Initial Degradation Research Articles

Development of poly (linear low‐density ethylene)/poly (ethylene‐methyl co‐acrylate) blends with enhanced thermal‐stability and toughening behavior with adding of carbonaceous fillers

AbstractIn this work, polymer blend nanocomposites based on carbon fillers were produced via melt‐compounding in a twin‐screw extruder. A combination of several matrices (LLDPE, EMA, and LLDPE/EMA) and fillers (FLG, FWCNT, and FLG/FWCNT) was used. Thermal enhancement as the consequence of few‐walled carbon nanotube addition, led to significant improvements in the initial degradation temperatures of LLDPE (383.2 > 441.2°C), EMA (371.2 > 417.3°C), and LLDPE/EMA (390.55 > 430.62°C) matrixes, respectively. The evaluation of the dynamic‐mechanical behavior of the compositions showed an increase of 80% in the storage module for LLDPE‐based nanocomposites, a reduction of 30% for blend‐based nanocomposites, and a non‐change for EMA nanocomposites. Tenacity property was considerably improved, achieving a value 78% higher to the LLDPE/EMA blend, mainly due to the possible migration of the nanoparticles from EMA phase to the LLDPE phase, creating a more efficient physical network with well‐developed percolating structure, which facilitates the dissipation of energy during mechanical loading. In summary, it can be observed that the morphology control as well as the nanofillers location, proved to be extremely relevant factors to produce a polymer film with enormous gains in the thermal and mechanical properties.

The effect of multi-directional seismic loading on the behaviour of tunnels in structured clays

Current research extensively relies on two-dimensional (2D) modelling to predict the seismic behaviour of tunnels. However, seismic wave propagation can occur in arbitrary direction with respect to the axis of the structure, leading to multi-directional loading of the soil deposit and the tunnel lining. Using 2D simplifications to represent these three-dimensional (3D) effects can significantly impact the prediction of the tunnel's seismic response. Furthermore, most natural soils typically exhibit high stiffness and peak strength due to their initial structure. During strong earthquakes, such soils may experience significant stiffness degradation which may alter the response of the soil-tunnel system. This behaviour cannot be captured by simple elasto-plastic constitutive models, requiring the need to use advanced constitutive laws which incorporate soil initial structure degradation during dynamic loading. This paper presents novel results from advanced 3D numerical simulations of shallow circular tunnels in natural clays subjected to multi-directional seismic motions while considering soil structure degradation. Notably, the results indicate that soil destructuration facilitates the transmission of higher longitudinal loads in the lining while reducing the transverse forces. Therefore, the work highlights the significance of soil destructuration in accurately predicting the magnitude of tunnel lining forces under arbitrarily-directed seismic loading.

Microbial degradation of biomass of Lyngbya aestuariі (Mertens) liebmann in hyperhaline brine from peloid deposits

Microbial degradation of organic matter of benthic macroscopic growths of Lyngbya aestuariі in brine from peloid deposits on the Arabat and Berdyansk spits was studied through laboratory experiments measuring the biomass of L. aestuarii and the quantity of different physiological groups of destructive microorganisms. The biomass of L. aestuarii was dried, placed in brine-filled flasks, and exposed to different temperatures for 300 days, with the mass loss measured every 30 days. It was found that 1/4 part of biomass decomposes in 8–10 months depending on the temperature regime. Degradation is not uniform and is divided into two phases: in the first (120–150 days) biomass loss does not exceed 2%; in the second stage – the degradation rate increases significantly, causing a decrease in algal biomass over the next 120–150 days for 20–40%. The study estimated the quantity of various destructive microorganisms (their colony-forming units) using different nutrient media: starch agar, meat-peptone agar, and pork lard agar. It was found that the initial degradation of L. aestuarii involves proteolytic and lipolytic bacteria. It is shown that the degradation of L. aestuariі is accompanied by a decrease in the amount of dissolved oxygen. Anaerobic conditions developed starting from the 30th day. The duration of degradation of prokaryotic mats and anaerobic conditions in the brine indicate that these benthic growths can serve as a substrate for microbial transformation and also as a preservative agent that retains the products of organic matter decomposition from oxidation for a long period. Such properties may indicate deposits of high-quality black silty sulfide peloids or they can be used in the production of artificial medical mud with properties that are close to natural ones.

