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A brick clay mixture from a company localized in the north west of France is used for this study. The feasibility of producing geopolymer materials from a clay mixture was investigated. The final aim is to find a new application for this aluminosilicate material. One metakaolin (for a reference), the brick clay mixture, and the clay mixture calcined at two temperatures were compared after reaction with each of three alkaline solutions with different reactivity (the reactivity of each is defined). Physical, chemical, structural (FTIR and XRD) and thermal characterization (DTA) were first performed on the raw materials. Then, the structural evolution of the formed geopolymers was investigated using FTIR spectroscopy and XRD. Thus, this study demonstrates the feasibility of producing consolidated materials from a calcined brick clay (containing calcium oxides), which exhibits higher reactivity than brick clay. Plus, from a mixture of 25 wt% of less reactive materials such as ground brick clay and 75 wt% of reactive materials, it is possible to obtain geopolymer materials. FTIR study reveals the presence of a Ca 2+ release phenomena, with a simultaneous polycondensation reaction for products based on calcined brick clay, which is different according to the silicate solution. Moreover, a link between [M + +M 2+ ] and the different networks formed in the samples based on calcined clay was found. Indeed, it appears that the concentration within the range 10.5–14 mol/l favors the geopolymer network formation. [ABSTRACT FROM AUTHOR]

Objectives: Silver-Russell syndrome (SRS) is an imprinted disorder characterised by intrauterine growth retardation, relative macrocephaly, failure to thrive, typical facial phenotype and frequent body asymmetry. Feeding difficulties are frequently noted, but no study described evolution of gastrointestinal signs during infancy and their management in SRS. The aim of this study was to describe these abnormalities in a large cohort of children with SRS. Design: We included 75 patients (median age 24.3 months (5.1-135.2)) in the study. We retrospectively analysed nutritional status before growth hormone therapy, the frequency of gastrointestinal signs, such as gastroesophageal reflux (GER), vomiting, constipation and feeding difficulties, and nutritional management. Results: Maternal uniparental disomy for chromosome 7 was found in 10 patients and 11p15 hypomethylation in 65 patients. Malnutrition (defined as a weight/ expected weight for height ratio <80%) was detected in 70% of the children. Gastrointestinal signs were found in 77%, including severe vomiting before the age of 1 year in 50% of cases, persistent vomiting from the age of 1 year in 29% of cases and constipation in 20% of cases. Severe GER was diagnosed in 55% of children by 24 h oesophageal pH-metry. Feeding difficulties were described in 65% of cases, with indications for dietary enrichment in 49%. Enteral nutrition by gastrostomy was indicated in 22% of cases. Conclusions: Digestive signs (GER, constipation) and malnutrition are frequent in children with SRS. The systematic exploration and management of these signs are crucial to improve the nutritional status of these children before initiating growth hormone therapy. [ABSTRACT FROM AUTHOR]

Solution precursor plasma spraying (SPPS) is an innovative process for obtaining finely structured coatings from metallic salt solutions. Lanthanum and zirconium precursors were studied to understand their influence on lanthanum zirconate (LaZrO) synthesis by SPPS. Thermal analysis revealed that the nature of the precursor and the solvent affected mixture decomposition by changing the decomposition temperature. The surface tensions of precursor solutions in various media were investigated and revealed the influence of the nature of the counter-cation. Different solutions of precursor mixtures were used to obtain LaZrO splats on metallic substrates. A decrease in solution surface tension led to an increase in splat size. Coating mechanisms by SPPS are governed by the nature of the precursors and solvents. [ABSTRACT FROM AUTHOR]

Boron carbide (B 4 C) is widely used as a neutron shielding material, but it is known to be difficult to sinter. Typically, B 4 C is sintered at ultra-high temperature (>2000 °C) and high pressure, or hardened using an organic binder such as silicone rubber. In this study, hardening by an inorganic binder, that is, a geopolymer binder was investigated. The raw materials for the binder were fly ash, sodium metasilicate anhydride (Na 2 SiO 3) and sodium metasilicate 9-hydrate (Na 2 SiO 3 ·9H 2 O), with the B 4 C being hardened at only 130 °C by novel "cold reaction sintering" using a warm-pressing device. The process involves a simultaneous reaction involving geopolymer formation (geopolymerization) and solidification. The effects of the geopolymer content and the mixing ratio with B 4 C powder with different particle sizes on the compressive strength and density of the B 4 C were investigated. When coarse B 4 C particles (∼100 μm), and fine B 4 C particles (∼1 μm) were combined, the fine B 4 C particles and the binder filled the voids between the coarse B 4 C particles. As a result, it was found that when appropriate pressure was applied to the raw materials, the binder was completely geopolymerized, and a strong hardened body was formed. The compressive strength of the hardened body exceeded 50 MPa when the content of fine B 4 C particles was 30 wt% and the content of the geopolymer binder was 20 wt%. Furthermore, neutron transmission test of the hardened bodies were conducted to evaluate their neutron shielding properties, and it was confirmed that the geopolymer-based B 4 C composites achieved a B 4 C volume occupancy of more than 70%, which is unreachable for commercial rubber-based B 4 C composites. [ABSTRACT FROM AUTHOR]

Abstract: This study is based on the understanding of the behavior of alkali silicates in a basic medium and aims to identify the mechanisms responsible for the formation of an irreversible gel and its consolidation. Commercial lithium, sodium and potassium silicate solutions were used to reveal the effect of the cation nature on the gelation process. Gels are obtained by acidifying alkaline silicate solutions with hydrochloric acid. A syneresis phenomenon during ripening that leads to the formation of a strongly consolidated solid has been observed. Whatever the cation, the gelation or syneresis mechanism would be similar. However, gelation time decreases and syneresis increases with the cation size. Gelation results from formation of small particles which grow in number and size and then gather to fill the available space. Ripening takes place through a dissolution/precipitation mechanism. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a method for preparing nanomaterials shaped into powder and balls (diameter: 1–2mm) is developed. The synthesis is performed by an oil-drop process using a sol–gel method. During the preparation, the sol was improved by the inclusion of some additives such as methylethylketone (MEK), Butvar (But) and ethylmethacrylate (EMC). BaTiO3 and Ba0.67Sr0.33TiO3 perovskite-type compounds synthesized by both procedures present the same physical–chemical properties. The development of this sol–gel process enables the formation of these shapes in amounts as large as the 50g scale in a laboratory. The use of synthesized spherical pellets in a non-thermal plasma reactor enables the increased conversion of ethanol when acting as a pollutant. [Copyright &y& Elsevier]

