Advanced Stage Of Degradation Research Articles

A new concept for the ecotoxicological assessment of plastics under consideration of aging processes

AbstractMicroplastics are widely distributed in aquatic and terrestrial environments, but up to now less is known about (eco)toxicological impacts under realistic conditions. Research so far has focused mainly on impacts on organisms by fresh, single‐origin plastic fragments or beads. However, plastics found in the environment are complex in composition, this means different polymer types and sources, with and without additives and in all stages of age, and therefore, in a more or less advanced stage of degradation. For oxidized degradation products that might be released from plastic materials during aging, there is a lack of information on potentially adverse effects on aquatic biota. The latter is of particular interest as oxidized degradation products might become more water soluble due to higher polarity and are more bioavailable, therefore. The present study focused on plastic leachates of polystyrene (PS) and polylactic acid (PLA), which were derived from alternating stress by hydrolysis and ultraviolet (UV) radiation—representing a realistic scenario in the environment. Test specimens of PS, PLA, or a PLA/PS layer (each 50%) were alternately exposed to UV radiation for 5 days followed by hydrolysis for 2 days, for several weeks alternating. Ecotoxicological effects of the storage water (artificial freshwater) of the test specimens and additionally, in a second experimental setup, the effects of five potential polymer degradation products were detected by 72 h algae growth inhibition tests with Desmodesmus subspicatus. Results clearly indicate inhibitory effects on algae growth by contaminants in the storage water of stressed plastics with increasing growth inhibition of proceeding hydrolysis and UV stress times. Different polymers caused variable inhibitions of algae growth with stronger inhibitions by PS and less effects by PLA and the mixed layer of both. Moreover, not microplastic particles but the resulting dissolved degradation products after aging caused the ecotoxicological effects—with strong effects by the oxidized degradation products. The existing data highlight the relevance of plastic aging as a framework for microplastic ecotoxicity evaluation and allow a proof of concept.

Relationship between failure strain, molecular weight, and chain extensibility in biodegradable polymers

Prior to degradation, biocompatible polymers exhibit ductile behaviour and yield stress offers a suitable design approach. However, as degradation proceeds the material transitions to a brittle failure mode, suggesting a more conservative design approach is necessary. Here, we predict the evolving ductility of biodegrading polymers, concentrating on the relationship between molecular weight and failure strain, εf, in poly (lactic acid). Several datasets are chosen from literature to explore the relationship, with an overview of the experimental techniques provided. Failure criteria are proposed and examined alongside these datasets: the first assumes εf is related to the finite chain extensibility of an average chain; the second introduces an exponential empirical trend; the third proposes a modified extensibility criterion (based on the first criterion) that considers the entire molecular weight distribution; and the fourth offers an alternative to the third by considering the effect of chain scissions. Combining the failure criteria with a previously introduced time-dependent kinetic scission model provides results as a function of degradation duration. The predictions obtained can offer insight into material failure, particularly at advanced stages of degradation.

Tantalum Oxide Coating of Ni-rich Cathode Active Material via Atomic Layer Deposition and its Influence on Gas Evolution and Electrochemical Performance in the Early and Advanced Stages of Degradation

Detrimental side-reactions of Ni-rich cathode active materials (CAMs) with the electrolyte have historically impeded the extension of the utilized voltage window to higher upper cut-off voltages. Doping and coating approaches are studied widely to further improve these materials and to reduce the intensity of bulk and surface degradation but suffer from poor control of film thickness and homogeneity, leading to partial doping of the bulk. We herein report the singular effect of a tantalum oxide (Ta2O5) thin film on Li[Ni0.8Mn0.1Co0.1]O2 (NMC811), generated by atomic layer deposition, offering the possibility of a high-level homogeneity and thickness control. After chemical analysis using X-ray photoelectron spectroscopy the composition of the deposited thin film is identified as a lithium tantalate chemistry (LiTaO3). At an early degradation stage, clear improvements directly attributed to the coating, such as suppressed exothermic side-reactions (−51%), reduced released gas amounts (−14.8%) and less charge-transfer resistance growth (2× lower) are observed. However, at an advanced degradation stage, the materials show similar cycle life, as well as similar gassing behavior and an even higher charge-transfer resistance growth as compared to the uncoated material. This study highlights the necessity of bulk stabilization and identifies the effect of surface coatings on undoped NMC811 without any doping influence.