Long-Term Sulfur Tolerance of Solid Oxide Fuel Cells with Alternative Titanate-Based Fuel Electrodes

Currently, solid oxide fuel cell systems rely on upstream desulfurization units to prevent sulfur poisoning of the state-of-the-art anodes based on Ni-cermets. Next-generation anode materials should be sulfur tolerant, without compromising the performance, to reduce system complexity and cost. In this study, all-ceramic La0.4Sr0.4Fe0.03Ni0.03Ti0.94O3 (LSFNT) anodes, infiltrated with Ni:Ce0.8Gd0.2O1.9 (CGO) or FeNi:CGO electrocatalysts, were integrated into large-area electrolyte supported cells. The cells were tested together with a SoA cell with Ni/CGO cermet anode in a short stack configuration using reformed grid natural gas and an upstream, bypassable desulfurization unit. The cell performances before exposure to sulfur were similar for all cell types at 850 °C. Exposure to sulfur revealed different degradation mechanisms. TheSoA cell shows a fast, initial degradation followed by limited further degradation. In contrast, the FeNi:CGO infiltrated LSFNT anode appears sulfur tolerant initially, followed by accelerated degradation of >50% kh-1 over long-term sulfur exposures. The Ni:CGO infiltrated LSFNT anode is remarkably sulfur tolerant.

Performance and Degradation of Electrolyte Supported SOECs with Advanced GDC Thin-film Layers in Long-term Stack Test

Electrolyte supported Solid Oxide Cells (ESCs) with advanced thin-film Gd-doped ceria layers deposited via EB-PVD method at 600 oC were assembled and electrochemically investigated in a so-called “rainbow” stack with 30 repeat units (RUs). At the initial stage of the SOEC operation, the stack reached a high performance with an electrical efficiency of 99.65 % at 75 % steam conversion and a total power input of 1.98 kW. A long-term stack test was performed in SOEC mode for over 5000 h and demonstrated a low voltage degradation of approx. +10.9 mV·kh–1 per RU (+0.9% kh–1). The RUs with EB-PVD GDC thin-films demonstrated similar initial performance and degradation rate to the state-of-the-art cells. In this paper, the investigation mainly focuses on the electrochemical characteristics of RUs containing the EB-PVD thin-film GDC layers.

PcaR, a GntR/FadR Family Transcriptional Repressor Controls the Transcription of Phenazine-1-Carboxylic Acid 1,2-Dioxygenase Gene Cluster in Sphingomonas histidinilytica DS-9.

In our previous study, the phenazine-1-carboxylic acid (PCA) 1,2-dioxygenase gene cluster (pcaA1A2A3A4 cluster) in Sphingomonas histidinilytica DS-9 was identified to be responsible for the conversion of PCA to 1,2-dihydroxyphenazine (Ren Y, Zhang M, Gao S, Zhu Q, et al. 2022. Appl Environ Microbiol 88:e00543-22). However, the regulatory mechanism of the pcaA1A2A3A4 cluster has not been elucidated yet. In this study, the pcaA1A2A3A4 cluster was found to be transcribed as two divergent operons: pcaA3-ORF5205 (named A3-5205 operon) and pcaA1A2-ORF5208-pcaA4-ORF5210 (named A1-5210 operon). The promoter regions of the two operons were overlapped. PcaR acts as a transcriptional repressor of the pcaA1A2A3A4 cluster, and it belongs to GntR/FadR family transcriptional regulator. Gene disruption of pcaR can shorten the lag phase of PCA degradation. The results of electrophoretic mobility shift assay and DNase I footprinting showed that PcaR binds to a 25-bp motif in the ORF5205-pcaA1 intergenic promoter region to regulate the expression of two operons. The 25-bp motif covers the -10 region of the promoter of A3-5205 operon and the -35 region and -10 region of the promoter of A1-5210 operon. The TNGT/ANCNA box within the motif was essential for PcaR binding to the two promoters. PCA acted as an effector of PcaR, preventing it from binding to the promoter region and repressing the transcription of the pcaA1A2A3A4 cluster. In addition, PcaR represses its own transcription, and this repression can be relieved by PCA. This study reveals the regulatory mechanism of PCA degradation in strain DS-9, and the identification of PcaR increases the variety of regulatory model of the GntR/FadR-type regulator. IMPORTANCE Sphingomonas histidinilytica DS-9 is a phenazine-1-carboxylic acid (PCA)-degrading strain. The 1,2-dioxygenase gene cluster (pcaA1A2A3A4 cluster, encoding dioxygenase PcaA1A2, reductase PcaA3, and ferredoxin PcaA4) is responsible for the initial degradation step of PCA and widely distributed in Sphingomonads, but its regulatory mechanism has not been investigated yet. In this study, a GntR/FadR-type transcriptional regulator PcaR repressing the transcription of pcaA1A2A3A4 cluster and pcaR gene was identified and characterized. The binding site of PcaR in ORF5205-pcaA1 intergenic promoter region contains a TNGT/ANCNA box, which is important for the binding. These findings enhance our understanding of the molecular mechanism of PCA degradation.