In this work, we present the opportunity to prepare perovskite materials in powder and in balls by sol–gel process. BaTiO3 as spheres of 1–2 mm in diameter, presenting the same physico-chemical properties than powders, have been prepared by an oil-drop process. The shape forming of a dielectric material permits its use in a plasma reactor and promotes the efficiency of the system. [ABSTRACT FROM AUTHOR]

Abstract: Catalytic wet air oxidation (CWAO) of aqueous solution of acetic acid (78mmolL−1) was carried out with pure oxygen (2MPa) at 200°C in a stirred batch reactor on platinum supported oxide catalysts (Pt/oxide, oxide=CeO2, Zr0.1Ce0.9O2, Zr0.1(Ce0.75Pr0.25)0.9O2 and ZrO2). Platinum was loaded on oxides by impregnation (5wt%), and then the catalysts were reduced under H2. Homogenous dispersions of 2–3nm metal crystallites were obtained. The catalytic activity depended on the ability of the support to resist to the formation of carbonates. Ce(CO3)OH species, determined by FT-IR and XRD, were rapidly formed during the CWAO reaction especially on mixed oxides. These carbonates were responsible to a drastic drop in catalytic performances. Amounts of carbonate species increase with the ability of the catalyst to transfer oxygen. [Copyright &y& Elsevier]

Abstract: CeO2 doped with praseodymium, neodymium and/or zirconium atoms were prepared by coprecipitation and by the sol–gel method. Structural properties were investigated by in situ XRD and Raman spectroscopy while oxygen storage capacity (OSC) was measured by transient CO oxidation. All the compounds, except pure Nd2O3, have a fluorite-type structure as well as a Raman band at 560cm−1 characteristic of the oxygen vacancies involving non-stoichiometric oxides. The lattice parameter under hydrogen, being dependent on the temperature, revealed two reduction mechanisms: one at a low temperature at the surface and another at a high temperature in the bulk. Ce–Nd binary oxides show a strong tendency towards crystallite aggregation, which reduces accessibility to gases and OSC properties. Zirconium improves the thermal resistance to sintering of both Ce–Nd and Ce–Pr oxides. The Zr–Ce–Pr–O followed by Zr–Ce–Nd–O compounds displaying high oxygen mobility at a low temperature, appear to be very promising for practical applications such as OSC materials. [Copyright &y& Elsevier]

Silver-Russell syndrome (SRS, OMIM 180860) is a congenital disorder characterized by severe intrauterine and postnatal growth retardation, dysmorphic facial features and body asymmetry. SRS is genetically heterogenous with maternal uniparental disomy with respect to chromosome 7 occurring in ∼10% of affected individuals. Given the crucial role of the 11p15 imprinted region in the control of fetal growth, we hypothesized that dysregulation of genes at 11p15 might be involved in syndromic intrauterine growth retardation. We identified an epimutation (demethylation) in the telomeric imprinting center region ICR1 of the 11p15 region in several individuals with clinically typical SRS. This epigenetic defect is associated with, and probably responsible for, relaxation of imprinting and biallelic expression of H19 and downregulation of IGF2. These findings provide new insight into the pathogenesis of SRS and strongly suggest that the 11p15 imprinted region, in addition to those of 7p11.2-p13 and 7q31-qter, is involved in SRS. [ABSTRACT FROM AUTHOR]

Several boehmite films were produced using the sol–gel route. The drying process, the film structure evolution and the final texture of the samples were investigated by means of combined X-ray diffraction and weight variation. A remarkable (0 1 0) preferred orientation (about 97% of the crystallites) was found for xerogel films with thickness ranging from 1.5 to 24 μm. The ordered structure is already present in the sol state and is appeared and enhanced during drying, before gelling. This phenomenon may be attributed to the particular boehmite structure that induces special crystallite organization in the aquagel. [Copyright &y& Elsevier]

This study concerns the project of high and intermediate level radioactive waste disposal (Cigéo project for Centre Industriel de stockage GEOlogique). Millions of tons of argillite will be excavated during the construction of the site. Therefore, the aim of this work is to reuse this argillite in the formulation of an injectable geopolymer grout and study its evolution in different storage conditions (T = 20 and 80 °C). To achieve this challenge, a metakaolin and calcined Callovo-Oxfordian (COx) argillite were used with potassium silicate solutions. The grouts were successfully obtained from both metakaolin and COx argillite in both temperatures 20 and 80 °C. The range of viscosity of several mixtures respected the required specifications (viscosity ≤5 Pa s and setting time superior to 6 h). The metakaolin-based geopolymers didn't display any major changes no matter the storage temperature, except for the pore size, a coalescence phenomenon was observed with the increase of temperature. In contrast, for argillite or argillite-metakaolin based samples, a decrease of pore size as well as in pH values were observed with the increase of temperature. This behaviour was attributed to the dissolution of argillite's impurities such as illite, providing more oligomers to allow the formation of different geopolymer networks. [ABSTRACT FROM AUTHOR]

This perspective article delves into the transformative potential of alkali‐activated materials, acid‐activated materials, and geopolymers in mitigating climate change and market challenges. To harness the benefits of these materials, a comprehensive strategy is proposed. This strategy aims to integrate these materials into existing construction regulations, facilitate certification, and promote market access. Emphasizing research and innovation, the article advocates for, increased funding to refine the chemistry and production of these materials, prioritizing low‐cost alternatives and local waste materials. Collaboration between academia and industry is encouraged to expedite technological advances and broaden applications. This article also underscores the need to develop economic and business models emphasizing the long‐term benefits of these materials, including lower life‐cycle costs and reduced environmental impact. Incentivizing adoption through financial mechanisms like tax credits and subsidies is suggested. The strategy also includes scaling up production technology, fostering industrial collaboration for commercial viability, and developing global supply chains. Educational programs for professionals and regulators are recommended to enhance awareness and adoption. Additionally, comprehensive life‐cycle assessments are proposed to demonstrate environmental benefits. The strategy culminates in expanding the applications of these materials beyond construction, fostering international collaboration for knowledge sharing, and thus positioning these materials as essential for sustainable construction and climate change mitigation. [ABSTRACT FROM AUTHOR]

Abstract: A series of N, S-substituted Titanium (IV) (diisopropoxide) bis (2,4-pentadionate) precursor were synthesized by the sol–gel method. The obtained solids were calcined at 550 °C for two hours to obtain photoactive phases. A thermogravimetric analysis of the solid precipitates shows that crystallization has been almost completed at this value of calcination temperature. The samples were characterized by X-Ray diffraction (XRD), determination of the BET specific surface area and UV–Vis diffuse reflectance spectroscopy. The photocatalytic activity of the obtained catalyst was estimated on a basis of decolouration of Congo red dye under near visible light. [Copyright &y& Elsevier]

