Polyolefin-Based Smart Self-Healing Composite Coatings Modified with Calcium Carbonate and Sodium Alginate.

Corrosion-related damage incurs significant capital costs in many industries. In this study, an anti-corrosive pigment was synthesized by modifying calcium carbonate with sodium alginate (SA), and smart self-healing coatings were synthesized by reinforcing the anti-corrosive pigments into a polyolefin matrix. Structural changes during the synthesis of the anti-corrosive pigment were examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Moreover, thermal gravimetric analysis confirmed the loading of the corrosion inhibitor, and electrochemical impedance spectroscopic analysis revealed a stable impedance value, confirming the improved corrosion resistance of the modified polyolefin coatings. The incorporation of the anticorrosive pigment into a polyolefin matrix resulted in improved pore resistance properties and capacitive behavior, indicating a good barrier property of the modified coatings. The formation of a protective film on the steel substrate reflected the adsorption of the corrosion inhibitor (SA) on the steel substrate, which further contributed to enhancing the corrosion resistance of the modified coatings. Moreover, the formation of the protective film was also analyzed by profilometry and elemental mapping analysis.

Mechanical properties of human hepatic tissues to develop liver-mimicking phantoms for medical applications.

Using liver phantoms for mimicking human tissue in clinical training, disease diagnosis, and treatment planning is a common practice. The fabrication material of the liver phantom should exhibit mechanical properties similar to those of the real liver organ in the human body. This tissue-equivalent material is essential for qualitative and quantitative investigation of the liver mechanisms in producing nutrients, excretion of waste metabolites, and tissue deformity at mechanical stimulus. This paper reviews the mechanical properties of human hepatic tissues to develop liver-mimicking phantoms. These properties include viscosity, elasticity, acoustic impedance, sound speed, and attenuation. The advantages and disadvantages of the most common fabrication materials for developing liver tissue-mimicking phantoms are also highlighted. Such phantoms will give a better insight into the real tissue damage during the disease progression and preservation for transplantation. The liver tissue-mimicking phantom will raise the quality assurance of patient diagnostic and treatment precision and offer a definitive clinical trial data collection.

Do research experience programs promote capacity building in Qatar: Investigating the trend and participation differences.

Research Experience programs (REPs) inspire students to pursue advanced degrees and shape their research career paths. Government and commercial organizations sponsor REPs to promote the capacity building of the country. In Qatar, the national youth is reported to show concerning participation in Science, Technology, Engineering, and Mathematics (STEM) disciplines at the K-12 level. However, none of the studies investigate these participation trends at the undergraduate level, especially in scientific research, which is deemed necessary for building a knowledge-based economy in Qatar. Therefore, to bridge this gap, the current study uses a quantitative approach to analyze the REP in Qatar through the participation data of 2455 undergraduate students. For this, statistical measures, including descriptive analysis, independent samples t-test, and Pearson's correlation analysis were used. Results indicated concerning trends in national student participation rate, implying underlying issues restricting their representation in undergraduate research activities. Also, statistically significant differences were found in student participation rates among students' gender and ethnic distributions. While female students demonstrated higher participation rates than males, national students showed lower participation than the non-nationals. Moreover, this low participation of national students suffered more drastically in STEM disciplines. Therefore, these findings determine the outlook for stakeholders and academic institutions in making meaningful educational decisions and envision synchronizing REPs at the university level, gauging measures to bolster the adjacent funding agencies and government organizations. Furthermore, being the first research addressing REPs in the Middle East region, this study has the potential to support educators in neighboring and other developing nations where STEM education is especially significant for human capacity building.

High school students' STEM interests and career aspirations in Qatar: An exploratory study.

This study sought to explore high school students' interest in science, technology, engineering, and mathematics (STEM) related disciplines and careers in the context of Qatar. Quantitative data was collected using a survey of 1492 high school students in grades 11-12. The normality tests (Shapiro-Wilk test and Kolmogorov Smirnov test) revealed the non-normal distribution of data, leading to employing non-parametric analyses, including Mann Whitney U test, Kruskal Wallis H, and logistic regression. Results indicated that whereas students' interest in mathematics and science subjects was aligned with their likelihood to pursue STEM careers, however, their interest in engineering and technology doesn't line up with their STEM career aspirations. The findings also revealed the variability of students' STEM interests across gender and nationality. In general, female students exhibited higher STEM interests than their male counterparts, while specially expatriates were more inclined toward STEM than Qatari nationals. Overall, these findings postulate the need to improve the exposure of males in general and Qatari nationals specifically to STEM fields of study, particularly the subjects of engineering and technology, to meet the goals of Qatar's National Vision 2030.

