Search

This study aims to investigate the magnetocaloric properties of a La0.77Mg0.23-x□xMnO3 (0 ≤ × ≤ 0.2) series elaborated using a solid-state method and published in Alloys Compd., 738, 2018, 528–539. In our crystallographic study, our compounds display an orthorhombic structure with Pnma group space. The Raman analysis confirms the structure formation of the compounds. The magnetic measurements show that all samples displayed a second-order magnetic phase transition from ferromagnetic to paramagnetic state, which is also supported by Landau's theory. The magnetic entropy change (ΔSM) and the relative cooling power (RCP) of La0.77-x□xMg0.23MnO3 (0 ≤ × ≤ 0.2) samples are determined from their measured magnetization data as a function of the magnetic applied field. At μ0H = 5 T, the maximum value of the magnetic entropy change ΔSmax was found to decrease from 2.59 J/kg.K for x = 0.0 to 0.38 J/kg.K for x = 0.2. Our results indicate that the optimum magnetocaloric effect at H = 5 T occurs for the composition x = 0.0, which makes it a promising material in magnetic refrigeration. [ABSTRACT FROM AUTHOR]

New compounds of the brownmillerite class Ca2Fe2 − xCuxO5 (x = 0 and 0.05) have been prepared by a sol–gel process. Two new compounds have a main phase consisting of a "Pcmn space group" orthorhombic structure. According to microstructural analyses, the grains have a random geometrical morphology. The prepared samples presented a non-Debye relaxation phenomenon based on measurements of the electric modulus and impedance. The activation energy related to ac conductivity is close to the activation energy deduced from the electric modulus. This is an affirmation that the conduction and relaxation phenomena are managed by the same type of charge. Three types of conducting mechanisms can describe the process of conduction in our samples. An impressive influence of grain and grain boundaries on the dielectric properties was detected by the frequency and temperature dependence of dielectric permittivity and impedance measurements. The modelling of the Nyquist data was performed using the real and imaginary parts of the impedance, which were well adapted to equivalent electric circuits. [ABSTRACT FROM AUTHOR]

In this work, the impact of La doping on structural and magnetic properties of Ca1-xLaxFe0.5Mn0.5O3-δ (0.05 ≤ x ≤ 0.15) elaborated using the solid-state method has been investigated in details by X-ray diffraction and magnetic measurements. Structural analysis showed that all the phases crystallize in the cubic system with a Pm-3m space group. The electron density (ED) study revealed that Mn/Fe-O and Ca/La-O form partial covalent and ionic bonds, respectively, in the unit cell. Importantly, the ED plots show also the formation of an alternate ordered arrangement of oxygen elements and their vacancies. The magnetic study revealed that all our investigated phases exhibit a paramagnetic (PM)-antiferromagnetic (AFM) transition. The decrease in Neel temperature (TN) with increasing x can be explained by the enhancement of ferromagnetic (FM) magnetic interactions due to La doping. Non-null magnetization and the magnetic hysteresis loop at room temperature confirm the presence of weak ferromagnetism in the PM region. These materials also have complex magnetic responses below TN, which are related to the formation of a variety of magnetic exchange interactions within the system, including AFM, FM and ferrimagnetic (FiM) ordering. As a result, exchange coupling between FM/FiM moments and the antiphase boundaries of AFM explains the observed exchange bias in the compounds. Given the practical applications of perovskites, the current observation of the exchange bias effect and ambient temperature ferromagnetism in these materials may be of major technological significance.Article Highlights: Ca1-xLaxFe0.5Mn0.5O3-δ (x = 0.05, 0.1 and 0.15) ceramics are elaborated. XRD patterns of all compounds are indexed in the Pm-3 m space group. An alternate arrangement of oxygen elements and their vacancies. Magnetic measurements indicate the formation of weak ferromagnetism in the paramagnetic (PM) region in the system. All the samples exhibit PM-AFM phase transition and the Neel temperature (TN) decreases with Ca content. Complex magnetic responses below TN induced the exchange bias. [ABSTRACT FROM AUTHOR]