A Hybrid Model-Based Approach on Prognostics for Railway HVAC

Prognostics and health management (PHM) of systems usually depends on appropriate prior knowledge and sufficient condition monitoring (CM) data on critical components’ degradation process to appropriately estimate the remaining useful life (RUL). A failure of complex or critical systems such as heating, ventilation, and air conditioning (HVAC) systems installed in a passenger train carriage may adversely affect people or the environment. Critical systems must meet restrictive regulations and standards, and this usually results in an early replacement of components. Therefore, the CM datasets lack data on advanced stages of degradation, and this has a significant impact on developing robust diagnostics and prognostics processes. This paper proposes a methodology for implementing a hybrid model-based approach (HyMA) to overcome the limited representativeness of the training dataset for developing a prognostic model. The proposed methodology is evaluated building an HyMA which fuses information from a physics-based model with a deep learning algorithm to implement a prognostics process for a complex and critical system. The physics-based model of the HVAC system is used to generate run-to-failure data. This model is built and validated using information and data on the real asset; the failures are modelled according to expert knowledge and an experimental test to evaluate the behaviour of the HVAC system while working, with the air filter at different levels of degradation. In addition to using the sensors located in the real system, we model virtual sensors to observe parameters related to system components’ health. The run-to-failure datasets generated are normalized and directly used as inputs to a deep convolutional neural network (CNN) for RUL estimation. The effectiveness of the proposed methodology and approach is evaluated on datasets containing the air filter’s run-to-failure data. The experimental results show remarkable accuracy in the RUL estimation, thereby suggesting the proposed HyMA and methodology offer a promising approach for PHM.

Surgical face masks as a source of emergent pollutants in aquatic systems: Analysis of their degradation product effects in Danio rerio through RNA-Seq.

Surgical face masks are the most popularised and effective personal equipment for protecting public health during the COVID-19 pandemic. They are composed of plastic polymer fibres with a large amount of inorganic and organic compounds that can be released into aquatic environments through degradation processes. This source of microplastics and inorganic and organic substances could potentially impact aquatic organisms. In this study, the toxicogenomic effects of face masks at different stages of degradation in water were analysed in zebrafish larvae (Danio rerio) through RNA-Seq. Larvae were exposed for 10 days to three treatments: 1) face mask fragments in an initial stage of degradation (poorly degraded masks -PDM- products) with the corresponding water; 2) face mask fragments in an advanced stage of degradation (highly degraded masks -HDM- products) with the corresponding water; and 3) water derived from HDM (W-HDM). Transcriptome analyses revealed that the three treatments provoked the down-regulation of genes related to reproduction, especially the HDM products, suggesting that degradation products derived from face masks could act as endocrine disruptors. The affected genes are involved in different steps of reproduction, including gametogenesis, sperm-egg recognition and binding or fertilisation. Immune-related genes and metabolic processes were also differentially affected by the treatments.

Are Chemical Properties of the Soil Influenced by Cover Crops in the Cerrado/Caatinga Ecotone?

ABSTRACT In Brazil, light-textured soils cover approximately 8% of the national territory. The present study assesses the effect of using cover crops, in monoculture or intercropping, and soil management systems, in different layers, on soil chemical properties in the Cerrado/Caatinga ecotone, Brazil. The study was carried out in the southwest region of Piauí State, Brazil, in an area of Andropogon grass (Andropogon gayanus Kunth) in an advanced stage of degradation. The experiment comprised cover plants in monoculture or intercropping. Cover crops improve the following soil chemical properties: pH (+15.94%), calcium (+93.54%), magnesium (+34.17%), sum of bases (+88.30%), base saturation (+198.52%), potassium (+7,767.90%), phosphorus (+673.86%), extractable aluminum (−52.67%), potential acidity (−9.15%), and aluminum saturation (−66.16%). However, soil organic matter content and cation exchange capacity decrease by 42.54% and 35.27%, respectively, in comparison to the values before the experiment. Intercroppings Urochloa brizantha + Oryza sativa and Crotalaria paulina + Zea mays have the potential to improve soil chemical properties in the medium and long term.

