Co-Doped Magnesium Oxychloride Composites with Unique Flexural Strength for Construction Use

In this study, the combined effect of graphene oxide (GO) and oxidized multi-walled carbon nanotubes (OMWCNTs) on material properties of the magnesium oxychloride (MOC) phase 5 was analyzed. The selected carbon-based nanoadditives were used in small content in order to obtain higher values of mechanical parameters and higher water resistance while maintaining acceptable price of the final composites. Two sets of samples containing either 0.1 wt. % or 0.2 wt. % of both nanoadditives were prepared, in addition to a set of reference samples without additives. Samples were characterized by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and energy dispersive spectroscopy, which were used to obtain the basic information on the phase and chemical composition, as well as the microstructure and morphology. Basic macro- and micro-structural parameters were studied in order to determine the effect of the nanoadditives on the open porosity, bulk and specific density. In addition, the mechanical, hygric and thermal parameters of the prepared nano-doped composites were acquired and compared to the reference sample. An enhancement of all the mentioned types of parameters was observed. This can be assigned to the drop in porosity when GO and OMWCNTs were used. This research shows a pathway of increasing the water resistance of MOC-based composites, which is an important step in the development of the new generation of construction materials.

The Effect of Various Grinding Aids on the Properties of Cement and Its Compatibility with Acrylate-Based Superplasticizer

The influence of grinding aids (pure triethanolamine and ethylene glycol) on the properties of cements, their compatibility with an acrylate-based superplasticizer and the rheological parameters of mortars were investigated. The presence of surfactants influences the standard properties of cements and the effectiveness of the superplasticizer. The results of the heat of hydration and setting time measurements indicate a delay in the hydration process and an increase in the induction period duration of the surfactant-doped pastes, in relation to the reference sample without grinding aids. Triethanolamine increases early-age compressive strength; the effect was observed for both standard and superplasticizer-containing mortars. The presence of grinding aids decreases the slump flow of mortars and increases rheological parameters such as yield stress (τ0) and viscosity (η).

Utilization of Waste Glass in Autoclaved Silica–Lime Materials

This paper aims to investigate the possibility of using waste glass of different colours as a complete substitute for quartz sand in autoclaved silica–lime samples. On the one hand, this increases the possibility of recycling waste glass; on the other hand, it allows obtaining autoclaved materials with better properties. In this research, reference samples with quartz sand (R) and white (WG), brown (BG), and green (GG) waste container glass were made. Parameters such as compressive strength, bulk density, and water absorption were examined on all samples. The samples were examined using a scanning electron microscope with an energy dispersive spectroscopy detector (SEM/EDS) and subjected to X-ray diffraction (XRD) analysis. The WG samples showed 187% higher compressive strength, BG by 159%, and GG by 134% compared to sample R. In comparison to the reference sample, volumetric density was 16.8% lower for sample WG, 13.2% lower for BG, and 7.1% lower for GG. Water absorption increased as bulk density decreased. The WG sample achieved the highest water absorption value, 15.84%. An X-ray diffraction analysis confirmed the presence of calcite, portlandite, and tobermorite phases. Depending on the silica aggregate used, there were differences in phase composition linked to compressive strength. Hydrated calcium silicates with varying crystallisation degrees were visible in the microstructure image.

Water Stabilization of Clay Bricks with Improved Tannin and Iron Mixes

Weak water resistance is a big obstacle for clay materials to overcome in modern construction industry. Compared to the hydraulic stabilized additives, bio-additives have a lower carbon footprint and have been used in many vernacular construction techniques to immobilize clay. In this work, the traditional recipes of tannin and iron have been revisited, in particular, the question of pH and iron solubility has been explored. Oak tannin and FeCl3 were chosen and their influence on the properties of clay materials in terms of rheological properties, compressive strength, and water resistance were characterized in the lab. Based on the results, tannin can reduce the yield stress of paste while with the addition of FeCl3, the yield stress of tannin dispersed pastes increased to a value similar to the reference sample but lower than the value contain only FeCl3. The increase was attributed to the complex reaction between tannin and Fe3+. The iron-tannin complexes can also increase the samples’ strength and water resistance. Although the complexes did not change the hydrophilic properties of the samples’ surface, they prevent the ingression of water. These results are very promising as they allow the production of a fluid earth material that is water-resistant. This opens a wide range of application potentials and can help to mainstream earth materials in construction.

