Search results for: Electron Paramagnetic Resonance (ESR)

Authors: Theresa Slump, Paula Neumeister, Katharina Feldker, Carina Y. Heitmann, Thomas Straube

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A characteristic feature of post-traumatic stress disorder (PTSD) is the automatic processing of disorder-specific stimuli that expresses itself in intrusive symptoms such as intense physical and psychological reactions to trauma-associated stimuli. That automatic processing plays an essential role in the development and maintenance of symptoms. The aim of our study was, therefore, to investigate the behavioral and neural correlates of automatic processing of trauma-related stimuli in PTSD. Although interpersonal traumatization is a form of traumatization that often occurs, it has not yet been sufficiently studied. That is why, in our study, we focused on patients suffering from interpersonal traumatization. While previous imaging studies on PTSD mainly used faces, words, or generally negative visual stimuli, our study presented complex trauma-related and neutral visual scenes. We examined 19 female subjects suffering from PTSD and examined 19 healthy women as a control group. All subjects did a geometric comparison task while lying in a functional-magnetic-resonance-imaging (fMRI) scanner. Trauma-related scenes and neutral visual scenes that were not relevant to the task were presented while the subjects were doing the task. Regarding the behavioral level, there were not any significant differences between the task performance of the two groups. Regarding the neural level, the PTSD patients showed significant hyperactivation of the hippocampus for task-irrelevant trauma-related stimuli versus neutral stimuli when compared with healthy control subjects. Connectivity analyses revealed altered connectivity between the hippocampus and other anxiety-related areas in PTSD patients, too. Overall, those findings suggest that fear-related areas are involved in PTSD patients' processing of trauma-related stimuli even if the stimuli that were used in the study were task-irrelevant.

Keywords: post-traumatic stress disorder, automatic processing, hippocampus, functional magnetic resonance imaging

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Authors: M. Nagaraja, H. M. Mahesh, K. Rajanna, M. Z. Kurian, J. Manjanna

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In recent years, composites of conjugated polymers with fullerenes (C60) has attracted considerable scientific and technological attention in the field of organic electronics because they possess a novel combination of electrical, optical, ferromagnetic, mechanical and sensor properties. These properties represent major advances in the design of organic electronic devices. With the addition of C60 in the conjugated polymer matrix, the primary photo-excitation of the conjugated polymer undergoes an ultrafast electron transfer, and it has been demonstrated that fullerene molecules may serve as efficient electron acceptors in polymeric solar cells. The present paper includes the systematic studies on the effect of electrical, structural and sensor properties of polyaniline (PANI) matrix by the presence of C60. Polyaniline-fullerene (PANI/C60) composite is prepared by the introduction of fullerene during polymerization of aniline with ammonium persulfate and dodechyl benzene sulfonic acid as oxidant and dopant respectively. FTIR spectroscopy indicated the interaction between PANI and C60. X-ray diffraction proved the formation of a PANI/C60 complex. SEM image shows the highly branched chain structure of the PANI in the presence of C60. The conductivity of the PANI/C60 was found to be more than ten orders of magnitude over the pure PANI.

Keywords: conductivity, fullerene, nanocomposite, polyaniline

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Authors: Escada A. L. A., Pereira C. A., Jorge A. O. C., Alves Claro A. P. R.

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In the present work, a susceptibility and efficacy of the Ti–7.5Mo alloy nanotube and Ti–7.5Mo alloy to bacterial biofilm formation after surface treatment was evaluated. The Ti–7.5Mo alloy was obtained in arc furnace under an argon atmosphere. Ingots were then homogenized under vacuum at 1100 ◦C for 86.4 ks to eliminate chemical segregation and after cold worked discs were cutting. Nanotubes were processed using anodic oxidation in 0.25% NH4F electrolyte solution. Biofilms were grown in discs immersed in sterile brain heart infusion broth (BHI) containing 5% sucrose, inoculated with microbial suspension (106 cells/ml) and incubated for 5 days. Next, the discs were placed in tubes with sterile physiological solution 0.9% sodium chloride (NaCl) and sonicated for to disperse the biofilms. Tenfold serial dilutions were carried and aliquots seeded in selective agar, which were then incubated for 48 h. Then, the numbers CFU/ml (log 10) were counted and analyzed statistically. Scanning electron microscopy (SEM) on discs with biofilms groupswas performed, atomic force microscope (AFM) and contact angle. The results show that there is no difference in bacterial adhesion between Ti–7.5Mo alloy nanotube pure titanium and Ti–7.5Mo alloy.

Keywords: biofilm, titanium alloy, brain heart infusion, scanning electron microscopy

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Authors: Navid Zanganeh, Hafez Balavi, Farbod Sharif, Mahla Zabet, Marzieh Bakhtiary Noodeh

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Cerium oxide (CeO2) also known as cerium dioxide or ceria is a pale yellow-white powder with various applications in the industry from wood coating to cosmetics, filtration, fuel cell electrolytes, gas sensors, hybrid solar cells and catalysts. In this research, attempts were made to synthesize and characterization of CeO2 nano-particles via sol-gel method. In addition, the effect of aging time on the size of particles was investigated. For this purpose, the aging times adjusted 48, 56, 64, and 72 min. The obtained particles were characterized by x-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), transmitted electron microscopy (TEM), and Brunauer–Emmett–Teller (BET). As a result, XRD patterns confirmed the formation of CeO2 nanoparticles. SEM and TEM images illustrated the nano-particles with cluster shape, spherical and a nano-size range which was in agreement with XRD results. The finest particles (7.3 nm) was obtained at the optimum condition which was aging time of 48 min, calcination temperature at 400 ⁰C, and cerium concentration of 0.004 mol. Average specific surface area of the particles at optimum condition was measured by BET analysis and recorded as 47.57 m2/g.

