Materials Engineering

Two new substoichiometric titania (TiO x ) coatings designated for cylinder liner application were deposited on specimen of grey cast iron GG20HCN with high carbon content by plasma spraying. First, a Ti n O 2n-1 coating was prepared by atmospheric plasma spraying (APS) using a sintered and agglomerated Magnéli-type spray powder. Second a TiO 1.95-x coating was deposited with a vacuum plasma spray (VPS) process using a commercial, fused and crushed TiO 1.95 powder. The tribological behaviour of these coatings under lubricated conditions was compared with uncoated specimen of this grey cast iron. As counter bodies a widespread used APS-sprayed Mo-NiCrBSi piston ring coating (MKP81A ® ), an advanced HVOF-sprayed WC/Cr 3 C 2 -based (MKJet502 ® ) ring coating as well as non-commercial prototype APS-sprayed Ti n O 2n-1 and APSsprayed (Ti,Mo)(C,N) + 23NiMo (TM23-1) coatings were tribotested. The interaction of the pairs with prototype engine oils based on esters and polyglycols were studied under mixed/boundary lubrication using the BAM test method. Lubricants were factory fill engine oils, ester-containing lubricants with low-SAP (sulphur-ash-phosphor) and/or bio-notox properties as well as polyglycole-based lubricants. The ester and polyglycole-based engine oils respond both to bio-no-tox criteria and are polymer-free. They follow different strategies to reduce zinc, phosphorus and sulphur to assure a low ash content. Both TiO x coatings designated for cylinder liners meet or exceed the wear resistance of the grey cast iron with high carbon content when paired with APS-sprayed Ti n O 2n-1 or Mo-NiCrBSi piston ring coatings. Overall, in nearly all pairs the wear rates of the APS Ti n O 2n-1 coating were lower than those of the VPS TiO 1.95-x coating. In order to characterize the tribological behaviour under oil-off, dry-running conditions, additional tests were performed under unlubricated unidirectional sliding conditions at 22 and 400 • C for a sliding speed of 1 m/s against sintered polycrystalline Al 2 O 3 as stationary specimen.

The effects of nickel (Ni) content on the mechanical properties and microstructure evolution in the weld metals of commercial K65 oil and gas pipeline steel were studied. Increase Ni content could significantly improve the strength and low temperature impact toughness (-40 °C and -60 °C) of the weld metal. The above influences of Ni were attributed to the formation of predominant acicular ferrite (AF), at the expense of grain boundary ferrite (GBF), ferrite side plates (FSP) and martensite/austenite (M/A) constituent in weld metal. EBSD results indicated that GBF keeps K-S or N-W relations only with the prior austensite grain that belongs to one side of the grain boundary and the variants belong to the same bain group which always forms low angle boundary. Moreover, the retained austenite as one part of M/A constituent was mainly found in the weld metal with lower Ni content. It indicated that the transformation process could be promoted more completely by the increase of Ni content. The mechanism of the toughness improvement brought by Ni increasing was ascribed to the relatively uniform transformation to final microstructure, which reduces the appearance of GBF and M/A constituents.

The nanostructured multilayer silica-titania or silica-titania-alumina films doped with Er 3+ were prepared by sol-gel method. The sol-gel method is a flexible and convenient way to prepare oxide films on several types of substrates, and for this reason it was extensively investigated for optical waveguides fabrication. The selected molar composition was 90%SiO 2 -10%TiO 2 or 85%SiO 2 -10%TiO 2 -5% Al 2 O 3 and 0.5% Er 2 O 3 . The films were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Spectroellipsometry (SE), as well as by Atomic Force Microscopy (AFM) and photoluminescence (PL). The films deposited on Si/SiO 2 substrate by dip-coating or spin-coating, followed by annealing at 900 °C, presented homogenous and continuous surface and good adherence to the substrate. Differences were noticed in the structure and properties of the prepared films, depending on the composition and the number of deposited layers. Channel optical waveguides were obtained by patterning Er 3+ -doped SiO 2 -TiO 2 and SiO 2 -TiO 2 -Al 2 O 3 sol-gel layers deposited on oxidized silicon wafers.

Electro-kinetic decontamination has been studied for radioactive concrete of nuclear power plants because of its effective removal of contaminants from deep inside concrete. Although many experiments have been conducted, a systematic comparison has been scarcely conducted. By a thorough review, this study reveals how different conditions of electro-kinetic decontamination changes the decontamination ratio and rate of Cs and Co. The tested conditions include cell configurations (i.e., geometry of concrete waste, electrode materials, and volume of solutions) and operating conditions (i.e., types and concentrations of solutions, electric field, and test duration). The careful analysis suggests the important roles of pH in electrolytic solution, electric field, and pre-treatment. We also discuss the chemical conditions under which the decontamination of Cs and Co was optimized in the presence of an applied voltage. In addition, we critically review the conditions of simulated concrete samples in the previous experiments in comparison with actual nuclear plant data.

The microstructure and corresponding tensile properties of both plain and Nb-microalloyed grades of ultrathin cast strip (UCS) low alloy steel produced using the CASTRIP Ò process were studied. Both as-cast and hot-rolled strip cast steels with various levels of Nb microalloying were manufactured and investigated in this study. Hot rolling had little effect on the yield strength of Nb microalloyed UCS specimens for a given chemical composition, but resulted in a slightly finer microstructure. The effect of Nb microalloying was significant, and this is attributable to the promotion of finer, tougher austenite transformation products such as bainite and acicular ferrite at the expense of large polygonal ferrite grains. A fine dispersion of Nb solute clusters was observed in all Nb-containing steels following hot rolling, and it is suggested that this also contributes to the observed strengthening.