Fault Detection and RUL Estimation for Railway HVAC Systems Using a Hybrid Model-Based Approach

Heating, ventilation, and air conditioning (HVAC) systems installed in a passenger train carriage are critical systems, whose failures can affect people or the environment. This, together with restrictive regulations, results in the replacement of critical components in initial stages of degradation, as well as a lack of data on advanced stages of degradation. This paper proposes a hybrid model-based approach (HyMA) to overcome the lack of failure data on a HVAC system installed in a passenger train carriage. The proposed HyMA combines physics-based models with data-driven models to deploy diagnostic and prognostic processes for a complex and critical system. The physics-based model generates data on healthy and faulty working conditions; the faults are generated in different levels of degradation and can appear individually or together. A fusion of synthetic data and measured data is used to train, validate, and test the proposed hybrid model (HyM) for fault detection and diagnostics (FDD) of the HVAC system. The model obtains an accuracy of 92.60%. In addition, the physics-based model generates run-to-failure data for the HVAC air filter to develop a remaining useful life (RUL) prediction model, the RUL estimations performed obtained an accuracy in the range of 95.21–97.80% Both models obtain a remarkable accuracy. The development presented will result in a tool which provides relevant information on the health state of the HVAC system, extends its useful life, reduces its life cycle cost, and improves its reliability and availability; thus enhancing the sustainability of the system.

Subgenome evolution in allotetraploid plants.

SUMMARYPolyploidization is a well‐known speciation and adaptation mechanism. Traces of former polyploidization events were discovered within many genomes, and especially in plants. Allopolyploidization by interspecific hybridization between two species is common. Among hybrid plants, many are domesticated species of agricultural interest and many of their genomes and of their presumptive parents have been sequenced. Hybrid genomes remain challenging to analyse because of the presence of multiple subgenomes. The genomes of hybrids often undergo rearrangement and degradation over time. Based on 10 hybrid plant genomes from six different genera, with hybridization dating from 10,000 to 5 million years ago, we assessed subgenome degradation, subgenomic intermixing and biased subgenome fractionation. The restructuring of hybrid genomes does not proceed proportionally with the age of the hybrid. The oldest hybrids in our data set display completely different fates: whereas the subgenomes of the tobacco plant Nicotiana benthamiana are in an advanced stage of degradation, the subgenomes of quinoa (Chenopodium quinoa) are exceptionally well conserved by structure and sequence. We observed statistically significant biased subgenome fractionation in seven out of 10 hybrids, which had different ages and subgenomic intermixing levels. Hence, we conclude that no correlation exists between biased fractionation and subgenome intermixing. Lastly, domestication may encourage or hinder subgenome intermixing, depending on the evolutionary context. In summary, comparative analysis of hybrid genomes and their presumptive parents allowed us to determine commonalities and differences between their evolutionary fates. In order to facilitate the future analysis of further hybrid genomes, we automated the analysis steps within manticore, which is publicly available at https://github.com/MatteoSchiavinato/manticore.git.