Design and optimization of four-terminal mechanically stacked and optically coupled silicon/perovskite tandem solar cells with over 28% efficiency.

Silicon/perovskite tandem devices are believed to be a favorite contender for improving cell performance over the theoretical maximum value of single-junction photovoltaic (PV) cells. The present study evaluates the design and optimization of four-terminal (4-T) mechanically stacked and optically coupled configurations using SCAPS (solar cell capacitance simulator). Low-cost, stable, and easily processed semitransparent carbon electrode-based perovskite solar cells (c-PSCs) without hole transport material (HTM) and highly efficient crystalline silicon (c-Si) PV cells were utilized as top and bottom cells, respectively. The wide bandgap multi-cation perovskite C s x ( F A 0.4 M A 0.6 ) 1 - x P b I 2.8 B r 0.2 and a low bandgap c-Si were employed as light-harvesting layers in the top and bottom cells, respectively. The impact of perovskite thickness and doping concentrations were examined and optimized for both tandem configurations. Under optimized conditions, thicknesses of 1000 nm and 1100 nm are the best values of the perovskite absorber layer for 4-T mechanically stacked and optically coupled arrangements, respectively. Likewise, 1 × 1017 cm-3 doping concentration of top cells revealed the highest performance in both structures. With these optimized parameters under tandem configurations, efficiency values of 28.38% and 29.34% were obtained in 4-T mechanically and optically coupled tandems, respectively. Results suggest that by optimizing perovskite thickness and doping concentration, the proposed designs using HTM-free c-PSCs could enhance device performance.

Comparative Study on Gas-Sensing Properties of 2D (MoS2, WS2)/PANI Nanocomposites-Based Sensor.

NH3 is a highly harmful gas; when inhaled at levels that are too high for comfort, it is very dangerous to human health. One of the challenging tasks in research is developing ammonia sensors that operate at room temperature. In this study, we proposed a new design of an NH3 gas sensor that was comprised of two-dimensional (TMDs, mainly WS2 and MoS2) and PANI. The 2D-TMDs metal was successfully incorporated into the PANI lattice based on the results of XRD and SEM. The elemental EDX analysis results indicated that C, N, O, W, S and Mo were found in the composite samples. The bandgap of the materials decreased due to the addition of MoS2 and WS2. We also analyzed its structural, optical and morphological properties. When compared to MoS2 and PANI, the proposed NH3 sensor with the WS2 composite was found to have high sensitivity. The composite films also exhibited response and recovery times of 10/16 and 14/16 s. Therefore, the composite PANI/2D-TMDs is a suitable material for NH3 gas detection applications.

A lightweight neural network with multiscale feature enhancement for liver CT segmentation.

Segmentation of abdominal Computed Tomography (CT) scan is essential for analyzing, diagnosing, and treating visceral organ diseases (e.g., hepatocellular carcinoma). This paper proposes a novel neural network (Res-PAC-UNet) that employs a fixed-width residual UNet backbone and Pyramid Atrous Convolutions, providing a low disk utilization method for precise liver CT segmentation. The proposed network is trained on medical segmentation decathlon dataset using a modified surface loss function. Additionally, we evaluate its quantitative and qualitative performance; the Res16-PAC-UNet achieves a Dice coefficient of 0.950 ± 0.019 with less than half a million parameters. Alternatively, the Res32-PAC-UNet obtains a Dice coefficient of 0.958 ± 0.015 with an acceptable parameter count of approximately 1.2 million.

Consequence of aging at Au/HTM/perovskite interface in triple cation 3D and 2D/3D hybrid perovskite solar cells.