Thermosensitive materials, such as PNIPAAm, are considered for the development of hydrogels for controlled release, especially for topical use. Bromelain is a set of proteases found in plants (Bromeliceae family) and it is known for having several medical uses, including healing of topical wounds. The combination of PNIPAAm hydrogels and bromelain could result in a potential formulation for topical injuries. In this work, different NIPAAm hydrogels were submitted to swelling tests for 24 h. The selected formulation presented a swelling ratio of 340%, and was used for bromelain loading, reaching up to 30% of protein loading. After loading, hydrogel disks were dried and immersed in phosphate buffer (pH 7.0) for release study. Release studies pointed to an initial burst release, followed by a modified (slower) release, reaching its optimum enzymatic activity release rates at around 60 min in both temperatures (25 ºC and 37 ºC). Scanning electron microscopy and Fourier transform infrared spectroscopy confirmed bromelain loading through hydrogen bonds, without interfering in intermolecular polymeric chains. Bromelain presence decreased mucoadhesion at 25 °C and increased at 37 °C; it also increases polymers crosslink, without interfering in elastic properties (drilling and resilience). Hydrogels (blank and loaded with bromelain) showed a typical behavior of crosslinked hydrogels at rheology tests, and bromelain increased storage modulus. Both hydrogels showed a significant cell death after 24h in NIH/3T3 cell line.

Consumer concerns about synthetic additives is increasing and it can be interesting to apply natural antioxidants with antimicrobial properties. Developing a packing material composed by a natural polymer, such as bacterial nanocellulose membrane (BNCm) loaded with nisin may be applied as a method to keep food quality and to inhibit growth of microbial contaminants. For this reason, the aim of this study was to evaluate antimicrobial activity of BNCm loaded with nisin. Antimicrobial activity of nisin, utilizing or not EDTA solution,was assessed by minimal inhibitory concentration and agar diffusion assay, utilizing Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Antioxidant activity and physico-chemical properties were also evaluated. For the MIC evaluation, the combination of nisin solution with EDTA showed a synergistic effect. Concerning E. coli nisin with EDTA 20-40 mM, MIC was 31.25 lg/mL. Concerning P. aeruginosa nisin with EDTA 10-20 mM, MIC was 125 lg/mL. Concerning S. aureus nisin with EDTA 10 mM, MIC was 15.63 lg/mL, two times lower than without EDTA. The BNCm antimicrobial activity for E. coli, by agar diffusion assay, was observed when nisin was loaded at 250 or 500 lg/mL with EDTA 10 or 20 mM. However, for S. aureus, the antimicrobial activity was observed for BNCm loaded with nisin 15 lg/mL with 10 mM EDTA. For P. aeruginosa, antimicrobial activity was not observed. Nisin exhibited significant antimicrobial and antioxidant activity. The results provide evidence that BNCm loaded with nisin is a promising control strategy to prevent microorganism contamination.

Four new cadmium(II) complexes [Cd 2 (bz) 4 (H 2 O) 4 (μ 2 -hmt)] 3 Hbz 3 H 2 O (1), [Cd 3 (bz) with hexamine (hmt) and monocarboxylate ions, benzoate (bz), phenylacetate (pa), or acetate (ac) have been synthesized and characterized structurally. Structure determinations reveal that 1 is dinuclear, 2 is trinuclear, 3 is a one-dimensional (1D) infinite chain, and 4 is a two-dimensional (2D) polymer with fused hexagonal rings consisting of Cd II and hmt. All the Cd II atoms in the four complexes (except one Cd II in 2) possess sevencoordinate pentagonal bipyramidal geometry with the various chelating bidentate carboxylate groups in equatorial sites. One of the Cd II ions in 2, a complex that contains two monodentate carboxylates is in a distorted octahedral environment. The bridging mode of hmt is μ 2 -in complexes 1-3 but is μ 3 -in complex 4. In all complexes, there are significant numbers of H-bonds, C-H/π, and π-π interactions which play crucial roles in forming the supramolecular networks. The importance of the noncovalent interactions in terms of energies and geometries has been analyzed using high level ab initio calculations. The effect of the cadmium coordinated to hmt on the energetic features of the C-H/π interaction is analyzed. Finally, the interplay between C-H/π and π-π interactions observed in the crystal structure of 3 is also studied.

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

The hot electron transport properties of the Cu/Si(001) interface have been studied using ballistic electron emission microscopy (BEEM). The Schottky barrier height was measured to be 0.64±0.02 eV. The scanning tunneling microscopy images provide evidence of Volmer–Weber growth of the metal, while Rutherford backscattering spectrometry data corroborated with Auger depth profiling indicate distinct Cu and Si regions with little intermixing. Comparison with Au/Si(001) BEEM data provides some insight into the hot electron transport and scattering properties of the Cu/Si(001) interface.

In search of materials with better properties, polycrystalline materials are often found superior to their respective single crystalline counterparts. Reduction of grain size in polycrystalline materials can drastically alter the properties of materials, and when the grains reach nanometer scale, the improved mechanical response of the materials make them attractive in many applications. Multicomponent solid solution alloys have shown higher radiation tolerance compared to pure materials. Combining these both advantages, we investigate the radiation tolerance of nanocrystalline multicomponent alloys. We find that the alloys are able to withstand a much higher irradiation dose before the nanocrystallinity collapses, compared to nanocrystalline Ni. Some of the alloys managed to uphold their nanocrystallinity even twice as long as pure Ni.

The ideal picture of a near-perfect 3D microscope often presented regarding Atom Probe Tomography faces several issues. These issues degrade the metrological performance of the instrument and find their roots in the phenomena acting at the atomic to the mesoscopic level in the vicinity of the surface of a field emitter. From the field evaporation process at the atomic scale, to the macroscopic scale of the instrument, the path to model the imaging process and to develop more accurate and reliable reconstruction algorithms is not a single lane road. This paper focused on the numerical methods used to understand, treat, and potentially heal imaging issues commonly affecting the data in atom probe experiments. A lot of room for improvement exists in solving accuracy problems observed in complex materials by means of purely electrostatic models describing the image formation in a classical approach. Looking at the sample at the atomic scale, the phenomena perturbing the imaging process are subtle. An examination of atomic scale modifications of the sample surface in the presence of a high surface electric field is therefore mandatory. Atomic scale molecular dynamic models integrating the influence of the high surface electric are being developed with this aim. It is also demonstrated that the complex behavior of atoms and molecules in high fields, and consequences on collected data, can be understood through the use of accurate ab-initio models modified to include the impact of the extreme surface electric field.

