The interaction between host and external environment mainly occurs in the gastrointestinal tract, where the mucosal barrier has a critical role in many physiologic functions ranging from digestion, ...absorption, and metabolism. This barrier allows the passage and absorption of nutrients, but at the same time, it must regulate the contact between luminal antigens and the immune system, confining undesirable products to the lumen. Diet is an important regulator of the mucosal barrier, and the cross-talk among dietary factors, the immune system, and microbiota is crucial for the modulation of intestinal permeability and for the maintenance of gastrointestinal tract (GI) homeostasis. In the present review, we will discuss the role of a number of dietary nutrients that have been proposed as regulators of inflammation and epithelial barrier function. We will also consider the metabolic function of the microbiota, which is capable of elaborating the diverse nutrients and synthesizing products of great interest. Better knowledge of the influence of dietary nutrients on inflammation and barrier function can be important for the future development of new therapeutic approaches for patients with mucosal barrier dysfunction, a critical factor in the pathogenesis of many GI and non-GI diseases.
About 90 of the volcanic rocks worldwide are basalt rocks utilized to produce basalt fibers. They are considered insulators electrically. Herein, the basalts’ electrical/dielectric properties have ...been significantly enhanced by introducing single-walled carbon nanotubes (SWCNT) to the basalt nanosized. We obtained nanosized basalt powders using ball milling with an average particle size of 67.86 nm. The basalt nano-powders were suspended on ethanol and mixed with SWCNT under rigorous sonication and stirring. Basalt/SWCNT nanocomposites were produced with SWCNT ratios 0, 1, 3, and 5 wt%. We evaluated their electrical conductivity, dielectric constant, and dielectric loss at different frequencies and temperatures ranging from room temperature (RT) to 1200 Kelvin. The results at 20 kHz revealed that the pure basalts’ electrical conductivity was 1.16 × 10
–7
S/cm at RT. At the same time, it was 0.03, 0.19, and 0.46 S/cm for the basalt/SWCNT nanocomposites at the SWCNT ratios 1, 3, and 5 wt%, respectively. These results proved that the basalts turned from insulators to become conductors even at the lowest ratio of SWCNT, i.e., 1 wt%. The basalt/SWCNT nanocomposites’ dielectric constant increased thousands of folds compared with pure basalts. Besides, theoretical calculations demonstrated a superior electromagnetic interference shielding (EMI) performance for the prepared nanocomposites. This study’s findings could open new horizons for using SWCNT in basalt for EMI shielding applications.
Graphical Abstract
Basalt/SWCNT nanocomposites were prepared and showed dramatically enhanced electrical conductivity, dielectric constant, and good EMI shielding performance.
Carbon nanotubes (CNTs) are widely investigated for preparing polymer nanocomposites, owing to their unique mechanical properties. However, dispersing CNTs uniformly in a polymer matrix and ...controlling their entanglement/agglomeration are still big technical challenges to be overcome. The costs of their raw materials and production are also still high. In this work, we propose the use of CNTs grown on oil fly ash to solve these issues. The CNTs of oil fly ash were evaluated as reinforcing materials for some common thermoplastics. High-density polyethylene (HDPE) was mainly reinforced with various weight fractions of CNTs. Xylene was used as a solvent to dissolve HDPE and to uniformly disperse the CNTs. Significantly enhanced mechanical properties of HDPE reinforced at a low weight fraction of these CNTs (1-2 wt.%), mainly the tensile strength, Young's modulus, stiffness, and hardness, were observed. The tensile strength and Young's modulus were enhanced by ~20 and 38%, respectively. Moreover, the nanoindentation results were found to be in support to these findings. Polycarbonate, polypropylene, and polystyrene were also preliminarily evaluated after reinforcement with 1 wt.% CNTs. The tensile strength and Young's Modulus were increased after reinforcement with CNTs. These results demonstrate that the CNTs of the solid waste, oil fly ash, might serve as an appropriate reinforcing material for different thermoplastics polymers.
