Chemical Engineering

Mg is one of the few materials of choice for biodegradable implants, despite its rapid degradation when used without surface protection treatment. This study presents the effect of carbonation time on the formation of hydrophobic carbonate coatings grown on pure magnesium using a simple, green chemical conversion method in carbonated water. The evolution of the coating with immersion time in carbonating solution was studied in order to ascertain the mechanistic of coating formation by Raman and EDS spectroscopy, XRD, SEM and AFM microscopy. Wettability was investigated by contact angle measurements. The formation mechanism of the hydrophobic coating involves the surface nucleation of carbonates mediated by the dissolution of the native corrosion product, brucite Mg(OH) 2 , surface conversion into hydroxycarbonates, surface calcite nucleation and growth by attachment of nanoparticles, leading to the lateral growth of a continuous carbonate coating layer of intertwined calcite microcrystals.

Cultural heritage metallic artifacts are often subjected to environmental factors that promote degradation through corrosion processes. Anticorrosion protection is needed both for the long-term preservation of outdoor monuments and the short-term conservation of archaeological artifacts. In this work, functional nanocoatings based on ZnO nanoparticles (NPs) in a silica matrix are prepared as a replacement for a commercial Incralac lacquer. Facile sol–gel synthesis is employed for obtaining silica filmogenic materials, using tetraethoxysilane (TEOS) and 3-glycidyloxypropyl trimethoxysilane (GPTMS). Silica-based nanocomposite coatings, with and without ZnO NPs and benzotriazole (BTA) as anticorrosion agents, applied on copper coupons by brushing are characterized by using VIS and FTIR spectroscopy, SEM and AFM and compared to Incralac lacquer as reference materials. The optical and morphological properties of the proposed silica coatings are similar to the Incralac specimens. The prot...

A simple method to fabricate organo-modified silane coatings for water-repellent surface modification was proposed, by using a microwave sol-gel synthesis of hybrid materials. Low-cost fluorine-free tetraethoxysilane (TEOS) and dodecyltriethoxysilane (DDTES) were used as silane derivatives. The organo-modified silica coatings were prepared by the drop-casting method and were characterized by UV-VIS, FTIR spectroscopy, and AFM and SEM microscopy. The morphology of the film show the existence of submicrometer scale roughness due to the aggregation of modified silica nanoparticles. Contact angles of water and diiodomethane on surfaces modified with as prepared nanostructured film were determined in order to assess the hydrophobic and oleophobic properties. The TEOS/DDTES ratio was proved to be a crucial factor in tuning the wettability properties. The results suggest that significant increase of hydrophobicity could be achieved by using non-fluorinated cost-effective silica nanomateria...

Multilayer films from hydrophobically modified poly(acrylic acid) (HMPA) and their complexes with cationic surfactants were successfully prepared using the layer-by-layer (LbL) method. Alkyl trimethylammonium bromide derivatives with various lengths of the hydrophobic chain (C10–C18) were used to interact with the HMPA polymer, generating highly hydrophobic domains in the films and contributing to the antimicrobial properties of the prepared coating. The antimicrobial efficiency against common pathogens such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans was investigated in relationship with the morphology and composition of the thin films. The wettability and roughness of the multilayered systems were evaluated using atomic force microscopy (AFM) and contact angle measurements. The effects of the microbial exposure on the surface properties of the prepared films were investigated in order to assess the stability of the HMPA-deposited multil...

Vanadyl-triisopropoxide (VOTIP) has been used for vapour deposition out of a carrier gas stream onto titania to prepare titania supported vanadia. The catalysts were characterized by means of temperature-programmed reduction (TPR), Raman-and slV nuclear magnetic resonance (NMR) spectroscopy and tested for the selective catalytic reduction of nitric oxide by ammonia. The influence of different preparation parameters on the structural and catalytic properties has been studied: (i) degree of dehydration (dehydroxylation) of the support, (ii) exposure to the VOTIP vapour phase and effect of successive depositions; and, (iii) calcination. The degree of dehydration of the support, which can be controlled by pretreatments, influences significantly the amount of deposited alkoxide. The upper limit of vanadia deposition that can be achieved by the used vapour deposition conditions is markedly lower than the one that can be reached by immersion of the carrier into liquid VOTIP. All preparation steps, including carrier pretreatment, deposition and calcination influence the structural and catalytic properties of the final catalysts. Highest intrinsic catalytic activity of the deposited vanadia has been observed above a threshold coverage, at which the formation of extended two-dimensional vanadia surface layers was revealed by Raman spectroscopy. Temperature-programmed desorption of ammonia showed a significant dependence of the profiles on the vanadia loading. On the pure titania support two distinct desorption maxima occurring at 405 K and at 520 K (broad) are observed. With increasing vanadia loading the broad maximum decreases, and simultaneously new sites are formed which correspond to ammonia weakly bound to Bransted sites desorbing at 350 K. The latter sites are considered to be most active for selective catalytic reduction of nitric oxide.

The present paper focuses on the effect of reduced hydrogen stoichiometry on the dynamic behavior of a PEMFC directly hybridized with SC or non-hybridized, using the European standard cycling protocol (FC-DLC) for transport applications. Two gas stoichiometry factors have been considered, at 1.2 and 1.1. Whereas direct hybridization of a single cell enables to reduce the hydrogen overconsumption from 28 % to 20 % at hydrogen stoichiometry of 1.2, the overconsumption was further reduced to 10 % by reducing the stoichiometry to 1.1. The durability of a single fuel cell has been investigated by comparing the long-term cycling operation depending on the hydrogen stoichiometric conditions, for both hybridized and nonhybridized fuel cell. The non-hybridized fuel cell, at hydrogen stoichiometry of 1.2, was operated for 687 h (end of life), whereas the non-hybridized fuel cell at 1.1, could not be operated due to the sudden, excessive voltage drop in the high current density period of the cycle. On the contrary, the hybridized fuel cell was successfully submitted to cycling for more than 1000 h at both conditions of hydrogen stoichiometry. The GDL appears to be responsible for the failure of non-hybridized fuel cell performance, whereas no particular degradation was evidenced with hybridized configurations. Finally, the technique has been successfully applied to a three-cell stack, with very comparable voltage profiles of the individual cells over the cycling protocol.