Electron emission from nanometric size emitters becomes of increasing interest due to its involvement to sharp electron sources, vacuum breakdown phenomena and various other vacuum nanoelectronics applications. The most commonly used theoretical tools for the calculation of electron emission are still nowadays the Fowler-Nordheim and the Richardson-Laue-Dushman equations although it has been shown since the 1990's that they are inadequate for nanometrically sharp emitters or in the intermediate thermal-field regime. In this paper we develop a computational method for the calculation of emission currents and Nottingham heat, which automatically distinguishes among different emission regimes, and implements the appropriate calculation method for each. Our method covers all electron emission regimes (thermal, field and intermediate), aiming to maximize the calculation accuracy while minimizing the computational time. As an example, we implemented it in atomistic simulations of the thermal evolution of Cu nanotips under strong electric fields and found that the predicted behaviour of such nanotips by the developed technique differs significantly from estimations obtained based on the Fowler-Nordheim equation. Finally, we show that our tool can be also successfully applied in the analysis of experimental I -V data.

Electron emission from nanometric size emitters becomes of increasing interest due to its involvement to sharp electron sources, vacuum breakdown phenomena and various other vacuum nanoelectronics applications. The most commonly used theoretical tools for the calculation of electron emission are still nowadays the Fowler-Nordheim and the Richardson-Laue-Dushman equations although it has been shown since the 1990's that they are inadequate for nanometrically sharp emitters or in the intermediate thermal-field regime. In this paper we develop a computational method for the calculation of emission currents and Nottingham heat, which automatically distinguishes among different emission regimes, and implements the appropriate calculation method for each. Our method covers all electron emission regimes (thermal, field and intermediate), aiming to maximize the calculation accuracy while minimizing the computational time. As an example, we implemented it in atomistic simulations of the thermal evolution of Cu nanotips under strong electric fields and found that the predicted behaviour of such nanotips by the developed technique differs significantly from estimations obtained based on the Fowler-Nordheim equation. Finally, we show that our tool can be also successfully applied in the analysis of experimental I -V data.

Single-phase multicomponent alloys of equal atomic concentrations ("equiatomic") have proven to exhibit promising mechanical and corrosion resistance properties, that are sought after in materials intended for use in hazardous environments like next-generation nuclear reactors. In this article, we investigate the damage production and dislocation mobility by simulating irradiation of elemental Ni and the alloys NiCo, NiCoCr, NiCoFe and NiFe, to assess the effect of elemental composition. We compare the defect production and the evolution of dislocation networks in the simulation cells of two different sizes, for all five studied alloys. We find that the trends in defect evolution are in good agreement between the different cell sizes. The damage is generally reduced with increased alloy complexity, and the dislocation evolution is specific to each material, depending on its complexity. We show that increasing complexity of the alloys does not always lead to decreased susceptibility to damage accumulation under irradiation. We show that, for instance, NiCo alloy behaves very similarly to Ni, while presence of Fe or Cr in the alloy even as a third component reduces the saturated level of damage substantially. Moreover, we linked the defect evolution with the dislocation transformations in the alloys. Sudden drops in defect number and large defect fluctuations from the continuous irradiation can be explained from the dislocation activity.

Bronze reacts with oxygen, humidity, and pollutants in the atmosphere so that a patina forms. Natural exposure to an outdoor atmosphere can be simulated and accelerated in order to achieve a patina that mimics outdoor ancient patina. In order to avoid the uncontrolled dissolving of either the natural or artificially formed patina, protection of the patina is needed. In this study, a multi-component fluoropolymer based coating for the protection of bronze patina was developed. In order to provide various functionalities of the coating (such as the hydrophobicity of the coating surface, obtaining interactions within the coating itself as well as a bronze substrate and inhibiting the corrosion processes), a fluoroacrylate coating with appropriate adhesion promoter was suggested, with and without a silane modified benzotriazole inhibitor. The protective efficiency and durability of the applied coatings were investigated electrochemically using potentiodynamic tests and electrochemical impedance spectroscopy in a simulated acid rain solution. All of the developed coatings showed a significant decrease in the corrosion current density. The self-assembled single layer coating (FA-MS) also showed 100% inhibition efficiency. After ageing the coating remained transparent and did not change by UV exposure and/or thermal cycling. The patina and coating investigations using FIB-SEM and EDX showed that the latter coating (FA-MS) successfully covered the surface of the patinated bronze. The mechanism of the bonding was proposed and supported with the spectroscopic observation of a thin and even coating.

When attempting to sufficiently protect outdoor bronze monuments from corrosion, searches for an effective solution are usually based on coating applications which have a high anticorrosive efficiency. In order to correctly assess the level of protection provided by such coatings, adherence (practical adhesion) measurements need to be performed for the proper evaluation of the deterioration of coating systems with aging. Although a coupled study of adherence with aging would be of great interest, very few such studies are available. In this work, a methodological approach is proposed for the evaluation of coatings applied to metallic cultural heritage monuments of, based on the use of a three-point bending test. Adherence characterization of different protective coatings has been performed both on bare and on traditionally black-patinated bronze coupons (Cu-Sn alloy with 5.9 wt% Sn), which were used as basic model substrates. The investigated coatings were Incralac Ò , silane, sol-gel oxysilane, and a silane-modified polymethacrylate (an adhesion promoter for fluoropolymer). The results of measurements which were obtained before and after accelerated aging in concentrated acid rain made it possible to more easily differentiate between the various adherence levels of different coating systems. Coupled with adherence measurements, the results of systematic optical and SEM observation of the different failure morphologies

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Two artificial ageing processes well simulate outdoor patinas of as-cast bronze. Distribution of chemical elements are detailed according to exposure conditions. -Surface characterization with in situ FIB cross-section highlights decuprification phenomenon. Alpha (Cu) solid solution is anodic towards (alpha þ delta) eutectoid. Nano-porosities are evidenced within patinas according to corrosion process.