Perovskite solar cells (PSCs) expressed great potentials for offering a feasible alternative to conventional photovoltaic technologies. 2D/3D hybrid PSCs, where a 2D capping layer is used over the 3D film to avoid the instability issues associated with perovskite film, have been reported with improved stabilities and high power conversion efficiencies (PCE). However, the profound analysis of the PSCs with prolonged operational lifetime still needs to be described further. Heading towards efficient and long-life PSCs, in-depth insight into the complicated degradation processes and charge dynamics occurring at PSCs' interfaces is vital. In particular, the Au/HTM/perovskite interface got a substantial consideration due to the quest for better charge transfer; and this interface is debatably the trickiest to explain and analyze. In this study, multiple characterization techniques were put together to understand thoroughly the processes that occur at the Au/HTM/perovskite interface. Inquest analysis using current-voltage (I-V), electric field induced second harmonic generation (EFISHG), and impedance spectroscopy (IS) was performed. These techniques showed that the degradation at the Au/HTM/perovskite interface significantly contribute to the increase of charge accumulation and change in impedance value of the PSCs, hence resulting in efficiency fading. The 3D and 2D/3D hybrid cells, with PCEs of 18.87% and 20.21%, respectively, were used in this study, and the analysis was performed over the aging time of 5000 h. Our findings propose that the Au/HTM/perovskite interface engineering is exclusively essential for attaining a reliable performance of the PSCs and provides a new perspective towards the stability enhancement for the perovskite-based future emerging photovoltaic technology.

Humidity sensor based on poly(lactic acid)/PANI-ZnO composite electrospun fibers.

The electrospinning technique has been successfully used to prepared micro-fibers of the poly(lactic acid)/polyaniline-zinc oxide (PLA/PANI-ZnO) composite. The polyaniline-zinc oxide (PANI-ZnO) nanocomposites are synthesized by hydrothermal and in situ polymerization methods. X-ray diffraction techniques are used to study the structural properties of the PLA/PANI-ZnO composite fibers and the PANI-ZnO nanocomposite. The average crystallite size of the PANI-ZnO nanocomposite is found to be 36 nm. The morphology and diameter of the composite fibers are analyzed by scanning electron microscopy (SEM). The average fiber diameter of the pure poly(lactic acid) (PLA) fiber is around 2.5 µm and that of the PLA/PANI-ZnO composite fiber is around 1.4 µm. Differential scanning calorimetry (DSC) provides the thermal properties of the PLA/PANI-ZnO composite fibers. The melting temperature (T m) for the pure PLA is observed at 149.3 °C, and it is shifted to 153.0 °C for the PLA/PANI-ZnO composite fibers. The enhanced thermal properties of the composite fibers are due to the interaction between the polymer and the nanoparticles. The water contact angle measurements probe the surface hydrophilicity of the PLA/PANI-ZnO composite fibers. The role of the PANI-ZnO nanocomposite on the sensing behavior of PLA fibers has also been investigated. The humidity sensing properties of the composite fiber based sensor are studied in the relative humidity (RH) range of 20-90% RH. The experimental results show that the composite fiber exhibited good response (85 s) and recovery (120 s) times. These results indicate that the one-dimensional (1D) fiber structure enhances the humidity sensing properties.

Long-Term Stability Analysis of 3D and 2D/3D Hybrid Perovskite Solar Cells Using Electrochemical Impedance Spectroscopy.

Despite the remarkable progress in perovskite solar cells (PSCs), their instability and rapid degradation over time still restrict their commercialization. A 2D capping layer has been proved to overcome the stability issues; however, an in-depth understanding of the complex degradation processes over a prolonged time at PSC interfaces is crucial for improving their stability. In the current work, we investigated the stability of a triple cation 3D ([(FA0.83MA0.17)Cs0.05]Pb(I0.83Br0.17)3) and 2D/3D PSC fabricated by a layer-by-layer deposition technique (PEAI-based 2D layer over triple cation 3D perovskite) using a state-of-art characterization technique: electrochemical impedance spectroscopy (EIS). A long-term stability test over 24 months was performed on the 3D and 2D/3D PSCs with an initial PCE of 18.87% and 20.21%, respectively, to suggest a more practical scenario. The current-voltage (J-V) and EIS results showed degradation in both the solar cell types; however, a slower degradation rate was observed in 2D/3D PSCs. Finally, the quantitative analysis of the key EIS parameters affected by the degradation in 3D and 2D/3D PSCs were discussed.

Capacitive type humidity sensor based on PANI decorated Cu-ZnS porous microspheres.