Keinginan konsumen untuk memperoleh produk pangan yang bercitarasa baik, berkualitas, terjangkau secara ekonomis, serta dikemas dalam bentuk makanan ringan yang efisien dan mudah dibawa kemana saja. Manusia tidak hanya membutuhkan makanan pokok, tetapi juga makanan ringan di sela-sela aktivitasnya. Kesibukan terhadap pekerjaan akan mengganggu asupan makanan dalam tubuh, sehingga diperlukan produk makanan ringan yang bersifat menyegarkan dan menyehatkan salah satunya adalah permen. Sampai saat ini Indonesia masih mengimpor permen dari negara luar, seperti China. Kekayaan sumber daya alam di Indonesia sangat melimpah dan masih belum dimanfaatkan sepenuhnya, sehingga diperlukan industri-industri yang inovasi untuk memanfaatkan kekayaan alam. Industri permen merupakan salah satu industri yang menggunakan kekayaan alam di Indonesia, dapat meningkatkan devisa negara, serta memanfaatkan sumber daya manusia. Salah satu kekayaan alam Indonesia yang tersedia melimpah adalah pohon asam. Asam j...

Ce projet vise à optimiser l'utilisation de l'eau dans une brasserie en réutilisant les eaux usées. Le procédé étudié étant discontinu, la méthode graphique décrite par Majozi et al. (2006), qui considère le temps comme contrainte principale, a été utilisée. L'étude démontre qu'il est possible d'optimiser la consommation d'eau dans la brasserie en intégrant des systèmes de réutilisation des eaux usées, ce qui entraînerait des économies significatives et une réduction des coûts liés à la gestion des eaux. Les résultats indiquent une amélioration notable de l'efficacité des ressources, avec un retour sur investissement rapide. Cette approche durable non seulement repondérait aux exigences environnementales, mais renforcerait également la viabilité économique de l'entreprise.

We have modelled a macrolipid polymer composed of lipid molecules (monomers) embedded in a lipid bilayer or monolayer and polymerized via their polar groups. Because of fluctuations perpendicular to the plane of the bilayer, the polar region occupied by the polymer chain possesses sufficient space so that the polymer might exhibit 'self-intersection' if its conformational state is projected onto the plane of the bilayer/monolayer. We represent the plane of the bilayer/monolayer by a triangular lattice. Each site can be occupied by a monomer or be empty (and thus occupied by one of the unpolymerizable lipids which make up the bilayer/monolayer). A macrolipid is represented by a sequence of N monomers connected by N-1 bonds. Bonds may be either short (connecting nearest neighbour monomers) or long (between second neighbour monomers), in accord with the average properties of the spacers between the polymerized lipids. We have carried out computer simulation of this system using the Carmesin-Kremer bond stretching algorithm. Although no two monomers can occupy the same site, bonds may cross each other. We analyzed the dependence of (R 2) and (R 2) ~ N 2~c and (Nsc) + (Nmc) ~ N 2crc, where N~ and Nmc are the number of bond-crossings in the same macrolipid ('self-crossing') or in two different macrolipids ('mutual-crossing'). For single macrolipids, we confirmed that u c = 3/4 and have found that tr c = 0.52, which we consider supports that tr c = 1/2. For the dense case with monomer concentration, c = 0.72, we found that vc = 1/2 and that tr c ---0.52 supports that ~r~ = 1/2. In the semi-dilute regime (c = 0.2) we found crossover behaviour, although tr~ = 1/2. The total number of bond crossings thus scale like N, independent of concentration. We studied the connectivity of the system by calculating the weight averaged cluster, or 'clique', size. Cliques are defined as being composed of all macrolipids which exhibit at least one crossing bond with one other member of the clique. We found that while the average clique contains about two macrolipids at low concentrations, the clique size approaches the maximum possible value at high concentrations if the macrolipids are sufficiently long. In the latter case a transition appears to occur as the macrolipid length increases. This transition occurs at length = 40 when c = 0.72. These observations should have experimental consequences for the viscoelastic properties of the system. We defined an order parameter, B, and showed that although B depended upon c, it appeared to be independent of N for both crossing and non-crossing macrolipids. We calculated the dependence of the lateral diffusion coefficient upon c for some values of N and compared it to the case of non-crossing macrolipids and single lipid molecules. We suggest how the existence of crossing bonds might be observed.

We consider systems that are well modelled as networks that evolve in time, which we call Moving Neighborhood Networks. These models are relevant in studying cooperative behavior of swarms and other phenomena where emergent interactions arise from ad hoc networks. In a natural way, the time-averaged degree distribution gives rise to a scale-free network. Simulations show that although the network may have many noncommunicating components, the recent weighted time-averaged communication is sufficient to yield robust synchronization of chaotic oscillators. In particular, we contend that such time-varying networks are important to model in the situation where each agent carries a pathogen (such as a disease) in which the pathogen's lifecycle has a natural time-scale which competes with the time-scale of movement of the agents, and thus with the networks communication channels.

Functionalized propiolamidine derivatives were prepared in good to excellent yields under very mild conditions via a copper‐catalyzed multicomponent reaction (MCR) of readily available terminal alkynes, acid chlorides and carbodiimides with the assistance of triethylamine. The mechanism of this MCR is postulated.

Fibroin (FB) and bacterial nanocellulose (BC) are natural products, being used in biomedicine, electronics, food industries and other areas. Both show biocompatibility, able to be used for many different purposes. The blending of fibroin and bacterial nanocellulose was design to produce a biocompatible material to be applied with a medical device. For this reason, the objective of this work was to evaluate the structure properties of the blending of BC and FB. Thus, FB was extracted from Bombyx mori and BC was produced by fermentation process utilizing Gluconacetobacter xylinus. The membranes composed of BC-FB were produced by immersion contact for 24 hours, at 25°C, in 100rpm; without crosslinking agent. After the production the membrane samples were dried and characterized by Fourier transform infrared spectroscopy (FTIR spectroscopy), mechanical proprieties, swelling efficiency, scanning electron microscopy (SEM) and computerized microtomography (µCt). Results indicate that the h...

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.