Double perovskite La1.75Ca0.25MnMO6 (with M = Ti and Fe) systems were elaborated employing a solid-state reaction method. The refinement of X-ray diffraction patterns shows that La1.75Ca0.25MnFeO6 (LCMFO) and La1.75Ca0.25MnTiO6 (LCMTO) compounds crystallize in an orthorhombic structure with the Pbnm space group. The electron density plots indicated the covalent nature between Mn/Ti/Fe and oxygen ions. The results of the temperature dependence of the magnetization show that these samples present a paramagnetic-antiferromagnetic transition at 230 K and 223 K for LCMFO and LCMTO, respectively. The non-null magnetization and magnetic hysteresis loop at room temperature can indicate the formation of weak ferromagnetism in the paramagnetic (PM) region in both compounds. Moreover, our magnetic results show a complex magnetic response in these materials below TN, which can be attributed to the formation of various types of magnetic exchange interactions within the system such as antiferromagnetic (AFM), (ferromagnetic) FM, and ferrimagnetic (FiM) couplings. Consequently, exchange coupling between the FM and/or FiM moments and AFM antiphase boundaries is responsible for the observation of exchange bias in the materials. Considering practical applications of perovskites, the present observation of the exchange bias effect and room temperature ferromagnetism in these materials may have great technological importance. [ABSTRACT FROM AUTHOR]

Polycrystalline compounds La0.77−xMg0.23MnO3 (0 ≤ x ≤ 0.2) were elaborated using the ceramic method. All the samples are indexed in the orthorhombic structure (Pnma space group). Zero-field-cooled (ZFC) and field-cooled (FC) magnetization measurements show that the samples undergo a paramagnetic-ferromagnetic phase transition and the transition temperature is found to increase from 140.82 K for x = 0.00 to 191.50 K, for x = 0.20. The compounds reveal a second-ordered magnetic phase transition around TC. Isothermal entropy change | - Δ S M | was estimated using the Maxwell relation method. The relative cooling power also increases from 158.12 (J/Kg) for x = 0.00 to 175.94 (J/Kg) for x = 0.20, under a magnetic field of 5 T. The results suggest that materials could be useful for magnetic refrigeration. [ABSTRACT FROM AUTHOR]

All-inorganic perovskites exhibit outstanding light absorption properties in the visible range suitable for solar energy applications. We focus on the synthesis of CsPb 2 (Br,I) 5 using mechanochemical procedures. Synchrotron X-ray diffraction (SXRD) data are essential for determining the crystallographic evolution in the 295-753 K temperature range. From room temperature to 573 K, the crystal structure is refined in a two-dimensional (2D) tetragonal framework (space group: I 4/ mcm ) consisting of layers of face sharing [Pb(Br,I) 8 ] polyhedra. Above a transition temperature of T t = 630 and 621 K, identified from differential scanning calorimetry (DSC) curves for CsPb 2 Br 5 and CsPb 2 I, respectively, a cubic three-dimensional (3D) corner-sharing perovskite structure is identified, showing substantial Cs and (Br,I) deficiency. A more ionic character for Cs-halide versus Pb-halide is derived from the evolution of the anisotropic atomic displacements. An ultralow thermal conductivity of 0.35-0.18 W m 4 I, respectively, a cubic three-dimensional (3D) corner-sharing perovskite structure is identified, showing substantial Cs and (Br,I) deficiency. A more ionic character for Cs-halide versus Pb-halide is derived from the evolution of the anisotropic atomic displacements. An ultralow thermal conductivity of 0.35-0.18 W m -1 K -1 is related to the low Debye temperatures. From high-pressure SXRD studies, the change in B 0 can be attributed to a basic expansion of the unit-cell volume caused by the chemical pressure from iodine within the CsPb 2 Br 5 framework. UV-vis-NIR spectroscopy revealed optical gaps of approximately 2.93 and 2.50 eV, respectively, which agrees with ab initio calculations.