Diagnóstico da degradação ambiental na Vertente Úmida do Maciço de Uruburetama/CE e seu entorno

The various interventions in the Uruburetama Massif have generated a situation of degradation that compromises local economic, social and environmental sustainability. As a way of warning about the worsening of environmental problems, this research aims to make a diagnosis of environmental degradation in the humid hillside of the Uruburetama Massif / CE and its surroundings, in order to assess the impacts generated from human actions. The research methodology consisted of data acquisition, with a bibliographic review, orbital images and vector data obtaining; and carrying out field activities to recognize and identify land use and occupation and its associated impacts. Subsequently, these data and actions supported the characterization and thematic mapping of the research area. From the integration of these data, it was verified that the humid slope of the Uruburetama Massif has an advanced stage of degradation from the urban expansion and agricultural activities. The interventions occur even in the areas of permanent preservation, contrary to the Brazilian Forest Code (12.651 / 2012 Law). The state and municipal public authorities contribute to the degradation situation by making road openings without the necessary care to stabilize the slopes. There is also the absence of legislation (Installment, Zoning and Use and Occupation) that supports the process of monitoring, inspection and control of urban expansion and agricultural activities in some municipalities. Although the municipalities in the study area (Iraucuba, Itapaje, Itapipoca, Pentecoste, Tejucuoca, Trairi, Tururu, Umirim and Uruburetama) have an environmental management body, their actions occur in a deficient manner due to lack of technical, financial and human resources, or because there are conflicts of interest when carrying out their activities integrated with other departments, such as agriculture, water resources, fishing, culture and tourism.

Contribution of ecological restoration in preservation of forests ecosystems in Algeria

Abstract Under the combined effect of anthropogenic pressures and climate change, forest ecosystems can no longer play their ecological and economic role if nothing is done to adapt them. The impacts of fires, overgrazing and overexploitation are that over 60% of forest ecosystems are in an advanced stage of degradation. It is in this context that a new strategy focused on ecological restoration must be quickly put in place. It must be based on ecological alternatives designed to adapt the composition and structure of these plant formations to environmental conditions. The concept of stable species, living space, keystone species, natural attributes and habitat identification. The ecological restoration proposed will allow preserving the vegetal cover at first time and then developing the species with resilience through a list of species that could develop under different pressures, both natural and anthropogenic.

Atributos físicos do solo de florestas urbanas como indicadores de degradação

A falta de planejamento urbano tem levado ao crescimento desordenado das cidades e a problemas sociais e ambientais como: a falta de saneamento básico, a poluição hídrica do ar e do solo, o desmatamento, dentre outros e também à fragmentação dos ecossistemas naturais. Nesse contexto, em áreas urbanas é possível observar um número menor e cada vez mais degradado de fragmentos florestais, sobretudo nas suas bordas, em razão de alteração física dos solos nesses locais, dentre outros fatores de degradação. Diante disso, o presente trabalho teve como objetivo analisar a degradação física do solo nas áreas de borda de dois fragmentos florestais localizados na Bacia Hidrográfica do Ribeirão Anhumas, em Campinas-SP. Para tanto, foram avaliados os índices físicos dos solos, além do Índice de Área Foliar (IAF) e do Índice de Avermelhamento do Solo (IAV). As amostras foram coletadas em pontos equidistantes entre 70 e 80 metros e a 20 metros da borda em cada fragmento de interesse. Com os resultados obtidos, procedeu-se à Análise de Componentes Principais (ACP) a fim de identificar se existem correlações entre os indicadores analisados. As análises físicas do solo indicaram que ambos os remanescentes se encontram em estágio de degradação avançado. Um deles, porém, apresentou resultados com maiores variações em todos os parâmetros físicos analisados. Apesar de não ter sido identificada correlação entre os índices físicos, o IAF e o IAV, os parâmetros são eficientes na análise e identificação da degradação do solo e os resultados contribuem para o estabelecimento de uma proposta de recuperação dessas áreas.