Three new trinuclear hetero-metallic complexes [(CuL)2Zn(NCS)2] (), [(CuL(R))2Zn(NCS)(μ1,1-NCS)] () and [(CuL(R))2Cd(μ1,3-NCS)2] () have been synthesized using [CuL] and [CuL(R)] as "metalloligands" (where H2L = N,N'-bis(salicylidene)-1,3-propanediamine and H2L(R) = N,N'-bis(2-hydroxybenzyl)-1,3-propanediamine). All three complexes are characterized by elemental analysis, spectroscopic methods and single crystal XRD. Complex is an angular trinuclear species, in which two terminal four-coordinate square planar "metalloligands" [CuL] are coordinated to a central Zn(ii) through double phenoxido bridges along with two mutually cis nitrogen atoms of terminal isothiocyanate ions as is usually found in such complexes. In contrast, in complex , the two terminal "metalloligands" [CuL(R)] are square pyramidal, as one of the SCN(-) ions makes an unusual μ1,1-NCS bridge between copper centers while the other one coordinates to Zn(ii) through a N atom in a u...

Three new trinuclear heterometallic Ni II -Mn II complexes have been synthesized using [NiL] metalloligand where H2L = N,N′-bis(salicylidene)-1,3-propanediamine. The complexes [(NiL)4Mn2(OCn)4(CH3OH)4]•2CH3OH (1), [(NiL)4Mn2(OPh)4(CH3OH)2]•H2O (2) and [(NiL)4Mn(OSal)2(CH3OH)2] (3) (where OCn = cinnamate, OPh = phenylacetate, OSal= salicylate) have been structurally characterized. In all three complexes, in addition to the double phenoxido bridge, the two terminal Ni II atoms are linked to the central Mn II by means of syn-syn bridging carboxylate, giving rise to a linear structure. Complexes 1 and 2 with Ni-O-Mn angle of 97.24 and 96.43° respectively exhibit ferromagnetic interactions ( JNi-Mn = +1.38 and +0.50 cm -1 respectively) whereas 3 is antiferromagnetic (JNi-Mn= -0.24 cm -1 ) having Ni-O-Mn angle of 98.51°. DFT calculations indicate that there is a clear magneto-structural correlation between Ni-O-Mn angle and JNi-Mn values which is in agreement with the experimental results.

The synthesis of two new sodium perchlorate adducts (1:2 and 1:3) with copper(II) ''ligand-complexes'' is reported. One adduct is trinuclear [(CuL 1 ) 2 NaClO 4 ] (1) and the other is tetranuclear [(CuL 2 ) 3 Na]-ClO 4 ÁEtOH (2). The ligands are the tetradentate di-Schiff base of 1,3-propanediamines and salicylaldehyde (H 2 L 1 ) or 2-hydroxyacetophenone (H 2 L 2 ). Both complexes have been characterized by X-ray single crystal structure analyses. In both structures, the sodium cation has a six-coordinate distorted octahedral environment being bonded to four oxygen atoms from two Schiff-base complexes in addition to a chelated perchlorate anion in 1 and to six oxygen atoms from three Schiff-base complexes in 2. We have carried out a DFT theoretical study (RI-B97-D/def2-SVP level of theory) to compute and compare the formation energies of 1:2 and 1:3 adducts. The DFT study reveals that the latter is more stabilized than the former. The X-ray crystal structure of 1 shows that the packing of the trinuclear unit is controlled by unconventional C-HÁÁÁO H-bonds and Cu 2+ -p non-covalent interactions. These interactions explain the formation of 1 which is a priori disfavored with respect to 2.

Oxime-based tridentate Schiff base ligands 3-[2-(diethylamino)ethylimino]butan-2-one oxime (HL 1 ) and 3-[3-(dimethylamino)propylimino]butan-2-one oxime (HL 2 ) produced the dinuclear complex [Ni 2 L 1 2 ](ClO 4 ) 2 (1) and trinuclear complex [Ni 3 (HL 2 ) 3 (μ 3 -O)](ClO 4 ) 4 •CH 3 CN (2), respectively, upon reaction with Ni(ClO 4 ) 2 •6H 2 O. However, in a slightly alkaline medium, both of the ligands underwent hydrolysis and resulted in tetranuclear complexes [{Ni(deen)(H 2 O)} 2 (μ 3 -OH) 2 {Ni 2 (moda) 4 }](ClO 4 ) 2 •2CH 3 CN (3) and [{Ni(dmpn)(CH 3 CN) 2 } 2 (μ 3 -OH) 2 {Ni 2 (moda) 4 }](ClO 4 ) 2 •CH 3 CN ( ), where deen = 2-(diethylamino)ethylamine, dmpn = 3-(dimethylamino)-1-propylamine, and modaH = diacetyl monoxime. All four complexes have been structurally characterized. Complex 1 is a centrosymmetric dimer where the square planar nickel(II) atoms are joined solely by the oximato bridges. In complex 2, three square planar nickel atoms form a triangular core through a central oxido (μ 3 -O) and peripheral oximato bridges. Tetranuclear complexes 3 and 4 consist of four distorted octahedral nickel(II) ions held together in a rhombic chair arrangement by two central μ 3 -OH and four peripheral oximato bridges. Magnetic susceptibility measurements indicated that dinuclear 1 and trinuclear 2 exhibited diamagnetic behavior, while tetranuclear complexes 3 and 4 were found to have dominant antiferromagnetic intramolecular coupling with concomitant ferromagnetic interactions. Despite its singlet ground state, both 3 and 4 serve as useful examples of Kahn's model for competing spin interactions. High-frequency EPR studies were also attempted, but no signal was detected, likely due to the large energy gap between the ground and first excited state. Complexes 3 and 4 exhibited excellent catecholase-like activity in the aerial oxidation of 3,5-di-tert-butylcatechol to the corresponding o-quinone, whereas 1 and 2 did not show such catalytic activity. Kinetic data analyses of this oxidation reaction in acetonitrile revealed that the catalytic activity of 3 (k cat = 278.4 h -1 ) was slightly lower than that of 4 (k cat = 300.0 h -1 ). X-band EPR spectroscopy indicated that the reaction proceeded through the formation of iminoxyl-type radicals.