Keywords: aging time, CeO2 nanoparticles, size distribution, sol-gel

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Authors: Rabah Bensaha, Badreeddine Toubal

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Un-doped TiO2, Co single doped TiO2 and (Cu-Co) co-doped TiO2 thin films have been growth on silicon substrates by the sol-gel dip coating technique. We mainly investigated both effects of the dopants and annealing temperature on the structural, optical and electrical properties of TiO2 films using X-ray diffraction (XRD), Raman and FTIR spectroscopy, Atomic force microscopy (AFM), Scanning electron microscopy (SEM), UV–Vis spectroscopy. The chemical compositions of Co-doped and (Cu-Co) co-doped TiO2 films were confirmed by XRD, Raman and FTIR studies. The average grain sizes of CoTiO3-TiO2 nanocomposites were increased with annealing temperature. AFM and SEM reveal a completely the various nanostructures of CoTiO3-TiO2 nanocomposites thin films. The films exhibit a high optical reflectance with a large band gap. The highest electrical conductivity was obtained for the (Cu-Co) co-doped TiO2 films. The polyhedral surface morphology might possibly improve the surface contact between particle sizes and then contribute to better electron mobility as well as conductivity. The obtained results suggest that the prepared TiO2 films can be used for optoelectronic applications.

Keywords: sol-gel, TiO2 thin films, CoTiO3-TiO2 nanocomposites films, Electrical conductivity

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Authors: Sorour Semsari Parapari, Mehmet Ali Gülgün, Melih Papila

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Cement production is one of the most energy-intensive processes consuming a high amount of thermal energy. Nowadays, alternative fuels are being used in cement manufacturing in a large scale as a help to provide the necessary energy. The alternative fuels could consist of any disposal like waste plastics, used tires and biomass. It has been suggested that the clinker properties might be affected by using these fuels because of foreign elements incorporation to the composition. Studying the distribution of clinker phases and their chemical composition is possible with scanning electron microscopy (SEM). In this study, clinker samples were produced using different alternative fuels in cement firing kilns. The microstructural observations by back-scattered electrons (BSE) mode in SEM (JEOL JSM-6010LV) showed that the clinker phase distribution was dissimilar in samples prepared with different alternative fuels. The alite to belite (a/b) phase content of samples was quantified by image analysis. The results showed that the a/b varied between 5.2 and 1.5 among samples as the average value for six clinker nodules. The elemental analysis by energy-dispersive x-ray spectroscopy (EDS) mounted on SEM indicated the variation in chemical composition among samples. Higher amounts of sulfur and alkalis seemed to reduce the alite phase formation in clinkers.

Keywords: alternative fuels, cement clinker, microstructure, SEM

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Authors: Habtamu Anagaw Muluneh, Gebregziabher Kahsay, Tamiru Negussie

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Theoretical study of the density of state, condensation energy, specific heat, and magnetization in a spin-triplet superconductor are the main goals of this work. Utilizing the retarded double-time temperature-dependent Green's function formalism and building a model Hamiltonian for the system at hand, we were able to derive the expressions for the parameters mentioned above. The phase diagrams are plotted using MATLAB scripts. From the phase diagrams, the density of electrons increases as the excitation energy increases, and the maximum excitation energy is equal to the superconducting gap, but it decreases when the value exceeds the gap and finally becomes the same as the density of the normal state. On the other hand, the condensation energy decreases with the increase in temperature and attains its minimum value at the superconducting transition temperature but increases with the increase in superconducting transition temperature (TC) and finally becomes zero, implying the superconducting energy is equal to the normal state energy. The specific heat increases with the increase in temperature, attaining its maximum value at the TC and then undergoing a jump, showing the presence of a second-order phase transition from the superconducting state to the normal state. Finally, the magnetization of both the itinerant and localized electrons decreases with the increase in temperature and finally becomes zero at TC = 1.6 K and magnetic phase transition temperature T = 2 K, respectively, which results in a magnetic phase transition from a ferromagnetic to a paramagnetic state. Our finding is in good agreement with the previous findings.

Keywords: spin triplet superconductivity, Green’s function, condensation energy, density of state, specific heat, magnetization

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Authors: Sanjay Bari, Vinod Ugale, Kamalkishor Patil

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Over the past several years the emergence of micro-organisms resistant to nearly all the class of antimicrobial agents has become a serious public health concern. In the present research, we report the synthesis and in-vitro antimicrobial activity of a new series of novel quinazolino-thiadiazoles 3 (a-j). The synthesized compounds were confirmed by melting point, IR, 1H-NMR, 13C NMR and Mass spectroscopy. In general, the results of the in-vitro antibacterial activity are encouraging, as out of 10 compounds tested, Compound 3f and 3i with a 4-chloro phenyl and 4-nitro phenyl at C-2 of thiadiazolyl of quinazolino-thiadiazoles, displayed the excellent antibacterial and antifungal activities against all the tested microorganisms (Bacterial and Fungal strain) with MIC values of 62.5 μg/mL. It is worth to mention that the combination of two biologically active moieties quinazoline and thiadiazole profoundly influences the biological activity. While evaluating the antimicrobial activity, it was observed that compounds having electron withdrawing groups on thiazole has shown profound activity in comparison to compounds having electron releasing groups. As a result of this study, it can be concluded that halogen substituent on thiazole ring increases antimicrobial activity. Possible improvements in the antimicrobial activity can be further achieved by slight modifications in the substituent’s and/or additional structural activity investigations to have good antimicrobial activity.