Effect of seasonal variations on the content of some osmolytes of Aleppo pine and holm oak

Abstract The forest of Chettaba is of great ecological importance for the Constantine region. It is characterized by a very heterogeneous forest cover, the dominance of forest species (Pinus halepensis and Quercus ilex) and an advanced stage of degradation. Vegetation in this region reflects the climate. The summer is dry and hot while the winter is rainy and cold. Indeed, the combination of rain and temperature directly influences the physiology of the vegetation in this forest. The main objective of this work is to characterize the different responses of Aleppo pine and holm oak seedlings and to specify the biochemical variations under the seasonal effect. Biochemical assays of proline, soluble sugars, total proteins and chlorophyll were quantified in the different organs of two species for each of the years 2018–2019. The results obtained show very significant accumulation of total soluble sugars and proline in holm oak and Aleppo pine leaves compared to stems and roots during the winter season (520 ± 20 and 370 ± 17.98 µmol/mg DM respectively). Contrary to the previous results, the highest total protein levels were recorded during the summer with levels of 0.666 ± 0.116 and 1,626 ± 0.107 mg/g FM. Parallel to the accumulation of these three solutes, a gradual decrease in the chlorophyll pigment content was recorded in winter and summer.

Steatite/Epoxy Composites for Restoration Works Through a Statistical Mixture Design Methodology

Currently many works of art made of soapstone and recognized as cultural patrimony of humanity are in an advanced stage of degradation. Hence, it is necessary to interrupt this process and recover the deteriorated parts. Composite materials consisted of steatite particles and epoxy polymer are designed and characterised for their application in the repair of sculptures made of soapstone. The material applied in restorations should provide coloration and texture similar to soapstone besides structural requirements. The degree of similarity of the artificial material to the rock is enhanced by the proper selection of the particle size range and the increase of steatite incorporation in the composites. A statistical methodology based on the mixture design is used to optimize the relative amount of three particle size fractions of steatite particles in order to maximise the proportion of the dispersed phase in the composites. The maximum particle packing density (1.50 g/cm³) is obtained for a ternary mixture, composed of 62% of coarse particles (1.18 mm - 0.60 mm), 6% of medium sized particles (0.60 mm - 0.30 mm) and 32% of fine particles (0.30 mm - 0.15 mm). In this manner, the fabrication of composites based on an epoxy polymer matrix with 70wt% of incorporated steatite particles has been possible, increasing the maximum amount by 10% as used in previous works.

CYT B L15601 and H15748 primers for genetic identification of cetacean species

Dolphins and other cetacean are protected species whose capture is illegal in many countries. Despite the high mercury content accumulated by these animals, occasional episodes of illegal fishing occur to supply certain black markets with dolphin meat. When fishing authority inspections detect meat portions presumably of cetacean origin, it is particularly necessary to identify the species before taking the case to court. The mitochondrial cytochrome b gene has been used extensively to identify species. In forensic cases, due to the degradation of the samples, short amplicons are preferable. The universal cyt b L15601 and H15748 primers, previously tested in 63 species, have been used in this work on individuals of seven species of cetaceans: Balaenoptera physalus, Delphinus delphis, Globicephala melas, Phocoena phocoena, Stenella coeruleoalba, Tursiops truncatus and Ziphius cavirostris. These universal primers, with a short amplicon of 148 bp, have the advantage of identifying postmortem samples even when showing obvious signs of degradation. Our results showed that all tested species were correctly identified, except S. coeruleoalba and S. clymene. This is because S. clymene arose by hybrid speciation between S. coeruleoalba and S. longirostris. Therefore, their identification requires the analysis of both mitochondrial DNA and nuclear DNA. In summary, the identification of illegally obtained cetacean meat can be easily performed in forensic laboratories by analyzing a short fragment of the mitochondrial cyt b in all the studied species except in S. coeruleoalba and S. clymene and even when the remains were in an advanced stage of degradation.

Plastome of mycoheterotrophic Burmannia itoana Mak. (Burmanniaceae) exhibits extensive degradation and distinct rearrangements.