Two new Mn(III) complexes of formulas [MnL 1 (N 3 )(OMe)] 2 (1) and [MnL 2 (N 3 ) 2 ] n (2) have been synthesized by using two tridentate NNO-donor Schiff base ligands HL 1 {(2-[(3-methylaminoethylimino)-methyl]-phenol)} and HL 2 {(2-[1-(2-dimethylaminoethylimino)methyl]phenol)}, respectively. Substitution of the H atom on the secondary amine group of the N-methyldiamine fragment of the Schiff base by a methyl group leads to a drastic structural change from a methoxido-bridged dimer (1) to a single μ 1,3azido-bridged 1D helical polymer (2). Both complexes were characterized by single-crystal X-ray structural analyses and variable-temperature magnetic susceptibility measurements. The magnetic properties of compound 1 show the presence of weak ferromagnetic exchange interactions mediated by double methoxido bridges (J = 0.95 cm -1 ). Compound 2 shows the existence of a weak antiferromangetic coupling along the chain (J = -8.5 cm -1 ) through the single μ 1,3 -N 3 bridge with a spin canting that leads to a long-range antiferromagnetic order at T c ≈ 9.3 K and a canting leading to a weak ferromagnetic long-range order at T c ≈ 8.5 K. It also exibits metamagnetic behavior at low temperatures with a critical field of ca.1.2 T due to the weak antiferromagnetic interchain interactions that appear in the canted ordered phase.

Two mixed bridged one-dimensional (1D) polynuclear complexes, [Cu 3 L 2 (μ 1,1 -N 3 ) 2 (μ-Cl)Cl] n (1) and {[Cu 3 L 2 (μ-Cl) 3 Cl] 3 0.46CH 3 OH} n (2), have been synthesized using the tridentate reduced Schiff-base ligand HL (2-[(2dimethylamino-ethylamino)-methyl]-phenol). The complexes have been characterized by X-ray structural analyses and variable-temperature magnetic susceptibility measurements. In both complexes the basic trinuclear angular units are joined together by weak chloro bridges to form a 1D chain. The trinuclear structure of 1 is composed of two terminal square planar [Cu(L)(μ 1,1 -N 3 )] units connected by a central Cu(II) atom through bridging nitrogen atoms of end-on azido ligands and the phenoxo oxygen atom of the tridentate ligand. These four coordinating atoms along with a chloride ion form a distorted trigonal bipyramidal geometry around the central Cu(II). The structure of 2 is similar; the only difference being a Cl bridge replacing the μ 1,1 -N 3 bridge in the trinuclear unit. The magnetic properties of both trinuclear complexes can be very well reproduced with a simple linear symmetrical trimer model (H = -JS i S iþ1 ) with only one intracluster exchange coupling (J) including a weak intertrimer interaction (j) reproduced with the molecular field approximation. This model provides very satisfactory fits for both complexes in the whole temperature range with the following parameters: g = 2.136(3), J = -93.9(3) cm -1 and zj = -0.90(3) cm -1 (z = 2) for 1 and g = 2.073(7), J = -44.9(4) cm -1 and zJ 0 = -1.26(6) cm -1 (z = 2) for 2.

A multifunctional porous metal organic framework based on mixed-valence hexa-nuclear [Mn III 2 Mn II 4 O 2 (pyz) 2 (C 6 H 5 CH 2 COO) 10 ] (pyz = pyrazine) units has been synthesized. The complex has been characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction analysis, and variable-temperature magnetic measurements. The structural analysis reveals that the bidentate pyz molecules connect each [Mn 6 ] unit to its four [Mn 6 ] neighbors through the peripheral Mn(II) centers, giving rise to a threedimensional (3D) distorted diamond-like porous framework. Variable-temperature (2-300 K) magnetic susceptibility measurements show the presence of dominant antiferromagnetic interactions within the discrete [Mn 6 ] cluster that have been fitted with a model containing three exchange constants developed for the complex (J 1 = -8.6 cm -1 , J 2 = -3.9 cm -1 , and J 3 = -100.0 cm -1 ). Using 3,5-di-tert-butyl catechol (3,5-DTBC) as the substrate, catecholase activity of the complex has been studied; the turn over number is determined to be of 2547 h -1 in acetonitrile. This porous compound shows remarkable selectivity for adsorption of CO 2 over N 2 that may be correlated with the effect of window flexibility of the pore to the corresponding adsorbate molecules.

Methanol is expected to be a possible solution for reducing global greenhouse gas emissions and minimizing the dependency on fossil fuels. This paper presents a systematic approach of methanol (MeOH) production from industrial waste gases including flue gas (FG) and coke oven gas (COG) that are considered an important threat to the environment. The impact of process parameters, including dimensional parameters (length, diameter, and number of tubes) and operational parameters (reactor temperature, pressure, and thermal fluid temperature) over the MeOH synthesis, are investigated by Aspen Plus. Firstly, the synthesis process is designed and optimized using syngas (SG) as a feed material. Secondly, by replacing the feed material with FG and COG, methanol production variability is investigated and demonstrated for the same optimized process. Afterward, an efficient heat exchange network system is developed for all three different processes using Aspen Energy Analyzer. The optimized dim...

Keying of lithium chloride alkali halide salt into the interlamellar space of nacrite clay mineral leads to a stable hybrid material that after calcination under inert atmosphere at 723 -873 K induces an amorphous metahybrid. The electrochemical impedance spectroscopy (EIS) was performed to investigate the electric/dielectric properties of the hybrid with various parameters: frequency and temperature. Equivalent circuit was proposed to fit the EIS data. The experiment results show that the ionic conduction mechanism is related to the motion of Li + cations which are thermally activated, named the hopping model. Furthermore, the resulting metahybrid obtained from dehydroxylation of the formal hybrid shows a superionic behavior with high ionic conductivity up to 10 -2 S•m -1 , good electrochemical stability and can be used as a solid electrolyte material for Li-ion batteries.