Keywords: antifungal, antimicrobial, quinazolino-thiazoles, synthesis

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Authors: S. Nqayi, B. Sondezi

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A rare-earth-based Sm₂MnRuO₆₊δ (SMRO) double perovskite was prepared using a high-temperature solid-state reaction. The structural, morphological, chemical, thermodynamic, and magnetic properties were measured with X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), X-ray photoemission spectroscopy (XPS), and vibrating sample magnetometer (VSM), respectively. The XRD revealed a tetragonal structure belonging to the I4/mmm space group, number 139, with linear Mn−O−Ru bonds. Replacing the well-studied alkaline earth metal with a rare-earth element increased the Mn-O bond length difference between the shorter equatorial (Mn-Oab) and the axial (Mn-Oc) bonds by approximately 6.3%. The elemental composition showed an O-rich double perovskite with a Ru deficit, which encourages the formation of a Ru⁶⁺ (d²) state. XPS spectra of Sm-3d, Ru-3d, and Mn-2p revealed the coexistence of a double oxidation state for each cation; Sm²⁺, Sm³⁺, Ru³⁺, Ru⁶⁺, Mn²⁺ , and Mn³⁺, in varying proportions. Entropy studies showed drastic ordering of spins at low temperatures (up to 12.4 K), whilst increasing temperatures above this point resulted in a drastic increase of disorder of the spins (up to 43.26 K), beyond which a constant slope of entropy is observed. Magnetic measurements revealed two magnetic ground states at TN = 12.4 K and TC = 43.3 K ordering antiferromagnetically (AFM) and ferromagnetically (FM), respectively. Kneller fit further showed that the materials become completely paramagnetic at TB = 88.1 K, (the blocking temperature). The existence of ferromagnetic (FM) super-exchange coupling in this work originating from Mn³⁺ (t³₂𝓰e¹𝓰)−O−Ru³⁺ (t⁵₂𝓰e⁰𝓰) and Mn²⁺ (t³₂𝓰e²𝓰−O−Ru⁶⁺ (t²₂𝓰e⁰𝓰) which plays an important role in suppressing the Mn/Ru−O−Mn/Ru antiferromagnetic (AFM) interactions.

Keywords: solid-state reaction, super-exchange coupling, ferromagnetic, Kneller’s law, entropy

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Authors: W. El-Alami, J. Araña, O. González Díaz, J. M. Doña Rodríguez

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The efficiency of the semiconductor TiO₂ needs to be improved to be an effective tool for pollutant removal. To improve the efficiency of this semiconductor, it is necessary to deepen the knowledge of the processes that take place on its surface. In this sense, the deactivation of the catalyst is one of the aspects considered relevant. In order to study this point, the processes of deactivation of TiO₂ during the gas phase degradation of ethanol have been studied. For this, catalysts with only the anatase phase (SA and PC100) and catalysts with anatase and rutile phases (P25 and P90) have been selected. In order to force the deactivation processes, different cycles have been performed, adding ethanol gas but avoiding the degradation of acetates to determine their effect on the process. The surface concentration of fluorine on the catalysts was semi-quantitatively determined by EDAX analysis. The photocatalytic experiments were done with four commercial catalysts (P25, SA, P90, and PC100) and the two fluoride catalysts indicated above. The interaction and photocatalytic degradation of ethanol were followed by Fourier transform infrared spectroscopy (FTIR). EDAX analysis has revealed the presence of sodium on the surface of fluorinated catalysts. In FTIR studies, it has been observed that the acetates adsorbed on the anatase phase in P25 and P90 give rise to electron transfer to surface traps that modify the electronic states of the semiconductor. These deactivation studies have also been carried out with fluorinated P25 and SA catalysts (F-P25 and F-SA) which have observed similar electron transfers but in the opposite direction during illumination. In these materials, it has been observed that the electrons present in the surface traps, as a consequence of the interaction Ti-F, react with the holes, causing a change in the electronic states of the semiconductor. In this way, deactivated states of these materials have been detected by different electron transfer routes. It has been identified that acetates produced from the degradation of ethanol in P25 and P90 are probably hydrated on the surface of the rutile phase. In the catalysts with only the anatase phase (SA and PC100), the deactivation is immediate if the acetates are not removed before adsorbing ethanol again. In F-P25 and F-SA has been observed that the acetates formed react with the sodium ions present on the surface and not with the Ti atoms because they are interacting with the fluorine.

Keywords: photocatalytic degradation, ethanol, TiO₂, deactivation process, F-P25

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Authors: Aouina Nabila Yasmina, Chaoui Zine El Abiddine

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This study presents a comprehensive investigation into the elastic mean free path (EMFP) of electrons colliding with pyrimidine, a precursor to the pyrimidine bases in DNA, employing the Screen Corrected Additivity Rule (SCAR) method. The SCAR method is introduced as a novel approach that combines classical and quantum mechanical principles to elucidate the interaction of electrons with pyrimidine. One of the most fundamental properties characterizing the propagation of a particle in the nuclear medium is its mean free path. Knowledge of the elastic mean free path is essential to accurately predict the effects of radiation on biological matter, as it contributes to the distances between collisions. Additionally, the mean free path plays a role in the interpretation of almost all experiments in which an excited electron moves through a solid. Pyrimidine, the precursor of the pyrimidine bases of DNA, has interesting physicochemical properties, which make it an interesting molecule to study from a fundamental point of view. These include a relatively large dipole polarizability and dipole moment and an electronic charge cloud with a significant spatial extension, which justifies its choice in this present study.

Keywords: elastic mean free path, elastic collision, pyrimidine, SCAR

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Authors: Bruno Baptista, Andreia S. R. Oliveira, Patricia V. Mendonca, Jorge F. J. Coelho, Fani Sousa

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Drug delivery systems are designed to allow adequate protection and controlled delivery of drugs to specific locations. These systems aim to reduce side effects and control the biodistribution profile of drugs, thus improving therapeutic efficacy. This study involved the synthesis of polymeric nanoparticles, based on amphiphilic diblock copolymers, comprising a biocompatible, poly (oligo (ethylene oxide) methyl ether methacrylate (POEOMA) as hydrophilic segment and a pH-sensitive block, the poly (2-diisopropylamino)ethyl methacrylate) (PDPA). The objective of this work was the development of polymeric pH-responsive nanoparticles to encapsulate and carry small RNAs as a model to further develop non-coding RNAs delivery systems with therapeutic value. The responsiveness of PDPA to pH allows the electrostatic interaction of these copolymers with nucleic acids at acidic pH, as a result of the protonation of the tertiary amine groups of this polymer at pH values below its pKa (around 6.2). Initially, the molecular weight parameters and chemical structure of the block copolymers were determined by size exclusion chromatography (SEC) and nuclear magnetic resonance (1H-NMR) spectroscopy, respectively. Then, the complexation with small RNAs was verified, generating polyplexes with sizes ranging from 300 to 600 nm and with encapsulation efficiencies around 80%, depending on the molecular weight of the polymers, their composition, and concentration used. The effect of pH on the morphology of nanoparticles was evaluated by scanning electron microscopy (SEM) being verified that at higher pH values, particles tend to lose their spherical shape. Since this work aims to develop systems for the delivery of non-coding RNAs, studies on RNA protection (contact with RNase, FBS, and Trypsin) and cell viability were also carried out. It was found that they induce some protection against constituents of the cellular environment and have no cellular toxicity. In summary, this research work contributes to the development of pH-sensitive polymers, capable of protecting and encapsulating RNA, in a relatively simple and efficient manner, to further be applied on drug delivery to specific sites where pH may have a critical role, as it can occur in several cancer environments.

