Composites In Different Environments Research Articles

Fabrication and Comparative Properties of Sustainable Epoxy Methacrylate of Bisphenol-C-Jute/Treated Jute- Natural Fibers Sandwich Composites: Part-1

Epoxy methacrylate of bisphenol-C-jute/treated jute and their sandwich composites of white coir, brown coir, wild almond, bamboo, betel nut, and palmyra were prepared by a compression molding technique under 5MPa pressure and at room temperature for three h. The neat sample showed almost double tensile strength than its jute composite, while it is comparable for treated jute. The composites revealed substantially improved flexural strength compared to neat. The neat, jute/treated jute and their sandwich composites indicated good impact strength, pretty good Barcol hardness, and fairly good electric strength. The neat sample showed excellent volume resistivity, while jute/treated jute and their sandwich composites revealed reasonably good volume resistivity. The composites showed high water ingress tendency, excellent hydrolytic stability, and different diffusivity in different environments at 30oC. Water ingress trend was observed the same for all the composites in different environments, and it is H2SO4 > HCl >NaOH >H2O>NaCl. The sandwich composites may find their applications as low-cost housing and insulating materials and also for marine vessels.

Analysis of The Impact of Human-Induced Pollutants on River Microbiology

In recent decades, water quality and contaminant concentrations have been tightly regulated by relevant laws and monitoring. However, detailed microbial composition in different environments and their interactions with human activities has yet to be fully characterized. This paper shows how different environments, including city environments and highways, can affect the properties of water bodies closely associated with them geographically. Two pairs of locations along Schuylkill and Wissahickon River were sampled. Through 16s rRNA metagenomic sequencing and prediction, the taxonomic and gene profile of samples from various locations were elucidated. Through comparative study of these samples, the effect of human activity on the river between the locations were suggested. In the Wissahickon River, metagenome analysis indicates that human-induced pollutants fostered the growth of bacteria that are able to utilize them but suggests no increment of genes’ abundance that resist their damaging effects, such as heavy metals exporting ATPase, and various antibiotic resistance genes. In the Schuylkill River, the analysis indicates that the growth of the aforementioned bacteria is insignificant, and the resistance genes are predicted to decrease in the urban area where it is anticipated to receive more influence from human activities, rendering the result inconclusive. This study is anticipated to become the starting point for future research on microbial populations in water bodies so that the dynamics of how human activities influence river microbiology can be determined more clearly.

The impact of long-term aging in artificial saliva media on resin-based dental composite strength.

Although salivary liquid can degrade constituents in resin-based dental composites in short-term incubations, there is a knowledge gap on how longer-term aging impacts their bulk strength. We address this through extended aging studies with resin-based dental composites in different environments. Two commercial composites (FIL and AEL) were aged aseptically at 37°C in air (A, control), artificial saliva (AS), and esterase enzyme amended AS (EAS). Diametral and pushout strength were measured after periods of 120-180 days. At 120 days, the diametral strength of composites aged in air was 69.9 ± 11.0 and 57.7 ± 3.31 MPa in FIL and AEL, respectively. These were significantly greater compared to composites aged in AS (32.1 ± 7.01 and 46.2 ± 9.38 MPa in FIL and AEL, respectively) or EAS (36.7 ± 8.49 and 43.5 ± 5.51 MPa in FIL and AEL, respectively). In contrast, pushout strength for both composites were smaller in A compared to those aged in AS and EAS, results attributed to AS absorption and polymer expansion. No significant change in either diametral or pushout strength occurred after 120 days. There was no significant difference between aging in AS and EAS, suggesting that esterase did not significantly decrease the bulk material strength to a greater extent than AS under the test conditions. Aqueous diffusivities for the composites ranged from 8.4 to 11 × 10-13 m2 /s, with associated porosities ranging from 0.06% to 0.10%. These results indicate that saturation of a typical dental composite occurs over a time frame of 4-5months, longer than typical aging studies. Together, the results demonstrate the importance of aging time on composite strength.

Connecting environmental and evolutionary microbiology for the development of new agrobiotechnological tools.

Connecting environmental and evolutionary microbiology for the development of new agrobiotechnological tools.

