Browse

11 - 20 of 1,173 items :

  • Materials Sciences, other x
  • Materials Sciences x
Clear All
Investigation of Murine T-Cells and Cancer Cells under Thermal Stressors and 2D Slow Rotating System Effects as a Testbed for Suborbital Flights

Abstract

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.

Open access
Effect of macromolecular mass transport in microgravity protein crystallization

Abstract

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.

Open access
The Analysis of Hospital Helicopter Landing Sites Location in Terms of their Vibroacoustic Impact

Abstract

According to the applicable regulations, in the case of a decision on the location of an investment consisting in the construction and commissioning of a helicopter landing field, it is necessary to carry out an environmental impact assessment. At the same time, due to the emission of noise related to the expected change of acoustic climate parameters, the indicators required under the applicable law related to building acoustics and also impact of vibration on the structure of buildings should be taken into account. The article discusses particular groups of issues related to the assessment of the impact of helicopter landing field on the environment and the hospital building. On the basis of the presented results of analyzes, a postulate concerning the necessity of introducing a comprehensive assessment methodology, including specific groups of issues, was formulated.

Open access
A Concept of Suborbital Scientific Mission and Technology Validation

Abstract

Suborbital platforms are one of alternatives for satellites. They offer cheaper access to space to perform broad range of scientific and technology R&D. One of suborbital platforms are sounding rockets, which are suitable for these applications. A concept of scientific mission utilizing the sounding rocket is presented by author in this paper. The novelty of this mission is the operational responsive launch approach, which presents the example of the mission which responds for payload user needs, not payload contest approach, which is often in scientific community competing for payload space in space agency sounding rocket launch campaigns. The main mission goal is to perform astronomical observation of NEO using IR/VIS telescope. The secondary goal is to qualify the instrument for use on astronomical satellite observatory and raise its technology readiness level from TRL 6 to TRL 8. The expected mission output is to gain scientific data on NEO object and perform new IR/VIS optoelectronic instrument technology validation.

Open access
Conformity of finished forming sieves for paper industry

Abstract

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.

Open access
Deposition time and annealing effects on morphological and optical properties of ZnS thin films prepared by chemical bath deposition

Abstract

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.

Open access
Determination of In-Plane Shear Properties of Laminate with V-Notch Rail Shear Test and Digital Image Correlation

Abstract

This article presents the results of the application of Digital Image Correlation (DIC) to measurements of in-plane shear modulus and strength of three different carbon fiber reinforced laminates. Three different approaches to shear strain calculations via DIC are evaluated and compared with standard strain gage measurements. Calculation of shear strain based on averaging DIC strain values of strain gages area in most cases yielded results closest to strain gages, while measurements based on single point strain measuring differed the most from strain gages. These results are attributed to shear strain distribution in the center area of the specimen. Thermoplastic matrix fabric reinforced composite had the lowest shear strength at 5% of shear strain, but the highest ultimate shear strength and strain at failure. Of thermosetting materials, laminate reinforced with unidirectional carbon fiber had shear modulus about 10% lower, than fabric reinforced laminate, but higher ultimate strength and strain at failure. This behavior is attributed to the presence of weaves in fabric reinforcing the laminate, causing shear stiffening of the material, but lowering its ability to deform under shear loading.

Open access
Development of sol-gel derived gahnite anti-reflection coating for augmenting the power conversion efficiency of polycrystalline silicon solar cells

Abstract

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.

Open access
DFT study of optoelectronic spectra of barium cadmium chalcogenides (Ba2CdX3, X = S, Se and Te)

Abstract

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.

Open access
The effect of changing injection temperature on some mechanical and morphological properties for polypropylene material (PP)

Abstract

This is a study of a medical injection factory-Babylon carried out in order to achieve proper mechanical and morphological properties, PP has been injection molded by using cold runner injection molding machine with temperature variation (198, 200, 203……220°C) for ten samples. The physical and mechanical properties of PP product were examined. It has been found that the Shore hardness decreases linearly with injection molding temperature increasing. The tensile strength has a similar behavior to the hardness. However, it has been found that the MIF (Melt Index Flow) rates increases with the increase of injection molding temperature. The density of PP has been found for both virgin PP and the samples, it has been found that the density decreases with increasing operation temperature. FTIR (Fourier Transmission Infrared) spectra were taken for both samples with high and low operation temperature. Besides the SEM (Scanning Electronic Microscopy) test shows the difference in the morphology of the product surface and the PP product at high and low operation temperature. Moreover, for all these properties, the PP product exhibits good mechanical properties (hardness, tensile strength, density) for the samples produced at temperature lower than 207°C. While the physical properties such as MIF improved with injection temperature increasing, additionally, the SEM images show that the sample produced in low temperature have surface damage.

Open access