Background: Impulsivity is associated with serious detrimental consequences on physical, mental, behavioral and social aspects of health among patients with psychosis. The present prospective 12-month follow-up study aimed to determine the prevalence of highly impulsive individuals among Ultra High Risk (UHR) patients, how impulsivity evolves over the follow-up period, and whether impulsivity impacts clinical, psychological and functional outcomes in this population., Method: UHR patients were invited to complete a battery of measurements at three-time points: at baseline, and at 6 and 12 months of follow-up. Impulsivity was assessed using both behavioral (the Wisconsin Card Sorting Test, WCST) and self-report (the Barratt Impulsiveness Scale, BIS-11) measures., Results: Findings showed that at 6 months of follow-up, higher 6-month BIS-11 attentional and motor impulsivity were significantly associated with lower quality of life and greater general psychological distress. In addition, higher baseline BIS-11 motor impulsivity significantly predicted more severe positive psychotic symptoms at 12 months of follow-up. However, WCST scores did not show any significant associations with study variables at the different times of follow-up., Conclusion: Interventions targeting impulsivity in UHR individuals could help decrease psychological distress and positive psychotic symptoms' severity, as well as improve quality of life in UHR individuals., Competing Interests: Declaration of competing interest None., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Due to their richness in organic substances and nutrients, seaweed (macroalgae) harbor a large number of epiphytic bacteria on their surfaces. These bacteria interact with their host in multiple complex ways, in particular, by producing chemical compounds. The released metabolites may have biological properties beneficial for applications in both industry and medicine. In this study, we assess the diversity of culturable bacterial community of the invasive alga Codium fragile ssp. fragile with the aim to identify key groups within this epiphytic community. Seaweed samples were collected from the Northern Tunisian coast. A total of fifty bacteria were isolated in pure culture. These bacterial strains were identified by amplification of the ribosomal intergenic transcribed spacer between the 16S and the 23S rRNA genes (ITS-PCR) and by 16S rRNA sequencing. Antimicrobial activity, biochemical, and antibiotic resistance profile characterization were determined for the isolates. Isolated strains were tested for their antimicrobial potential against human and fish bacterial pathogens and the yeast Candida albicans , using the in vitro drop method. About 37% of isolated strains possess antibacterial activity with a variable antimicrobial spectrum. Ba1 (closely related to Pseudoalteromonas spiralis ), Ba12 (closely related to Enterococcus faecium ), and Bw4 (closely related to Pseudoalteromonas sp.) exhibited strong antimicrobial activity against E. coli . The isolated strain Ba4, closely related to Serratia marcescens , demonstrated the most potent activity against pathogens. The susceptibility of these strains to 12 commonly used antibiotics was investigated. Majority of the isolates were resistant to oxacillin, cefoxitin, tobramycin, and nitrofurantoin. Ba7 and Ba10, closely related to the Vibrio anguillarum strains, had the highest multidrug resistance profiles. The enzymes most commonly produced by the isolated strains were amylase, lecithinase, and agarase. Moreover, nine isolates produced disintegration zones around their colonies on agar plates with agarolitic index, ranging from 0.60 to 2.38. This investigation highlighted that Codium fragile ssp. fragile possesses an important diversity of epiphytic bacteria on its surface that could be cultivated in high biomass and may be considered for biotechnological application and as sources of antimicrobial drugs.

Background: The nature of the relationship between Internet Gaming Disorder (IGD) and psychosis is unclear so far. There is evidence that greater time spent in playing video games may expose players to both insomnia and a toxic online environment with widespread cyberbullying. These two possible consequences of IGD may, in turn, be associated with greater psychotic experiences (PE). Based on this theoretical framework, the present study proposed to contribute the body of the knowledge in this area, by testing the possible indirect effects of insomnia severity, cyber-victimization and cyberbullying in the cross-sectional association between IGD and PE in a sample of Tunisian university students., Method: We conducted a cross-sectional study over 4 months (February-May 2022). The Arabic versions of the Brief Symptom Inventory, the Internet Gaming disorder-20 Test, the Insomnia Severity Index, and the Revised Cyber Bullying Inventory-II were administered to a total of 851 students (mean age = 21.26 ± 1.68 years, 53.7% females)., Results: We found that 25% of students were at risk of IGD, and 1.8% had an IGD. The results of the mediation analysis showed that insomnia severity fully mediated the association between IGD and paranoid ideation. Higher IGD was significantly associated with more insomnia severity, which was, in turn, significantly associated with more paranoid ideation. Cyberbullying partly mediated the association between IGD and psychoticism. Higher IGD scores were significantly associated with more cyberbullying, which was, in turn, significantly associated with more psychoticism. Finally, greater IGD was significantly and directly associated with higher psychoticism., Conclusion: Our findings suggest that insomnia and cyberbullying may be regarded as potential targets for youth mental health promotion, as well as community-focused prevention and early intervention in psychosis. More particular attention should be devoted to the huge potential for engaging in cyberbullying among online gamers. Sleep deprivation should be prevented, assessed and treated in heavy gamers., (© 2023. The Author(s).)

