To optimize the performance of the magnetocaloric effect in the perovskite LaMnO
3
compound, it is important to study the electronic structure, magnetic, magnetocaloric, and thermoelectric properties ...of this material. Using the first-principles method, the magnetic moment, the coupling interactions between magnetic atoms Mn-Mn
and the crystal field are calculated. The magnetic properties of the perovskite LaMnO
3
material are determined by using the Monte Carlo simulation. It is shown that, at low temperature, the magnetization value is in good agreement with the corresponding spin at
. In addition, the obtained Curie temperature
is in good agreement with the experimental value. The magnetic entropy
, the adiabatic temperature
and the relative cooling power
values are
,
,
, respectively. Finally, the thermoelectric properties are discussed. This material is applicable for magnetic refrigeration at Curie temperature.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
To cite this article: Mrabet-Dahbi S, Maurer M. Does allergy impair innate immunity? Leads and lessons from atopic dermatitis. Allergy 2010; 65: 1351-1356. Host defence responses against invading ...pathogens are well-balanced, inflammatory processes of the innate and adaptive immune system. Impaired development or abnormal function of either system can result in failure to control pathogens and to clear infections. Infections have been claimed to modulate the onset and course of allergic diseases. This so-called hygiene hypothesis is still an active area of research. In contrast, the effects of allergies on infections and pathogen-directed immune responses are less well understood. Here, we have reviewed the existing evidence that allergies result in impaired innate immunity and we discuss recent observations that may explain why and how innate immunity is dysfunctional in allergic patients. With a focus on atopic dermatitis as a model of allergic disease, we speculate that one of the key features of allergic conditions, namely Th2 polarization, leads to several independent inhibitory effects on host defence and consequently to a higher risk of infections in allergic patients. A better understanding of impaired host defence and its mechanisms in allergic subjects will help to improve the management of these diseases.
Summary
Background
Staphylococcus aureus is a well known trigger factor of atopic dermatitis (AD). Besides the superantigens, further exotoxins are produced by S. aureus and may have an influence on ...the eczema.
Objective
To explore the impact of staphylococcal α‐toxin on human T cells, as those represent the majority of skin infiltrating cells in AD.
Methods
Adult patients with AD were screened for cutaneous colonization with α‐toxin producing S. aureus. As α‐toxin may induce necrosis, CD4+ T cells were incubated with sublytic α‐toxin concentrations. Proliferation and up‐regulation of IFN‐γ on the mRNA and the protein level were assessed. The induction of t‐bet translocation in CD4+ T cells was detected with the Electrophoretic Mobility Shift Assay.
Results
Thirty‐four percent of the patients were colonized with α‐toxin producing S. aureus and α‐toxin was detected in lesional skin of these patients by immunohistochemistry. Sublytic α‐toxin concentrations induced a marked proliferation of isolated CD4+ T cells. Microarray analysis indicated that α‐toxin induced particularly high amounts of IFN‐γ transcripts. Up‐regulation of IFN‐γ was confirmed both on the mRNA and the protein level. Stimulation of CD4+ T cells with α‐toxin resulted in DNA binding of t‐bet, known as a key transcription factor involved into primary T helper type 1 (Th1) commitment.
Conclusion
α‐toxin is produced by S. aureus isolated from patients with AD. We show here for the first time that sublytic α‐toxin concentrations activate T cells in the absence of antigen‐presenting cells. Our results indicate that α‐toxin is relevant for the induction of a Th1 like cytokine response. In AD, this facilitates the development of Th1 cell dominated chronic eczema.
The Ghiss-Nekor aquifer, located in the north-east of the action area of the ABHL, plays a strategic role in the drinkable water supply of the city of Al Hoceima and of the neighboring urban areas. ...It also participates in the irrigation of PMH. However, this aquifer has problems such as over-exploitation and pollution. In the face of these problems, the only Solution is the establishment of a new mode of governance, which privileges the participation, the involvement and the responsibility of the actors concerned in a negotiated contractual framework, namely the aquifer contract. The purpose of this study is to diagnose the current state of the Ghiss Nekor aquifer, the hydrogeological characterization of the aquifer, the use of the waters of the aquifer, the Problem identification and the introduction of the aquifer contract, which aims at the participatory and sustainable management of underground water resources in the Ghiss- Nekor plain, to ensure sustainable development.