Plastomes of heterotrophs went through varying degrees of degradation along with the transition from autotrophic to heterotrophic lifestyle. Here, we identified the plastome of mycoheterotrophic species Burmannia itoana and compared it with those of its reported relatives including three autotrophs and one heterotroph (Thismia tentaculata) in Dioscoreales. B. itoana yields a rampantly degraded plastome reduced in size and gene numbers at the advanced stages of degradation. Its length is 44,463 bp with a quadripartite structure. B. itoana plastome contains 33 tentatively functional genes and six tentative pseudogenes, including several unusually retained genes. These unusual retention suggest that the inverted repeats (IRs) regions and possibility of being compensated may prolong retention of genes in plastome at the advanced stage of degradation. Otherwise, six rearrangements including four inversions (Inv1/Inv2/Inv3/Inv4) and two translocations (Trans1/Trans2) were detected in B. itoana plastome vs. its autotrophic relative B. disticha. We speculate that Inv1 may be mediated by recombination of distinct tRNA genes, while Inv2 is likely consequence of extreme gene losses due to the shift to heterotrophic lifestyle. The other four rearrangements involved in IRs and small single copy region may attribute to multiple waves of IRs and overlapping inversions. Our study fills the gap of knowledge about plastomes of heterotroph in Burmannia and provides a new evidence for the convergent degradation patterns of plastomes en route to heterotrophic lifestyle.

Composite materials for the restoration of historical monuments made of soapstone (steatite): a statistical approach

Currently many works of art made of soapstone and recognized as cultural patrimony of humanity are in an advanced stage of degradation. Hence, it is necessary to interrupt this process and recover the deteriorated parts. Composite materials consisted of steatite particles and epoxy polymer are designed and characterised for their application in the repair of sculptures made of soapstone. The material applied in restorations should provide coloration and texture similar to soapstone besides structural requirements. The degree of similarity of the artificial material to the rock is enhanced by the proper selection of the particle size range and the increase of steatite incorporation in the composites. A statistical methodology based on the mixture design is used to optimize the relative amount of three particle size fractions of steatite particles in order to maximise the proportion of the dispersed phase in the composites. The maximum particle packing density (1.50 g/cm³) is obtained for a ternary mixture, composed of 62% of coarse particles (1.18 mm - 0.60 mm), 6% of medium sized particles (0.60 mm - 0.30 mm) and 32% of fine particles (0.30 mm - 0.15 mm). In this manner, the fabrication of composites based on an epoxy polymer matrix with 70wt% of incorporated steatite particles has been possible, increasing the maximum amount by 10% as used in previous works.

Pastures Degradation and the Relation with Pedo-Geomorphological Attributes in Watershed

ABSTRACT The objective of this study was to map the levels of degradation of pastures and its association with chemical properties of the soil and relief. We selected a sub-basin located in the municipality of Vicosa, Minas Gerais, and we mapped the degradations through Ikonos images that were submitted for classification. Soil samples were collected and analyzed chemically; the results were transformed in spatial data using cokriging, based on variables of the digital elevation model. We associated the maps (cokriging) with data from exposure of the hillside, levels of solar radiation and levels of the pastures’ degradation. The pastures were mainly classified in moderate (44%) and very strong (30%) degradation levels. The areas with mild degradation tend to increase when there is a higher sum of bases, cationic exchange capacity and organic matter. The portions facing North and the increase of solar radiation showed more advanced stages of degradation.

New insights into the degradation mechanism of cellulose nitrate in cinematographic films by Raman microscopy

AbstractThe degradation of cellulose nitrate cinematographic films stored inside an aluminum can was studied by infrared spectroscopy and Raman microscopy. Cellulose nitrate image heritage is strongly susceptible to degradation, being a major conservation challenge. Infrared spectroscopy has been the traditional technique in the assessment of the polymer degradation, but new in situ diagnostic tools to monitor the initial stages of degradation are needed. In this work, cellulose nitrate films were produced and irradiated as aging references to understand how chemical changes were observed in Raman spectroscopy. In comparison with infrared spectroscopy, this technique confirmed the mechanisms proposed in the literature and, at advanced stages of degradation, provided new relevant information detecting an intense peak at 1046 cm−1 associated to nitric acid. Comparing these results with the cinematographic films, it was observed that the plasticizers, which identification was more straightforward using Raman microscopy, have contributions in the regions were chemical changes occur, making it difficult to draw conclusions. Nevertheless, nitric acid and silver nitrate peaks were found in Raman spectra confirming the unstable and noxious environment inside de aluminum can and proving that Raman microscopy can be a valuable complementary in situ technique for cellulose nitrate degradation studies.