Operation-induced degradation mechanisms of 275-nm-band AlGaN-based deep-ultraviolet light-emitting diodes fabricated on a sapphire substrate

Degradation mechanisms of 275-nm-band AlxGa1-xN multiple quantum well deep-ultraviolet light-emitting diodes fabricated on a (0001) sapphire substrate were investigated under hard operation conditions with the current of 350 mA and the junction temperature of 105 °C. The optical output power (Po) initially decreased by about 20% within the operating time less than 102 h and then gradually decreased to about 60% by 484 h. For elucidating the causes for the initial and subsequent degradations, complementary electrical, time-resolved photoluminescence (TRPL), and impurity characterizations were carried out making a connection with the energy band profiles. Because the degradation of the wells was less significant than the Po reduction, the initial degradation is attributed essentially to the decrease in carrier injection efficiency (ηinjection), not in internal quantum efficiency of the wells, most likely due to depassivation of initially H-passivated preexisting nonradiative recombination centers (NRCs) in a Mg-doped p-type Al0.85Ga0.15N electron blocking layer. The principal cause for the subsequent Po reduction until 484 h is attributed to further decrease in ηinjection due to the appearance of certain current bypasses in addition to continuous depassivation of the NRCs in p-type AlxGa1-xN layers. According to our database on the species of vacancy-type defects acting as NRCs in GaN and AlN, which have been identified using the combination of positron annihilation and TRPL measurements, vacancy clusters comprised of a cation vacancy (VIII) and nitrogen vacancies (VN), such as VIIIVN2∼4, are the most suspicious origins of the NRCs in Mg-doped p-type AlxGa1-xN layers.

Preparation of lignin-based epoxy resins with tunable properties through constructing a partially ordered crosslinking network

In this work, lignin-based epoxy resins with tunable thermomechanical properties were prepared through constructing a partially ordered crosslinking network, which is designed on the curing behavior of phenyl glycidyl ether (PGE) and phenolated lignin-based epoxy resin (PLBER) with methyl nadic anhydride. Curing kinetics analysis illustrated that the introduction of PLBER could substantially reduce the activation energy (Ea) of curing reaction, indicating that PLBER have higher reactivity than PGE. Epoxy resins exhibited improved flexural strength, impact toughness, storage modulus, and glass transition temperature with the increase in lignin content. Based on the atomic force microscopic images of the thermosets, the highly crosslinked lignin-based epoxy resin was embedded in the epoxy matrix to form a heterogeneous network structure, which confirms that PGE reacted with PLBER as an active monomer to form a partially ordered crosslinked network, where PLBER represents the high-density region in the epoxy network. Moreover, the incorporation of lignin decreased the initial degradation temperature (Td5%) of epoxy resins, whereas Td50% (the temperature at 50% weight loss), Tmax (the temperature at the maximum rate of weight loss), and char yield (Char800) were improved with the increase in lignin content. This result may be attributed to the abundant β–O–4 bonds in lignin, which are degraded rapidly to form a protective carbon layer at the initial stage of decomposition, thereby slowing down the decomposition rate of epoxy resins.