Abstract: In this paper, we discuss the alternative interpretation of NMR spectra from (i) “Structural characterization of geomaterial foams—Thermal behavior” by Prud''homme et al. published in Journal of Non-Crystalline Solid, 2011, and from (ii) the reply proposed by J. Provis and S.A. Bernal in this journal. In this contribution, other alternatives for the NMR bands assignment are discussed and compared with infrared spectroscopy and thermo-gravimetric results since closed relationship between NMR-IR-TG is effective. In agreement with these authors, the analysis of prepared foams requires additional work addressed to detect the presence of two phases with different tetrahedral condensation. Relative arrangement of these two phases could affect in a significant way the physical chemical properties of prepared foams. [Copyright &y& Elsevier]

Purpose: X-linked hypophosphatemia (XLH) is a rare, chronic, genetic condition characterized by renal phosphate wasting and abnormal bone and teeth mineralization. It represents a challenging and multifaceted disease that causes wide-ranging impacts on patients' lives. In this context, a scientific committee has designed a support initiative for patients treated for XLH: the aXess program. We sought to determine if a patient support program (PSP) could help XLH patients cope with their condition. Methods: During the 12 months of participation in the aXess program, XLH patients were contacted by phone by a nurse to coordinate their treatment, ensure treatment adherence, and provide motivational interviews. A Pediatric QOL inventory was conducted on all participants at enrollment (D0), at month 6, and month 12. Results: Altogether, a total of 59 patients were enrolled in the program. Most patients reported an improvement in QOL in all examined dimensions by month 12 (physical, emotional, social, and school, 85.4 ± 0.2 at month 12 versus 75.6 ± 0.3 at enrollment, p< 0.05). Patients were very satisfied with the program, with a mean overall satisfaction score of 9.8 ± 0.6 (on a scale from 0 to 10) at month 6 and 9.2 ± 1.5 at month 12. Conclusion: Our findings indicate that this program might improve the QOL for patients with chronic conditions such as XLH through patient education, therapy adherence, motivational interviews, and frequent follow-up. It links the home environment and overall illness management, bringing patients, families, and caregivers together. [ABSTRACT FROM AUTHOR]

The valorization of local materials in public building construction in emerging countries is a necessity from a sustainable development perspective. In Cameroon, laterite is an abundant and easily accessible local resource that can be used for the development of light and insulating materials, which until now have been made from metakaolin. Moreover, since metakaolin is not easily accessible in Cameroon, it would be interesting to compare to a model mixture based on metakaolin and hematite. The objective of this study is related to the feasibility and characterization of geopolymer foams based on laterite or on a model mixture (metakaolin-hematite) in different drastic conditions, such as fire resistance and freeze‒thaw cycles. The geopolymer foams were synthesized from a calcined laterite or metakaolin-hematite mixture, an alkaline silicate solution, a surfactant and metallic aluminum powder and then placed in an oven at 70 °C for 24 h. Structural data (X-ray diffraction) as well as determination of thermal conductivity and mechanical strength data of the foams were evaluated. The results show that the laterite and metakaolin-hematite mixture allows the elaboration of geopolymer foam, which is characterized by a low thermal conductivity (90 mW/(m. K)) and can be used as insulating materials. The freeze‒thaw treatment does not affect the thermal and mechanical properties. The treatment at 1175 °C slightly improves the mechanical strength and the thermal conductivity, leading to a good application of these materials. [ABSTRACT FROM AUTHOR]

Geopolymers are attracting attention in the field of concrete building materials from the viewpoint of reducing CO 2 emissions. This study demonstrates the effects of the addition of silica fume in the warm press method on the densification and mechanical properties of a geopolymer. First, geopolymer products hardened by conventional slurry curing, using fly-ash and sodium hydroxide solution as starting materials, were prepared. The hardened geopolymer products were then pulverized into small grains. Subsequently, various amounts of silica fume were mixed into the fine geopolymer particles to form the starting powder mixtures. A series of these mixtures (10 mass% water added) were placed into a steel mold, which was then inserted into a warm press device. An uniaxial pressure of 240 MPa was applied at room temperature and then the temperature was raised from 80 to 180 °C. When the warm press temperature was set at 80 °C, the compressive strength of the hardened bodies increased in line with the amount of added silica fume. Particularly, in the case of a hardened body with 30 wt% silica fume, the compressive strength reached 195 MPa, which was about three times that of a hardened body with 0 wt% silica fume. The added silica fume was found to improve the fine stacking of starting geopolymer particles in the early stages of warm pressing and help form objects with tightly packed voids between the original geopolymer particles. In contrast, for heat treatment at a warm press temperature of 180 °C, the compressive strength of the hardened bodies with 30 wt% silica fume decreased compared to those for the hardened bodies with 0, 10 and 20 wt% silica fume. From the results of nuclear magnetic resonance analysis, this decrease in strength was considered to be due to an increase in the silica-rich phase. [ABSTRACT FROM AUTHOR]

A microstructural approach to the prediction of heat flux transport in porous geopolymers is used experimentally to understand the effects of the pore size distribution and pores connectivity to the transfer of the thermal flux across the porous network of geopolymers. Controlling the mix design and the concentration of porogen agent, capillary pores can be introduced into the system for a final homogeneous microstructure. The roundness of pores, their geometrical distribution, and their connectivity allow the possibility to extend the length of the pathway of the tortuous route for potential heat flux. The nonlinear relationship between tortuosity–porosity and tortuosity–thermal conductivity confirms that the volume of pores is not the only parameter affecting the heat flux transport. The results achieved in terms of homogeneous microstructure with geometric description of pore, their level of isolation, and the spatial distribution allow the prediction of the heat flux transport in environmentally friendly and sustainable porous geopolymer materials. [ABSTRACT FROM AUTHOR]

This study addresses the thermal behavior of La 2 Zr 2 O 7 powders prepared via two different synthetic routes and the effect of the zirconium counter-cation on their properties, as carried out by dilatometric experiments. Citrate-based compounds exhibit shrinkage, regardless of the precursors used. Preliminary thermal treatment permits the reduction in shrinkage. Nitrate based compounds calcinated at 600 °C show a higher shrinkage (−9.4%) than at 1200 °C (−5.2%) because of the decomposition of the trapped precursors, as revealed by DTA–TGA–MS. Coprecipitated samples present different behaviors as a function of the counter-cation nature. Chloride based compounds leads to shrinkage and phase mixtures, whereas expansion is observed for pure pyrochlore compounds that are synthesized with nitrate. The thermal expansion coefficients of the different compounds are similar to the literature values (9.5–10.10 −6 K −1 ). This study allowed for a better understanding of the densification of the La 2 Zr 2 O 7 material and its adjusted properties, as a function of the precursor nature and the preparation mode, for application in thermal barrier coatings. [ABSTRACT FROM AUTHOR]