Compositional aspects of herbaceous litter decomposition in the freshwater marshes of the Florida Everglades

Litter decomposition in wetlands is an important component of ecosystem function in these detrital systems. In oligotrophic wetlands, such as the Florida Everglades, litter decomposition processes are dependent on nutrient availability and litter quality. The aim of this study was to assess the differences and changes in chemical composition of above- and belowground plant tissues at different stages of decomposition, and to compare them to organic matter accumulating in wetland surface soils. To understand the chemical changes occurring during the early stages of litter decomposition in wetlands, short-term subaqueous decomposition patterns of above- and belowground tissues from Cladium jamaicense and Eleocharis cellulosa were investigated at two freshwater marsh sites in the Florida Everglades. The composition of litter at different stages of decomposition was compared to that of the two end-members, namely fresh plant tissues and soil organic matter (SOM), in an effort to assess both the gradual transformation of this organic matter (OM) and the incorporation of above- vs. belowground biomass to wetland soils. The chemical composition of the litter and of surface soils was assessed using solid-state 13C nuclear magnetic resonance spectroscopy. Decomposition indices (alkyl/O-alkyl ratio, Aromaticity index) of Cladium and Eleocharis leaves varied during incubation likely reflecting physical leaching processes followed by a shift to microbial decomposition. Overall, Eleocharis leaves were more labile compared to Cladium leaves. Relative to aboveground litter, the belowground biomass of both species was more resistant to degradation, and roots were more resistant than rhizomes. Compared to the observed early diagenetic transformations of the plant litter, the SOM is at a more advanced stage of degradation, suggesting that the decomposition of litter and belowground biomass prior to its incorporation into wetland soils requires longer degradation times than those applied in this study. Litter decomposition in Everglades’ freshwater marshes is driven by a combination of tissue quality and site characteristics such as hydroperiod and nutrient availability, ultimately leading to the accumulation of peat.

\u03b2-TCP/HA with or without enamel matrix proteins for maxillary sinus floor augmentation: a histomorphometric analysis of human biopsies

BackgroundIt is still unclear whether enamel matrix proteins (EMD) as adjunct to bone grafting enhance bone healing. This study compared histomorphometrically maxillary sinus floor augmentation (MSFA) with β-TCP/HA in combination with or without EMD in humans.MethodsIn ten systemically healthy patients needing bilateral MSFA, one side was randomly treated using β-TCP/HA mixed with EMD (BC + EMD) and the other side using only β-TCP/HA (BC). After 6 months, biopsies were harvested from grafted areas during implant installation, being histologically and histomorphometrically analyzed. Differences between the groups considering new bone formation, soft tissues, and remaining BC were statistically evaluated.ResultsAll patients showed uneventful healing after MSFA, and dental implant installation was possible in all patients after 6 months. Histological analysis showed newly formed bone that was primarily woven in nature; it was organized in thin trabeculae, and it was occasionally in contact with residual bone substitute particles, which appeared in various forms and sizes and in advanced stage of degradation. Mean bone area was 43.4% (CI95 38.9; 47.8) for the BC group and 43.0% (CI95 36.6; 49.5) for the BC + EMD group. Mean soft tissue area was 21.3% (CI95 16.5; 26.2) for BC group and 21.5% (CI95 17.7; 25.3) for BC + EMD group, while the remaining biomaterial was 35.3% (CI95 36.6; 49.5) and 35.5% (CI95 29.6; 41.3) for BC and BC + EMD group, respectively.ConclusionsMSFA with BC resulted in adequate amounts of new bone formation allowing successful implant installation; adding EMD did not have a significant effect.