Analysis On The Impact of Human-Induced Pollutants On River Microbiology

In recent decades, water quality and contaminant concentrations have been tightly regulated by relevant laws and monitoring. However, detailed microbial composition in different environments and their interactions with human activities has yet to be fully characterized. This paper shows how different environments, including city environments and highways, can affect the properties of water bodies closely associated with them geographically. Two pairs of locations along Schuylkill and Wissahickon river were sampled. Through 16s rRNA metagenomic diversity sequencing and a functional gene prediction approach, the taxonomic and predicted gene profiles of
 samples from various locations were elucidated. Through comparative study of these samples, the effect of human
 activity on the river between the locations were evaluated. In the Wissahickon river, metagenome analysis
 indicates that human-induced pollutants potentially fostered the growth of bacteria that are able to utilize them, but
 suggests no increment of genes’ abundance that resist their damaging effects, such as heavy metals exporting
 ATPase, and various antibiotic resistance genes. In the Schuylkill river, the analysis indicates that the growth of the
 aforementioned bacteria is insignificant, and the resistance genes were predicted to decrease in the urban area
 where it was anticipated to receive more influence from human activities, rendering the result inconclusive. We
 anticipate that this study will become the starting point for future research on microbial populations in water bodies
 so that the dynamics of how human activities influence river microbiology can be determined more clearly.

Advances of Hydroxyapatite Hybrid Organic Composite Used as Drug or Protein Carriers for Biomedical Applications: A Review

Hydroxyapatite (HA), especially in the form of HA nanoparticles (HANPs), has excellent bioactivity, biodegradability, and osteoconductivity and therefore has been widely used as a template or additives for drug delivery in clinical applications, such as dentistry and orthopedic repair. Due to the atomically anisotropic distribution on the preferred growth of HA crystals, especially the nanoscale rod-/whisker-like morphology, HA can generally be a good candidate for carrying a variety of substances. HA is biocompatible and suitable for medical applications, but most drugs carried by HANPs have an initial burst release. In the adsorption mechanism of HA as a carrier, specific surface area, pore size, and porosity are important factors that mainly affect the adsorption and release amounts. At present, many studies have developed HA as a drug carrier with targeted effect, porous structure, and high porosity. This review mainly discusses the influence of HA structures as a carrier on the adsorption and release of active molecules. It then focuses on the benefits and effects of different types of polymer-HA composites to re-examine the proteins/drugs carry and release behavior and related potential clinical applications. This literature survey can be divided into three main parts: 1. interaction and adsorption mechanism of HA and drugs; 2. advantages and application fields of HA/organic composites; 3. loading and drug release behavior of multifunctional HA composites in different environments. This work also presents the latest development and future prospects of HA as a drug carrier.

Thermal stability of C/Mullite composites in different environments

In the present study, the mechanical properties and microstructure of C/Mullite composites with a PyC-SiC double-layer interfacial coating after annealing were systematically studied to evaluate the evolution of thermal stability in an inert atmosphere and a vacuum. The C/Mullite composites annealed in the inert atmosphere exhibited better thermal stability than those annealed under the vacuum. The main factor for failure of the composites was carbothermal reduction. The activation temperature of carbothermal reduction in composites in the inert atmosphere was ∼100 °C higher than that in the vacuum. Once carbothermal reduction was activated, the microstructure of composites was destroyed, resulting in a significant weight loss and mechanical property degeneration. The degeneration of mechanical properties was unrecoverable.

Genome-scale metabolic modelling when changes in environmental conditions affect biomass composition.

Genome-scale metabolic modeling is an important tool in the study of metabolism by enhancing the collation of knowledge, interpretation of data, and prediction of metabolic capabilities. A frequent assumption in the use of genome-scale models is that the in vivo organism is evolved for optimal growth, where growth is represented by flux through a biomass objective function (BOF). While the specific composition of the BOF is crucial, its formulation is often inherited from similar organisms due to the experimental challenges associated with its proper determination.A cell’s macro-molecular composition is not fixed and it responds to changes in environmental conditions. As a consequence, initiatives for the high-fidelity determination of cellular biomass composition have been launched. Thus, there is a need for a mathematical and computational framework capable of using multiple measurements of cellular biomass composition in different environments. Here, we propose two different computational approaches for directly addressing this challenge: Biomass Trade-off Weighting (BTW) and Higher-dimensional-plane InterPolation (HIP).In lieu of experimental data on biomass composition-variation in response to changing nutrient environment, we assess the properties of BTW and HIP using three hypothetical, yet biologically plausible, BOFs for the Escherichia coli genome-scale metabolic model iML1515. We find that the BTW and HIP formulations have a significant impact on model performance and phenotypes. Furthermore, the BTW method generates larger growth rates in all environments when compared to HIP. Using acetate secretion and the respiratory quotient as proxies for phenotypic changes, we find marked differences between the methods as HIP generates BOFs more similar to a reference BOF than BTW. We conclude that the presented methods constitute a conceptual step in developing genome-scale metabolic modelling approaches capable of addressing the inherent dependence of cellular biomass composition on nutrient environments.