Porous microstructure materials are considered good candidates for the development of highly sensitive and fast humidity sensors. In this regard, we prepared polyaniline (PANI) decorated Cu-ZnS porous microsphere structures (PMSs) for the fabrication of humidity sensors. PANI coated Cu-ZnS PMSs were synthesized by a hydrothermal method and in situ polymerization process. The synthesized PMSs were characterized by different techniques to study the structural, morphological and surface absorption properties. Several compositions for the PANI/Cu-ZnS PMS were investigated, which were then compared with pure PANI. The experimental observations demonstrate that a PANI/1%Cu-ZnS PMS has better sensitivity, fast response and good stability compared to pure PANI and other PANI/CuZnS compositions. Finally, a PANI/1% Cu-ZnS PMS was found to be optimized for humidity sensors due to its well distributed roughness, porosity and hydrophilicity. The average response and recovery times for PANI/1% Cu-ZnS were found to be 42 s and 24 s, respectively, which outperform recent results.

Investigation of the structural, optical and gas sensing properties of PANI coated Cu-ZnS microsphere composite.

Polyaniline (PANI)/Cu-ZnS composites with porous microspheres are prepared by a hydrothermal and in situ polymerization method. The structural, optical, and morphological properties are characterized by X-ray powder diffraction, FTIR, UV-vis, scanning electron microscope, transmission electron microscope. The XRD results confirmed that the PANI/Cu-ZnS composite is formed. The morphological analyses exhibited that the PANI/Cu-ZnS composite comprises the porous microspherical structures. The emission peaks obtained in photoluminescence spectra confirm the presence of surface defects in the prepared composite. The UV-DRS study shows that the bandgap of the samples is found to decrease for the PANI/Cu-ZnS composite compared to the pure Cu-ZnS sample. The calculated band gap (E g) value of PANI/Cu-ZnS composite is 2.47 eV. Furthermore, the fabricated gas sensor based on PANI/Cu-ZnS can perform at room temperature and exhibits good gas sensing performance toward CO2 gas. In particular, PANI/Cu-ZnS sensor shows good response (31 s) and recovery time (23 s) upon exposure to CO2 gas. The p/n heterojunction, surface defects, and porous nature of the PANI/Cu-ZnS composite microsphere enhanced sensor performance.

Fabrication of flexible conductive films by rubbing in technology for application in elastic thermo-electric cells.

This method solves the problem of fabrication of flexible elastic conductive thin film samples for thermoelectric applications. For this purpose, rubbing in technology at room temperature condition has been used which is simple, economical and reliable. As a result, elastic thermo-electric cells have been fabricated that can be used for low power applications and for measurement of the gradient of temperature in industry, medicine and in instrumentation as well. The elastic nature of the thermo-electric cells allows us to place the "hot" and "cold" points of the thermo-electric cells in different planes that make these thermo-electric cells useful for different kind of applications without limitation to place them in a line or in a plane.

Fabrication of polyaniline-graphene/polystyrene nanocomposites for flexible gas sensors.

This research work presents the fabrication of polyaniline (PANI) and graphene-polyaniline (graphene-PANI) nanocomposite-coated polystyrene (PS) nanofibre mats, as well as their application in flexible and highly sensitive gas sensors. The surface morphology of the flexible films is investigated using a number of techniques. The profilometry studies confirmed that the electrospun fibres are evenly distributed over a large surface area and there was no visible difference between coated and uncoated fibres. The SEM morphology studies revealed that a nanocomposite consisting of 10 nm PANI nanofibres and graphene forms a uniform coating around 3 µm diameter PS fiber. AFM showed differences in the 3D surface topography between plain PS nanofibres and coated ones, which showed an increased roughness. Moreover, conductive AFM has indicated an increase in the electrical current distribution from picoamperes to nanoamperes of the PS samples coated with PANI and graphene-PANI because of the applied voltage to the AFM tip that contacted the sample surface. The chemical properties of all the samples are analysed by Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD), which revealed the presence of chemical interactions between the nanocomposites and the polymeric backbones. The TGA study indicated that graphene-PANI coated fibres have the highest thermal stability compared to the pure fibres. The addition of the nanocomposite layer to the PS fibre significantly increased the electrical conductivity. Therefore, nanocomposite-coated flexible membranes are used to fabricate carbon dioxide gas sensors (sensing range: 20-100 ppm). Due to the higher surface area of the nanocomposite coated fibre the availability of adsorption area is also higher, which leads to an increase in sensitivity to carbon dioxide gas. The sensitivity increases with the increase in gas concentration. The average response time of the sensor is calculated to be 65 seconds, with good and uniform repeatability.