Utilization of a kinetic isotope effect to decrease decomposition of ceftriaxone in a mixture of D2O/H2O

The discovery of cephalosporin and demonstration of its improved stability in aqueous solution, as well as enhanced in vitro activity against penicillin-resistant organisms, were major breakthroughs in the development of β-lactam antibiotics. Although cephalosporins are more stable with respect to hydrolytic degradation than penicillins, they still experience a variety of chemical transformations. The present study offers an insight into the rates and mechanisms of ceftriaxone degradation at the therapeutic concentration in water, a mixture of water and deuterium oxide, and deuterium oxide itself at the neutral pH.Specific ceftriaxone degradation products were observed in aged samples (including a previously unreported dimer-type species), and by comparing the degradation rates in H2O and D2O, the observation of a kinetic isotope effect provided some valuable insight as to the nature of the initial ceftriaxone degradation. The effect of protium to deuterium isotope change on the degradation kinetics of ceftriaxone was evaluated using the method of initial rates based on HPLC analysis as well as by quantitative 1H NMR spectroscopy. Moreover, computational analysis was utilized to get a molecular insight into chemical processes governing the ceftriaxone degradation and to rationalize the stabilizing effect of replacing H2O with D2O.

Synergistic catalysis induced by a multi-component system constructed by DBD plasma combined with α-Fe2O3/FeVO4/HCP and peroxymonosulfate for gatifloxacin removal

The dielectric barrier discharge (DBD) multi-component system containing plasma, α-Fe2O3/FeVO4, and peroxymonosulfate (PMS) with high catalytic activity was successfully constructed. Thereinto, α-Fe2O3/FeVO4 was loaded on the honeycomb ceramic plate (HCP) surface (α-Fe2O3/FeVO4/HCP) and placed under the water surface below the discharge area. The catalytic activity was evaluated by the removal rate of gatifloxacin (GAT), and the DBD+α-Fe2O3/FeVO4+PMS system exhibited the optimal catalytic activity. The enhanced catalytic activity can be attributed to the fact that the occurrence of synergistic catalysis that simultaneously includes plasma oxidation, photocatalysis, PMS oxidation, O3 catalysis, and Fenton reaction. The effect of various initial degradation parameters including input power, PMS dosage, pH, etc. On GAT removal was investigated. DBD+α-Fe2O3/FeVO4+PMS system has a significant increase in the concentration of H2O2 and O3, and the role played in the multi-component system was analyzed. The identification and analysis of organic matters during GAT degradation were visualized with the help of 3D EEMs. HPLC-MS and theoretical calculations identified the major intermediates and further deduced the possible GAT degradation pathways. Additionally, the acute toxicity of the major intermediates was predicted by the QSAR model. Finally, the possible mechanisms of synergistic catalysis to enhance catalytic activity were discussed based on the characteristics of several advanced oxidation processes (AOPs) and the results of experimental and characterization. This work provides a feasible technical route and theoretical basis for wastewater treatment by plasma combined with other AOPs.

Key role of •O2− in promoting deep degradation of VOCs in VUV-based process

VUV photolysis presents a simple process for VOCs degradation, while the poor mineralization rate and extensive by-products greatly limit its application. In this study, the contribution and synergy between •OH and •O2− to toluene degradation in the VUV-based process were comprehensively investigated by controlling water and oxygen in the gas flow. It was found that •OH promoted the initial degradation of toluene and macromolecular intermediates, while •O2− dominated toluene mineralization by boosting the formation of small molecules and CO2. Compared with the •OH-dominated VUV photolysis, the presence of catalyst greatly changed the degradation pathway, promoted toluene mineralization into CO2 and reduced health toxicity via promoting •O2− formation. This study originally focuses on the key role of •O2− in VOCs deep oxidation and provides an effective strategy to boost its clean mineralization via the VUV-based process.

Design of polyarylates containing tert‐butyl cyclohexyl bulky side group with high transparency and low dielectric properties

