyst concentration and temperature on triacetin production using glycerol from esterification process and acetic acid at volume ratio of 1:3 as raw materials. An activated charcoal as catalyst is activated with sulfuric acid at concentration of 2% and 3% (w/w). The esterification temperatures are varied at 90 and 100°C and the reaction time is set for 3 hours. The samples are taken frequently at certain interval times of 15, 30, and 60 minutes for chemical analysis using Gas Chromatography Mass Spectometry. It is observed that using 2% and 3% (w/w) of catalysts at 90°C and 60 minutes reaction time converts 41.037% and 57.441% of glycerol respectively.

Sand Ridges on Rocky Coastal Platforms as Markers of Tsunami Impact: A Multi-Disciplinary Analysis along the Ionian Coast of Southern Apulia (Italy)

Along the Ionian coast of Southern Apulia, a sand ridge has been detected at the inner border of a wide, low-elevated rocky platform. A multi-disciplinary analysis was carried out to define the main geomorphological and sedimentological features of this dune-like coastal deposit, to clarify its nature as well as to obtain chronological constraints for its development. The geomorphological survey reveals that the sand ridge is about 40–60 m wide, reaching a maximum elevation of 3.9 m above m.s.l., whereas its thickness can be estimated between 1.0 and 2.8 m. The sand ridge is in some places associated with large-size boulders. Grain size analysis shows that it is made up of poorly sorted coarse-medium sands with a gravelly fraction, without significant sedimentary structures, as confirmed by Ground Penetrating Radar survey. The micro and macro-faunal assemblage sampled in the sand ridge can be related to shallow-water environments with Posidonia oceanica meadows occurring offshore. The development of the studied sand ridge can be ascribed to a tsunami event able to mix up very coarse bioclastic sands placed at submerged platforms, storm beach deposits covering the low-elevated coastal platform in patches, and possibly older tsunami deposits. Accelerator Mass Spectometry radiocarbon age determinations on mollusc shells sampled from the sand ridge span from 929–1168 AD to 1707–1950 AD and cluster around the 18th–19th centuries, suggesting a possible association with a recent tsunami event. Data reported in the Euro-Mediterranean Tsunami Catalogue would indicate as the most likely event that one of the 25th April 1836, produced by a strong earthquake with its epicenter near Rossano village, on the Ionian coast of the Calabria region.