Upset testing of cylindrical specimens generates circumferential tensile stresses at the barreled surfaces. These stresses can be utilized in the same manner as the tensile stresses in the tension test to evaluate the ductility of materials. Using the upset test method, the anisotropy of ductile fracture in AISI 1045 hot-rolled steel plates was determined. Ductility parallel to the plane of inclusions is found to be ~ 50 pct higher than that perpendicular to the inclusions. It is shown that the local surface strains at fracture in upset testing correlate well with the true zero-gage-length fracture strain in tension testing, provided the tensile stresses in the respective tests are in the same direction relative to the inclusion orientation. Thus, compression tests parallel to the inclusion direction, which generate tensile stresses perpendicular to the inclusions, can be utilized to measure ductility transverse to the fiber of wrought materials. This is particularly useful in determining the short transverse or through-thickness ductility in hot-rolled or forged materials having thin sections.

The flow and fracture of MP35N (35 Co, 35 Ni, 20 Cr, 10 Mo) has been studied by uniaxial compression and plane strain bending in the temperature range 1000 to 1200 ~ and strain rate range 0.01 to 10 s -~. This covers the normal bar rolling production conditions (~ 1100 ~ and 1 to 5 s-l). The strain to fracture in plane strain bending was found to increase with increasing strain rate, roughly coinciding with the increase of the strain to the peak stress in the flow curves. Within most of the temperature and strain rate ranges investigated and under plane strain bending deformation conditions, microvoid nucleation was found to be concurrent with or greatly enhanced by the onset of dynamic recrystallization. Under these deformation conditions, flow concentration or localization along the soft layers of newly recrystallized grains oriented along the maximum shear stress directions near the surface generated microvoid nucleation and damage, in effect overriding the stress relieving and crack isolation effects normally associated with the occurrence of dynamic recrystallization. As the temperature was decreased toward 1000 ~ and the strain rate was increased toward 10 s -l, an apparent transition to a microvoid nucleation mode by wedge cracking was observed, even at the maximum rate of 10 s -~. A further decrease in deformation temperature to 900 ~ at a strain rate of 10 s -l, however, removed all evidence of microvoid nucleation (of the wedge type or otherwise) as well as any trace of dynamic recrystallization within the maximum strain imposed in the plane strain bending tests.

Background: Tissue engineering represents a promising new method for treating heart valve diseases. The aim of this study was evaluate the importance of conditioning procedures of tissue engineered polyurethane heart valve prostheses by the comparison of static and dynamic cultivation methods. Methods: Human vascular endothelial cells (ECs) and fibroblasts (FBs) were obtained from saphenous vein segments. Polyurethane scaffolds (n = 10) were primarily seeded with FBs and subsequently with ECs, followed by different cultivation methods of cell layers (A: static, B: dynamic). Group A was statically cultivated for 6 days. Group B was exposed to low flow conditions (t 1 = 3 days at 750 ml/min, t 2 = 2 days at 1100 ml/min) in a newly developed conditioning bioreactor. Samples were taken after static and dynamic cultivation and were analyzed by scanning electron microscopy (SEM), immunohistochemistry (IHC), and real time polymerase chain reaction (RT-PCR). Results: SEM results showed a high density of adherent cells on the surface valves from both groups. However, better cell distribution and cell behavior was detected in Group B. IHC staining against CD31 and TE-7 revealed a positive reaction in both groups. Higher expression of extracellular matrix (ICAM, Collagen IV) was observed in Group B. RT-PCR demonstrated a higher expression of inflammatory Cytokines in Group B. Conclusion: While conventional cultivation method can be used for the development of tissue engineered heart valves. Better results can be obtained by performing a conditioning step that may improve the tolerance of cells to shear stress. The novel pulsatile bioreactor offers an adequate tool for in vitro improvement of mechanical properties of tissue engineered cardiovascular prostheses.

Summary: Novel temperature sensitive poly(N‐isopropylacrylamide‐co‐acryloyl beta‐cyclodextrin) (P(NIPA‐co‐A‐CD)) hydrogels with fast shrinking rates were prepared by radical polymerization of NIPA, A‐CD and crosslinker in a mixture of water/1,4‐dioxane as solvent. Because the mixed solvent was a poor solvent for the copolymers, phase separation occurred during the polymerization, which resulted in a heterogeneous, porous structure of the hydrogels. In contrast to the normal PNIPA hydrogel and the homo P(NIPA‐co‐A‐CD) gel prepared in water, the P(NIPA‐co‐A‐CD) hydrogels synthesized in water/1,4‐dioxane as solvent exhibited higher swelling ratios at the temperature below the lower critical solution temperature (LCST) and shrunk rapidly to equilibrium within shorter time when the temperature was increased above LCST. Increasing the acryloyl beta‐cyclodextrin content in the gels led to a slight decrease of the swelling ratio at lower temperature and had no marked influence on the shrink...

By utilising the tungsten inert gas welding process, plates of Zn-22Al-2Cu (wt-%) alloy were welded. The weld bead was tested under tension in the transverse direction in order to study the structural changes. Once the tension samples were fractured, the weld bead and the contiguous region were analysed by means of X-ray diffraction. It was found that the applied load through the parent metal is responsible for the transformations in the crystalline phases inside the weld bead. From spectrum analysis, the a' M aluminium rich solid solution, the g' M zinc rich solid solution and the e' M (CuZn 4 ) phases resulting from tension shifted to the low 2h position. To explain these transformations, the reactions g' T ?a' M zg' M zt' and t'zg' T ?a' M ze' M were considered. To supply the necessary thermal energy so that these reactions happen, the hypothesis that the friction in the slip planes at the moment of deformation it produced the required heat for atomic diffusion is established. Finally, with the aid of scanning electron microscope, the morphology of the contiguous region to the fracture was observed. Near the fracture line, the lamellas inside the two-phase dendrites showed a tendency to be guided in parallel address to that of the tension load. In addition, as a result of the heating process, a coarsening of these lamellas can be observed. In a practical sense, the observed results are points to favour in the selection of this alloy for structures since no thermal treatments are needed for its stabilisation after welding.