AbstractA new kind of novel low dielectric constant (Dk) and high transparency polyarylate had been synthesized through interfacial polycondensation with 1,1′‐ bis (4‐hydroxybenzene)‐4‐tert‐butylcyclohexane (Bt‐BPZ) containing tert‐butyl cyclohexyl bulky side group. As we expect, that the introduction of tert‐butyl cyclohexyl with large free volume is proved to be an efficient strategy for obtaining low dielectric constant and high transparency polyarylate. The optimal dielectric property is obtained with 90% Bt‐PZA in polyarylate (Bt‐PZA91), which show aDkas low as 2.14 at 1 MHz. Meanwhile, Bt‐PZA91 also demonstrates good transmittance of 81.08%–88.34% at 450 nm and 78.67–88.26 at 400 nm. The cut‐off wavelength of Bt‐PZA91 is 304 nm, which is 16 nm shorter than commercial product U‐100 (λc: 320 nm). In addition, the resultant polyarylates showed good comprehensive performance such asTgof 202.2–220.5°C,Td 5%(the initial thermal degradation temperature) of 455.4–468.4°C, tensile strength of 64.7–86.8 MPa and low water absoption (0.41% of Bt‐PZA91). Also it was found to can be thermal process, that its convenient thermoplastic processability makes it a great candidate for light‐electronic industry, 5G communication, and we believe that Bt‐PZA will have a broad application prospect.

Safety of Reinforced Concrete Columns: Effect of Initial Imperfections and Material Deterioration under Emergency Actions

The effect of (1) initial imperfections and (2) material degradation of reinforced concrete columns on their safety in emergency situations was investigated. The research was limited to low- and medium-flexibility columns. Numerical modeling and proven regulatory methods of analysis were applied to determine the ultimate bearing capacity, taking into account supplementary dynamic loading by a longitudinal force and a bending moment in case of emergency. The numerical model, describing the column structure, has 3D elements simulating concrete, and rebars simulating reinforcement frames (cages). Imperfections are simulated by (1) the physical loss of elements, (2) unzip of nodal elements, and (3) unzip and further zip using nonlinear elements simulating gaps and cohesion between concrete and reinforcement. Implicit dynamics and an incremental method were employed to make computations. Within the framework of this computational scheme, a nonlinear problem was solved using the Newton–Raphson method with nodal forces convergence. The effect of imperfections, such as geometrical deviations and deterioration of mechanical characteristics, on the bearing capacity of compressed bending elements was identified under emergency actions. Risks of mechanical safety loss were analyzed to find that columns in the frame structures of highly hazardous, technically complex, and unique buildings and structures, subjected to supplementary loading, need an additional safety margin in the range of 3–21%. Rectangular cross-sections of columns are the most effective in terms of the safety criterion.

Hydrogen-induced degradation dynamics in silicon heterojunction solar cells via machine learning

Among silicon-based solar cells, heterojunction cells hold the world efficiency record. However, their market acceptance is hindered by an initial 0.5% per year degradation of their open circuit voltage which doubles the overall cell degradation rate. Here, we study the performance degradation of crystalline-Si/amorphous-Si:H heterojunction stacks. First, we experimentally measure the interface defect density over a year, the primary driver of the degradation. Second, we develop SolDeg, a multiscale, hierarchical simulator to analyze this degradation by combining Machine Learning, Molecular Dynamics, Density Functional Theory, and Nudged Elastic Band methods with analytical modeling. We discover that the chemical potential for mobile hydrogen develops a gradient, forcing the hydrogen to drift from the interface, leaving behind recombination-active defects. We find quantitative correspondence between the calculated and experimentally determined defect generation dynamics. Finally, we propose a reversed Si-density gradient architecture for the amorphous-Si:H layer that promises to reduce the initial open circuit voltage degradation from 0.5% per year to 0.1% per year.

Preparation and characterization of photocurable fluorinated polyether‐based reactive inks