In this work, we study the effect of maximum packing fraction of powders on the rheology of geopolymer pastes. A large range of metakaolin powders is generated either by blending or grinding powders. Blends of metakaolin with quartz and limestone are also studied. We show that the compressive packing model is able to predict correctly over a wide range of values the maximum packing fraction of these powders. We show that an increase of the maximum packing of powders leads to a decrease of the viscosity of geopolymer suspension at a constant solid volume fraction. We finally show that the viscosity of studied geopolymer suspensions can be well predicted by the Krieger Dougherty relation. We suggest that the highest potential degree of freedom allowing for the control of the viscosity of geopolymer pastes without modifying the composition of the suspension lies in the maximum packing fraction of the solid powders. [ABSTRACT FROM AUTHOR]

An optimized sol–gel protocol was carried out to produce an yttrium aluminum garnet (YAG) xerogel from aluminum alkoxide and an yttrium salt on a semi-pilot scale. This xerogel was successfully used without prior pyrolysis as a solid load with the aid of additives in the preparation of pastes. Thermal treatment of the green bodies, obtained by robocasting of the paste, led to cohesive single-phase YAG ceramics. Manufacturing ceramic pieces by additive methods will allow shaping complex forms, while the single step conversion/consolidation would simplify the technological process, reducing global energy costs. Since YAG possesses high strength and good creep behavior at high temperatures, these refractory pieces could replace the metal alloys used in turbine blades for deep space exploration. Structural, thermal and chemical characterizations were performed on xerogel powders, pastes, and YAG ceramics. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this work is to identify the effect of the cation nature on mechanisms of the sand consolidation with alkaline silicate solution at low temperature (70°C). Three diluted lithium, sodium and potassium silicate solutions with [Si]=2.8mol/l were used to agglomerate sand composed of grains which mean diameter is 340μm. According to the cation, different behaviors were observed in terms of the drying time and the material cohesion. Essentially, the drying time increases with decreasing cation size. In contrast, the compressive strength raises when the cation size increases inducing intra-granular rupture highlighted by SEM observations. This could find an explanation in the cation hydration sphere of cations. The strength of the cation–water electrostatic interaction becomes less important as the size of the cations increase leading to more ionic bonds. Despite their strong consolidation, potassium-based materials have a high solubility in water. This result is consistent with the ionic nature of bonds. [Copyright &y& Elsevier]

Abstract: A dynamic reactor with mass spectroscopy online product analysis has been used to study the thermal and catalytic decompositions of ionic liquid HAN-based monopropellants. The activity of different catalysts has been evaluated by determining qualitatively and quantitatively the reaction products. A careful calibration of the expected products detected by the mass spectrometer (MS) (N2, O2, N2O, NO and NO2) has been performed. The analytical results have been supplemented by Raman spectroscopy of the aqueous solutions trapped after the reactor. The thermal and catalytic decomposition of water–HAN (80wt.%, hydroxylammonium nitrate NH3OH+NO3 −) mixture gave primary products (major N2, medium NO) and secondary products (medium N2O and traces NO2). From the data, a reaction mass balance could be proposed, based on the combination of two parallel competitive reactions: The influence of the catalyst shape (powder or spheres) has been followed. The isothermal tests at 50°C display the best activity for the powder catalyst with a complete decomposition of the HAN solution, due to a good contact between catalyst bed and monopropellant. On the other hand, the sphere-shaped catalyst leads only to a partial HAN decomposition, due to preferential paths through the catalyst bed. The thermal decomposition at 200°C, leads also to a partial reaction. [Copyright &y& Elsevier]

Abstract: Binary aqueous hydroxylammonium nitrate (HAN: [NH3OH]+[NO3]−) and hydrazinium nitroformate (HNF: [N2H5]+[C(NO2)3]−) have been prepared, then thermally and catalytically decomposed. The HAN solutions were prepared with different concentrations (20, 40, 79wt.%), whereas HNF solution contains is 40wt.% due to its lower solubility limit (about 50wt.%). The catalyst was prepared by impregnation of modified support (Si-modified alumina) with monometallic active phase precursor (platinum) and characterized by transmission electron microscopy, X-ray diffraction and chemisorption. The reactions were followed by thermal analysis and by using a constant volume batch reactor. This work shows the essential effect of the monopropellant concentration to determine the best formulation for an industrial application. Moreover, HAN laboratory made solutions are more efficient for catalytic decomposition due to the absence of stabilizer to inhibit the catalyst. The Pt(10%)/Al2O3Si+HAN79% lab association shows lower decomposition temperatures (down to room temperature), larger reaction rates and leads to higher amount of gaseous products, giving the most efficient system. With the same catalyst, HNF solution gave lower performances than HAN solutions, suggesting that the catalyst needs to be improved for this oxidizer. [Copyright &y& Elsevier]

Sotos syndrome is an overgrowth syndrome characterized by pre- and postnatal overgrowth, macrocephaly, advanced bone age, variable degrees of mental retardation, and typical facial features. Defects of the NSD1 gene account for &ges;60% of cases of Sotos syndrome, whereas the disease-causing mechanism of other cases remains unknown. Beckwith-Wiedemann syndrome (BWS) is a distinct overgrowth condition characterized by macroglossia, abdominal-wall defects, visceromegaly, embryonic tumors, hemihyperplasia, ear anomalies, renal anomalies, and neonatal hypoglycemia. Deregulation of imprinted growth-regulatory genes within the 11p15 region is the major cause of BWS, whereas the molecular defect underlying a significant proportion of sporadic BWS cases remains unknown. Owing to clinical overlaps between the two syndromes, we investigated whether unexplained cases of Sotos syndrome could be related to 11p15 anomalies and, conversely, whether unexplained BWS cases could be related to NSD1 deletions or mutations. Two 11p15 anomalies were identified in a series of 20 patients with Sotos syndrome, and two NSD1 mutations were identified in a series of 52 patients with BWS. These results suggest that the two disorders may have more similarities than previously thought and that NSD1 could be involved in imprinting of the chromosome 11p15 region. [ABSTRACT FROM AUTHOR]