This paper presents a bibliometric analysis of thermochromic materials for building applications to identify research trends, gaps, and future opportunities. The study reviewed 571 publications selected from the Scopus database. It examines global research patterns, including publication trends, patent activity, geographic distribution, leading authors, and growth trends. Key findings highlight the dominance of inorganic pigments, such as vanadium dioxide (VO2), in smart window applications. In contrast, organic thermochromic pigments remain less explored due to challenges such as photodegradation, despite their potential to improve energy efficiency. Emerging nanotechnologies based on hydrogels and perovskites are promising ways to improve the stability and multifunctionality of thermochromic materials. In contrast, additives such as TiO2 and SiO2 can help address durability and photodegradation issues. Although glass applications dominate the research, the potential for thermochromic coatings on roofs and walls remains underexplored. The study highlights ongoing challenges, including the need for improved durability, cost-effective solutions, and multifunctional capabilities. It emphasizes the importance of interdisciplinary collaboration to accelerate innovation and drive significant advances in thermochromic materials for building applications, ultimately promoting their wider implementation. Continued research is essential to achieve the full potential of these materials for energy-efficient and climate-responsive buildings.

A number of works have been focused on the study of polymers microtacticity and the probability of iso-, syndio-, and atactic arrangement of monomers such as polypropylene and poly(methacrylic esters) before the 1980s. This type of study was fewer in the last four decades despite the importance of stereochemical knowledge of macromolecules in the biomedical field. NMR analysis was the invaluable tool for the study of stereochemistry. This work detailed the synthesis and the physicochemical and microtacticity characterizations of new semicrystalline and amorphous polyesters, poly(3-allyl-3methylmalic acid) (PAlMMLA) derivatives which are part of the poly(malic acid) family. This polymer is biodegradable and biocompatible. It can also be chemically modified for a possible combination with bioactive molecules. It can be synthesized from chiral product leading a stereoregular and semicrystalline structure. In the case of a racemic starting product, the obtained macromolecular structure is amorphous. Semi-crystalline polyester presented a highly diisotactic structure.

Various optically active (4R)-alkyloxycarbonyl-3,3dialkyl-2-oxetanones as monomers were synthesized from L-(S)-malic acid in six steps to prepare a new family of stereopolyesters for biomedical applications. The synthesis began with an esterification followed of a dialkylation in the aim to introduce hydrophobic groups as methyl or reactive group as allyl. Then, a saponification has permitted to obtain the corresponding diacids that reacted with appropriate alcohols to furnish different monoesters. The last and most important step was activation of hydroxyl group of monoesters with the asymmet-ric carbon configuration inversion according to the Mitsunobu reaction. Thus, this reaction has provided lactones from monoesters with 100% enantiomeric excess which was confirmed by 1 H NMR and by the synthesis of corresponding isotactic and semicrystalline homopolyesters. V

This article presents the synthesis of a new family of synthetic isotactic polyesters derived from poly((S)-3,3-dimethylmalic acid) (PDMMLA). These polyesters are prepared via the lactone route bearing functionalized groups in its main or side chain. The aim of this work is twofold: metabolism and stereochemistry. First, the synthesis of these new polyesters is chosen to provide biodegradable polyesters biocompatible and bioassimilable by the human body. Next, the molecular chain of this family contains a stereogenic center in the aim to provide 100% isotactic homopolymers and copolymers (statistical and block). Finally, these polymers have been characterized by several analytical techniques: FTIR, 1 H and 13 C NMR, SEC, DSC, and TGA. The greatest importance will be given to the 13 C NMR and DSC to principally confirm the stereoregularity and crystallinity of these stereopolyesters. V

A number of works have been focused on the study of polymers microtacticity and the probability of iso-, syndio-, and atactic arrangement of monomers such as polypropylene and poly(methacrylic esters) before the 1980s. This type of study was fewer in the last four decades despite the importance of stereochemical knowledge of macromolecules in the biomedical field. NMR analysis was the invaluable tool for the study of stereochemistry. This work detailed the synthesis and the physicochemical and microtacticity characterizations of new semicrystalline and amorphous polyesters, poly(3-allyl-3methylmalic acid) (PAlMMLA) derivatives which are part of the poly(malic acid) family. This polymer is biodegradable and biocompatible. It can also be chemically modified for a possible combination with bioactive molecules. It can be synthesized from chiral product leading a stereoregular and semicrystalline structure. In the case of a racemic starting product, the obtained macromolecular structure is amorphous. Semi-crystalline polyester presented a highly diisotactic structure.

In-stent restenosis is currently treated with drug eluting stents based on biodegradable polymers which can deliver a therapeutic agent and be degraded in a few months preventing the risk of thrombosis. Poly([R,S]-3,3-dimethylmalic acid) (PDMMLA) is a new and original biodegradable and biocompatible polymer which contains a carboxylic acid functional group in its side chain. This gives it the particularity to be chemically modified and custom-synthesized to meet an adequate degradation time. It was prepared in order to develop new coating exhibiting different groups in its side chain and give natural and non-toxic primary products after a complete degradation. Herein we present the study of hydrolytic degradation of PDMMLAs under physiological conditions for a 6-month period. The most important factors that influence the kinetic degradation of polymers (molecular weight, nature and stability of functional groups, natural biological enzymes, pH and temperature) were studied in order to understand the behavior of PDMMLAs hydrolysis. It has been shown that the different PDMMLA polymers were degraded according to a bulk or erosion-surface profiles. Therefore, a hydrophilic loaded side chain, high temperature, high pH and the presence of specific enzyme accelerated the degradation rate of PDMMLAs with an erosion-surface profile. Since these new biomaterials as promising coating-stent will be in direct contact with the arterial wall, their biocompatibility was evaluated in this study in human vascular endothelial cells which are essential for the repair of the arterial wall to inhibit multiple processes leading to in-stent restenosis. The products of long-term degradation of PDMMLA polymers were noncytotoxic.