Keywords: drug delivery systems, pH-responsive polymers, POEOMA-b-PDPA, small RNAs

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Authors: S. Divya, M. Jose

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Over the past years, industrial dyes have emerged as a significant threat to aquatic life, extensively detected in drinking water and groundwater, thus contributing to water pollution due to their improper and excessive use. To address this issue, the utilization of core-shell structures has been prioritized as it demonstrates remarkable efficiency in utilizing light energy for catalytic reactions and exhibiting excellent photocatalytic activity despite the availability of various photocatalysts. This work focuses on the photocatalytic degradation of Nd₂O₃@SiO₂ CSNs under UV light irradiation against MB and RhB dyes. Different characterization techniques, including XRD, FTIR, and TEM analyses, were employed to reveal the material's structure, functional groups, and morphological features. VSM and XPS analyses confirmed the soft, paramagnetic nature and chemical states with respective atomic percentages, respectively. Optical band gaps, determined using the Tauc plot model, indicated 4.24 eV and 4.13 eV for Nd₂O₃ NPs and Nd₂O₃@SiO₂ CSNs, respectively. The reduced bandgap energy of Nd₂O₃@SiO₂ CSNs enhances light absorption in the UV range, potentially leading to improved photocatalytic efficiency. The Nd₂O₃@SiO₂ CSNs exhibited greater degradation efficiency, reaching 95% and 96% against MB and RhB dyes, while Nd₂O₃ NPs showed 90% and 92%, respectively. The enhanced efficiency of Nd₂O₃@SiO₂ CSNs can be attributed to the larger specific surface area provided by the SiO₂ shell, as confirmed by surface area analysis using the BET surface area analyzer through N₂ adsorption-desorption.

Keywords: core shell nanocomposites, rare earth oxides, photocatalysis, advanced oxidation process

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Authors: Josef Fládr, Jiří Němeček, Veronika Koudelková, Petr Bílý

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Mechanical parameters of cementitious composites differ quite significantly based on the composition of cement matrix. They are also influenced by mixing times and procedure. The research presented in this paper was aimed at identification of differences in microstructure of normal strength (NSC) and differently mixed high strength (HSC) cementitious composites. Scanning electron microscopy (SEM) investigation together with energy dispersive X-ray spectroscopy (EDX) phase analysis of NSC and HSC samples was conducted. Evaluation of interfacial transition zone (ITZ) between the aggregate and cement matrix was performed. Volume share, thickness, porosity and composition of ITZ were studied. In case of HSC, samples obtained by several different mixing procedures were compared in order to find the most suitable procedure. In case of NSC, ITZ was identified around 40-50% of aggregate grains and its thickness typically ranged between 10 and 40 µm. Higher porosity and lower share of clinker was observed in this area as a result of increased water-to-cement ratio (w/c) and the lack of fine particles improving the grading curve of the aggregate. Typical ITZ with lower content of Ca was observed only in one HSC sample, where it was developed around less than 15% of aggregate grains. The typical thickness of ITZ in this sample was similar to ITZ in NSC (between 5 and 40 µm). In the remaining four HSC samples, no ITZ was observed. In general, the share of ITZ in HSC samples was found to be significantly smaller than in NSC samples. As ITZ is the weakest part of the material, this result explains to large extent the improved mechanical properties of HSC compared to NSC. Based on the comparison of characteristics of ITZ in HSC samples prepared by different mixing procedures, the most suitable mixing procedure from the point of view of properties of ITZ was identified.

Keywords: electron diffraction spectroscopy, high strength concrete, interfacial transition zone, normal strength concrete, scanning electron microscopy

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Authors: Fatima S. Mohammed, Derrick Crump

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Harmattan, a dusty weather condition characterized by thick smog-like suspended particles and dust storm are the peculiar events that happen during ¾ of the year in the Sahelian regions including Damaturu Town, Nigeria), resulting in heavy dust deposits especially indoors. The inhabitants of the Damaturu community are always inflicted with different ailments; respiratory tract infections, asthma, gastrointestinal infections and different ailments associated with the dusty nature of the immediate environment. This brought the need to investigate the nature of the settled indoor dust. Vacuum cleaner bag dust was collected from indoor of some Nigerian and UK homes, as well as outdoors including during seasonal dusty weather event (Harmattan and Storm dust). The dust was sieved, and the (150 µm size) particles were examined using scanning electron microscope (SEM). The physical characterization of the settled dust samples has revealed the various shapes and sizes, and elemental composition of the dust samples is indicating that some of the dust fractions were the respirable fractions and also the dust contained PM10 to PM 2.5 fractions with possible health effects. The elemental compositions were indicative of the diverse nature of the dust particle sources, which showed dust as a complex matrix.

