ALBERT

Description: Hexagonal boron nitride (BN) was synthesized through the carbothermic reduction reaction (CRR) of boric acid by using lactose as a carbon source under the nitrogen atmosphere at 1500  o  C for 3 h. The boron/carbon (B/C) molar ratio was controlled during the CRR, and the produced samples were investigated by XRD diffraction pattern, FTIR analysis, and Raman spectra. Boron carbide (B 4 C) was formed in samples that have a higher carbon content, in addition to boron nitride. While boron nitride pure sample was produced from lower carbon content samples. Formation of B 4 C was found to depend on the B/C molar ratio. The morphology of the produced powder was also investigated by SEM and TEM, which revealed that the samples consist of nanoneedles of BN and hexagonal particles of B 4 C. The vapor-solid (VS) reaction mechanism was processed greatly with increasing boron amount, producing boron nitride nanoneedles, which compete with the liquid-solid (LS) reaction mechanism. The physicochemical properties of the produced samples were studied by DTA, UV, PL and AC impedance measurements, and revealed that the samples are promising to many proper applications. This article is protected by copyright. All rights reserved

Description: Large wild ungulates are a major biotic factor shaping plant communities. They influence species abundance and occurrence directly by herbivory and plant dispersal, or indirectly by modifying plant-plant interactions and through soil disturbance. In forest ecosystems, researchers’ attention has been mainly focused on deer overabundance. Far less is known about the effects on understory plant dynamics and diversity of wild ungulates where their abundance is maintained at lower levels to mitigate impacts on tree regeneration. We used vegetation data collected over ten years on 82 pairs of exclosure (excluding ungulates) and control plots located in a nation-wide forest monitoring network (Renecofor). We report the effects of ungulate exclusion on (i) plant species richness and ecological characteristics, (ii) and cover percentage of herbaceous and shrub layers. We also analysed the response of these variables along gradients of ungulate abundance, based on hunting statistics, for wild boar ( Sus scrofa ) , red deer ( Cervus elaphus ) and roe deer ( Capreolus capreolus ). Outside the exclosures, forest ungulates maintained a higher species richness in the herbaceous layer (+15%), while the shrub layer was 17% less rich, and the plant communities became more light-demanding. Inside the exclosures, shrub cover increased, often to the benefit of bramble ( Rubus fruticosus agg.). Ungulates tend to favour ruderal, hemerobic, epizoochorous and non-forest species. Among plots, the magnitude of vegetation changes was proportional to deer abundance. We conclude that ungulates, through the control of the shrub layer, indirectly increase herbaceous plant species richness by increasing light reaching the ground. However, this increase is detrimental to forest-specialist species, and contributes to a landscape-level biotic homogenisation. Even at population density levels considered to be harmless for overall plant species richness, ungulates remain a conservation issue for plant community composition. This article is protected by copyright. All rights reserved.

Description: Background Dentin hypersensitivity is an important clinical problem affecting a large percentage of the population, and various therapies have been suggested for its treatment—among them desensitizing agents and lasers. The aim of this study was to evaluate the in vitro effects of different in-office desensitizing agents and different type lasers, alone or in combination, on human dentinal tubules. Materials and Methods Eighty-four dentinal specimens obtained from freshly extracted impacted third molars were included and subsequently divided into seven groups: Group 1 (Control), Group 2 (Gluma desensitizer), Group 3 (Teethmate desensitizer), Group 4 (Nd:YAG laser), Group 5 (Er:YAG laser), Group 6 (Gluma desensitizer + Er:YAG laser), and Group 7 (Teethmate desensitizer + Er:YAG laser). The dentinal specimens of all groups were evaluated using SEM. A total of 12 images per sample were taken, and the numbers of open, partially occluded, and totally visible (open + partially occluded) dentinal tubules were counted. AFM was used to further substantiate the blocking mechanism. The data were analyzed by one-way ANOVA and Dunnett-C tests. Results Comparison of the number of occluded dentinal tubules per 100 µm 2 revealed that the laser and laser combined-treated groups showed the most occluded dentinal tubules. Gluma desensitizer + Er:YAG laser combination demonstrated significantly more tubule occlusion than all the other groups ( p  〈 .05). Conclusions The results of this study show that combined treatment methods were effective in the occlusion of dentinal tubules.