Various optically active (4R)-alkyloxycarbonyl-3,3dialkyl-2-oxetanones as monomers were synthesized from L-(S)-malic acid in six steps to prepare a new family of stereopolyesters for biomedical applications. The synthesis began with an esterification followed of a dialkylation in the aim to introduce hydrophobic groups as methyl or reactive group as allyl. Then, a saponification has permitted to obtain the corresponding diacids that reacted with appropriate alcohols to furnish different monoesters. The last and most important step was activation of hydroxyl group of monoesters with the asymmet-ric carbon configuration inversion according to the Mitsunobu reaction. Thus, this reaction has provided lactones from monoesters with 100% enantiomeric excess which was confirmed by 1 H NMR and by the synthesis of corresponding isotactic and semicrystalline homopolyesters. V

This article presents the synthesis of a new family of synthetic isotactic polyesters derived from poly((S)-3,3-dimethylmalic acid) (PDMMLA). These polyesters are prepared via the lactone route bearing functionalized groups in its main or side chain. The aim of this work is twofold: metabolism and stereochemistry. First, the synthesis of these new polyesters is chosen to provide biodegradable polyesters biocompatible and bioassimilable by the human body. Next, the molecular chain of this family contains a stereogenic center in the aim to provide 100% isotactic homopolymers and copolymers (statistical and block). Finally, these polymers have been characterized by several analytical techniques: FTIR, 1 H and 13 C NMR, SEC, DSC, and TGA. The greatest importance will be given to the 13 C NMR and DSC to principally confirm the stereoregularity and crystallinity of these stereopolyesters. V

In the recent work of , it has been shown that Pb nanocrystals (NCs) grown on the electron accumulation layer at the (110) surface of InAs are in the regime of Coulomb blockade. This enabled the first Scanning Tunneling Spectroscopy (STM) study of the superconducting parity effect across the Anderson limit. The observation of Coulomb blockade implies the existence of a tunnel barrier between the NCs and the substrate. This tunnel barrier has been ascribed to a quantum constriction of the electronic wave function at the interface between the NCs and the electron accumulation layer owing to its large Fermi wavelength. In this proceeding, we detail and review the arguments leading to this conclusion.

The influence of the anisotropy of the (5×n) reconstructed (100) face of gold on the generation of vacancy islands by sputtering with 600 eV Ar+ ions has been investigated by scanning tunneling microscopy. The shapes of these islands, bounded by monoatomic steps, are shown to be growth shapes, rather than equilibrium shapes. The growth mechanisms leading to these shapes are discussed.

TTF-TCNQ is a one-dimensional charge transfer compound. Charge density wave (CDW) transition occurs at 54 K in TTF-TCNQ, and CDW presents three phases: high temperature commensurate phase (T > 49 K; 2a  3:39b); inter-mediated incommensurate phase (T ¼ 38À49 K; ma  3:39b) and low temperature commensurate phase (T < 38 K; 4a  3:39b). In this report, we present our experimental result on cleaved (0 0 1) surfaces of TTF-TCNQ with UHV-LT-STM (Omicron LTSTM). For a broad temperature range (33-100 K), molecular resolution of TTF-TCNQ has been obtained. Below 54 K an additional two-dimensional superstructure of CDW appears in our images. The ordering of CDW modulation both along a and b direction are first revealed by our STM measurement. Our result shows that, on (0 0 1) surface of TTF-TCNQ, C-I-C CDW phase transition persists in nanometer scale and C-I-C transition is homogeneous. The determination of local CDW phase shift will be presented in this report too. At high temperature (60-280 K), we observed a v-shape pseudogap. The pseudo-gap and Peierls-gap co-exist at low temperature.

Novel chitosan scaffolds containing different weight ratios of electrospun hydroxyapatite nanofibers (n-HA) were fabricated. The fibers possessed diameters in the range of 110-170 nm. A fixed concentration of glycidyloxypropyl-trimethoxysilane (GPTMS) as a crosslinking agent was added to the chitosan solution (CG). The porosity percentage was increased when GPTMS and n-HA were added to the chitosan structure. The presence of GPTMS in chitosan structure caused a decrease in the average pore size. The pores were more irregular in shape than pure chitosan and CG scaffolds when n-HA was added. The uniform distribution of n-HA was seen for chitosan-GPTMS hybrid scaffold containing 25 wt% n-HA (CGH25) using EDS spectrum and mapping. The best values of compressive strength and elastic modulus were achieved for CGH25. The swelling ratio was decreased by adding GPTMS in the chitosan scaffold. Different morphologies of hydroxyapatite deposits on the surface of CG and CGH25 (string-like versus needle-like precipitates) were observed after 14 days of soaking in simulated body fluid (SBF). For CGH25, the viability of MG-63 osteoblastic cells was approximately varied with respect to CG up to 72h of cell culture. These results reveal the potential of the chitosan-CGH25 scaffold to be used in bone tissue engineering.

Novel chitosan scaffolds containing different weight ratios of electrospun hydroxyapatite nanofibers (n‐HAs) were fabricated. The fibers possessed diameters in the range 110–170 nm. A fixed concentration of glycidyloxypropyl‐trimethoxysilane (GPTMS) as a crosslinking agent was added to the chitosan solution (CG). The porosity percentage was increased when GPTMS and n‐HAs were added to the chitosan structure. The presence of GPTMS in the chitosan structure caused a decrease in the average pore size. The pores were more irregular in shape than pure chitosan and CG scaffolds when n‐HAs were added. A uniform distribution of n‐HAs was seen for a chitosan‐GPTMS hybrid scaffold containing 25 wt% n‐HAs (CGH25) using energy dispersive X‐ray spectroscopy and mapping. The best values of compressive strength and elastic modulus were achieved for CGH25. The swelling ratio was decreased on adding GPTMS to the chitosan scaffold. Different morphologies of hydroxyapatite deposits on the surface of C...