Keywords: indoor dust, Harmattan dust, SEM, health effects

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Authors: Dong Tang, Yongli Zhao

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The study of the microstructure of asphalt is of great importance for the analysis of its macroscopic properties. However, the peculiarities of the chemical composition of the asphalt itself and the limitations of existing direct imaging techniques have caused researchers to face many obstacles in studying the microstructure of asphalt. The advantage of small-angle X-ray scattering (SAXS) is that it allows quantitative determination of the internal structure of opaque materials and is suitable for analyzing the microstructure of materials. Therefore, the SAXS technique was used to study the evolution of microstructures on the nanoscale during asphalt aging. And the reasons for the change in scattering contrast during asphalt aging were also explained with the help of Fourier transform infrared spectroscopy (FTIR). SAXS experimental results show that the SAXS curves of asphalt are similar to the scattering curves of scattering objects with two-level structures. The Porod curve for asphalt shows that there is no obvious interface between the micelles and the surrounding mediums, and there is only a fluctuation of the hot electron density between the two. The Beaucage model fit SAXS patterns shows that the scattering coefficient P of the asphaltene clusters as well as the size of the micelles, gradually increase with the aging of the asphalt. Furthermore, aggregation exists between the micelles of asphalt and becomes more pronounced with increasing aging. During asphalt aging, the electron density difference between the micelles and the surrounding mediums gradually increases, leading to an increase in the scattering contrast of the asphalt. Under long-term aging conditions due to the gradual transition from maltenes to asphaltenes, the electron density difference between the micelles and the surrounding mediums decreases, resulting in a decrease in the scattering contrast of asphalt SAXS. Finally, this paper correlates the macroscopic properties of asphalt with microstructural parameters, and the results show that the high-temperature rutting resistance of asphalt is enhanced and the low-temperature cracking resistance decreases due to the aggregation of micelles and the generation of new micelles. These results are useful for understanding the relationship between changes in microstructure and changes in properties during asphalt aging and provide theoretical guidance for the regeneration of aged asphalt.

Keywords: asphalt, Beaucage model, microstructure, SAXS

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Authors: I. Miličević, M. Hadzima Nyarko, R. Bušić, J. Simonović Radosavljević, M. Prokopijević, K. Vojisavljević

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This paper investigates the effects of different treatment methods of rubber aggregates for self-compacting concrete (SCC) on compressive strength and modulus of elasticity. SCC mixtures with 10% replacement of fine aggregate with crumb rubber by total aggregate volume and with different aggregate treatment methods were investigated. The rubber aggregate was treated in three different methods: dry process, water-soaking, and NaOH treatment plus water soaking. Properties of SCC in a fresh and hardened state were tested and evaluated. Scanning electron microscope (SEM) analysis of three different SCC patches were made and discussed. It was observed that applying the proposed NaOH plus water soaking method resulted in the improvement of fresh and hardened concrete properties. It resulted in a more uniform distribution of rubber particles in the cement matrix, a better bond between rubber particles and the cement matrix, and higher compressive strength of SCC rubberized concrete.

Keywords: compressive strength, modulus of elasticity, NaOH treatment, rubber aggregate, self-compacting rubberized concrete, scanning electron microscope analysis

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Authors: Hassan Youssef Mohamed

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In this paper, we show new wave equations, and by using the equations, we concluded that the strong force and the weak force are not fundamental, but they are quantum effects for electromagnetism. This result is different from the current scientific understanding about strong and weak interactions at all. So, we introduce three evidences for our theory. First, we prove the asymptotic freedom phenomenon in the strong force by using our model. Second, we derive the nuclear shell model as an approximation of our model. Third, we prove that the leptons do not participate in the strong interactions, and we prove the short ranges of weak and strong interactions. So, our model is consistent with the current understanding of physics. Finally, we introduce the electron-positron model as the basic ingredients for protons, neutrons, and all matters, so we can study all particles interactions and nuclear interaction as many-body problems of electrons and positrons. Also, we prove the violation of parity conservation in weak interaction as evidence of our theory in the weak interaction. Also, we calculate the average of the binding energy per nucleon.

Keywords: new wave equations, the strong force, the grand unification theory, hydrogen atom, weak force, the nuclear shell model, the asymptotic freedom, electron-positron model, the violation of parity conservation, the binding energy

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Authors: Iftikhar Ahmad, Mohammad Islam

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Thermally exfoliated graphene nanomaterial was reinforced into Al2O3 ceramic and the nanocomposites were consolidated using rapid high-frequency induction heat sintering route. The resulting nanocomposites demonstrated higher mechanical properties due to efficient GNS incorporation and chemical interaction with the Al2O3 matrix grains. The enhancement in mechanical properties is attributed to (i) uniformly-dispersed GNS in the consolidated structure (ii) ability of GNS to decorate Al2O3 nanoparticles and (iii) strong GNS/Al2O3 chemical interaction during colloidal mixing and pullout/crack bridging toughening mechanisms during mechanical testing. The GNS/Al2O3 interaction during different processing stages was thoroughly examined by thermal and structural investigation of the interfacial area. The formation of an intermediate aluminum oxycarbide phase (Al2OC) via a confined carbothermal reduction reaction at the GNS/Al2O3 interface was observed using advanced electron microscopes. The GNS surface roughness improves GNS/Al2O3 mechanical locking and chemical compatibility. The sturdy interface phase facilitates efficient load transfer and delayed failure through impediment of crack propagation. The resulting nanocomposites, therefore, offer superior toughness.

Keywords: ceramics, nanocomposites, interfaces, nanostructures, electron microscopy, Al2O3

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Authors: Soheir Mohamed Fathey

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Biofilms are complex biological communities which are hard to be eliminated by conventional antibiotic administration and implemented in eighty percent of humans infections. Green remedies have been used for centuries and have shown obvious effects in hindering and combating microbial biofilm infections. Nowadays, there has been a growth in the number of researches on the anti-biofilm performance of natural agents such as plant essential oil (EOs) and propolis. In this study, we investigated the antibiofilm performance of various natural agents, including four essential oils (EOs), cinnamon (Cinnamomum cassia), tea tree (Melaleuca alternifolia), and clove (Syzygium aromaticum), as well as propolis versus the biofilm of both Gram-positive pathogenic bacterium Staphylococcus aureus and Gram-negative pathogenic bacterium Pseudomonas aeruginosa which are major human and animal pathogens rendering a high risk due to their biofilm development ability. The antibiofilm activity of the tested agents was evaluated by crystal violet staining assay and detected by scanning electron and fluorescent microscopy. Antibiofilm performance declared a potent effect of the tested products versus the tested bacterial biofilms.