Despite contemporary research calls for promoting learners' feedback dialogue, how feedback dialogue occurs and contributes to learners' uptake has been little addressed. This study on 28 pairs of ...EFL undergraduates attempts to explore the process of feedback dialogue, its potential and the main factors affecting it. The data collected from learners' screencast records of feedback dialogue archived in Blackboard Collaborate Ultra, first and final essay drafts in Google Docs, notes on students' screencast dialogue and follow-up interviews were analyzed. Findings illustrate that learners engaged in multidirectional (writer-writer, writer-non-writer and writer-teacher) and bimodal (oral/voice and written) dialogue and negotiations. The observed and perceived potential of feedback dialogue is realized through learners' understanding of feedback, revising and enhancing their writing and learning how to give feedback as well as reducing instructor's time in giving feedback. Yet, learners' engagement in dialogue varied among the pairs from high to moderate/partial and low. Factors behind this variation are learner-related, teacher feedback formulation-related, learner-pairing and grouping-related as well as technical issue-related.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
TiO2 samples with different ratios of anatase/rutile phases were synthesized via a microwave assisted sol–gel method and by applying particular concentrations of titanium(iv) isopropoxide as a single ...source precursor (SSP) with a constant concentration of nitric acid, which was used as the structure directing agent. The effect of the TiO2 composition ratio of anatase to rutile on the physicochemical and photocatalytic properties was studied. The structural, morphological, and optical properties of the as-prepared samples were studied via X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and UV-Vis diffuse reflectance spectroscopy (DRS), respectively. In addition, the functional groups were determined via Fourier transform infrared (FTIR) spectroscopy. The characterization results showed that the crystallite sizes were in the range of 30–70 nm and also revealed the different crystalline phase ratios of anatase and rutile depending on the concentrations of the Ti precursor. The photocatalytic degradation of the as-synthesized samples was evaluated with crystal violet (CV) and methylene blue (MB) solutions under UV light irradiation. The results confirmed that the TiO2 sample containing 81.65 wt% anatase exhibited a high photoactivity of organic dye degradation. The inhibitory effects of the as-synthesized samples of TiO2 nanoparticles were determined against different multidrug resistant Gram-positive and negative bacterial pathogens. The most active sample was the one with the highest ratio of anatase to rutile.
The effects of thermal treatment on the structural, electrical, and dielectric properties of scoria collected from Harrat Rahat in Saudi Arabia have been investigated. The raw scoria was thermally ...treated at two different temperatures (800 and 1000 °C). The crystalline phase, morphology, and chemical group functions of natural and treated scoria samples were studied using XRD, SEM, FTIR/Raman spectroscopies, respectively. The XRD results showed no apparent differences between the raw sample and treated at the temperature of 800 °C. While it showed a decrease in the intensities of the XRD pattern and Raman spectra of the scoria treated at the temperature of 1000 °C, this could be attributed to the formation of a hematite–ilmenite solid solution. The tested raw scoria showed excellent thermal stability up to the temperature of 800 °C. At higher temperatures, however, its mineral and chemical compositions can be slightly affected. Electrical and dielectric properties were explored in detail at different temperatures and frequencies. The results did not show any considerable changes between raw and treated scoria samples. Likewise, conductivities and dielectric constants revealed stable values up to 700 K. This type of scoria, therefore, can be a promising material for use as high-voltage power insulators.
Organic light-emitting diodes (OLEDs) play a key role in modern display devices and systems. A highly desirable material for fabricating OLEDs is tris(8-hydroxyquinoline)aluminum (Alq
3
). In this ...work, a highly efficient OLED based on dysprosium (Dy)-incorporated Alq
3
(Alq
3
-Dy) was fabricated. The fabricated OLED had four layers, namely, those of indium tin oxide (ITO),
N
,
N
′-Di(1-naphthyl)-
N
,
N
′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB), Alq
3
-Dy, and aluminum (Al). The ITO and Al layers were used as electrodes, while the NPB was selected as a hole transport layer. All the layers were deposited sequentially on a glass substrate. The surface morphologies of these layers clarified that the materials were deposited as nanosphere particles. The OLED performance showed significant improvement in terms of the operating voltage, current efficiency, and luminance of the fabricated Alq
3
-Dy OLED compared with that of the pure Alq
3
OLED device. The luminance value was significantly enhanced from approximately 250 cd/m
2
for the pure Alq
3
OLED to approximately 5000 cd/m
2
for the Alq
3
-Dy OLED. Moreover, the electroluminescence (EL) intensity of the Alq
3
-Dy OLED was 20 times higher than that of the Alq
3
OLED. These findings may have a significant impact on the fabrication of the OLEDs and display devices.