The CirPAD, a circular 1.4 M hybrid pixel detector dedicated to X-ray diffraction measurements at Synchrotron SOLEIL

One of the challenges of all synchrotron facilities is to offer the highest performance detectors for all their specific experiments, in particular for X-ray diffraction imaging and its high throughput data collection. In that context, the DiffAbs beamline, the Detectors and the Design and Engineering groups at Synchrotron SOLEIL, in collaboration with ImXPAD and Cegitek companies, have developed an original and unique detector with a circular shape. This detector is based on the hybrid pixel photon-counting technology and consists of the specific assembly of 20 hybrid pixel array detector (XPAD) modules. This article aims to demonstrate the main characteristics of the CirPAD (for Circular Pixel Array Detector) and its performance – i.e. excellent pixel quality, flat-field correction, high-count-rate performance, etc. Additionally, the powder X-ray diffraction pattern of an LaB6 reference sample is presented and refined. The obtained results demonstrate the high quality of the data recorded from the CirPAD, which allows the proposal of its use to all scientific communities interested in performing experiments at the DiffAbs beamline.

The effect of adding natural wastes on some properties of gypsum: تأثير إضافة المخلفات الطبيعية على بعض خواص الجبس

In this research, the effect of adding some natural wastes to gypsum was studied in order to use them as thermal insulation materials in buildings and to recycle these wastes. Thermal insulation panels were installed from gypsum (as a basic material) and natural wastes (sawdust, peanut shells, wheat straw, cottonwood) at percentages (10, 15, 20) %, and some of their mechanical and physical properties, and their thermal conductivity were studied. The results indicated an improvement in some properties of gypsum after adding wastes, and obtaining thermal building materials that have better properties than the reference sample (gypsum) in some cases. Rough sawdust samples (SdR15, SdR20) achieved the highest compressive strength exceeding (4MPa). The flexural strength was for peanut shells samples (P10:1.76 MPa, P15:1.8 MPa), while the most efficient samples as thermal insulation were ground straw and smooth sawdust samples (SdS15, SdS20, GSt15, GSt20) where their thermal conductivity was (0.194-0.141W/m.K), which makes it acceptable according to the Syrian thermal insulation code.

Resistance of Aluminide Coatings on Austenitic Stainless Steel in a Nitriding Atmosphere

A new slurry cementation method was used to produce silicide-aluminide protective coatings on austenitic stainless steel 1.4541. The slurry cementation processes were carried out at temperatures of 800 and 1000 °C for 2 h with and without an additional oxidation process at a temperature of 1000 °C for 5 min. The microstructure and thickness of the coatings were studied by scanning electron microscopy (SEM). The intention was to produce coatings that would increase the heat resistance of the steel in a nitriding atmosphere. For this reason, the produced coatings were subjected to gas nitriding at a temperature of 550–570 °C in an atmosphere containing from 40 to 60% of ammonia. The nitriding was carried out using four time steps: 16, 51, 124, and 200 h, and microstructural observations using SEM were performed after each step. Analysis of the chemical composition of the aluminide coatings and reference sample was performed using wavelength (WDS) and energy (EDS) dispersive X-ray microanalysis, and phase analysis was carried out using X-ray diffraction (XRD). The resistance of the aluminide coatings in the nitriding atmosphere was found to depend strongly on the phase composition of the coating. The greatest increase in resistance to gas corrosion under nitriding atmosphere conditions was achieved using a manufacturing temperature of 1000 °C.