Acid‐based geopolymers are known for their high temperature resistance and good mechanical performances. Some compositions also exhibit water resistance, which make them suitable for outdoor applications. This work aims to understand accurately the steps occurring during the geopolymerization process and focuses on the type of networks forming at early stages of the reaction. The sample, prepared from metakaolin and phosphoric acid, has been analyzed at different durations and temperatures during its solidification, in order to identify which compounds would crystallize. The structural characterizations have been performed using Fourier transform infrared spectroscopy and X‐ray diffraction. Several Al–O–P compounds and especially AlPO4 polymorphs crystallize in these conditions. They belong to three families of aluminophosphates and are a reliable indication of the amorphous organization of the original sample. The first one is similar to the phases that appear in the phase transition sequences of silica, the second one is composed of AlPO4‐based zeolites, and the last one is characterized by the presence of aluminum in an octahedral network. The transitions between the different phases are also discussed. Finally, the water resistance of the calcined samples is improved, and the release of acidic species in the water is limited even after a calcination at low temperature. [ABSTRACT FROM AUTHOR]

The influence of drying on the microstructure, physical and chemical properties of some tropical wood species has been investigated using thermogravimetric analysis, differential scanning calorimetric (DSC), FTIR-ATR spectroscopy, mercury intrusion porosimetry (MIP) and environmental scanning electron microscopy (ESEM) analysis. Eleven tropical species were used in this study. Results showed that the common Cameroonian wood species can be grouped into three classes: Ga (lightwood) with cross-linking fibers having high volume of macropores, density in the range 0.2–0.4 g cm−3 and high lignin content; Gb (medium dense) with unidirectional fibers packing, density around 0.6 g cm−3 and Gc group showing high densification of unidirectional fibers and low porosity justifying the density > 0.8 g cm−3. Both the Gb an Gc groups have less significant lignin content. A relatively high rate of drying for Ga with respect to low drying rate for Gc was observed in direct relation with their porosity of ~ 72 Vol% and ~ 36 Vol%, respectively. LTF and WG showed similar cumulative pore volume (0.44 mL g−1) with different pore size distribution: 28% and 22% of macropores, 39% and 60% of mesopores and 33% and 18% micropores, respectively. Thermal analysis revealed that lightwoods have the highest amounts of residues and lower thermal stability of chemical components than dense woods. It has been found that the degradation process of hemicellulose, cellulose and lignin occurs mainly at about 200–300 °C, 300–350 °C and 350–500 °C, respectively. The group Ga with low drying rate, a low cycle of reproduction, a high volume of porosity together with large pore sizes appeared promising candidates for the design of ecological, environmental and sustainable management policy of wood transformation in developing countries and even worldwide. [ABSTRACT FROM AUTHOR]

[Display omitted] • Evaluation of activating solution influence on high temperature resistance in AAMs. • Higher availability of silicon and aluminum and better feasibility of the pastes. • Monitoring formation of Si-O-Si and Si-O-Ca networks. • Positive influence of the new crystallizations on mechanical resistance after 1000 °C. • Densification behavior of K sample contrary to the melting of that Na. Thermal performances at 1000 °C of volcanic ash-based alkali-activated materials by both sodium or potassium solutions have been tested. Once defined the feasibility for the potassium set, a multidisciplinary characterization including spectroscopic, thermal, mechanical, diffractometric before and after treatment and dilatometric analyses was applied. The formation kinetics of different networks was evaluated. A correlation between the high mechanical properties and the least amount of water was observed in non-treated samples. Treated samples at 1000 °C showed higher compressive strengths due to the crystallization of wollastonite, leucite and nepheline. Thermal stability was observed increased with the solid content in the potassium-based formulations. [ABSTRACT FROM AUTHOR]

The thermal behavior of a model MK based K‐geopolymer (Si/Al = 1.38 and K/Al = 0.68; obtained by alkaline activation of a very pure metakaolin) was investigated between room temperature and 1400°C in order to evaluate its potentiality for high‐temperature applications. The purpose of our study was to monitor the behavior of a geopolymer during a temperature rise in order to better understand its variations with respect to temperature. The works from the present paper focus only variations in the internal structure of the mineral matrix. The results presented here show that the amorphous mineral matrix is preserved up to 900°C. The results also show that there is a densification of the internal structure of tetrahedral network during heating, due to changes in the Q3 environments in fully‐connected Q4 for both silicates and aluminates. Thus, our work provides a new more precise vision of the 3D geopolymeric mineral matrix for which the silicoaluminous network is not exclusively composed of Q4 entities, contrary to what is frequently encountered in the literature before. [ABSTRACT FROM AUTHOR]

The thermal behavior of a model MK‐based K‐geopolymer was investigated between room temperature and 1400°C in order to evaluate its potentiality for high‐temperature applications. The purpose of our study was to monitor the behavior of a geopolymer during a temperature rise in order to better understand its variations with respect to temperature. The works from the present paper focus only changes in the porous network; it follows a first part devoted to variations in the mineral matrix. The results obtained here show that the geopolymer material preserves its porous integrity up to 800°C, while maintaining the reversibility of water exchanges corresponding to about 25 weight percent. Together with the results of part 1, the findings of this study allow us to affirm that geopolymer materials are only very little affected by temperatures up to 800°C, or even 900°C (keeping its mesoporous amorphous structure). [ABSTRACT FROM AUTHOR]

Decreasing the pH value of a concentrated sodium silicate solution while maintaining its basic environment, largely affects solution stability. The charge modification induces by the presence of acidic species is expected to destabilize initial equilibrium, thus affecting original structure. Acidification along with dilution of a concentrated sodium silicate solution ([Si] = 7 mol/L, Si/Na = 1.71, pH = 11.56) was realized by slightly adding a 0.5–2 mol/L hydrochloric acid solution under stirring. Through small angle X-ray scattering (SAXS), Fourier Transform Infrared (FTIR) spectroscopy, specific surface area and elementary chemical analysis, chemical species involved in the gelation and maturation of a concentrated sodium silicate solution were characterized. Results show that the initial mother solution which is a high pH-sensitive solution, is composed of both neutral and charged species such as Si 7 O 18 H 4 Na 4 , Si 7 O 18 H 5 Na 3 , (Si 7 O 18 H 3 Na 4)− and (Si 7 O 18 H 4 Na 3)−. These complex species are likely to dissociate, aggregate and/or condense as a function of both pH and silicon concentration. Accordingly, it is possible to master these solutions for appropriate usage. • Characterization of species involved in Na silicate gelation and maturation • Si 7 -type colloids responsible for stabilization of high concentrated Na silicate • Low pH variation of Na silicate solution induces great behavior changes • Reversible gels controlled by physical interactions such as Van der Waals • Stable silica compound obtained by dissolution/precipitation reactions [ABSTRACT FROM AUTHOR]