In the present work, sol–gel‐synthesized titanium oxide nanoparticles (TiO2 NPs) were added to polyvinyl chloride (PVC) and polymethyl methacrylate (PMMA) to create polymer nanocomposites (PNCs) ...samples. The preparation was carried out via the solution casting method. The synthesized TiO2 NPs have a tetragonal anatase phase and an average grain size of 15.7 nm. XRD analysis reveals that the TiO2 NPs' addition to PVC/PMMA causes a decrease in the crystallinity of PNCs films. Infrared Fourier analysis demonstrated the interplay/complexity between the PVC/PMMA blend and TiO2 NPs. The UV/visible spectrum of the PVC/PMMA blend showed two absorbance peaks at 278 and 208 nm, which may result from the n → π* and π → π* transitions. Also, optical bandgaps for indirect and direct allowed transitions decreased with increasing TiO2 NPs concentration. The samples' AC electrical conductivity and dielectric properties were measured at room temperature. As the TiO2 NPs content in the nanocomposite rises, a percolating network begins to emerge inside the composite, demonstrating that AC electrical conductivity obeys Jonscher's law. Additionally, it has been demonstrated that nanoparticle concentration leads to a higher composite dielectric loss and dielectric constant. These findings suggest the possibility of using the prepared nanocomposites in capacitive energy storage and optoelectronic devices.HighlightsPVC/PMMA‐TiO2 nanocomposites' films were fabricated via the solution casting method.Adding TiO2 NPs to PVC/PMMA reduces the crystallinity of the PNCs films.The allowed direct and indirect bandgaps decreased with rising TiO2 NPs content.AC conductivity, impedance, and dielectric characteristics were discussed.The findings indicate the use of prepared samples in optoelectronic devices.
Herein, we enhanced the epoxy resin's mechanical, thermal, and radiation shielding properties by introducing graphitic heavy oil fly ash (HOFA) to produce composite sheets at various weight fractions ...of HOFA, namely, 0, 10, 20, and 30 wt%. The morphology, chemical group functions, mechanical properties, thermal properties, and the X-ray and neutron shielding properties of the produced epoxy resin/HOFA composite sheets were rigorously tested. The SEM images showed a uniform distribution for the HOFA particles in the polymer matrix. The FTIR spectra revealed a new peak of C=C bounds, suggesting that the epoxy resin/HOFA composites were tightly bounded through these functional sites. The mechanical results showed that Young's modulus and stiffness were enhanced gradually by increasing the HOFA weight fraction; for instance, Young's modulus increased by ∼20% compared with neat epoxy. The hardness obtained by the nanoindentation test was also significantly enhanced by around 25% by increasing the HOFA weight fraction. The observed micro scratch confirmed these mechanical enhancements. The thermal conductivity and diffusivity were slightly increased by increasing the load of HOFA, but this was combined with an apparent increase in the value of the char yields, suggesting improvements in the thermal properties. The X-ray shielding results showed increases in the linear attenuation coefficients and decreases in the half-value layer, indicating better shielding properties; no effects were detected in the neutron shielding while HOFA addition. These results clearly demonstrated the possibility of reinforcing the epoxy resin thermal, mechanical, and radiation shielding properties using the waste HOFA material to be a valuable and economical material used in polymer composite applications, such as constructions, piping, and automobiles.
•Heavy oil fly ash (HOFA) was used to enhance epoxy resin composition.•The HOFA epoxy resin composition enhanced the mechanical and the thermal properties of the material.•The HOFA epoxy resin composition can be used as a radiation shielding material for photons.
The immune system is exposed to extremely low doses of neutrons under different circumstances, such as through exposure to cosmic rays, nuclear accidents, and neutron therapy. Peripheral blood ...mononuclear cells (PBMCs) are the primary immune cells that exhibit selective immune responses. Changes in the functions of the protein components of PBMC can be induced by structural modifications of these proteins themselves. Herein, we have investigated the effect of low-dose fast neutrons on PBMC proteins at 0, 2, 4, and 8 days post-whole body irradiation. 64
Wistar
rats were used in this study of which, 32 were exposed to fast neutrons at a total dose of 10 mGy (
241
Am-Be, 0.2 mGy/h), and the other 32 were used as controls. Blood samples were drawn, and PBMCs were isolated from whole blood. Fourier transform infrared (FTIR) spectroscopy and fluorescence spectroscopy were used to estimate the changes in the proteins of PBMCs. An alkaline comet assay was performed to assess DNA damage. Hierarchical cluster analysis (HCA) and principal components analysis (PCA) were utilized to discriminate between irradiated and non-irradiated samples. FTIR and fluorescence spectra of the tested samples revealed alterations in the amides and tryptophan, and therefore protein structure at time intervals of 2 and 4 days post-irradiation. No changes were recorded in samples tested at time intervals of 0 and 8 days post-irradiation. The FTIR band intensities of the PBMC proteins of the irradiated samples decreased slightly and were statistically significant. Curve fitting of the amide I band in the FTIR spectra showed changes in the secondary structure of the proteins. At 2 days post-irradiation, fluorescence spectra of the tested samples revealed decreases in the band tryptophan. The comet assay revealed low levels of DNA damage. In conclusion, low-dose fast neutrons can affect the proteins of PBMC.
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