Keywords: biofilm, essential oils, electron microscopy, fluorescent

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Authors: Franca De Sarno, Alfonso Maria Ponsiglione, Enza Torino

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Recent advances in diagnostic imaging technology have significantly contributed to a better understanding of specific changes associated with diseases progression. Among different imaging modalities, Magnetic Resonance Imaging (MRI) represents a noninvasive medical diagnostic technique, which shows low sensitivity and long acquisition time and it can discriminate between healthy and diseased tissues by providing 3D data. In order to improve the enhancement of MRI signals, some imaging exams require intravenous administration of contrast agents (CAs). Recently, emerging research reports a progressive deposition of these drugs, in particular, gadolinium-based contrast agents (GBCAs), in the body many years after multiple MRI scans. These discoveries confirm the need to have a biocompatible system able to boost a clinical relevant Gd-chelate. To this aim, several approaches based on engineered nanostructures have been proposed to overcome the common limitations of conventional CAs, such as the insufficient signal-to-noise ratios due to relaxivity and poor safety profile. In particular, nanocarriers, labeling or loading with CAs, capable of carrying high payloads of CAs have been developed. Currently, there’s no a comprehensive understanding of the thermodynamic contributions enable of boosting the efficacy of conventional CAs by using biopolymers matrix. Thus, considering the importance of MRI in diagnosing diseases, here it is reported a successful example of the next generation of these drugs where the commercial gadolinium chelate is incorporate into a biopolymer nanostructure, formed by cross-linked hyaluronic acid (HA), with improved relaxation properties. In addition, they are highlighted the basic principles ruling biopolymer-CA interactions in the perspective of their influence on the relaxometric properties of the CA by adopting a multidisciplinary experimental approach. On the basis of these discoveries, it is clear that the main point consists in increasing the rigidification of readily-available Gd-CAs within the biopolymer matrix by controlling the water dynamics, the physicochemical interactions, and the polymer conformations. In the end, the acquired knowledge about polymer-CA systems has been applied to develop of Gd-based HA nanoparticles with enhanced relaxometric properties.

Keywords: biopolymers, MRI, nanoparticles, contrast agent

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Authors: Raheleh Hajilou

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In this study, we report the synthesis and characterization of YBa2Cu3O7-δ (YBCO) high-temperature superconductor prepared by solid-state method and doped with Sm in different weight percentages, 0, 0.01, 0.02 and 0.05 wt. The result of X-ray diffraction (XRD) analysis conforms to the formation of an orthorhombic phase of superconductivity in our samples. This is an important finding and indicates that the samples may exhibit superconductivity properties at certain conditions. Our results unequivocally point to a different structural order or disorder in SM/Y samples as compared to Sm based samples. We suggest that different site preferences of oxygen vacancies, predominantly created in CuO2 planes (CuO chains) of Y and Sm-based samples, might be responsible for the observed difference in the behavior. This contention is supported by a host of other considerations and experimental observations. The study investigated the effects of Sm doping on the YBCO system on various properties such as structural, critical temperature (Tc), scanning electron microscope (SEM), irresistibility line(IL), critical current density, jc, and flux line pinning force. It Seems the sample x=0.05 undergoes an insulator transition, which suppresses its superconducting transition temperature (Tc). Additionally, magnetization was measured as a function of temperature (M-T) and magnetic loops (M-H) at constant temperatures of 10. 20, 30, 40, 50 and 60K up to 10KG.

Keywords: high-Tc superconductors, Scanning electron microscopy, X-ray scattering, Irreversibility line

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Authors: Uliana N. Tumanova, Viacheslav M. Lyapin, Vladimir G. Bychenko, Alexandr I. Shchegolev, Gennady T. Sukhikh

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All cases of stillbirth undoubtedly subject to postmortem examination, since it is necessary to find out the cause of the stillbirths, as well as a forecast of future pregnancies and their outcomes. Determination of the time of death is an important issue which is addressed during the examination of the body of a stillborn. It is mean the period from the time of death until the birth of the fetus. The time for fetal deaths determination is based on the assessment of the severity of the processes of maceration. To study the possibilities of postmortem magnetic resonance imaging (MRI) for determining the time of intrauterine fetal death based on the evaluation of maceration in the kidney. We have conducted MRI morphological comparisons of 7 dead fetuses (18-21 gestational weeks) and 26 stillbirths (22-39 gestational weeks), and 15 bodies of died newborns at the age of 2 hours – 36 days. Postmortem MRI 3T was performed before the autopsy. The signal intensity of the kidney tissue (SIK), pleural fluid (SIF), external air (SIA) was determined on T1-WI and T2-WI. Macroscopic and histological signs of maceration severity and time of death were evaluated in the autopsy. Based on the results of the morphological study, the degree of maceration varied from 0 to 4. In 13 cases, the time of intrauterine death was up to 6 hours, in 2 cases - 6-12 hours, in 4 -12-24 hours, in 9 -2-3 days, in 3 -1 week, in 2 -1,5-2 weeks. At 15 dead newborns, signs of maceration were absent, naturally. Based on the data from SIK, SIF, SIA on MR-tomograms, we calculated the coefficient of MR-maceration (M). The calculation of the time of intrauterine death (MP-t) (hours) was performed by our formula: МR-t = 16,87+95,38×М²-75,32×М. A direct positive correlation of MR-t and autopsy data from the dead at the gestational ages 22-40 weeks, with a dead time, not more than 1 week, was received. The maceration at the antenatal fetal death is characterized by changes in T1-WI and T2-WI signals at postmortem MRI. The calculation of MP-t allows defining accurately the time of intrauterine death within one week at the stillbirths who died on 22-40 gestational weeks. Thus, our study convincingly demonstrates that radiological methods can be used for postmortem study of the bodies, in particular, the bodies of stillborn to determine the time of intrauterine death. Postmortem MRI allows for an objective and sufficiently accurate analysis of pathological processes with the possibility of their documentation, storage, and analysis after the burial of the body.