This article presents a comparative study of the production of hydrogen by the electrolysis of water using two forms of electrodes; cylindrical and flat. The objective of this comparison is to select ...the best type of electrolyzer to produce hydrogen for the same volume of water and the same operating voltage. An analytical study and experimental tests were carried out on a cylindrical electrolyser consisting of two concentric cylindrical electrodes separated by a variable thickness e (3.5 mm, 4 mm, 5.5 mm, 8.5 mm and 9 mm), then a flat electrolyser consisting of two flat electrodes spaced by a distance d (2 mm, 4 mm, 6 mm, 10 mm and 15 mm). For each cylindrical electrolyser there corresponds a single electrolyser with flat electrodes. The preliminary study revealed that the production of hydrogen in an electrolyzer is significantly affected by the distance separating the two electrodes and their shapes. Indeed, the comparative electrolysis results show that in each case the electrolyzer with cylindrical electrodes clearly prevails over its counterpart with flat electrodes for the same operating conditions and for the same quantity of water injected into the electrolysis.
•The technique used to produce hydrogen is water electrolysis.•The production of hydrogen in an electrolyzer is significantly affected by the distance separating the two electrodes.•The production of hydrogen in an electrolyzer depends on the shapes of the electrodes (cylindrical or flat).•An electrolyzer with cylindrical electrodes produces more hydrogen than its counterpart with flat electrodes.•The approval of the two electrolysers is based on the same quantity of water to be electrolysed.
The effects of Sulfur, Selenium or Tellurium-doped AZrO3 (A = Ca, Ba and Sr) on electronic and optical properties have been investigated using ab initio calculations. We can confirm that the ...forbidden band decreases with the increase of chalcogens’ concentration, especially for Te and Se doped AZrO3. Moreover, the absorption and the optical conductivity in the visible spectrum were stimulated essentially for Te doped AZrO3. Hence, Te would be the better substitute of O in Lead-Free Zirconate perovskites for a new class of promising eco-friendly solar cells.
•The effects of S, Se or Te doped AZrO3 on electronic and optical properties are investigated.•The forbidden band decreases with the increase of chalcogens' concentration, especially for Te and Se doped AZrO3.•The absorption and the optical conductivity in the visible spectrum were stimulated essentially for Te doped AZrO3.•The better substitute of O in Lead-Free Zirconate perovskites is a new class of promising eco-friendly solar cells.
The effects of Sulfur (S), Selenium (Se), or Tellurium (Te) doped SrHfO3 (SHO) on the electronic, optical and photocatalytic properties have been investigated using Density Functional Theory, taking ...into account the intrinsic F-center defect (Ov) in oxide materials. The findings showed that the substitution of oxygen atoms by chalcogens impurities decreased the forbidden band of SHO effectively. Furthermore, there is a huge improvement of the absorption coefficient in the visible spectrum when chalcogens’ impurities meet an Ov defect in SHO, especially when 8.333% of S or Se meet an Ov in SHO (S/Se@OII + Ov) due to the shifting of the Fermi level to the lowest unoccupied molecular orbital which caused the n-type semiconductor behavior giving rise to the enhancement of carrier concentrations. Otherwise, the positions of the highest occupied molecular orbital and the lowest unoccupied molecular orbital respect the limits necessary to split water except for 12.5% of Se or Te-doped SHO (Se/Te@OIII), 8.333% of Te doped SHO with the presence of an Ov (Te@OII + Ov), and 12.5% of Se or Te doped SHO with an Ov defect (Se/Te@OIII + Ov) structures. In addition, the formation energy confirms that all studied structures are thermodynamically stables. We believe that our research will serve as a base for future studies on SHO to be used as semiconductors for photovoltaic and photocatalytic hydrogen production from water splitting applications.1.