In this work, MNA (2-methyl-4-nitroaniline) and sub stituted carbazoles were incorporated into silica matrix to form composite thin films on the glass sub strate by a sol-gel processing for NLO applications. In the composite thin films, the thermal stability was de pendent on the type of functional groups incorporated into the organic compounds. Carbazole-2 (5-nitro-9 -hydroxylethyl-carbazole) which has a terminal -OH group showed enhanced thermal stability, whereas car bazole-1 (5-nitro-9-ethyl-carbazole) and MNA, which do not have a reactive functional group, showed rapid degradation upon thermal treatment. This strongly suggests that the thermal stability of incorporated or ganic compounds can be enhanced by a reactive termi nal group in organic compound without severely damaging the NLO property.

A very simple procedure for the synthesis of fibrous mesoporous silica using a spinning method was developed. It was based on the sol-gel process and solvent evaporation process using cetyltrimethylammonium chloride as a template. Fibrous mesoporous silica was drawn by using a viscous solution which consisted of a surfactant (cetylmethylammonium chloride) and hydrolyzed silica alkoxide (TMOS). Fibrous mesoporous materials have two distinct pores, 0.9 and 1.9 nm, with a specific surface area of about 580 m 2 /g in 1000 rpm of spinning speed. The intensity of the X-ray diffraction pattern of the mesoporous fibers was increased after both the fiber spinning and calcination process. Increasing the spinning speed from 500 to 2000 rpm in the spinning process increased the specific surface area of the mesoporous fibers from 547 to 605 m 2 /g, and simultaneously decreased the diameter of the fibers from 80 to 20 lm.

h i g h l i g h t s g r a p h i c a l a b s t r a c t A new approach to form the electroconductive hydrogels is described. Dispersion of two polymers can be chemically crosslinked by deposition in acetone. The hydrogels demonstrate electroactivity and elastic deformation.

Composite membranes consisting of microporous polyethylene films and the layers of electroconducting polymers have been elaborated. Polyethylene films were prepared in the process based on melt extrusion with subsequent annealing, uniaxial extension, and thermofixation. Permeability, the size distribution of the through flow channels, and mechanical characteristics of porous films have been determined. Polypyrrole and polyaniline were used as conducting polymers which were deposited onto porous films by oxidative polymerization from a gas (polypyrrole) or liquid (polyaniline) phase of a monomer. It has been shown that the relief‐like character of the surface and the porous structure of polyethylene films provide very high adhesion of conducting layer to porous support. Conducting layers were deposited onto the surface of the porous support and also on the pore walls of pores. The layers inside through flow channels in the porous support form microtubules connecting two membrane surf...

Conducting composite systems containing polyaniline layers produced on the surface and inside the pores of polyethylene support have been prepared. Microporous polyethylene films were obtained by melt extrusion with subsequent annealing, uniaxial extension, and thermal fixation. Polyaniline layers were formed by in-situ polymerization of aniline onto polyethylene porous support placed into the aqueous reaction mixture. Structural and chemical transformations upon heating of these systems in air in free state and in vacuum under load have been investigated by thermo-mechanical tests, IR spectrometry, and electron microscopy. Changes in mechanical properties of composites after heating have been analyzed. Composite systems have been found to demonstrate a considerably lower shrinkage upon heating than microporous polyethylene substrates. It has been discovered that the composites preserve mechanical integrity on heating up to temperatures much higher than the polyethylene melting point. It is concluded that thermo-mechanical behaviour of the composites is determined by the space-continuous phase of polyaniline on the surface and in the bulk of polyethylene support.

Palladium-catalysed oxidative carbonylation (PCOC) of alkynes is a promising engine for building smart pulsatile polymeric systems, as it has demonstrated (in certain configurations) sustained regular oscillations in pH and redox potential for up to one month of monitoring in a batch reactor. Recent developments in polymer-supported palladium catalysts allowed to demonstrate the full capacity of this reaction -in a macrogel that experienced oscillations in volume, while releasing a drug load. In this work, we demonstrate reproducible oscillations (more than 100 h duration) in proline-functionalised chitosan-palladium system (Chi-Pro-Pd), using both small molecule (phenylacetylene) and polymeric (pegylated dialkyne) substrate, for the first time. Moreover, by functionalising chitosan with proline ligands, we dramatically reduced halide-mediated leaching of palladium, which readily occurred in non-functionalised chitosan-palladium catalysts (Chi-Pd). Oscillatory patterns for both systems confirm the need for fabricating functionalised chitosan supports to improve catalyst reusability and minimise loss of palladium.

The Need for Detection of Antibiotic Residues The World Health Organization (WHO) predicts ten million annual deaths, globally, due to antibiotic-resistant infections, by 2050. The rise in antimicrobial resistance (AMR) bacteria is therefore considered a global threat. Cassini et al. studied deaths linked to drug-resistant infections in Europe and concluded that %700 000 infections in 2015 were related to resistant bacteria, of which 5% were fatal. Similarly, a study by Ventola demonstrated that two million patients in the USA developed hospital-acquired infections (HAIs), of which 99 000 cases proved fatal, a significant proportion of which were also caused by resistant bacteria. In addition to their impact on mortality, these resistant bacteria also pose a serious financial burden. Misurski et al. demonstrated that incorrect antibiotic prescription was estimated to be a $211 million burden,

A differential pulse voltammetric method for the determination of kojic acid (KA) was developed. The electrochemical behavior of KA at a multi-walled carbon nanotubes modified screen-printed electrode (MWCNTs-SPCE) was explored. A single irreversible oxidation peak was observed at a potential of 0.791 V and 0.989 V on the MWCNTs-SPCE and screen-printed carbon electrode (SPCE), respectively. Under the optimized conditions, the anodic peak current of KA recorded by differential pulse voltammetry varies linearly with KA concentration in the range 0.02-5 mM with a detection limit of 0.016 mM. The MWCNTs-SPCE was used for quantitative analysis of KA in food samples and the results indicate the feasibility of the amperometric method for KA analysis in routine detection.