AbstractPhotocurable polymer provides fast curable properties via ultraviolet (UV) light for 3D‐printed propellants. This work outlines the preparation and characterization of photocurable fluorinated polyether‐based reactive inks. Acrylate‐terminated poly‐2‐((2,2,3,3,3‐pentafluoropropoxy)‐methyl) ethylene oxide (P5F‐AA) was synthesized as photocurable binder through the esterification of acrylic acid, and the terminal hydroxyl group of poly‐2‐((2,2,3,3,3‐pentafluoropropoxy)‐methyl) ethylene oxide (P5F), which was synthesized through cationic ring‐opening polymerization of 2‐((2,2,3,3,3‐pentafluoropropoxy)methyl) oxy‐ethane (PFEE) by using butane diol as initiator. In comparison with P5F, P5F‐AA had a lower glass transition temperature (Tg) of −63.3°C. A new type of photocurable resin, which may be used for additive manufacturing of energetic materials, was prepared via UV radiation in an LED UV curing tank by using P5F‐AA as prepolymer, diphenyl (2,4,6‐trimethyl benzoyl) phosphine oxide (TPO) as photo‐initiator, and tri‐fluoroethyl acrylate (3F‐AA) and 1,6‐hexanediol diacrylate (HDDA) as mono‐ and multifunctional diluents, respectively. When the mass ratio of P5F‐AA/3F‐AA/HDDA binder matrix was 1:1:0.5, the sample exhibited maximal mechanical strength of 6.56 MPa with elongation at break of 13.38%, which was due to the introduction of HDDA effectively increasing the “entanglement” between molecular chains. Thermogravimetric analysis (TGA‐DTG) was utilized to evaluate the ability to decompose thermally of the binder matrix, and the results showed the initial degradation temperature started at nearly 181°C and two consecutive stages in thermal decomposition. Overall, the obtained results from the different techniques suggested that P5F‐AA/3F‐AA/HDDA binder matrix may be a photocurable reactive ink for 3D‐printed propellants, which would provide a certain reference value and guiding importance for design of reactive inks.

PERMANENT DAMAGE ON IMPLANTED BONE SCREWS OCCURS SIGNIFICANTLY EARLIER THAN THE APPARENT FAILURE

Primary implant stability is critical for osseointegration and subsequent implant success. Small displacements on the screw/bone interface are necessary for implant success, however, larger displacements can propagate cracks and break anchorage points which causes the screw to fail. Limited information is available on the progressive degradation of stability of an implanted bone screw since most published research is based on monotonic, quasi-static loading [1]. This study aims to address this gap in knowledge.A total of 100 implanted trabecular screws were tested using multi-axial loading test set-up. Screws were loaded in cycles with the applied force increasing 1N in each load cycle. In every load cycle, Peak forces, displacements, and stiffness degradation (calculated in the unloading half of the cycle) where recorded. 10 different loading configurations where tested.The damage vs displacement shows a total displacement at the point of failure between 0.3 and 0.4 mm while an initial stiffness reduction close to 40%. It is also shown that at a displacement of ~0.1 mm, the initial stiffness of every sample had degraded by 20% (or more) meaning that half of the allowable degradation occurred in the first 25-30% of the total displacement.Other studies on screw overloading [1] suggests similar results to our concerning initial stiffness degradation at the end of the loading cycle. Our results also show that the initial stiffness degrades faster with relatively small deformations suggesting that the failure point of an implanted screw might occur before the common failure definition (pull-out force, for example). These results are of great significance since primary implant stability is better explained by the stiffness of the construct than by its failure point.

Agarolytic Pathway in the Newly Isolated Aquimarina sp. Bacterial Strain ERC-38 and Characterization of a Putative β-agarase

Marine microbes, particularly Bacteroidetes, are a rich source of enzymes that can degrade diverse marine polysaccharides. Aquimarina sp. ERC-38, which belongs to the Bacteroidetes phylum, was isolated from seawater in South Korea. It showed agar-degrading activity and required an additional carbon source for growth on marine broth 2216. Here, the genome of the strain was sequenced to understand its agar degradation mechanism, and 3615 protein-coding sequences were predicted, which were assigned putative functions according to their annotated functional feature categories. In silico genome analysis revealed that the ERC-38 strain has several carrageenan-degrading enzymes but could not degrade carrageenan because it lacked genes encoding κ-carrageenanase and S1_19A type sulfatase. Moreover, the strain possesses multiple genes predicted to encode enzymes involved in agarose degradation, which are located in a polysaccharide utilization locus. Among the enzymes, Aq1840, which is closest to ZgAgaC within the glycoside hydrolase 16 family, was characterized using a recombinant enzyme expressed in Escherichia coli BL21 (DE3) cells. An enzyme assay revealed that recombinant Aq1840 mainly converts agarose to NA4. Moreover, recombinant Aq1840 could weakly hydrolyze A5 into A3 and NA2. These results showed that Aq1840 is involved in at least the initial agar degradation step prior to the metabolic pathway that uses agarose as a carbon source for growth of the strain. Thus, this enzyme can be applied to development and manufacturing industry for prebiotic and antioxidant food additive. Furthermore, our genome sequence analysis revealed that the strain is a potential resource for research on marine polysaccharide degradation mechanisms and carbon cycling.

