La Addition Research Articles

Effect of alpha-lipoic acid on relieving ammonia stress and hepatic proteomic analyses of broilers

Ammonia in poultry houses not only affects worker health but also induces a variety of poultry diseases. Alpha-lipoic acid (LA) is an effective antioxidant that protects cells against oxidative injury during various toxic and pathological processes. This study was designed to evaluate the mitigating effects of LA supplementation on ammonia stress and hepatic proteome changes in broilers. Male broilers (22 d old) were allocated to 3 groups: (1) a control group without ammonia stress (CTRL); (2) exposure to 70 ppm ammonia (AM); and (3) exposure to 70 ppm ammonia and dietary administration of 300 mg/kg LA (AM+LA). Ammonia exposure significantly decreased broiler growth performance and plasma glutathione peroxidase activity (P < 0.05), and increased plasma malondialdehyde content and glutamic-pyruvic transaminase activity (P < 0.05). These negative effects were eliminated by LA supplementation. Comparative proteomic analyses revealed 291 differentially expressed proteins in the AM group compared to the CTRL and AM+LA groups. A total of 30 proteins were differentially expressed between the AM/CTRL and (AM+LA)/AM groups. The addition of LA restored 24 of these proteins to control levels; these proteins were mainly related to transcription regulation, detoxification, protein translation and degradation, and immune and stress responses. The differentially expressed proteins included the high mobility group box (HMGB) and glutathione S-transferase (GST), which is closely related to immune response and oxidative stress, and collagens, which are implicated in liver injury. The addition of LA to broiler diet may reduce ammonia toxicity by maintaining the antioxidant system, xenobiotic metabolism, and metabolic pathways.

Role of Lanthanum Addition on Acicular Ferrite Transformation in C–Mn Steel

Acicular ferrite formation in C–Mn steel after rare earth La addition and the potency of different La-containing inclusions inducing the formation of acicular ferrite have been investigated. It was found that there would be a large amount of acicular ferrite in quenched steel after 0.020 mass% La additions. The size of effective inclusion for acicular ferrite nucleation is mainly 1–4 µm. The best single La-containing effective inclusion is La2O2S. When MnS attached to the surface of La2O2S forming complex inclusion, the potency of inclusion on nucleating acicular ferrite is enhanced significantly. Low lattice mismatch between α–Fe and La2O2S plays an important role on acicular ferrite nucleation. When patches of MnS precipitated on the surface La2O2S forming the complex inclusion, the main mechanism for that inclusion is the combine of low degree of lattice mismatch and existing of Mn-depleted zone.

Effect of La on arc erosion behaviors and oxidation resistance of Cu alloys

Cu with and without La addition was prepared and the effect of a trace amount of La on the arc erosion behaviors and oxidation resistance of Cu alloys was investigated. The results indicate that CuLa alloy exhibits superior oxidation resistance and arc erosion resistance. The contact resistance and temperature rise were obviously improved. The oxidation resistance of CuLa alloy mainly is due to the interface wrapping of La2O3 particles and CuLa alloy phase on Cu atoms. Thermodynamic calculation indicated that La2O3 could form preferentially in the CuLa alloy, which was beneficial for the protection of the Cu substrate. According to kinetics analysis, the activation energy of CuLa alloy was higher than that of pure Cu, indicating the better oxidation resistance of CuLa alloys.

Effect of Solidification Rate and Rare Earth Metal Addition on the Microstructural Characteristics and Porosity Formation in A356 Alloy

The present study was performed on A356 alloy with the main aim of investigating the effects of La and Ce additions to 356 alloys (with and without 100 ppm Sr) on the microstructure and porosity formation in these alloys. Measured amounts of La, Ce, and Sr were added to the molten alloy. The results showed that, in the absence of Sr, addition of La and Ce leads to an increase in the nucleation temperature of the α-Al dendritic network with a decrease in the temperature of the eutectic Si precipitation, resulting in increasing the freezing range. Addition of 100 ppm Sr results in neutralizing these effects. The presence of La or Ce in the casting has a minor effect on eutectic Si modification, in spite of the observed depression in the eutectic temperature. It should be noted that Ce is more effective than La as an alternate modifying agent. According to the atomic radius ratio, rLa/rSi is 1.604 and rCe/rSi is 1.559, theoretically, which shows that Ce is relatively more effective than La. The present findings confirm that Sr is the most dominating modification agent. Interaction between rare earth (RE) metals and Sr would reduce the effectiveness of Sr. Although modification with Sr causes the formation of shrinkage porosity, it also reacts with RE-rich intermetallics, resulting in their fragmentation.