A single-junction solar cell with a direct and ideal photovoltaic forbidden bandgap value which maximizes the photon absorbed is needed for the diversity of solar energy conversion, as well as other ...optoelectronic applications. Here, the ternary calcium nitrides inverse perovskites Ca3PN, Ca3AsN, Ca3SbN, and Ca3BiN were investigated in the frame of Density Functional Theory (DFT). The principal novelty of this research essentially projects detailed information on the structural, elastic, electronic, transport, and optical properties of Ca3PN, Ca3AsN, Ca3SbN, and Ca3BiN compounds. The understudy compounds are founded to be thermodynamically and elastically stable at ambient pressure. The electronic properties demonstrate that the understudy compounds have direct semiconductor behaviors with the ideal solar cells forbidden band gaps values which overlap very well with the visible zone of the solar spectrum leading to these materials high absorption coefficients percentage of around 80%, low reflectance and transmittance along the visible zone. Besides, the inter-atomic bonds between M and surrounded atoms are ionic while Ca–N inter-atomic bond is polar covalent. Otherwise, the understudy compounds exhibit low recombination rates as well as low charge carrier's effective masses which boost the carrier mobility. In addition, with rising temperatures up to 1000 K, the Ca3PN, Ca3AsN, and Ca3SbN compounds undergo from n to p-type semiconductor behaviors while Ca3BiN shows a p-type semiconductor behavior. While the CSN compound has better characteristics in TE applications at 50 K where the ZT value is 80%. Accordingly, these out studying properties make the understudy compounds as new single-junction solar cells non-silicon based.
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•The electronic, magnetic, magnetocaloric and thermoelectric properties of perovskite LaFeO3 material are calculated.•These properties are investigated using ab initio calculations ...and Monte Carlo simulations.•The total magnetization, the susceptibility and the specific heat of the perovskite LaFeO3 material are determined.•The Neel temperature obtained using Monte Carlo simulations is in good agreement with the experimental results.•The magnetocaloric effect is obtained around the critical temperature with no hysteresis loss.
In the present paper, the electronic structure, magnetic, magnetocaloric, and thermoelectric properties of the perovskite LaFeO3 compound are investigated, by using first-principles calculations and Monte Carlo simulations. By applying the first-principles calculations, the exchange coupling interactions (J1,J2) and the crystal field are calculated. The magnetization, the susceptibility, and the specific heat of the perovskite LaFeO3 compound are determined. It is found that, at low-temperature values, the magnetization behavior is in good agreement with the corresponding spin-value at T≈0.0K. In addition, the Neel temperature value TN=747K calculated using Monte Carlo simulations is in good agreement with the experimental value TN=750K. The magnetocaloric properties such as magnetic entropy change and the relative cooling power are calculated. The Seebeck coefficient, electrical conductivity, total thermal conductivity, lattice thermal conductivity, and dimensionless figure of merit of this compound are discussed. Finally, the perovskite LaFeO3 compound is the best candidate for refrigeration magnetic at high temperatures.
Summary
Background and aim
Atopic dermatitis (AD) is a common chronic inflammatory skin disease often accompanied by cutaneous Staphylococcus aureus colonization and, in this regard, especially ...complicated by the presence of superantigen‐producing strains. Because IgG antibodies comprise an important defence mechanism of the adaptive immune system against bacteria, it was investigated whether AD patients have an abnormal pattern or distribution of superantigen‐specific IgG subclass antibodies in association with disease severity and activity.
Methods
Staphylococcal enterotoxin B (SEB) and staphylococcal enterotoxin C1 (SEC1) specific IgG antibody subclasses were assessed in n=89 adult AD patients with mild to severe disease activity as determined by the SCORAD score and in n=28 healthy age‐matched controls. Results were correlated with the current status of bacterial skin colonization and severity score.
Results
Thirty‐eight per cent of the AD patients showed a selective deficiency in IgG2 antibodies against SEC1 compared with only 14% in the control group. The absence of these antibodies was found in both currently colonized and non‐colonized AD patients and was associated with a severe phenotype (SCORAD more than 40 points in two‐thirds of the deficient patients). However, these patients had normal production levels of IgG2 antibodies against pneumococcal capsular polysaccharide (PCP) and SEB, but higher IgG1 and IgG4 titres against SEC1. Except for elevated total IgG1, total IgG subclass levels were normal in this AD subgroup. Yet, peripheral blood mononuclear cells (PBMCs) derived from these patients clearly produced IL‐4 and IL‐5 upon SEC1 re‐stimulation whereas PBMCs from those providing SEC1‐specific IgG2 antibodies failed in the production of these cytokines.
Conclusion
A subgroup of AD patients suffers from a selective deficiency to produce anti‐SEC1 IgG2 antibodies. This patient group is characterized by a severe AD phenotype.
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