Knowledge of alkaline silicate solutions is crucial in order to optimize geopolymer properties. Geopolymers are new binders resulting from the activation of an aluminosilicate by an alkaline solution. It is well established that the solution reactivity strongly affects the geopolymerization and therefore the geopolymer working properties. As a consequence, an evaluation of the reactivity degree of alkaline silicate solutions prior synthesis is of the utmost interest. However, the determination of the solution reactivity is currently tedious, and for geopolymer commercialization, it would be necessary to find an easy way to determine it. Therefore, Raman spectroscopy, combined with chemometric techniques, is proposed as a solution to easily determine the alkaline silicate solution reactivity. To conduct this investigation, 65 silicate solutions were characterized by Raman spectroscopy, and reference values of their reactivity degree were determined. Finally, principal component analysis and partial least squares regression were performed to build a statistical model able to predict the alkaline silicate solution reactivity from Raman spectra. [ABSTRACT FROM AUTHOR]

This study presents a new design of a reduced volumetric ultra-wideband (UWB) antenna using innovative dielectric based on the use of geopolymer material which is safe and eco-friendly. The created antenna is intended to radiate in the air. The impedance mismatch due to interface dielectric/air at the aperture of the antenna imposes to choose dielectric material with an appropriate permittivity value. In this study, the authors focus on the experimental protocol that they use to elaborate a dielectric material with suitable dielectric properties over an UWB domain. An experimental phase of dielectric properties assessment is also described. The conceived antenna is inspired by K-antenna which constitutes the starting point of the proposed new antenna design, particularly because of their small dimensions. The antenna is intended to operate in a frequency band ranging from 300 MHz to 3 GHz. The authors demonstrate that the use of an appropriate innovative dielectric material like a geopolymer is an efficient way to reduce the antenna size. Furthermore, the behaviour of the antenna filled with geopolymer is validated using experimental results. [ABSTRACT FROM AUTHOR]

Background: The paradox of normal growth despite a lack of growth hormone (GH) is an unexplained phenomenon described in some pathological (sellar, suprasellar, and hypothalamic disorders) and overgrowth syndromes. It has been suggested that the paradoxical growth is due to other GH variants, GH-like moieties, prolactin, insulin, insulin-like growth factors (IGFs), and unidentified serum factors or growth mechanisms. The objective of this study was to determine the mechanism underlying this normal growth without GH. Case Description: We describe here growth, hormonal, and genetic analyses for an adolescent boy with panhypopituitarism who achieved an adult height above his genetic potential. Results: Normal growth was observed despite low serum GH, IGF-I, IGF-II, IGF binding protein 3 (IGFBP-3) and acid labile subunit (ALS) concentrations, but the IGF-II/IGFBP-3 molar ratio was slightly high. Panhypopituitarism was associated with a heterozygous missense mutation of HESX1, with variable penetrance in heterozygous relatives. Exome analysis detected heterozygous missense mutations of various genes involved in intracellular signaling pathways. The growth-promoting activity of the patient's serum was unable to induce AKT phosphorylation in the MCF-7 cell line. Conclusion: The high IGF-II/IGFBP-3 molar ratio was not the cause of the sustained high growth velocity, due to the low affinity of IGF-II for IGF type 1 receptor. The key finding was the HESX1 mutation, as similar cases have been described before, suggesting a common mechanism for growth without GH. However, the variable penetrance of this variant in heterozygous relatives suggests that modifier genes or mechanisms involving combinations with mutations of other genes involved in intracellular signaling pathways might be responsible. [ABSTRACT FROM AUTHOR]

Acid-based geopolymers exhibit interesting properties, such as higher temperature resistance (up to 1450 °C) and better mechanical properties, as compared to alkali-based geopolymers. The aim of this work was to highlight the origin of water and thermal resistances of acid-based geopolymers, demonstrated in our previous study, by 27Al, 29Si and 31P NMR and XRD experiments. Different networks were indeed identified in consolidated materials, such as Al-O-P, Si-O-P, vitreous silica and Si-O-Al (only for Al/P = 4, due to unreacted metakaolin) depending on processing conditions. The final properties are induced by the proportion of these networks which are controlled by the Al/P ratio and the setting temperature. It was shown that a higher amount of Al-O-P bonds and the absence of unreacted metakaolin conduct to a thermally resistant sample. A more organized structure with a low proportion of Q0(1Al) and a preference for Q1(2Al), as seen by 31P NMR, induces a great water resistance of geopolymers. After heating at 1000 °C, different AlPO 4 polymorphs crystallize, as well as mullite in the case of Al/P = 4. Resistance of acid-based geopolymers with associated structural and working properties. Image 1 • Acid-based geopolymers display different processing-dependent working properties. • Acid-based geopolymers are mostly composed of Al-O-P and Si(OH) 4 networks. • The quantities of Al-O-P and unreacted metakaolin govern the thermal resistance. • The increase of the Young's modulus is related to a higher thermal resistance. • Ordered structures and low amounts of physisobed water lead to water resistance. [ABSTRACT FROM AUTHOR]

Abstract The influence of spark plasma sintering (SPS) parameters (temperature, time, pressure) and the role of particle size on densification, microstructure and mechanical properties of commercial additive-free TiB 2 , SiC and composites thereof were studied by X-ray diffraction, scanning electron microscopy, the ultrasonic method and indentation. Three particle sizes of SiC and 2 of TiB 2 were processed. An optimal cycle was found for TiB 2 and SiC: 2000 °C, 3 min dwell time, and 100 MPa applied at 600 °C. The relative density of pure SiC increases linearly from 70% to 90% when the initial particle size decreases from 1.75 µm to 0.5 µm. Pure TiB 2 was densified up to 87%. Using 2.5 wt% SiC in TiB 2 , the relative density increases to 97%. Young's modulus and the hardness of all samples were measured, with results discussed. The higher properties were obtained for additive-free TiB 2 –5%SiC with a relative density of 97% and with the Young's modulus and Vickers hardness values being close to 378 GPa and 23 GPa, respectively. [ABSTRACT FROM AUTHOR]

Abstract Different formulations of geopolymers were synthesized in acidic media (phosphoric acid) starting from three different raw metakaolin materials to identify compositions of interest. Four different property groups were highlighted based on the most favorable thermal and water resistance properties (while maintaining acceptable mechanical properties). The groups were related to the chemical composition, setting time and setting temperature of the synthesized geopolymers. Indeed, mechanical strength was determined by chemical composition, such as the aluminum content and the amount of water in each sample. The results showed that the sample with Si/Al ≥ 1 and Al/ P = 1 exhibited compressive stress to rupture values ranging between 66 and 120 MPa and was thermal resistant. Water resistance with a mechanical strength of 50 MPa was obtained for the samples with Al/ P = 1 or 4 and Si/Al ≤ 1. This work highlights the possibility of selecting a specific property associated with the mechanical performance for an acidic geopolymer. Highlights • Acid geopolymer with various properties were determined. • The Al/P and Si/Al ratios control the mechanical properties. • Thermal and water resistant materials depend on the quantity of aluminum. • Water content in materials control the mechanical properties. [ABSTRACT FROM AUTHOR]