The development of eco-friendly and nontoxic processes for the synthesis of nanoparticles is one of the most important discussed issues in nanotechnology science. This study reports the green synthesis of silver nanoparticles (AgNPs) using aqueous extract of leaf, stem, and root of Avicennia marina, the native and dominant mangrove plant in southern Iran. Among the different plant parts, the extract of leaves yielded the maximum synthesis of AgNPs. Synthesized AgNPs were investigated using UV-visible spectrophotometry, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) spectroscopy. Absorption spectrum in 420 nm confirmed the synthesis of AgNPs. TEM images revealed that the synthesized AgNPs had the same spherical morphology with a size range between 0 and 75 nm. The distribution size histogram indicated that the most frequent particles were in the range of 10-15 nm and the mean size of nanoparticles was 17.30 nm. The results of SEM image showed nanoparticles with a size range between 15 and 43 nm. XRD pattern indicated the crystalline nature of synthesized nanoparticles. EDS results confirmed the presence of elements like silver, carbon, chlorine, nitrogen, and oxygen in the nanoparticles produced from leaf extract. Silver had the maximum percentage of formation, 51.6%. FTIR indicated the presence of different functional groups such as amines, alcohol, alkanes, phenol, alkyl halides, and aromatic loops in the synthesis process. Green biosynthesis of AgNPs using aqueous extract of native A. marina appears rapid, reliable, nontoxic, and eco-friendly.

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.

ABSTRACTWe used sporopollenin prepared from Lycopodium Clavatum to encapsulate living yeast cells as a model for probiotics. The microencapsulation of cells was achieved by using the trilite scars of the sporopollenin microcapsules which can open up by compressing the sporopollenin into a pellet. Such compressed pellets were exposed to an aqueous suspension of yeast cells in the presence of a biocompatible surface active agent which allowed living cells to be loaded inside the sporopollenin particles by the influx of liquid to the sporopollenin interior as the deformed microcapsules re-inflated to their original state. We demonstrated that the cells viability and biological activity is preserved after the microencapsulation in the sporopollenin. Such microencapsulation technology could find application in preserving cells from mechanical stress and aggressive environments which can be used in protection of probiotics in food formulations.

Au/ZnO-CeO 2 hybrid structure was prepared by in-situ synthesis of 15-20nm CeO 2 particles in aqueous environment, in which ZnO particles (400-500nm) were dispersed, using surfactant assisted precipitation method. Au was loaded on prepared structures through the reduction of AuCl 3 by ascorbic acid. TEM analysis and Raman spectroscopy showed that synthesized hybrid structure is composed of both hexagonal ZnO and cubic CeO 2 phases. While methylene blue test solution was degraded totally within 8 minutes in the presence of Au/ZnO-CeO 2 hybrid catalysis, use of Au/ZnO and Au/CeO 2 led to a significantly low degradation rate (about 22% and 11%, respectively). As proven by XPS analysis the incorporation of ZnO to CeO 2 seem to trigger the formation of Ce +3 /Ce +4 dynamic equilibria and this enhances the catalytic efficiency enormously.

In this study, the effect of the synthesis method (solid state, sol-gel and hydrothermal) on the photocatalytic activity of the anatase and rutile phases of TiO2 was evaluated. As a result of XRD, FESEM and BET analysis of pure phase TiO2 powders in anatase and rutile phases, the changes in particle structures, surface areas and morphologies were examined and the differences in both synthesis method and phase structures were evaluated with Photodegradation experiments. The results of the X-ray diffraction (XRD) analysis showed that the TiO2 compound synthesized in the anatase phase and by the synthesized hydrothermal method exhibited a much smaller crystal size than the other synthesis methods and the rutile phase. Surface morphology examinations of the samples were made with scanning electron microscopy (FESEM), particle sizes were determined in the range of 90-200 nm, and their surface areas were examined by Brunauer-Emmett-Teller (BET) analysis.The adsorption-desorption isotherms shown also support the XRD data of the highest surface area.The photocatalytic behavior of the compounds was investigated using methylene blue degradation.As a result of all the syntheses and characterization studies, it has been shown that TiO2 obtained by hydrothermal method exhibits the best photocatalytic activity.

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.

Twelve terpenes were tested as pure fuels in a direct injection diesel engine. The terpenes are potential products of a genetically engineered cyanobacteria. Molecular structure of the terpenes impacted significantly on ignition quality. Four terpenes were tested as diesel and gasoline extenders up to 60% terpene. Terpene toxicity to the suggested producing cyanobacteria was also assessed.

The present work addresses the application of a water spray system in case of a fire event in large-scale experiments for nuclear safety issues. It focuses on the interaction between a water spray system and a stratified smoke layer due to a pool fire in a mechanically ventilated enclosure. This study is supported by a set of four large-scale tests and one numerical simulation with a 3D CFD software, named CALIF 3 S/ISIS, and developed by the French Institut de Radioprotection et de Sûreté Nucléaire (IRSN). The modelling used in this paper is based on an Eulerian-Lagrangian approach. The fire tests are performed in a 165 -m 3 mechanically ventilated single room. The fire is a lubricant oil pool fire of about 400 kW. The ventilation flow rate is 2550 m 3 .h -1 and corresponds to a renewal rate of 15.5 h -1 . The spray nozzles are deluge and sprinkler type. The test parameters are the water flow rate, the time of activation, and the duration of activation. Based on the large-scale experiments and the numerical simulation, four typical physical mechanisms have been enlightened. The first one corresponds to the cooling of the gas phase that is the straightforward consequence of the heat transfer exchange between the water droplets and the surrounding gas. The second effect is the process of gas mixing and homogenization induced by the water spraying system. The gas concentrations (O 2 , CO 2 ) in the upper and lower parts of the room tend to the same level. The third effect is the significant increase of the fire heat release rate (HRR), up to 25 %, when the water spray is activated. Then, the last noteworthy effect is the occurrence of gas pressure peaks when the water spray is activated or shut off, consequence of the sudden change of the gas temperature. The processes of gas cooling and fire HRR increase are showed to be the main causes of these variations of gas pressure.