Nanocrystalline SnO2 Functionalized with Ag(I) Organometallic Complexes as Materials for Low Temperature H2S Detection

This paper presents a comparative analysis of H2S sensor properties of nanocrystalline SnO2 modified with Ag nanoparticles (AgNPs) as reference sample or Ag organic complexes (AgL1 and AgL2). New hybrid materials based on SnO2 and Ag(I) organometallic complexes were obtained. The microstructure, compositional characteristics and thermal stability of the composites were thoroughly studied by X-ray diffraction (XRD), X-ray fluorescent spectroscopy (XRF), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and Thermogravimetric analysis (TGA). Gas sensor properties to 2 ppm H2S demonstrated high sensitivity, selectivity toward other reducing gases (H2 (20 ppm), NH3 (20 ppm) and CO (20 ppm)) and good reproducibility of the composites in H2S detection at low operating temperatures. The composite materials also showed a linear detection range in the concentration range of 0.12–2.00 ppm H2S even at room temperature. It was concluded that the predominant factors influencing the sensor properties and selectivity toward H2S in low temperature region are the structure of the modifier and the chemical state of silver. Thus, in the case of SnO2/AgNPs reference sample the chemical sensitization mechanism is more possible, while for SnO2/AgL1 and SnO2/AgL2 composites the electronic sensitization mechanism contributes more in gas sensor properties. The obtained results show that composites based on nanocrystalline SnO2 and Ag(I) organic complexes can enhance the selective detection of H2S.

Few-Photon Spectral Confocal Microscopy for Cell Imaging Using Superconducting Transition Edge Sensor

A superconducting transition edge sensor (TES) is an energy-dispersive single-photon detector that distinguishes the wavelength of each incident photon from visible to near-infrared (NIR) without using spectral dispersive elements. Here, we introduce an application of the TES technique for confocal laser scanning microscopy (CLSM) as proof of our concept of ultra-sensitive and wide-band wavelength range color imaging for biological samples. As a reference sample for wide-band observation, a fixed fluorescence-labeled cell sample stained with three different color dyes was observed using our TES-based CLSM method. The three different dyes were simultaneously excited by irradiating 405 and 488 nm lasers, which were coupled using an optical fiber combiner. Even when irradiated at low powers of 80 and 120 nW with the 405 and 488 nm lasers respectively, emission signals were spectrally detected by the TES and categorized into four wavelength bands: up to 500 nm (blue), from 500 to 600 nm (green), from 600 to 800 nm (red), and from 800 to 1,200 nm (NIR). Using a single scan, an RGB color image and an NIR image of the fluorescent cell sample were successfully captured with tens of photon signals in a 40 ms exposure time for each pixel. This result demonstrates that TES is a useful wide-band spectral photon detector in the field of life sciences.

An unsupervised one-class-classifier support vector machine to simultaneously monitor location and scale of multivariate quality characteristics

PurposeThe purpose of this study is to propose an effective unsupervised one-class-classifier (OCC) support vector machine (SVM)-based single multivariate control chart (OCC-SVM) to simultaneously monitor “location” and “scale” shifts of a manufacturing process.Design/methodology/approachThe step-by-step approach to developing, implementing and fine-tuning the intrinsic parameters of the OCC-SVM chart is demonstrated based on simulation and two real-life case examples.FindingsA comparative study, considering varied known and unknown response distributions, indicates that the OCC-SVM is highly effective in detecting process shifts of samples with individual observations. OCC-SVM chart also shows promising results for samples with a rational subgroup of observations. In addition, the results also indicate that the performance of OCC-SVM is unaffected by the small reference sample size.Research limitations/implicationsThe sample responses are considered identically distributed with no significant multivariate autocorrelation between sample observations.Practical implicationsThe proposed easy-to-implement chart shows satisfactory performance to detect an out-of-control signal with known or unknown response distributions.Originality/valueVarious multivariate (e.g. parametric or nonparametric) control chart(s) are recommended to monitor the mean (e.g. location) and variance (e.g. scale) of multiple correlated responses in a manufacturing process. However, real-life implementation of a parametric control chart may be complex due to its restrictive response distribution assumptions. There is no evidence of work in the open literature that demonstrates the suitability of an unsupervised OCC-SVM chart to simultaneously monitor “location” and “scale” shifts of multivariate responses. Thus, a new efficient OCC-SVM single chart approach is proposed to address this gap to monitor a multivariate manufacturing process with unknown response distributions.