Keywords: intrauterine death, maceration, postmortem MRI, stillborn

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Authors: Supriya, J. K. Basu, S. Sengupta

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Silver nanoparticles have caught a lot of attention because of its unique physical and chemical properties. Silver nanoparticles embedded in polyvinyl alcohol (PVA/Ag) free-standing film have been prepared by microwave irradiation in few minutes. PVA performed as a reducing agent, stabilizing agents as well as support for silver nanoparticles. UV-Vis spectrometry, scanning transmission electron (SEM) and transmission electron microscopy (TEM) techniques affirmed the reduction of silver ion to silver nanoparticles in the polymer matrix. Effect of irradiation time, the concentration of PVA and concentration of silver precursor on the synthesis of silver nanoparticle has been studied. Particles size of silver nanoparticles decreases with increase in irradiation time. Concentration of silver nanoparticles increases with increase in concentration of silver precursor. Good dispersion of silver nanoparticles in the film has been confirmed by TEM analysis. Particle size of silver nanoparticle has been found to be in the range of 2-10nm. Catalytic property of prepared silver nanoparticles as a heterogeneous catalyst has been studied in the reduction of p-Nitrophenol (a water pollutant) with >98% conversion. From the experimental results, it can be concluded that PVA encapsulated Ag nanoparticles film as a catalyst shows better efficiency and reusability in the reduction of p-Nitrophenol.

Keywords: biopolymer, microwave irradiation, silver nanoparticles, water pollutant

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Authors: Valentina A. Mikhailova, Serguei V. Feskov, Anatoly I. Ivanov

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In the last decade the nonequilibrium charge transfer have attracted considerable interest from the scientific community. Examples of such processes are the charge recombination in excited donor-acceptor complexes and the intramolecular electron transfer from the second excited electronic state. In these reactions the charge transfer proceeds predominantly in the nonequilibrium mode. In the excited donor-acceptor complexes the nuclear nonequilibrium is created by the pump pulse. The intramolecular electron transfer from the second excited electronic state is an example where the nuclear nonequilibrium is created by the forward electron transfer. The kinetics of these nonequilibrium reactions demonstrate a number of peculiar properties. Most important from them are: (i) the absence of the Marcus normal region in the free energy gap law for the charge recombination in excited donor-acceptor complexes, (ii) extremely low quantum yield of thermalized charge separated state in the ultrafast charge transfer from the second excited state, (iii) the nonexponential charge recombination dynamics in excited donor-acceptor complexes, (iv) the dependence of the charge transfer rate constant on the excitation pulse frequency. This report shows that most of these kinetic features can be well reproduced in the framework of stochastic point-transition multichannel model. The model involves an explicit description of the nonequilibrium excited state formation by the pump pulse and accounts for the reorganization of intramolecular high-frequency vibrational modes, for their relaxation as well as for the solvent relaxation. The model is able to quantitatively reproduce complex nonequilibrium charge transfer kinetics observed in modern experiments. The interpretation of the nonequilibrium effects from a unified point of view in the terms of the multichannel point transition stochastic model allows to see similarities and differences of electron transfer mechanism in various molecular donor-acceptor systems and formulates general regularities inherent in these phenomena. The nonequilibrium effects in photoinduced ultrafast charge transfer which have been studied for the last 10 years are analyzed. The methods of suppression of the ultrafast charge recombination, similarities and dissimilarities of electron transfer mechanism in different molecular donor-acceptor systems are discussed. The extremely low quantum yield of the thermalized charge separated state observed in the ultrafast charge transfer from the second excited state in the complex consisting of 1,2,4-trimethoxybenzene and tetracyanoethylene in acetonitrile solution directly demonstrates that its effectiveness can be close to unity. This experimental finding supports the idea that the nonequilibrium charge recombination in the excited donor-acceptor complexes can be also very effective so that the part of thermalized complexes is negligible. It is discussed the regularities inherent to the equilibrium and nonequilibrium reactions. Their fundamental differences are analyzed. Namely the opposite dependencies of the charge transfer rates on the dynamical properties of the solvent. The increase of the solvent viscosity results in decreasing the thermal rate and vice versa increasing the nonequilibrium rate. The dependencies of the rates on the solvent reorganization energy and the free energy gap also can considerably differ. This work was supported by the Russian Science Foundation (Grant No. 16-13-10122).

Keywords: Charge recombination, higher excited states, free energy gap law, nonequilibrium

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Authors: Vikas Chawla, Buta Singh Sidhu, Amita Rani, Amit Handa

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The main objective of the present work is microstructural and mechanical characterization of the conventional and nanostructured TiAlN and AlCrN coatings deposited on T-11 boiler steel. In case of conventional coatings, Al-Cr and Ti-Al metallic powders were deposited using plasma spray process followed by gas nitriding of the surface which was done in the lab with optimized parameters after conducting several trials on plasma-sprayed coated specimens. The physical vapor deposition process (PAPVD) was employed for depositing nanostructured TiAlN and AlCrN coatings. The field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray analysis (EDAX) attachment, X-ray diffraction (XRD) analysis, atomic force microscopy (AFM) analysis and the X-Ray mapping analysis techniques have been used to study surface and cross-sectional morphology of the coatings. The surface roughness and micro-hardness were also measured. A good adhesion of the conventional thick TiAlN and AlCrN coatings was found. The coatings under study are recommended for the applications to super-heater and re-heater tubes of the boilers based upon the outcomes of the research work.

Keywords: nanostructure, physical vapour deposition, oxides, thin films, electron microscopy

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Authors: Tanu Khanuja, Harikrishnan N. Unni

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Head is the most vulnerable part of human body and may cause severe life threatening injuries. As the in vivo brain response cannot be recorded during injury, computational investigation of the head model could be really helpful to understand the injury mechanism. Majority of the physical damage to living tissues are caused by relative motion within the tissue due to tensile and shearing structural failures. The present Finite Element study focuses on investigating intracranial pressure and stress/strain distributions resulting from impact loads on various sites of human head. This is performed by the development of the 3D model of a human head with major segments like cerebrum, cerebellum, brain stem, CSF (cerebrospinal fluid), and skull from patient specific MRI (magnetic resonance imaging). The semi-automatic segmentation of head is performed using AMIRA software to extract finer grooves of the brain. To maintain the accuracy high number of mesh elements are required followed by high computational time. Therefore, the mesh optimization has also been performed using tetrahedral elements. In addition, model validation with experimental literature is performed as well. Hard tissues like skull is modeled as elastic whereas soft tissues like brain is modeled with viscoelastic prony series material model. This paper intends to obtain insights into the severity of brain injury by analyzing impacts on frontal, top, back, and temporal sites of the head. Yield stress (based on von Mises stress criterion for tissues) and intracranial pressure distribution due to impact on different sites (frontal, parietal, etc.) are compared and the extent of damage to cerebral tissues is discussed in detail. This paper finds that how the back impact is more injurious to overall head than the other. The present work would be helpful to understand the injury mechanism of traumatic brain injury more effectively.