Advanced oxidation processes utilizing both UV/H 2 O 2 and photo-Fenton UV/H 2 O 2 /Fe +3 systems were investigated using pilot-scale experiments for the degradation and mineralization of 4-chlorophenol (4-CP). The experiments were conducted by using a photoreactor, which consists of three UV lamps fixed in staggered form. Three baffles were fixed vertically at the reactor side walls. These baffles reduce the presence of low radiation zones near the reactor walls. The study shows that the photo-Fenton process was the most effective treatment process under acidic conditions pH = 3, and produced a higher rate of degradation of 4-CP at a very short irradiation time. The reaction was found to follow the first order through both systems. A colored solution of benzoquinone can be observed through the first 5 min of irradiation time for the UV/H 2 O 2 system when a low concentration (0.01 mol/L) of H 2 O 2 was used. The colored solution of benzoquinone can also be observed through the first 5 min for the UV/ H 2 O 2 /Fe +3 system at a high concentration (100 ppm) of 4-CP. The experimental results show that the optimum reagents for complete degradation of 4-CP (50 ppm) were H 2 O 2 = 0.005 mol/ L, Fe +3 = 0.16 Â 10 À3 mol/L under acidic conditions (pH = 3), and irradiation time of 15 min for the UV/H 2 O 2 /Fe +3 system with a molar ratio of H 2 O 2 /Fe +3 /4-CP equals 13/0.4/1.

In order to reduce restenosis, the necessity to develop the appropriate coating material of metallic stent is a challenge for biomedicine and scientific research over the past decade. Therefore, biodegradable copolymers of poly((R,S)-3,3 dimethylmalic acid) (PDMMLA) were prepared in order to develop a new coating exhibiting different custom groups in its side chain and being able to carry a drug. This material will be in direct contact with cells and blood. It consists of carboxylic acid and hexylic groups used for hydrophilic and hydrophobic character, respectively. The study of this material wettability and dynamic surface properties is of importance due to the influence of the chemistry and the potential motility of these chemical groups on cell adhesion and polymer kinetic hydrolysis. Cassie theory was used for the theoretical correction of contact angles of these chemical heterogeneous surfaces coatings. Dynamic Surface Analysis was used as practical homogenizer of chemical heterogeneous surfaces by cycling during many cycles in water. In this work, we confirmed that, unlike receding contact angle, advancing contact angle is influenced by the difference of only 10% of acidic groups (%A) in side-chain of polymers. It linearly decreases with increasing acidity percentage. Hysteresis (H) is also a sensitive parameter which is discussed in this paper. Finally, we conclude that cycling provides real information, thus avoiding theoretical Cassie correction. H 10 is the most sensible parameter to %A.

In order to reduce restenosis, the necessity to develop the appropriate coating material of metallic stent is a challenge for biomedicine and scientific research over the past decade. Therefore, biodegradable copolymers of poly((R,S)-3,3 dimethylmalic acid) (PDMMLA) were prepared in order to develop a new coating exhibiting different custom groups in its side chain and being able to carry a drug. This material will be in direct contact with cells and blood. It consists of carboxylic acid and hexylic groups used for hydrophilic and hydrophobic character, respectively. The study of this material wettability and dynamic surface properties is of importance due to the influence of the chemistry and the potential motility of these chemical groups on cell adhesion and polymer kinetic hydrolysis. Cassie theory was used for the theoretical correction of contact angles of these chemical heterogeneous surfaces coatings. Dynamic Surface Analysis was used as practical homogenizer of chemical heterogeneous surfaces by cycling during many cycles in water. In this work, we confirmed that, unlike receding contact angle, advancing contact angle is influenced by the difference of only 10% of acidic groups (%A) in side-chain of polymers. It linearly decreases with increasing acidity percentage. Hysteresis (H) is also a sensitive parameter which is discussed in this paper. Finally, we conclude that cycling provides real information, thus avoiding theoretical Cassie correction. H 10 is the most sensible parameter to %A.

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.

We demonstrate that small-angle neutron scattering (SANS) can be used to determine the density and volume fraction of the adsorbed fluid phase in porous materials. The developed methodology is used to study the adsorption of near-critical CO2 and propane in aerogel as a function of pressure and temperature. For the first time the variation of the density and volume fraction of the adsorbed phase of nearcritical fluids is reported and analyzed. These parameters are used to determine the absolute fluid adsorption without additional assumptions commonly used in the literature. The adsorption of CO2 and propane (8 g/g and 1 g/g, respectively) is found to be significantly higher in aerogels than in activated carbons and silica gels. The results provide new insights in the adsorption behavior of supercritical fluids, such as a non-monotonic variation of the density of the adsorbed phase and depletion of aerogel at high pressures.

An accurate gravimetric method was used to explore water adsorption/desorption isotherms between 105 and to 250°C for a number of synthetic and natural porous solids including controlled pore glass, activated carbon fiber monoliths, natural zeolites, pillared clay, and geothermal reservoir rocks. The main goal of this work was to evaluate water adsorption results, in particular temperature dependence of hysteresis, for relatively uniform, nano-structured solids, in the context of other state-of-the-art experimental and modeling methods including nitrogen adsorption, spectroscopy, neutron scattering, and molecular simulation. Since no single method is able to provide a complete characterization of porous materials, a combination of approaches is needed to achieve progress in understanding the fluid-solid interactions on the way to developing a predictive capability.

Stabilisers are used in propellants to prevent the various effects such as oxidation, chain scission, energy loss and uncontrolled heat generation that are caused by homolytic and heterolytic cleavage of the weakest Nitrogen-Oxygen bond of the nitrate ester functional group. Conventional stabilisers for nitrocellulose-based propellants belong to a-aromatic amines (e. g., diphenylamine, 4-nitro-N-meth-ylaniline…) or b-aromatic urea derivatives (e. g., Akardite, centralite…) and are/or produce highly toxic and/or potentially carcinogenic species at some point during a propellant's lifetime. There is an obvious need for alternative sta-bilisers presenting a low toxicity profile and providing efficiencies similar to, or better than conventional stabilisers. This paper presents novel, environmentally friendly, efficient and readily-available stabilisers for use in nitrocellulose-based compositions. With REACh legislation (1907/2006), industry in Europe has made progress in using less toxic compounds, that are often more environmentallyfriendly. The aim of this work is to go beyond REACh and to anticipate the inclusion of other molecules that produce non-or less toxic daughter products and that can fulfil their role in the propellant's formulation.