Assessment of the Impressed Current Cathodic Protection system after 4 years operation: Case study of the Saint-Cloud Viaduct (France)

Impressed Current Cathodic Protection (ICCP) is an electrochemical technique widely used, especially for repairing reinforced concrete structures contaminated with chlorides. This paper represents the results of the feedback of the ICCP system implemented on a road bridge, the Viaduct of Saint-Cloud in France. In 2012, a field trial was conducted in order to evaluate the effectiveness and the reliability of an ICCP system with embedded anodes designed for impressed current. The full-scale ICCP system was energized in 2018. Results of the four years monitoring including the variations of the applied current density and the polarization of the various anodic zones are presented. The ICCP data analysis is performed taking into consideration the initial degradation level of the span segments and the presence of prestressed tendons ducts. The electrical resistance of the circuit is influenced by several factors, the most important of which is the temperature. Considerations about the heterogeneity of the concrete resistivity are discussed.

Whey protein isolate and kraft lignin multifunctional films for potential food packaging application: UV block and antioxidant potential

Kraft lignin (KL) is a promising additive for obtaining multifunctional biodegradable packaging. However, the hydrophobic properties of lignin hinder its dispersion in hydrophilic matrices. The prior alkaline solubilization of lignin before adding it to the filmogenic dispersion could be an alternative to overcome this limitation. In this sense, this study aimed to produce whey protein isolate (WPI) multifunctional films incorporated with different concentrations of KL, ranging from 0% to 8%, previously solubilized in alkaline solution, and characterize them in terms of morphological, molecular, mechanical, optical, hydrophobicity, thermal, sealability, antioxidant, and UV-blocking properties. The prior solubilization of KL allowed the obtainment of homogeneous films of a dark color with greater resistance to fracture, higher hydrophobicity, higher glass transition temperature than the control film, and a slightly greater thermal stability: the initial and maximum degradation temperature of 166.1 °C and 305.3 °C, respectively. Lignin presence in the matrix also gave the films functionalities compared to the control: the films added with 2% of KL blocked 95% of UVA and 100% UVB radiation without impairing the passage of visible light, and the films with 8% of KL showed 34.69% of antioxidant activity in DPPH analysis. However, the films were not heat sealable, which was an undesirable outcome. Nevertheless, lignin solubilization in alkali proved to be an efficient methodology for producing multifunctional WPI films, with potential application on foods susceptible to oxidation.

Effect of water on the mechanical and thermal properties of natural fibre reinforced hybrid composites

Research and development on natural fibre-reinforced composites (NFRCs) is constantly increasing and their use is expanding into new areas of applications. One of the main problems is the absorption of humidity due to the hydrophilic characteristic of the natural fibre, which leads to low interfacial adhesion between the fibre and the hydrophobic matrix and consequently, relatively low mechanical properties. One method to reduce the sensitivity of mechanical and thermal properties of NFRCs to water uptake is the hybridization by using synthetic fibres and/or fillers. This research investigates the effect of ageing on the mechanical and thermal properties of different natural fibre and hybrid composites. Pure jute, pure jute modified with two different types of fillers (micro glass and nano TiO2) and interlaminar hybrid jute/glass fibre-reinforced polymer composites were fabricated. Bulk specimens were used to measure the diffusion coefficient of water in the composites, and tensile and flexural specimens were used to measure the mechanical properties of the conditioned specimens. A thermogravimetric technique (TGA) analysis was used to measure and compare the degradation temperature of all composites studied as a function of ageing. Finally, a scanning electron microscopy (SEM) analysis was performed to examine the fracture surfaces of the specimens tested. It was found that the water uptake decreases by adding the synthetic fibres and the fillers to the NFRCs. The mechanical properties of the composites (the tensile and flexural strength and modulus) tend to decrease with the increase of water content, and they are partially recovered after desorption at the same temperature as the absorption. The thermal properties of natural fibre composites are affected by water absorption and by the hybridization. The hybridization of the composites increased the maximum degradation temperature when compared to the pure jute, while the addition of fillers improved the thermal properties of aged specimens (the initial degradation temperature values were higher than those for the pure jute composites).