Description: A realistic simulation of the Atlantic Multidecadal Variability (AMV) and related teleconnections is essential to resolve and understand the potential predictability over Europe at decadal time-scale. Based on a large ensemble of state-of-the-art climate models, we show that a considerable inter-model spread exists in the spatio-temporal properties of the simulated AMV and teleconnections with European summer temperature. The greater the persistence, variance and basin-scale spatial coherence, the stronger the teleconnection. We demonstrate that only a few members of a few models produce a teleconnection that is consistent with observational estimates over the instrumental period. This highlights the possible extreme nature of the last century teleconnection and/or a detrimental underestimation of ocean-land teleconnectivity in many climate models. Yet, we emphasize the considerable uncertainties due to methods used to disentangle internal and externally forced variations in observations, and to sampling, which must be correctly accounted when analyses are performed on short temporal records.

Description: ABSTRACT The climate of Morocco is characterized by a strong spatial and inter-annual variability. This study provides an evaluation of high-resolution regional climate model (RCM) simulations of precipitation and temperature over Morocco and future projections based on two emission scenarios. The evaluation of the RCM ensemble over the historical period is performed with a network of 20 weather stations, using Taylor and Portrait diagrams. The results show that the four simulations considered (CLM, CNRM, KNMI and IPSL) are generally able to simulate climate indices and no model is performing significantly better. This ensemble of RCM simulations captures the precipitation and temperature spatiotemporal patterns in the evaluation and historical runs. Climate change scenarios are presented with the goal to identify spatial patterns of change over Morocco, to provide information for climate policy and adaptation. The RCP4.5 and RCP8.5 emission scenarios are considered for two time horizons, 2036–2065 and 2066–2095. A large increase in temperature is observed by the end of the century in particular for the RCP8.5 scenario over the Southeast regions. The minimum temperature is expected to increase more than maximum temperature in most parts of Morocco, with the exception of the Eastern regions. The different RCMs show a strong agreement towards similar changes for most temperature-based indices. The climate change signal is less homogeneous in the different simulations for most of the precipitation indices. Nevertheless, there is a clear decrease of precipitation totals in the different simulations, following a north to south gradient. However, for heavy rainfall events, there are strong uncertainties in projections and the four RCM simulations disagree about the future changes. Study area and geographical locations of the 20 SYNOP weather stations used in the study and the gauge-based spatial distribution of annual precipitation during the 1981–2010 period. (Source: Maroc-Météo.)

Description: The recycling process toward the elimination of varistor wastes into new electro-active silicon composites has been investigated. We studied the dependence of the E - J characteristics on the aggregate content in the polymer matrix. Formulations with 40 vol.% metal oxide varistor aggregates in the 100-200 μm range exhibit reliable nonlinear behavior with a switching voltage of 280±30 V/mm. The breakdown voltage of the composite decreases as both filler's diameter and filler's volume fraction increases in the 550-220 V/mm and 440-280 V/mm range, respectively. This paves the way for the valorization of varistors based zinc oxide (ZnO) ceramics.

Description: Symbiosis with micro-algae (photosymbiosis) is a common feature among marine planktonic protists, but very little is known about the physiology and ecological significance of these associations. High concentrations of dimethylsulfoniopropionate (DMSP), a metabolite produced by marine microalgae, are commonly observed in coral-microalgae symbiosis, where DMS(P) is involved in multiple physiological functions. Knowledge on concentration and role of DMSP in analogous photosymbiosis in plankton is lacking. Here, we assess the total DMSP (DMSPt = DMSP + DMS) concentration and natural stable isotopes of sulfur across ecologically relevant symbiotic plankton groups, the Radiolaria and Foraminifera. We found that intracellular DMSPt concentrations in microalgal symbionts were among the highest recorded (range = 170–702 mmol L −1 ), while lower concentrations (range = 0.1–23 mmol L −1 ) were characteristic of the holobiont (i.e., host-microalgae). The contribution of symbiotic Radiolaria to the water column particulate DMSPt concentration ranged 0.1–8%. Sulfur isotopic composition ( 34 S) of DMSPt in the Collodaria holobionts was significantly higher than their symbiotic microalgae isolated in culture. Despite their high intracellular DMSPt content, uptake in these holobionts throughout 3-d incubations was not detected. We observed a systematic 34 S depletion (∼ 1.5‰) of DMS relative to DMSP in experimental incubations containing filtered seawater, which we hypothesize is related to the bacterial preference for the uptake of 34 S-depleted DMS. Overall, the results indicate that plankton symbiosis can, at times, represent a potentially important source of DMS(P). Specific differences in 34 S provided new insights into sulfur isotopic fractionation associated with DMS(P) biotransformation processes, with potential implications for current interpretations of isotopically tracked biogenic sources of marine aerosols.