The article presents problem of non-uniform foundation of structures in weak wet subsoil. The problem is illustrated with the case study of two-chamber-reinforced concrete water tank constructed in 1920s of 20th century, which cracked during construction. Under part of foundation, where the peat was found, the concrete piles were introduced.
The results of five-year measurement of crack widths with crack gauges and geodesic measurements of vertical displacement of tank were presented. These results indicate that the tank is not stable and part of broken tank supported on piles is movable.
On the basis of the presented data, the general conclusions concerning the non-uniform founding of tanks are formulated.
Imad Kadiri, Younès Tahir, Omar Iken, Saïf ed-Dîn Fertahi and Rachid Agounoun
Extractive industries often use explosives to destroy rocks, and productivity requirements tend to increase the charges of the explosives. The blasts induce vibrations, which result in a potential damage of the surrounding structures. Therefore, the prediction of vibrations should be described with accuracy, in order to ensure the safety of engineered structures. However, the prediction of vibrations’ levels remain a complicated issue, because it involves numerous parameters correlated to the quarry site.
In this paper, statistical analysis based on the peak particle velocity (PPV) and the attenuation law has been carried out to assess the safety charges (Q) for different distances (R) between the blast and the considered structure to secure. Moreover, the experimental investigations were conducted on the quarry site of “Sococim”, which is located on the south coast of Senegal. To ensure the safety of the “Conveyor belt” and “Panel 1 (Upper exploitation level)” sites, the PPV should be less than 10 mm/s. In fact, the attenuation model has been used to assess the safe charge weights of the explosive (Q) to be used at the “Conveyor belt” site and at the “Panel 1 (Upper exploitation level)” site. Therefore, the safe charge weights per delay (Q) were respectively 116 kg and 13.75 kg.
Research indicates that exposure to microgravity leads to immune system dysregulation. However, there is a lack of clear evidence on the specific reasons and precise mechanisms accounting for these immune system changes. Past studies investigating space travel-induced alterations in immunological parameters report many conflicting results, explained by the role of certain confounders, such as cosmic radiation, individual body environment, or differences in experimental design. To minimize the variability in results and to eliminate some technical challenges, we advocate conducting thorough feasibility studies prior to actual suborbital or orbital space experiments. We show how exposure to suborbital flight stressors and the use of a two-dimensional slow rotating device affect T-cells and cancer cells survivability. To enhance T-cell activation and viability, we primed them alone or in combination with IL-2 and IL-12 cytokines. Viability of T-cells was assessed before, during the experiment, and at the end of the experiment for which T-cells were counted every day for the last 4 days to allow the cells to form clear structures and do not disturb their evolution into various geometries. The slow rotating device could be considered a good system to perform T-cell activation studies and develop cell aggregates for various types of cells that react differently to thermal stressors.
Arayik Martirosyan, Lawrence J. DeLucas, Christina Schmidt, Markus Perbandt, Deborah McCombs, Martin Cox, Christopher Radka and Christian Betzel
To investigate the effect of macromolecular transport and the incorporation of protein aggregate impurities in growing crystals, experiments were performed on the International Space Station (ISS) and compared with control experiments performed in a 1G laboratory environment. Crystal growth experiments for hen egg-white lysozyme (HEWL) and Plasmodium falciparum glutathione S-transferase (PfGST) were monitored using the ISS Light Microscopy Module (LMM). Experiments were performed applying the liquid–liquid counter diffusion crystallization method using rectangular, optically transparent capillaries. To analyze the quantity of impurity incorporated into growing crystals, stable fluorescently labeled protein aggregates were prepared and subsequently added at different percent concentrations to nonlabeled monomeric protein suspensions. For HEWL, a covalent cross-linked HEWL dimer was fluorescently labeled, and for PfGST, a stable tetramer was prepared. Crystallization solutions containing different protein aggregate ratios were prepared. The frozen samples were launched on 19.02.2017 via SpaceX-10 mission and immediately transferred to a -80°C freezer on the ISS. Two series of crystallization experiments were performed on ISS, one during 26.02.2017 to 10.03.2017 and a second during 16.06.2017 to 23.06.2017. A comparison of crystal growth rate and size showed different calculated average growth rates as well as different dimensions for crystals growing in different positions along the capillary. The effect of macromolecular mass transport on crystal growth in microgravity was experimentally calculated. In parallel, the percentage of incorporated fluorescent aggregate into the crystals was monitored utilizing the fluorescent LMM and ground-based fluorescent microscopes.
Hala Hammadeh, Farzat Askifi, Andrzej Ubysz, Marek Maj and Amjad Zeno
This paper presents an experimental investigation of the discharge flow pressure in the vertical silo and the hopper due to the use of insert (top cone with trunk cone bottom). Using the Insert inside the silos is one of the proposed solutions to avoid the problems of having funnel flow pattern, which has a significant effect on the distribution of flow pressure exerted on the silo wall and the hopper. The experiments were performed on a metal cylinder prototype; corn was used as a granular material, and the wall and hopper pressure distribution was measured by a special pressure transducer. The experiments revealed an important result in the flow pressure due to the change in the location of the insert. The experiments were conducted in Damascus University laboratories.