Effects of alpha-lipoic acid supplementation on growth performance, antioxidant capacity and biochemical parameters for ammonia-exposed broilers.

In order to estimate the effect of alpha-lipoic acid (LA) supplementation on relieving ammonia stress of broilers, 180 22-day-old male broilers were assigned to three groups, six replicates in each group and 10 birds per replicate. The three groups were: (1) a control group without ammonia stress; (2) exposure to 70ppm atmospheric ammonia (AM); (3) exposure to 70ppm atmospheric ammonia and administration of 300mg/kg LA (AM+LA). The experimental period was 3weeks. Results showed that average daily weight gain was increased and feed conversion ratio was decreased in the AM+LA group, compared with the AM group (P<0.05). Total superoxide dismutase and glutathione peroxidase activities in serum, and glutathione content in liver were higher in the AM+LA group than that in the AM group (P<0.05); however, serum malondialdehyde content was decreased by LA addition (P<0.05). Additionally, serum glutamic-pyruvic transaminase, creatine kinase and lactate dehydrogenase activities were reduced and albumin level was increased by LA addition (P<0.05). In conclusion, LA addition could relieve ammonia stress to restore broiler production performance to normal levels.

Effect of lanthanum on the precipitation and dissolution of NbC in microalloyed steels

The effect of lanthanum on the precipitation and dissolution of NbC in microalloyed steel was investigated using a combination method of thermo-mechanical experiment and the first-principle calculations. The interaction of niobium with lanthanum is attractive in the 2nn to 6nn shell, and that of carbon with lanthanum is relatively strongly attractive in 4nn(B) and 5nn coordination shells. These attractive interactions lead to an increase in the Nb and C solubility in fcc Fe, and a decrease in the chemical potential of these two solutes, thereby suppressing the formation of NbC. The strain-induced precipitation intensity was characterized using field emission scanning electron microscope (FE-SEM) and inductively coupled plasma optical emission spectrometry (ICP-OES). The experimental results reveal that after deformation NbC precipitated more in La free steel than in La addition steel. And since the relatively higher dissolution rate of NbC in La addition steel, the Zener pinning effect decreased slightly faster, leading to a higher coarsening rate of austenite grain during isothermally heating at 1200°C.

La effect on the long-term durability of Ni-Mg-Al2O3 catalysts for syngas methanation

Various contents of La (1–10wt.%) were added to Ni-Mg-Al2O3 catalyst to improve its catalytic activity and long-term stability for CO methanation. The optimum amount of La for the highest CO conversion is obtained at 1wt.% La addition for fresh catalysts, whereas at 5wt.% La for aged catalyst. During a long term ageing test at a high severity condition (850°C, space velocity=250,000h−1 and 40% steam in the feed), catalysts having 0–3wt% La rapidly lose their activity at the initial 10h period due to the sintering of Ni particles, and this is followed by slower degradation due to the thermal sintering of the support alumina. Catalysts having higher La contents (5–10wt.%) exhibit an increase in the CO conversion at a certain period, which is attributed to the uncovering effect of La on the Ni surface through the agglomeration of dispersed La into aggregates. For fresh catalysts, the CO conversion and turnover frequency are highest at 1wt.% La and 7wt.% La, respectively. For aged catalysts, both of these are highest at 5wt.% La.

Thermal and corrosion behavior of as cast Al[sbnd]Si alloys with rare earth elements

Aluminum silicon based alloys are the most important commercial casting alloys. Their cast microstructure is strongly related to their technical properties. By adding other selected alloying elements, the alloy microstructure is known to be modified, thus improving its desired properties. Rare earths (RE) can be used as alloying elements to achieve better technical performance of AlSi based alloys.In this work, the effects of individual RE (La, Pr, Nd, Sm, Gd, Tb, Dy or Er) addition on a hypoeutectic as cast AlSi alloy were studied. In order to investigate the correlation between microstructure changes and thermal and corrosion behavior, the microstructure of the samples and of the intermetallic phases was examined by scanning electron microscopy, electron microprobe analysis, and X-ray powder diffraction. Differential thermal analysis was performed to determine ternary eutectic reaction temperature. A similar decrease in eutectic temperature was recorded for all AlSi-RE samples. Decreased hardness due to RE addition was shown by Vickers hardness measurements. DC polarization potentiodynamic measurements showed that RE addition increased corrosion resistance in 3.5 wt% NaCl solution.