Background: The limited studies that focused on suicidality in individuals at Ultra-High Risk (UHR) of psychosis were predominantly cross-sectional, emerging from Western countries. We aimed to examine suicide risk among Tunisian UHR and First Episode Psychosis (FEP) patients at baseline, and to evaluate the evolution and correlates of suicidal ideation over a 12-month period in the UHR group exclusively., Methods: 35 UHR (aged 22.8 ± 4.0 years, 45.7% male) and 33 FEP (aged 27.3 ± 4.8 years, 63.6% male) participants were included. The Comprehensive Assessment of at Risk Mental States, the Positive and Negative Syndrome Scale (PANSS), The Rosenberg Self-Esteem Scale, and The Multidimensional Scale of Perceived Social Support were used., Results: No significant differences were found between the UHR and the FEP groups with regard to levels of suicidal ideation at baseline. Suicidal ideation scores showed a significant decrease over time in UHR participants (p=.014; η2=0.242). An increase in total PANSS scores at 1 year (Beta=0.03; p=.048; 95%CI 0.001, 0.060; η2=0.182) significantly increased suicidal ideation scores at 1 year in the UHR group., Conclusion: Our findings contribute to the limited body of evidence on this topic by providing new prospective data from a population, country and region that has never been researched previously., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The t (8; 21) (q22; q22) with the resulting RUNX1- RUNX1T1 rearrangement is one of the most common cytogenetic abnormalities in acute myeloid leukemia (AML). It is associated with favorable prognosis. The t (5; 17) (q35; q21) is an uncommon translocation, fuses the gene for the nucleophosmin (NPM) to the retinoic acid receptor α(RARA) and was described essentially in acute promyelocytic leukemia (APL) variant. We present the case of a 19-year-old male patient who developed an AML with t (8; 21) (q22; q22) associated to t (5; 17) (q35; 21). Morphology and immunophenotype of the leukemic cells were compatible with AML. The patient received chemotherapy based on cytarabine and anthracycline without all-trans retinoic acid (ATRA) followed by allogenic stem cell transplantation in first remission. To the best of our knowledge, this is the first report of an association between a rare translocation t (5; 17) and t (8; 21) in AML. In this report, we will discuss the prognosis of this association as well as the treatment., Competing Interests: CONFLICTS OF INTEREST Authors have no conflicts of interest to declare.

Background: The main goal of the present study was to examine the characteristics of schizotypal traits and their correlations with genetic (i.e., family history of mental illness), demographic (i.e., age, sex), environmental (e.g., income, urbanicity, tobacco/alcohol/cannabis use), and psychological (i.e., personal history of mental illness other than psychosis) factors in Tunisian high-school and university students. Our secondary goal was to contribute the literature by examining the factor structure and factorial invariance of the Arabic Schizotypal Personality Questionnaire (SPQ) across sex and age (adolescents [12-18 years] vs. young adults [18-35 years]) groups., Method: This was a cross-sectional study involving 3166 students: 1160 (36.6%) high-school students (53.0% females, aged 14.9 ± 1.8); and 2006 (63.4%) university students (63.9% females, aged 21.8 ± 2.3). All students were asked to complete a paper-and-pencil self-administered questionnaire containing sociodemographic characteristics as well as the Arabic version of the SPQ., Results: The total sample yielded total SPQ scores of 24.1 ± 16.6 out of 74. The SPQ yielded good composite reliability as attested by McDonald's omega values ranging from .68 to .80 for all nine subscales. Confirmatory Factor Analysis indicated that fit of the 9-factor model of SPQ scores was acceptable. This model is invariant (at the configural, metric and structural levels) across sex and age. Except for "Odd or eccentric behavior", all schizotypy features were significantly higher among female students compared to males. Multivariable analyses showed that female sex, being a university student, lowest family incomes, tobacco use, and having a personal history of psychiatric illness were significantly associated with higher positive, negative and disorganized schizotypy subscales scores., Conclusion: Future research still needs to confirm our findings and investigate the contribution of the identified factors in the development of clinical psychosis. We can also conclude that the Arabic SPQ is appropriate for measuring and comparing schizotypy across age and sex in clinical and research settings. These findings are highly relevant and essential for ensuring the clinical utility and applicability of the SPQ in cross-cultural research., (© 2023. The Author(s).)