The sieves’ manufacturers that want to be competitive at the market must have the implemented quality control system. Different methods, based on taking the sample, which is a representative of the total quantity of the forming sieves production, are applied for evaluation of the sieve’s conformity. The basic characteristics of this type of the quality function are control, measuring and testing of the forming sieves’ properties at the end of the manufacturing process. The objective is to detect and separate the products that deviate from the set criteria, to remain in the factory, then to be repaired if possible or discarded in the opposite case and thus to prevent delivery of the defective sieves to the paper manufacturers.
Nanocrystalline zinc sulfide thin films were prepared on glass substrates by chemical bath deposition method using aqueous solutions of zinc chloride, thiourea ammonium hydroxide along with non-toxic complexing agent trisodium citrate in alkaline medium at 80 °C. The effect of deposition time and annealing on the properties of ZnS thin films was investigated by X-ray diffraction, scanning electron microscopy, optical transmittance spectroscopy and four-point probe method. The X-ray diffraction analysis showed that the samples exhibited cubic sphalerite structure with preferential orientation along 〈2 0 0〉 direction. Scanning electron microscopy micrographs revealed uniform surface coverage, UV-Vis (300 nm to 800 nm) spectrophotometric measurements showed transparency of the films (transmittance ranging from 69 % to 81 %), with a direct allowed energy band gap in the range of 3.87 eV to 4.03 eV. After thermal annealing at 500 °C for 120 min, the transmittance increased up to 87 %. Moreover, the electrical conductivity of the deposited films increased with increasing of the deposition time from 0.35 × 10−4 Ω·cm−1 to 2.7 × 10−4 Ω·cm−1.
The present research is focused on developing ZnAl2O4 (gahnite) spinel as an antireflection coating material for enhanced energy conversion of polycrystalline silicon solar cells (PSSC). ZnAl2O4 has been synthesized using dual precursors, namely aluminum nitrate nonahydrate and zinc nitrate hexahydrate in ethanol media. Diethanolamine has been used as a sol stabilizer in sol-gel process for ZnAl2O4 nanosheet fabrication. ZnAl2O4 nanosheet was deposited layer-by-layer (LBL) on PSSC by spin coating method. The effect of ZnAl2O4 coating on the physical, electrical, optical properties and temperature distribution in PSSC was investigated. The synthesized antireflection coating (ARC) material bears gahnite (ZnAl2O4) spinel crystal structure composed of two dimensional (2D) nanosheets. An increase in layer thickness proves the LBL deposition of ARC on the PSSC substrate. The ZnAl2O4 2D nanosheet comprising ARC on the PSSC was tested and it exhibited a maximum of 93 % transmittance, short-circuit photocurrent of 42.364 mA/cm2 and maximum power conversion efficiency (PCE) 23.42 % at a low cell temperature (50.2 °C) for three-layer ARC, while the reference cell exhibited 33.518 mA/cm2, 15.74 % and 59.1 °C, respectively. Based on the results, ZnAl2O4 2D nanosheets have been proven as an appropriate ARC material for increasing the PCE of PSSC.
Sachin Kumar, Naven Kumar, Kamna Yadav, Annveer and R.P. Singh
DFT analyses of electronic and optical spectra of barium cadmium chalcogenides (Ba2CdX3, X = S, Se, Te) have been carried out. The study of electronic spectra has been made in terms of band structure and density of states using full potential linear augmented plane wave plus local orbital method. Band structure calculations have been carried out under the approximations PBE-GGA, PBE-Sol, LDA and TB-mBJ. Band structures of these materials show that Ba2CdS3, Ba2CdSe3 and Ba2CdTe3 crystals possess a band gap less than 1 eV, underestimated relative to the experimental/theoretical literature values. Optical spectra of these chalcogenides have been analyzed in terms of real and imaginary parts of dielectric function, reflectivity, refractive index, extinction coefficient, absorption coefficient, optical conductivity and electron energy loss. Optical results show large anisotropy along different directions. These results provide a physical basis of barium cadmium chalcogenides for potential application in optoelectronic devices.
A. Irekti, M. Oualit, H. Siahmed, D. Buncianu and F. Zibouche
Lignin is the second most abundant natural polymer. Due to the high content of carbon and hydrogen (C-H, C-C, C=O), it can be used as a potential dispersant for cement matrix. The objective of this study is to extract lignin from date palm and study its effect in the form of black liquor (BL) on the rheological and physic-mechanical properties of the cements and concrete. The lignin in black liquor form represents approximately 30 wt% dry weight of date palm. It is a heteropolymer composed primarily of methoxylated phenylpropylene alcohol monomeric units interconnected by a variety of stable carbon-carbon and carbon-oxygen-carbon (ether and esters) linkages. The results found show the positive effect on the workability of cement and concrete and confirms its dispersion effect by improving compressive strength of concrete during the early and the later ages of hydration.