A simply and high selectively electrochemical method for simultaneous determination of hydroquinone (HQ) and catechol (CC) has been developed at an electrochemically activated screen-printed carbon electrode (SPCE) modified with Prussian Blue (PB). The PB acted as a mediator and thereby enhanced the rate of electron transfer in chemical reaction. Various optimization studies such as the pH of the measuring solution, linear range of response, sensitivity and detection limit, were conducted to obtain maximum amperometric responses for analytes measurement. Differential pulse voltammetry (DPV) was used for the simultaneous determination of HQ and CC in their mixture, and the peak-to-peak separation for HQ and CC was about 0.11 V. The two corresponding well-defined oxidation peaks of HQ and CC at activated Prussian Blue-modified screen-printed carbon electrode (PB-SPCE) occur at -0.012 V and +0.094 V, respectively. Under the optimized condition in DPV, the oxidation peak current of HQ and of CC is linear over a range from 4.0 × 10 -6 M to 9.0 × 10 -5 M HQ and from 1.0 × 10 -6 M to 9.0 × 10 -5 M CC. The obtained detection limit for HQ and CC was 1.17 × 10 -7 M and 4.28 × 10 -7 M, respectively. DPV can be used for individual or simultaneous determination of HQ and CC. The proposed activated PB-SPCE was successfully applied to the simultaneous determination of HQ and CC in spiked tap water. Using the standard addition method, the average recovery of the proposed method based on activated PB-SPCE was 99.03% and 95.87% for HQ and CC, respectively.

This study considers the effects of hydrostatic pressure on the line position and fluorescence lifetime for 5 D 0 → 7 F 2 transitions in Ga 3 Ga 5 O 12 doped with Eu 3+ nanoparticles. The results indicate that the pressure induced lines red shift towards longer wavelengths for all considered lines with different rate. The fluorescence lifetime rapidly decreases with pressure from an ambient pressure up to about 20 kbar and after that it is essentially unchanged up to the end of the considered pressure range. High pressure induced red-shift and fluorescence lifetime can be explained by a simple model. A satisfactory agreement between measured and theoretical predicted lines position and was obtained.

To evaluate the immediate microshear resin-enamel bond strength (μSBS) and the immediate and 6month microtensile bond strength (μTBS) and nanoleakage (NL) of the adhesive interface performed by different pHs of 40% meta-phosphoric acid (MPA) were compared with conventional 37% ortho-phosphoric acid (OPA) under different application times. Additionally, the enamel etching patterns were evaluated and the chemical/ morphological changes induced by these differents groups were evaluated. Materials and methods: One hundred and ninety-eight extracted human molars were randomly assigned into experimental groups according to the combination of independent variables: Acid [37% ortho-phosphoric acid (OPA), 40% meta-phosphoric acid (MPA) at pHs of: 0.5, 1 and 2] and Application Time [7, 15 and 30 s]. Enamelbond specimens were prepared and tested under μSBS. Resin-dentin beams were tested under μTBS tested immediately or after 6-months of water storage. Nanoleakage was evaluated using bonded-beams of each tooth/ time-period. Enamel etching pattern and chemical and ultra-morphology analyses were also performed. The μSBS (MPa) data were subjected to a two-way repeated measures ANOVA (Acid vs. Application time). For μTBS, Acid vs application time vs storage time data were subjected to three-way ANOVA and Tukey's test (α = 0.05). Results: MPA pH 0.5 showed μTBS similar to OPA, independently of the application time on enamel (p > 0.05) or dentin (p > 0.05). OPA provided higher nanoleakage values than MPA (p = 0.003). Significant decreases in TBS and increases in NL were only observed for OPA after 6 months (p = 0.001). An increase in the application time resulted in a more pronounced etching pattern for MPA. Chemical analysis showed that dentin demineralized by MPA depicted peaks of brushite and octacalcium phosphate. MPA exposed less collagen than OPA. However, optimal results for MPA were dependent on pH/application time. The use of 40% meta-phosphoric acid with a pH of 0.5 is an alternative acid-etching agent for dentin and enamel bonding. Furthermore, the use of MPA preserves the resin-dentin interface over a 6-months period, due to presence of brushite and octacalcium phosphate and a reduced demineralization pattern.

In general, the low-temperature brittle fracture mode of unembrittled ferritic steel is transgranular cleavage. During temper embrittlement, impurity elements, such as sulfur (S), phosphorus (P), antimony (Sb), arsenic (As), and tin (Sn), segregate to prior austenite grain boundaries, which results in a decrease in the grain boundary cohesive strength. As a result, the brittle transgranular cleavage fracture mode changes to intergranular decohesion in association with the decrease in the critical fracture stress ( F ) as well as the fracture toughness (K). However, the appearance of intergranular facets on the fracture surface does not cause a decrease in the K and F values. In this work, quenched and fully tempered 2.25Cr-1Mo steel (in an unembrittled condition that exhibits almost 100% brittle transgranular cleavage fracture) has been embrittled for 24, 96, and 210 h at 520 °C to produce different proportions of intergranular fracture. These unembrittled and embrittled steel specimens were tested to measure K (at -120 and -196 °C) and F (at -196 °C). The experimental results and detailed fractographic observations show that the K and F values decrease with an increase in the area fraction of intergranular fracture, provided that the area fraction of the intergranular facet on the brittle fracture surface exceeded a certain critical level, approximately 20-22%.