The syntheses and characterization of a series of binuclear bis(p-oxo)dimanganese(III,III), -(III,IV), and -(IV,IV) complexes of the general type [ ( A ) ~M I I ( O ) ] ~~+ / ~+ / ~+ , where the symbol A4 represents the four nitrogen atoms from a tetradentate ligand, are described. The ligands (A)4 used are N,N'-bis(2-pyridylmethyl)-N,N'dimethyl-1,2ethanediamine (bispicMe2en) and N,N'-bis( 2-pyridylmethyl)-N,N'-dimethyl-(-)~-1,2-~yclohexanediamine (bispicMq-(-)chxn). The syntheses and properties of the (IIIJII), (IIIJV), and (IV,IV), complexes (where (111,111) represents dimanganese(III,III), etc.) of bispicMe2en are described, as are those of the (II1,IV) and (IV,IV) complexes of bispicMe2(-)chxn. The (II1,IV) complex [(bispicMe2en)Mn(O)]2(C104)3.H20 (1) crystallizes in the monoclinic space group P21/c with 4 formula units in a cell of dimensions a = 19.839(4) A, b = 12.468(3) A, c = 19.878(3) A, and / 3 = 120.657( )O. The structure refined to a final R-factor of 0.062 based on 2874 reflections. The isomer crystallized is the cis-a-species, in which the pyridine nitrogen atoms are trans. The Mn( 1)-0 bonds are approximately 0.06 8, longer than the Mn(2)-0 bonds, and the geometry at Mn( 1) is significantly axially elongated; hence, the manganese atoms can be distinguished as Mn( 1) being Mn(II1) and Mn(2) being Mn(1V). The M w M n separation in the dimer is 2.678(2) A. The (111,111) complex [(bispicMe~en)Mn(O)]2(C104)2-5H20 (3) crystallizes in space group Aba2 of the orthorhombic system with four dinuclear formula units in a cell of dimensions a = 15.561(3) A, b = 16.703(3) A, and c = 16.430(3) A. The structure has been refined to a final R-factor of 0.0564 based on 2548 observed independent reflections. The isomer is again the cis-a-species. There is a crystallographic 2-fold axis passing through the center of the dimer and relating one manganese(II1) center to the other. As is expected for a d4 Mn(II1) ion, the geometry at manganese is axially elongated, the average Mn-N(axia1) bond being approximately 0.12 8, longer than the average of the equatorial Mn-N bonds. The Mn.-Mn separation in the dimers of 2.699(2) A is comparable to that in related systems. The (II1,IV) complex [(bispicMe2(-)chxn)MnO2Mn-(bispicMe2(-)chxn)](ClO& (4) crystallizes in the orthorhombic space group P212121 with four dinuclear formula units in a cell of dimensions a = 13.098(3) A, b = 16.297(3) A, and c = 23.273(4) A. The structure has been refined to a final R-factor of 0.0620 based on 3057 observed independent reflections. The isomer is cis-a, with roughly isotropic geometry at Mn(2) and axial elongation at Mn(1). Thus atom Mn( 1) is the localized d4 Mn(II1) site and Mn(2) is the localized d3 Mn(1V) center. The Mn-Mn separation in the dimer is 2.693(2) A. The complexes exhibit antiferromagnetic interactions, the (111,111) complex 3 having 25 = -201 cm-1, the (IVJV) complexes 2 and 5 25 values of -205 and -21 1 cm-l, respectively, and the (II1,IV) complexes 1 and 4 2 J values of -320 and -293 cm-I, respectively.

White Light Reflectance Spectrometry (WLRS) allows the wavelength dispersion of reflectance (Ro) values to be measured and recorded. Previous studies have extensively evaluated the wavelength dispersion of macerals in various coal ranks and types. This study examines the wavelength dispersion of recycled vitrinite and inertinite macerals as well as bituminite macerals in an immature oil shale with the objective of studying the variation in wavelength dispersion associated with changes in Ro due to bacterial degradation of bituminite macerals and recycling of vitrinite macerals. Four samples were measured from the thermally immature zone of the Upper Cretaceous Second White Specks Formation in Central Alberta. These samples were analyzed geochemically (using Rock-Eval) and petrographically for reflectance and using WLRS. Red/green wavelength reflectance ratios in bituminite macerals demonstrate a drop off in variation due to bacterial degradation at Ro of approximately 0.55%, which is close to the onset of maturity. This dropoff suggests that the transformation of the organic matter (OM) leading to the liberation of hydrogen and oxygen rich molecules not only increases Ro but also results in a shift in the R/G ratio of the measured maceral. Wavelength dispersion trends in recycled vitrinite/inertinite macerals follows similar trends to those observed previously in coals, with a gradual decrease in reflectance toward lower wavelengths. Results indicate that the wavelength dispersion trends of recycled vitrinite/inertinite macerals in an organic rich mud rock closely follow the trends previously observed in coals. Determination of unaltered macerals is a difficult but important step in characterizing the organic matter of the oil shale and in calculating its source rock potential. This study demonstrates that the WLRS method can be used in conjunction with Ro by observing the R/G variability dropoff in order to distinguish the best preserved primary OM population from OM that has been bacterially or thermally degraded or altered.