Investigation of Electro-chemical performance of AZ31 Magnesium alloy – CaSiO3 Metal Matrix Composites in different environments

The electrochemical behaviour of AZ31 magnesium alloy as matrix made as metal matrix composites (MMC) by adding the reinforcement with various weight percentages of Calcium Silicate (CaSiO3) powder was investigated under the influence of 3.5 percent Sodium Chloride (NaCl) and Simulated Body Fluid (SBF) environments using electrochemical workstation. After experimentation, the results exhibit that the pure magnesium alloy sample with 0% calcium silicate exhibits the corrosion rate higher value (40.562mmpy) compared to the other samples when 4 % of calcium silicate is added as additive which exhibits the lower corrosion rate (25.510mmpy). Similarly, the polarisation resistance is also calculated for the samples and the average value of polarisation resistance for the pure magnesium sample is 153.813mA and the other for other samples it lies in between 140.5 mA to 185.72mA respectively. By experimentation it concludes that addition of reinforcement with various weight percentages plays a significant role in the reduction of corrosion rate of AZ31 magnesium alloy rather than using it in a pure form.

Impact of environmental conditions on phospholipid fatty acid composition: implications from two contrasting estuaries

Phospholipid (PL) composition has a tremendous influence on the cell integrity and physiological competency. At the same time, plankton PL make important metabolic fuels for higher trophic levels. The goal of this study was to identify environmental control on PL production and their molecular identity of the suspended particles in two different estuaries. We conducted research in subtropical, eutrophic Wenchang River Estuary in China and temperate pristine, mesotrophic Krka River Estuary in Croatia. In agreement with the more abundant phytoplankton, PL concentrations were much higher in the Wenchang River Estuary (30.3–178.2 μg L−1) than in the Krka River Estuary (8.4–18.8 μg L−1). Given that six PL classes investigated (phosphatidylcholine (PC), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidic acid (PA), phosphatidylinositol (PI), and phosphatidylserine (PS)) have different roles in the cell, we expected their different fatty acid composition in different environments. We found small differences in the fatty acid composition of PC, PG, and PI between two estuaries. These results suggest that the essential fatty acid compositions of these PL in estuarine plankton are relatively constant in order to preserve membrane functions and/or cell processes in which they are involved regardless of environmental conditions. In contrast, PE, PA and PS fatty acid composition substantially differed between two estuaries as well as throughout the salinity gradient in each estuary. This suggests the adaptability of plankton to remodel these PL depending on the environmental conditions and the plankton community structure. Good environmental conditions (favorable N/P ratio, temperature) are important for increased PL content (% in POC and total lipids) in estuarine plankton and increased essential polyunsaturated fatty acid content in PL, which is beneficial to higher trophic levels.

“Microplastic communities” in different environments: Differences, links, and role of diversity index in source analysis

Microplastics have been detected in various environments, yet the differences between microplastics in different environments are still largely unknown. Scientists have proposed the concept of the “microplastic cycle,” but the evidence for the movement of microplastics between different environments is still scarce. By screening the literature and extracting information, we obtained microplastic data from 709 sampling sites in freshwater, seawater, freshwater sediment, sea sediment, and soil in China. Based on the similarity between microplastics and biological communities, here we propose the concept of a “microplastic community” and examine the differences, links, and diversity of microplastic communities in different environments. Wilcoxon sign-ranks test, Kruskal-Wallis test, and analysis of similarities (ANOSIM) showed that there were significant differences in abundance, proportion of small microplastics, and community composition (shape, color, and polymer types) of microplastics in different environments. The Mantel test showed that there were significant correlations between microplastic community composition in different environments. Network analysis based on community similarity further confirmed the links between microplastic communities. The distance decay models revealed that the links weakened with the increase of geographic distance, suggesting that sampling sites with closed geographical locations had similar pollution sources and more easily to migrate or exchange microplastics. The microplastic diversity integrated index (MDII) was established based on the diversity of microplastic shape, color, and polymer types, and its indication of the number of microplastic pollution sources was verified by the statistical fitting relationship between the number of industrial pollution sources and MDII. Our study provides new insight into the differences and links between microplastics in different environments, which contributes to the microplastic risk assessment and demonstrates the “microplastic cycle.” The establishment of the microplastic diversity integrated index could be used in source analysis of microplastics.