Background: There is evidence that culture deeply affects beliefs about mental illnesses' causes, treatment, and help-seeking. We aimed to explore and compare knowledge, attitudes toward mental illness and help-seeking, causal attributions, and help-seeking recommendations for mental illnesses across various Arab countries and investigate factors related to attitudes toward help-seeking., Methods: We carried out a multinational cross-sectional study using online self-administered surveys in the Arabic language from June to November 2021 across 16 Arab countries among participants from the general public., Results: More than one in four individuals exhibited stigmatizing attitudes towards mental illness (26.5%), had poor knowledge (31.7%), and hold negative attitudes toward help-seeking (28.0%). ANOVA tests revealed a significant difference between countries regarding attitudes (F = 194.8, p < .001), knowledge (F = 88.7, p < .001), and help-seeking attitudes (F = 32.4, p < .001). Three multivariate regression analysis models were performed for overall sample, as well as Palestinian and Sudanese samples that displayed the lowest and highest ATSPPH-SF scores, respectively. In the overall sample, being female, older, having higher knowledge and more positive attitudes toward mental illness, and endorsing biomedical and psychosocial causations were associated with more favorable help-seeking attitudes; whereas having a family psychiatric history and endorsing religious/supernatural causations were associated with more negative help-seeking attitudes. The same results have been found in the Palestinian sample, while only stigma dimensions helped predict help-seeking attitudes in Sudanese participants., Conclusion: Interventions aiming at improving help-seeking attitudes and behaviors and promoting early access to care need to be culturally tailored, and congruent with public beliefs about mental illnesses and their causations., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)

Carbon burning is a key step in the evolution of massive stars, Type 1a supernovae and superbursts in x-ray binary systems. Determining the ^{12}C+^{12}C fusion cross section at relevant energies by extrapolation of direct measurements is challenging due to resonances at and below the Coulomb barrier. A study of the ^{24}Mg(α,α^{'})^{24}Mg reaction has identified several 0^{+} states in ^{24}Mg, close to the ^{12}C+^{12}C threshold, which predominantly decay to ^{20}Ne(ground state)+α. These states were not observed in ^{20}Ne(α,α&#95;{0})^{20}Ne resonance scattering suggesting that they may have a dominant ^{12}C+^{12}C cluster structure. Given the very low angular momentum associated with sub-barrier fusion, these states may play a decisive role in ^{12}C+^{12}C fusion in analogy to the Hoyle state in helium burning. We present estimates of updated ^{12}C+^{12}C fusion reaction rates.

In the present research, polycrystalline samples of La 0.5 Sm 0.2 Sr 0.3 Mn 1- x Cr x O 3 are prepared using the self-combustion method. Then, we have studied their crystalline structure, and dielectric and electrical properties. The X-ray diffraction study shows that all the samples exhibit a single phase with orthorhombic structure (space group Pnma ). The studied samples were also characterized by complex impedance spectroscopy in a wide range of temperatures and frequency. AC conductivity analyses are used to study the transport property of the investigated samples. These analyses indicate that the conduction mechanism is strongly dependent on temperature and frequency. It is also found that the conductivity decreases with Cr concentration. Complex impedance analysis confirms the contributions of grain and grain boundaries in the conduction mechanism. Finally, the impedance spectra, characterized by the appearance of semicircle arcs at different temperatures, were well modeled in terms of equivalent electrical circuits to explain the impedance results., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)