Keywords: dynamic impact analysis, finite element analysis, intracranial pressure, MRI, traumatic brain injury, von Misses stress

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Authors: Qingjin Liu, Jinpeng Niu, Kangjia Chen, Jiao Li, Huafu Chen, Wei Liao

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Functional connectomics is essential in cognitive science and neuropsychiatry, offering insights into the brain's complex network structures and dynamic interactions. Although neuroimaging has uncovered functional connectivity issues in Major Depressive Disorder (MDD) patients, the dynamic shifts in connectome topology and their link to gene expression are yet to be fully understood. To explore the differences in dynamic connectome topology between MDD patients and healthy individuals, we conducted an extensive analysis of resting-state functional magnetic resonance imaging (fMRI) data from 434 participants (226 MDD patients and 208 controls). We used multilayer network models to evaluate brain module dynamics and examined the association between whole-brain gene expression and dynamic module variability in MDD using publicly available transcriptomic data. Our findings revealed that compared to healthy individuals, MDD patients showed lower global mean values and higher standard deviations, indicating unstable patterns and increased regional differentiation. Notably, MDD patients exhibited more frequent module switching, primarily within the executive control network (ECN), particularly in the left dorsolateral prefrontal cortex and right fronto-insular regions, whereas the default mode network (DMN), including the superior frontal gyrus, temporal lobe, and right medial prefrontal cortex, displayed lower variability. These brain dynamics predicted the severity of depressive symptoms. Analyzing human brain gene expression data, we found that the spatial distribution of MDD-related gene expression correlated with dynamic module differences. Cell type-specific gene analyses identified oligodendrocytes (OPCs) as major contributors to the transcriptional relationships underlying module variability in MDD. To the best of our knowledge, this is the first comprehensive description of altered brain module dynamics in MDD patients linked to depressive symptom severity and changes in whole-brain gene expression profiles.

Keywords: major depressive disorder, module dynamics, magnetic resonance imaging, transcriptomic

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Authors: Balthazar Temu, Zhao Yan, Bogdan-Petrin Ratiu, Sang Soon Oh, Qiang Li

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Photonic Crystal Surface Emitting Lasers (PCSELs) are structures which are made up of a periodically repeating patterns with a unit cell consisting of changes in refractive index. The variation in refractive index can be achieved by etching air holes in a semiconductor material to get hole based PCSELs or by growing nanowires to get nanowire based PCSELs. As opposed to hole based PCSELs, nanowire based PCSELs can be integrated on silicon platform without threading dislocations, thanks to the small area of the nanowire that is in contact with silicon substrate that relaxes the strain. Nanowire based PCSELs reported in the literature have been designed using a triangular, square or honeycomb patterns. The triangular and square pattern PCSELs have limited degrees of freedom in tuning the design parameters which hinders the ability to design high quality factor (Q-factor) and/or variable wavelength devices. Nanowire based PCSELs designed using triangular and square patterns have been reported with the lasing thresholds of 130 kW/〖cm〗^2 and 7 kW/〖cm〗^2 respectively. On the other hand the honeycomb pattern gives more degrees of freedom in tuning the design parameters, which can allow one to design high Q-factor devices. A deformed honeycomb pattern device was reported with lasing threshold of 6.25 W/〖cm〗^2 corresponding to a simulated Q-factor of 5.84X〖10〗^5.Despite this achievement, the design principles which can lead to realization of even higher Q-factor honeycomb pattern PCSELs have not yet been investigated. In this work we study how the resonance wavelength and the Q-factor of three different resonance modes of the device vary when their design parameters are tuned. Through this study we establish the design and simulation of devices operating in 970nm wavelength band, O band and in the C band with quality factors up to 7X〖10〗^7 . We also investigate the quality factors of undeformed device and establish that the band edge close to 970nm can attain high quality factor when the device is undeformed and the quality factor degrades as the device is deformed.

Keywords: honeycomb PCSEL, nanowire laser, photonic crystal laser, simulation of photonic crystal surface emitting laser

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Authors: A. Srion, W. Thepsuwan, N. Monmaturapoj

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Two Lithium disilicate (LD) glass ceramics based on SiO2-Li2O-K2O-Al2O3 system were prepared through glass melting method and then fabricated into dental crowns via hot pressing at 850˚C and 900˚C in order to study the effect of the pressing temperatures on theirs phase formation and microstructure. The factor such as heat treatment temperature (as-cast glass, 600˚C and 700˚C) of the glass ceramics used to press was also investigated the effect of an initial microstructure before pressing. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to determine phase formation and microstructure of the samples, respectively. X-ray diffraction result shows that the main crystalline structure was Li2Si2O5 by having Li3PO4, Li0.6Al0.6Si2O6, Li2SiO3, Ca5 (PO4)3F, SiO2 as minor phases. Glass compositions with different heat treatment temperatures exhibited a difference phase formation but have less effect during pressing. Scanning electron microscopy analysis showed microstructure of lath-like of Li2Si2O5 in all glasses. With increasing the initial heat treatment temperature, the longer the lath-like crystals of lithium disilicate were increased especially when using glass heat treatment at 700˚C followed by pressing at 900˚C. This could be suggested that LD1 heat treatment at 700˚C which pressing at 900˚C presented the best formation by hot pressing and compiled microstructure.

Keywords: lithium disilicate, hot pressing, dental crown, microstructure

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