Biodegradation of polylactide-based composites with an addition of a compatibilizing agent in different environments

Presented work describes the influence of a compatibilizing agent on the degradation process of polylactide-based composites in different environments. Biodegradation of composites, containing polymer matrix in form of polylactide (PLA), nanofillers montmorillonite and Nanofil2 and poly(ε-caprolactone) (PCL) acting as a compatibilizing agent, was carried out for 28 days in lake water, soil and compost. OXI TOP Control analysis as well as the test for the activity of hydrolytic enzymes were performed and revealed that the presence of PCL significantly increases activity of hydrolytic enzymes and oxygen consumption during biodegradation of the studied materials in the above mentioned environments. The influence the PCL has got on the decomposition process was studied during the analysis of thermal properties of the degraded films as well as by means of a scanning electron microscopy, atomic force and epifluorescence microscopy. In summary, the compatibilizing agent accelerates the degradation of polylactide-based composites in all of the examined scenarios. Results of studies constitute a valuable source of knowledge on effective biodegradation process of polylactide-based composites containing a compatibilizing agent as well as the influence of poly(ε-caprolactone) on the decomposition progress of the studied materials.

Combustion of Aluminum‐Metal Fluoride Reactive Composites in Different Environments

AbstractCombustion of two nanocomposite powders comprising equal mass fractions of aluminum and a metal fluoride, BiF3 or CoF2, is characterized experimentally. The powders were prepared by arrested reactive milling; earlier work showed that they are readily ignited upon heating and are insensitive to ignition by electrostatic discharge. Here, powder particles were ignited in air by passing through a focused CO2 laser beam. They were also ignited and burned in oxygen‐starved environments produced in the combustion products of an air‐acetylene and air‐hydrogen flames. Burn times and color temperatures of the particles were measured optically. Combustion products were collected and examined using electron microscopy. Correlations of burn times with particle sizes showed that the composites containing BiF3 burned faster than those containing CoF2. In air, the burn rates of both composite powders exceeded that of pure Al; in the oxygen‐starved environments the burn rates of the prepared composites were comparable to that of Al. The flame temperatures of the CoF2‐containing composite were limited by the Al boiling point while BiF3 containing composites burned at higher temperatures. Combustion mechanisms for the prepared materials are discussed qualitatively.

(Bio)degradable Polymeric Materials for Sustainable Future-Part 2: Degradation Studies of P(3HB-co-4HB)/Cork Composites in Different Environments.

The degree of degradation of pure poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] and its composites with cork incubated under industrial and laboratory composting conditions was investigated. The materials were parallelly incubated in distilled water at 70 °C as a reference experiment (abiotic condition). It was demonstrated that addition of the cork into polyester strongly affects the matrix crystallinity. It influences the composite degradation independently on the degradation environment. Moreover, the addition of the cork increases the thermal stability of the obtained composites; this was related to a smaller reduction in molar mass during processing. This phenomenon also had an influence on the composite degradation process. The obtained results suggest that the addition of cork as a natural filler in various mass ratios to the composites enables products with different life expectancies to be obtained.

Evaluation of the ribosomal DNA internal transcribed spacer (ITS), specifically ITS1 and ITS2, for the analysis of fungal diversity by deep sequencing.

The nuclear ribosomal DNA internal transcribed spacer (ITS) has been widely used to assess the fungal composition in different environments by deep sequencing. To evaluate the ITS in the analysis of fungal diversity, comparisons of the clustering and taxonomy generated by sequencing with different portions of the whole fragment were conducted in this study. For a total of 83,120 full-length ITS sequences obtained from the UNITE database, it was found that, on average, ITS1 varied more than ITS2 within the kingdom Fungi; this variation included length and GC content variations and polymorphisms, with some polymorphisms specific to particular fungal groups. The taxonomic accuracy for ITS was higher than that for ITS1 or ITS2. The commonly used operational taxonomic unit (OTU) for evaluating fungal diversity and richness assigned several species to a single OTU even with clustering at 99.00% sequence similarity. The clustering and taxonomic capacities did not differ between ITS1 and ITS2. However, the OTU commonality between ITS1 and ITS2 was very low. To test this observation further, 219,741 pyrosequencing reads, including 39,840 full-length ITS sequences, were obtained from 10 soil samples and were clustered into OTUs. The pyrosequencing results agreed with the results of the in silico analysis. ITS1 might overestimate the fungal diversity and richness. Analyses using ITS, ITS1 and ITS2 yielded several different taxa, and the taxonomic preferences for ITS and ITS2 were similar. The results demonstrated that ITS2 alone might be a more suitable marker for revealing the operational taxonomic richness and taxonomy specifics of fungal communities when the full-length ITS is not available.