The valorization of oyster or mussel shells toward metakaolin-based geomaterials was investigated. The aim is to better understand the feasibility and the reaction involved during the incorporation of shells (natural or calcined) into a metakaolin-based alkaline solution for potential building or contaminants sorbents applications. Mixtures are realized by (i) the substitution of metakaolin (MK) source by shells raw material (from 0 to 100% mass) or (ii) addition up to 50% mass. Substitution of MK by shells was conducted without material structure loss up to 40% and 30% addition, whether the type and treatment of shells used. In each addition or substitution, the results highlight the duality between both reactions i.e. polycondensation versus hydration. (i) using natural shells, only polycondensation reaction occurs due to the unreactivity of shells (interaction of shells with matrix by surface binding: role of aggregates or fillers); (ii) using calcined shells, coexistence of polycondensation in first followed (or stopped) by hydration reaction: presence of portlandite and C(A)SH. Then the results traduce the role of MK (Al and Si source) reactivity and calcium form (carbonate versus lime; reactivity) in MK-based alkali activated materials. The geochemical leaching approach can be used as a sensitive probe of the structural network. [ABSTRACT FROM AUTHOR]

Here, the valorization of Callovo-Oxfordian (COx) argillite from the geological layer focused by the Cigéo project (Industrial Center for Geological Disposal of radioactive waste) is studied by Andra. Its reuse by alkali-activation is studied in order to develop thermally resistant binders. The thermal properties of various argillite-based samples are studied at 800 °C, and they present a good resistance to a slow firing environment but a lower resistance to thermal shock. This article discusses the influence of the sample compositions on the thermal resistance. First, the thermal activation of argillite has a significant impact on the thermal resistance of the alkali-activated samples. Indeed, a higher resistance is reached with the use of furnace-calcined argillite due to the complete dehydroxylation of clay minerals and decomposition of carbonates. However, the use of flash-calcined argillite (partial dehydroxylation and decompositions) leads to different species present in the mixture and therefore may be conducive to higher structural evolutions during sample firing. Then, the influence of the nature of the alkaline silicate solution is highlighted. It appears that the use of sodium-potassium silicate powder-based solution (Si-Na-K) is conducive to lower reactivity and more viscous flow than a liquid-based potassium solution (Si-K). Finally, the addition of filler, sand (SiO 2 ) and calcined clay (Al 2 O 3 -SiO 2 ) allows for better thermal resistance but limits the development of mechanical properties. [ABSTRACT FROM AUTHOR]

This study focused on identifying the differences in a clay quarry that is used in brick production to understand the variation between samples based on two kinds of clays: the first kind was suitable for brick production, but the second one did not show good production efficiency. Various samples were characterized by physical and chemical methods. In addition, free iron extraction by a CBD method and calcination at various temperatures were performed. The clay samples were then structurally characterized by XRD, FTIR and 27 Al NMR spectroscopy and thermally characterized using dilatometry. Finally, these results were correlated to the SEM investigation. These results revealed variations in the Si/Al molar ratio (1.4 to 3.3) due to the mineralogy variation within the quarry. Indeed, the non-secondary phase and clay phase contents differed according to the location in the quarry. NMR analysis also revealed that some iron atoms were located in a kaolinite structure, whereas other iron phases, in goethite form, interacted with clay minerals only on the surface of, e.g., kaolinite and muscovite and were not in their structures. From the thermal characterization, the influence of this structural iron in the kaolinite was also evidenced by an increase in the total shrinkage. In conclusion, this work determined the structural differences and their impact on brick production. [ABSTRACT FROM AUTHOR]

This study was undertaken to valorize naturally occurring clays in the synthesis of new geopolymers materials from the mixture of commercial metakaolins and calcined clays (550 °C). For the purpose of this work, three raw clay samples were collected from various locations in Tunisia where clayey deposits extended over large areas. A simple synthesis method was adopted by mixing calcined clays and metakaolins with an alkali silicate solution of the desired Si/K ratio. The obtained geopolymers were stored for subsequent analyses. Both metakaolins and prepared geopolymers were characterized by FTIR, XRD, TG-DTA, SEM and mechanical properties. It was demonstrated that samples based on clay and different metakaolins present amorphous consolidated geopolymer materials. Also, the obtained geopolymer materials have a smooth and amorphous appearance characterizing the polycondensation reactions. Addition of natural clay decreased the compressive strength of the geopolymer materials, because of impurities (i.e. illite, calcite, iron). Despite their low kaolinite contents, raw clays from Tunisia provided good geopolymers in the presence of metakaolins and alkaline solution. [ABSTRACT FROM AUTHOR]

Due to their interesting properties, geopolymers have found various applications in different domains. The evaluation of the dielectric properties of a geopolymer matrix for RF applications is innovative. In this context, this paper focuses, first, on the evaluation of the suitability of a geopolymer matrix with dielectric materials, and then on the improvement of the real permittivity value of the obtained material. For this purpose, the precursors either dielectric powder or aluminosilicate powder were first characterized. Then, the feasibility of the geopolymer matrix was investigated. Based on the feasibility test, it was shown that these kinds of materials can be successfully filled with various types of dielectric materials, such as ZrO 2 , BaTiO 3 and Y 2 O 3 . Moreover, the optimized parameters of the synthesis process, which included a small amount of water in the formulation, were 20 °C for the synthesis temperature, 85% for the humidity level and 7 days for the setting time. The measurement of the dielectric properties evidenced, first, that the real part of the relative permittivity strongly depends on the formulation and storage process. Then, the incorporation of a high percentage of BaTiO 3 (60%) induced an increase in the real part of the permittivity value and a decrease in the loss tangent. Finally, the mixing law of Maxwell-Garnet was applied to compare the theoretical and measured values of the permittivity. It was deduced that the small difference detected at low percentages whatever the dielectric materials can be explained by the preponderant effect of the geopolymer matrix compared to ZrO 2 or BaTiO 3 , it seems that the mixing law well functioned with BaTiO 3 than ZrO 2 . This is in accordance with the better dielectric properties for samples containing BaTiO 3 . [ABSTRACT FROM AUTHOR]