Absorptivity and purification of La in as-cast pure copper

Cu-La alloys with various additions of La were prepared in a vacuum electric furnace. The effects of La additions on the absorptivity and purification of La in as-cast pure copper were investigated. The results show that the absorptivity of La increases with increasing additions. However, this is as a result of reactions with impurity elements in the copper and further oxidation in the atmosphere. Meanwhile, the addition of La further reduces the contents of impurity elements such as Si, Pb and S, and purifies liquid copper more effectively, which can help to improve the mechanical properties of as-cast pure copper. However, excessive rare earth element additions can lead to decreases in elongation due to the excessive formation of intermetallic compounds.This paper is part of a Themed Issue on Brass Alloys.

Hydrogen production via methanol steam reforming over Ni-based catalysts: Influences of Lanthanum (La) addition and supports

The effect of the addition of Lanthanum (La), the different loading of nickel oxide and various supports on the catalytic performance of Ni-based catalysts was investigated for methanol steam reforming to produce hydrogen. TEM, N2 adsorption-desorption, XRD, and TPR were used to characterize the catalysts. Separated NiO particles, La–Ni or La–Ni–Al mixed oxides as well as NiAl2O4 spinel were detected. The results showed that the addition of lanthanum into Ni-based catalyst decreased the steamed temperature and the selectivity of CO. This change was closely associated with separated NiO particles with the smaller size and higher dispersion as well as the different interaction between NiO particles and support upon the modification of lanthanum. It was also found that the moderate loading of nickel facilitates the catalytic performance for methanol steam reforming due to the generation of separated NiO species with moderate particle size. Moreover, the different interaction strength between nickel species and support could give rise to the difference in the catalytic performance of active Ni species, depending on the support. The Al2O3 supported catalyst exhibits better conversion of CH3OH, higher hydrogen selectivity and lower CO selectivity than those of SiO2 and MgO supported catalysts.

Influence of Ti and La Additions on the Formation of Intermetallic Compounds in the Al-Zn-Si Bath

The effect of Ti and La additions on the formation of intermetallic compounds (IMCs) in the galvalume (55Al-Zn-1.6Si wt pct) bath was investigated experimentally and further studied with first-principles calculation. The studied baths contain: 1 wt pct Fe, with Ti content ranging from 0.05 to 0.15 wt pct and La content ranging from 0.05 to 0.30 wt pct. Combination of the experimental results with the thermodynamic analysis shows that the solubility of Fe in the alloy bath decreases with an increase of Ti content, which results in the formation of mass dross. Compared with the Ti-containing alloy, La promotes the formation of τ 5 phase (Fe2Al8Si). When both Ti and La are added, Fe4Al13, τ 5, τ 6 (β-Al4.5FeSi), TiAl3, and Ti2Al20La phases were observed. Since these IMCs would consume more Si in the bath, the decrease of Si content with Ti and La additions is more significant than that of the bath without these additions. Furthermore, the formation mechanism of Ti/TiAl3/Ti2La20La core–shell structure in the coating bath is proposed. This study has implications for strategic design of industry hot-dip production with exceptional mechanical properties of Al alloy coating.

Enhancement of La addition on glass forming ability and thermal stability of Al85Ni7Er8 − xLax (x = 0–4) glassy alloys

We optimized the alloy compositions by adding La content in the Al85Ni7Er8−xLax (x=0, 1, 2, 3, 4) alloys to improve the glass forming ability (GFA) and thermal stability. When increasing the La content x from 0 to 4, the glass transition temperature, Tg, and the crystallization temperature, Tx, of melt-spun Al85Ni7Er8−xLax (x=0–4) alloys increased from 531 and 555.4K to 550.5 and 577.1K, respectively. The Al85Ni7Er8−xLax (x=0–4) alloys exhibited high reduced glass transition temperature Trg (= Tg/Tl, with Tl is the liquidus temperature) (>0.44), and a wide supercooled liquid region, ΔTx (= Tx−Tg) (>24.3K). Meanwhile, Al85Ni7Er8−xLax (x=0–4) alloys exhibited high crystallization activation energies (384.5–439.8kJ/mol), exhibiting excellent thermal stability.

The enhancement effect and kinetics of rare earth assisted salt bath nitriding

A rapid salt bath nitriding technology was primarily developed by adding rare earth lanthanum (RE La) in the salt bath media on the basis of normal salt bath nitriding technique (NT). Characterization of the modified surface layers was made by means of optical microscopy, X-ray diffraction, energy dispersive spectroscopy (EDS) and micro-hardness tester. The results showed that the nitriding efficiency could be significantly enhanced assisted by RE La, and the enhancement effect was RE La concentration dependent. The thickness of compound layer was increased from 13.3 μm up to 18.5 μm with 5% La addition at the temperature of 833 K for 2 h. Higher surface hardness, modestly higher sub-surface hardness and superior micro-hardness profile were obtained due to the solution of RE La atoms and consequent lattice expansion in the surface layer. Meanwhile, kinetics analysis showed that the diffusion coefficient was increased and activation energy was decreased with enhancement effect of RE La, the following kinetics formulas were obtained, dNT=0.1exp−21990/Tt and dRE=4.3×10−3exp−16319/Tt for NT and RE treatment, respectively. And the confidence level of the kinetics is examined to be perfectly agreed with the data. The main enhancement mechanism is that RE La can accelerate the decomposition rate of CNO− and thus increase the concentration of active nitrogen atoms in the salt bath medium, and especially increase the number of nitrogen atoms that meet the requirements for diffusing toward the substrate by reducing the energy barrier.