Investigation of Moisture Diffusion Process in Fibre Reinforced Composites in Different Environments at Elevated Temperature of Accelerated Hot Wet Resin Matrix

In this study, three types of Fibre Reinforced Composites; Glassfibre/epoxy, Glassfibre/vinylester and Glassfibre/polyester resin were fabricated using Hand lay-up process and compacted in a Hotpress. The specimens of these three types of laminates were studied for Moisture Diffusion in two different environments of Fresh water and Sea water soaking at elevated temperature of 90°C. The kinetics of the Diffusion process for accelerated hot wet resin matrix was studied by computing the Diffusion factors in Fresh water and Sea water and theoretically evaluated. To assess the accelerating effect of higher temperature tests were conducted at elevated temperature of 90°C.

Comparative Analysis of Low‐Cycle Fatigue Behavior of 2D‐Cf‐PyC/SiC Composites in Different Environments

A carbon fiber‐reinforced silicon carbide matrix composite with pyrolytic carbon interface (Cf‐PyC/SiC) and a protective coating was prepared by isothermal low pressure chemical vapor infiltration. Low‐cycle fatigue behavior of this material system was investigated at high temperatures up to 1800°C in a combustion environment and at room temperature in air, respectively. The combustion environment includes thermal mechanical loading, high temperatures, and oxidizing atmosphere. Low‐cycle fatigue tests were conducted at a maximum stress level of 180 MPa but at various temperatures and fatigue cycles. The residual strength variation of fatigue‐survived samples was due to different damage mechanisms in different environments.

Biodegradation paths of Mater‐Bi®/kenaf biodegradable composites

AbstractComposites obtained from biodegradable polymers and natural–organic fillers are attracting increasing interest, thanks to the environmental advantages they promise. On the other hand, the real biodegradation performance of a biodegradable polymer/natural organic filler composite should be assessed by performing specific biodegradation tests. These are often carried out under laboratory conditions, but more realistic conditions should be taken into account. In this work, a systematic study on the biodegradation of kenaf fiber‐filled Mater‐Bi® composites in different environments is presented, and some interesting parameters for the understanding of the optimum way to obtain a fast degradation of the composites can be extrapolated. In particular, it was found that the presence of the fibers, the environmental conditions, and the manufacturing procedures of the composites can significantly affect the biodegradation behavior. The results can be used to determine the most suitable disposal environments for biodegradation of Mater‐Bi®‐based wastes. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Acoustic Emission Research on Thermal Shock Behaviors of Three-Dimensional C/SiC Composites in Different Environments

Three-dimensional (3D) carbon fiber reinforced silicon carbide matrix composites (C/SiC) were prepared by a low-pressure chemical vapor infiltration method. The thermal shock behaviors of the composites in different environments were researched using an advanced acoustic emission (AE) system. Damage initiation and propagation were easily detected and evaluated by AE. The thermal shock damage to C/SiC composites mainly occurred at the process of cooling and was limited at argon but unlimited at wet oxygen atmosphere. Also correlations have been established between the different damage mechanisms and the characteristics of acoustic emission signals obtained during thermal shock tests. In this way, the paper contributes to the development of the acoustic emission technique for monitoring of damage development in ceramic-matrix composites.

Environmental durability of banana‐fiber‐reinforced phenol formaldehyde composites

AbstractWe explored the environmental aging behavior of banana‐fiber‐reinforced phenol formaldehyde (PF) composites. The composites were subjected to water aging, thermal aging, soil burial, and outdoor weathering. The effects of chemical modification and hybridization with glass fibers on the degradability of the composites in different environments were analyzed. The extent of degradation was measured by changes in the weight and tensile properties after aging. Absorbed water increased the weight of water‐aged composites, and chemical treatments and hybridization decreased water absorption. The tensile strength and modulus of the banana/PF composites were increased by water aging, whereas the strength and modulus of the glass/PF composites were decreased by water aging. As the glass‐fiber loading was increased in the hybrid composites, the increase in strength by water aging was reduced, and at higher glass‐fiber loadings, a decrease in strength was observed. The tensile properties of the composites were increased by oven aging. The percentage weight loss was higher for soil‐aged samples than for samples weathered outdoors. The weight loss and tensile strength of the glass/PF composites and banana/glass/hybrid/PF composites were much lower than those of the banana/PF composites. Silane treatment, NaOH treatment, and acetylation improved the resistance of the banana/PF composites on outdoor exposure and soil burial. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2521–2531, 2006