The effects of alkaline solution and calcined clays on vibrational spectra and mechanical properties were studied on geopolymer samples prepared from two alkaline solutions, calcined clays and three metakaolins. Structural evolution of the prepared geopolymers was characterized using FTIR spectroscopy and compression tests. Our results indicated high positive correlation between reactivity and compressive strength of the studied samples. Commercial potassium silicate and laboratory prepared k-silicate solutions were used to assess their effects on the prepared geopolymers. It was also observed that various secondary phases appeared, causing a slight change in the species' reactivity. Finally, it was concluded that changing alkaline solution and calcined clays decreased the mechanical properties, but increased the FTIR shift values. However, further work is needed to study the effects of alkaline solutions and natural clays from Tunisia on the properties of the prepared geopolymer. This is compulsory for prospective application of those products in various industries. [ABSTRACT FROM AUTHOR]

The objective of this study is to investigate and characterize geopolymers based on laterite or metakaolin-hematite mixture model. The model has been used to reproduce laterite in areas where laterite is not available. The geopolymers were synthetized using (i) calcined laterite and (ii) a mixture of metakaolin and hematite as solid precursors and two alkaline solutions of SiO 2 /Na 2 O and SiO 2 /K 2 O equal to 1.3. The obtained results reveal that both laterite and metakaolin/hematite-based geopolymers display efficient mechanical properties, regardless of the alkaline activating solution used. Thermal conductivity and compressive strength vary almost linearly, from 0.7 to 1 W/(m.K) and from 20 to 70 MPa, respectively: Na-activated laterite (NaLc) > Na-activated metakaolin + hematite (NaMF) > K-activated metakaolin + hematite (KMF) > K- activated laterite (KLc). This order can be explained by structural modifications after thermal treatment at 1175 °C. In the case of NaLc and NaMF, the samples display weak porosity due to higher crystallinity of the powder. In contrast, KMF and KLc are more heterogeneous with higher porosity. [Display omitted] • It is possible to synthetize geopolymer based metakaolin-hematite model. • Sodium-geopolymer has higher compressive strength and lower porosity than potassium-geopolymer. • Sodium-geopolymer-laterite has higher properties than sodium-geopolymer-metakaolin-hematite. [ABSTRACT FROM AUTHOR]

Clay based ceramic composite materials with hydraulic permeability were elaborated using sawdust as porogent agent. Their mechanical, morphological, microstructural and pore network properties were investigated. Mixtures in various ratios of two kaolinite clay minerals, Ba (highly plastic) and Va (sand-rich) constitute the five ceramic matrixes studied (CM1, CM2, CM3, CM4 and CM5). Due to their high flexural strength, CM3 and CM4 received 0%, 5%, 10% and 15% sawdust before firing, to improve the porosity of the final matrixes. Results revealed that 900–1000 °C is the range of temperature necessary to get good sintering and flexural strength (≥2 MPa). A typical clay-sawdust based materials (parallepipedic bricks) present porosity ≥40 vol% and 1.5 g/cm 3 density. Characterizations such as FTIR, SEM, MIP and flow permeability of ceramic candles were performed. A Hydraulic permeability of ~10 mDarcy was obtained and the mean pore diameter varies from 0.05 to 0.1 µm, in agreement with the microstructure exhibited by the ceramic candles. In the presence of sawdust, pores with size up to 10 µm were observed, justifying the increase of flowing permeability. The elaborated matrixes are promising candidates for microfiltration. [ABSTRACT FROM AUTHOR]

The safe management of iodine coming from spent nuclear fuels by storage in deep geological repositories requires durable materials. For this purpose, we have recently developed an iodate-substituted hydroxyapatite (HA-CaI). In the present article, the chemical durability of this material is assessed as a function of leaching media and apatite stoichiometry. First, the maximum rate for iodine release was determined in unsaturated conditions leading to a congruent dissolution of HA-CaI. In these conditions, the forward rate was equal to 2 × 10 −2 g m −2 d −1 at 50 °C independently of apatite stoichiometry. During this regime, dissolution was controlled by surface reaction and diffusion phenomena. When concentrations of calcium and phosphate ions in solution increased, the system became saturated towards non-substituted hydroxyapatite Ca 10 (PO 4 ) 6 (OH) 2 and the rate of iodine release consecutively decreased. Consequently, tests were carried out to determine the behaviour of HA-CaI in such experimental conditions (saturated conditions), which were thought to be time-prevalent given the half-life of 129 I (15.7 million years). During this regime, also called residual regime, iodine was released in the solution at a constant rate without being trapped in a secondary phase. The residual rate at 50 °C on the basis of iodine release was of 10 −4 g m −2 d −1 in an initially deionized water, and it fell by one order of magnitude (r = 10 −5 g m −2 d −1 ) in a clay-equilibrated groundwater (hereafter called Callovo-oxfordian (COx) groundwater). This singular behaviour was ascribed to the presence of calcium in COx water. These preliminary results on the chemical durability of HA-CaI suggest that this material is a viable candidate as repository iodine waste form. [ABSTRACT FROM AUTHOR]

The aim of this study is to assess the effects of the addition of aluminum (NaAlO 2 ) into the activating solution on the geopolymerization reactions and the characteristics of the porous network. It was established by liquid state NMR that the speciation of the aluminosilicate oligomers and then the mean degree of polymerization were modified by the addition of sodium aluminate in the activating solution. Time-resolved SAXS and rheology results on geopolymer pastes showed that the molar ratios Si/Al and (Si + Al)/Na 2 O in the activating solution play a major role in the geopolymer properties at liquid and solid state. Indeed, the geopolymer percolating network appeared sooner and the properties of the porous network were dramatically changed with the addition of the NaAlO 2 . On the other hand, two geopolymers having identical final chemical composition but a different activating solution composition, showed to the same setting time and the same porous network characteristics. [ABSTRACT FROM AUTHOR]

The study of bitumen substitution in the field of road construction is necessary to overcome the effects of limited oil resources and economic problems. The elaboration of new materials based on geopolymer binders and aggregates was investigated in this work. Two series of formulations of geopolymer binders based on sodium or potassium were prepared with the incorporation of granite or diorite. The formulation of these binder was investigated by the study of (i) the effect of the nature of the alkaline solution by modify the pH value with base and (ii) the mass percentage of the incorporated aggregates. The time evolution study shows different aspects of the synthesized materials, which depend essentially on the composition of the activating solutions and the nature of the alkaline solutions. The formulations using these ratios (Si/Na=1.55; Si/K=1.94 and 2.96) appear the best. Moreover, it was evidenced that materials based on the potassium alkaline solution present a consolidated aspect faster than the materials based on the sodium alkaline solution. Additionally, it is possible to incorporate diorite or granite until 60 w% with some formulations. These various formulations are promising to be use not as a substitute of bitumen but in addition between bitumen and ground. [ABSTRACT FROM AUTHOR]