The Laird Basin one of the "world-scale" shale basins in Canada, has significant shale gas resources in Devonian-Mississippian strata, but despite the shale gas potential of the Lower Cretaceous Garbutt Formation, it remains under-explored. This study presents organic matter (OM) characterization, thermal maturity, hydrocarbon potential and reservoir characteristics of the lower part of the Lower Cretaceous Garbutt Formation known as the "radioactive zone" (RZ), in the eastern parts of Liard Basin in British Columbia, Canada. The Garbutt Formation is an organic-rich shale with mean total organic carbon (TOC) content of 3.5 ± 2.2 wt% (1.1-15.1 wt%; n = 101). The predominant OM constituents comprised of liptinite group (alginite) with a lower abundance of vitrinite and intertinite group macerals that define as Type II/III kerogen. Thermal maturity varies from the onset of the oil window to the condensate zone, with a progressive north to south increasing trend. Differential burial and uplift between north and south of the basin can be a possible explanation for the observed thermal maturity trend. Porosity and specific surface area values of the Garbutt shales (n = 28) range from 3 to 11%, and 0.3 to 10.9 m 2 /g, respectively and appear to increase with thermal maturity. The scanning electron microscopy (SEM) images reveal that, intercrystalline and intergranular porosity are the two major types of porosity, together with minor fracture porosity. Intercrystalline porosity is dominant in the shale matrix in the northern part of the basin, and associated within pyrite framboids and clay aggregates. Intergranular porosity forms the major pores within the condensate zone in southern part of the basin due to higher quartz content and lower clay content in comparison to north of the basin. The TOC appears to have no major contribution to the total porosity as there is no correlation between porosity and TOC. Scanning electron microscopy (SEM) imaging and low-pressure gas (N 2 ) adsorption analyses reveal a complex and wide range of pore size distribution from micro-(< 2 nm) to macropores (> 50 µm). Kaolinite appears to have a detrimental effect on porosity, while illite/smectite "honey comb" structure contributes to porosity. Although porosity increases with thermal maturity, no statistical correlation between porosity and TOC, suggests OM has no major contribution in the total porosity. It appears that concurrent mineralogical variations with thermal maturity from north to south of the basin has the major control on porosity variation. To the contrary, the predominant migrabitumen is observed to clog both intergranular and intercrystalline pores. In general, based on the complete dataset, much of the porosity within Lower Cretaceous Garbutt Formation appears to be largely intragranular and intergranular (adjacent to inorganic constituents), so the hydrocarbon storage potential in this organic-rich shale largely resides in inorganic pores. The results of this study suggests that the Garbutt Formation, near the eastern margin of the Liard Basin in British Columbia, could potentially be a good target for unconventional oil and condensate exploration.

h i g h l i g h t s Different non-steady-state gas permeability techniques are compared. Permeability of the Duvernay shale is documented at different conditions. The impacts of different controlling factors on porosity/permeability are analyzed. Gas permeability of the Duvernay shale range between 3.7 Â 10 À7 and 1 mD. Profile (probe) permeability P pulsedecay permeability P crushed-rock permeability.

Herein, magnetite/graphene oxide hybrid (MGO) was facilely synthesized and analyzed by various techniques such as X‐ray diffraction spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, Brunauer, Emmett, and Teller surface area analyzer, and Raman spectroscopy. A computational density functional theory (DFT) has been applied for the first time to determine the removal mechanism of zinc (Zn2+), nickel (Ni2+), and chromium (Cr6+) hydrates onto the prepared MGO. The adsorption binding energy and geometries of the metal hydrates with oxygen functional group (i.e., hydroxyl, epoxide, carboxylic, carbonyl groups, and magnetite on the MGO surface) were estimated. The complexes configurations comprised via sitting the metal ion perpendicular and above the MGO surface. The zinc hydrate portended to bind more strongly than Ni2+ and Cr6+. Zinc hydrate is favorable to coordinate with hydroxyl and carboxylic group than the other functional groups. The pseudo‐se...

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.

Bioinorganics and the use of metal ions in the synthesis and design of new materials have received considerable attention with regard to use as new biomaterials. One of the important roles of metal ions is the control of dissolution in biomaterials, which has an influence on their biological and chemical properties. Up until now, metal ions such as magnesium (Mg), zinc (Zn), titanium (Ti) and zirconium (Zr) have been used to dope silicate-and phosphate-based ceramics. Calcium silicate (CaSiO 3 , CS) ceramics are biocompatible and bioactive. Some CS ceramics have exhibited superior apatite formation ability in simulated body fluids (SBF) and their ionic dissolution products have been shown to enhance cell proliferation and differentiation. Their main drawback, however, is the high dissolution rate as this is detrimental to cells. Metal ions are used to modify their chemical composition and structure in order to overcome this complication. In this review paper, we consider the apatite formation ability, dissolution and the in vitro and in vivo biological properties of ion-doped CS ceramics such as bredigite, akermanite, monticellite, diopside, merwinite, hardystonite, baghdadite and sphene. Overall, according to the studies conducted on CS bioceramics, they may be a good candidate for bone tissue regeneration.

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...

S53P4 bioactive glass nanoparticles (BGn) were prepared by the melting-quenching method at 1400 ℃ followed by ball milling. The prepared glass nanoparticles were used for surface decoration of poly-L-lactic acid (PLLA) nanofibers fabricated by electrospinning method. The microstructure, morphology and chemical functional groups of the nanomaterials were characterized by XRD, FESEM, and FTIR techniques. The results confirmed the successful synthesis of amorphous glass nanoparticles with the diameter ranged from ~100 to 800 nm and PLLA nanofibers with an average diameter of 500 nm. PLLA/BGn nanocomposites showed a uniform distribution of the BGn on the surface of PLLA nanofibers. The growth, viability, and proliferation of the cultured human bone marrow mesenchymal stem cells (hMSCs) on the prepared nanomaterials were examined using various biological assays, including MTT cytotoxicity, ALP activity, calcium biomineralization, Alizarin red staining, and gene expression. The biological results clearly showed that the growth, proliferation and osteogenic ability of hMSCs were significantly improved due to the surface modification of PLLA nanofibers with

Superhydrophobic nanoporous anodic aluminum oxide (alumina) surfaces were prepared using treatment with vapor-phase hexamethyldisilazane (HMDS). Nanoporous alumina substrates were first made using a two-step anodization process. Subsequently, a repeated modification procedure was employed for efficient incorporation of the terminal methyl groups of HMDS to the alumina surface. Morphology of the surfaces was characterized by scanning electron microscopy, showing hexagonally ordered circular nanopores with approximately 250 nm in diameter and 300 nm of interpore distances. Fourier transform infrared spectroscopy-attenuated total reflectance analysis showed the presence of chemically bound methyl groups on the HMDS-modified nanoporous alumina surfaces. Wetting properties of these surfaces were characterized by measurements of the water contact angle which was found to reach 153.2 ± 2°. The contact angle values on HMDS-modified nanoporous alumina surfaces were found to be significantly larger than the average water contact angle of 82.9 ± 3°on smooth thin film alumina surfaces that underwent the same HMDS modification steps. The difference between the two cases was explained by the Cassie-Baxter theory of rough surface wetting.