Effect of La addition on the microstructure and mechanical properties of Mg–6 wt% Zn alloys

The Mg–6wt% Zn alloys microalloyed with different amounts of La were cast and extruded. The second phase in the as-cast Mg–Zn alloy is Mg4Zn7, which was replaced by Mg–Zn–La intermetallics with orthorhombic structure after La addition. Microalloying with La refined the grain size of dynamic recrystallization slightly, which was due to La solute atom in α-Mg alloy. Addition of La weakened the texture and gave rise to the formation of non-basal texture component, attributing to the existence of La in the form of solute atoms in matrix. The ductility was enhanced significantly by adding La to Mg–6wt% Zn alloy, while the strength was reduced. Such phenomenon was related to the weakening texture of the La containing alloys. The Mg–6Zn–0.2La (wt%) alloy exhibited a superior ductility with the elongation-to-fracture up to 35%. However, with further increasing of La content to 1wt%, the strength of the as-extruded Mg–Zn–La alloys was not improved but the ductility was reduced, suggesting that small addition of La is preferred for the improvement of mechanical properties.

Effect of La addition on the particle characteristics, mechanical and electrical properties of in situ Cu-TiB2 composites

In situ Cu-TiB2 composites can be synthesized via metallurgical process by mixing Cu-B and Cu-Ti master alloys before casting. In this paper, La, as a rare earth element was added to the composites to improve the comprehensive properties and the effects of its addition on the microstructures, mechanical and electrical characteristics of Cu-TiB2 composites were investigated. Results show that addition of La significantly diminishes the average size and facilitates a homogeneous distribution of TiB2 particles in the copper matrix. As a result, an improvement in mechanical properties was achieved. In particular, a remarkable change in the conductivity of the composites appears with the variation of La content. The mechanisms of particle refinement and improvements in properties by La alloying were analyzed.

Magnetic properties and photocatalytic activity of ZnFe2−x La x O4 nanoparticles synthesized by sol–gel autocombustion method

Sol–gel autocombustion technique was employed to synthesize ZnFe2−x La x O4 (0 < x < 0.2) nanoparticles. Cation distribution among the tetrahedral and octahedral sites and optical properties is highly dependent on La substitution in the spinel structure which was examined by X-ray diffraction, Raman spectroscopy and diffuse reflectance spectroscopy. The ZnFe2−x La x O4 nanoparticles exhibited strong absorption in the visible region with the optical band gap calculated from Tauc’s plot in the range of 1.93–1.98 eV. Furthermore, the effects of La substitution on the photodegradation of the methyl orange (MO) under visible light were also studied. The degradation of MO dye was enhanced with increasing La3+ substitution from x = 0 to x = 0.2, which may be due to the higher redox potential of La3+ ion as compared to those of iron. Moreover, the magnetic measurements showed that the magnetization decreased from 7.06 to 2.35 emu/g with La additions, due to the reduction in the total magnetic moments.

Influence of Lanthanum on Solidification, Microstructure, and Mechanical Properties of Eutectic Al-Si Piston Alloy

The effects of Lanthanum (La) concentration on the solidification parameters of the α-Al, Al-Si, and Al-Cu phases and on the microstructure, tensile, and hardness properties of eutectic Al-Si-Cu-Mg alloy were systematically investigated. The solidification parameters were examined using computer-aided cooling curve thermal analysis (CA-CCTA). The cooling curve and microstructure analysis showed that La altered the Si structure. The nucleation and growth temperatures of eutectic Si decreased when 0.3 wt.% La was added, and a high depression temperature was obtained with 1.0 wt.% La. High amounts of La considerably modified the Si structure and decreased the area and aspect ratio by 69.9 and 51%, respectively. The thermal analysis result recorded a faster freezing time with the La addition and a 36% alteration in the secondary dendrite arm spacing. Two secondary or ternary La-rich intermetallic phases were formed with needle- and plate-like structures. Furthermore, the mechanical properties were investigated by hardness and tensile tests with different La concentrations. The addition of small amounts of La (0.1 wt.%) significantly improved the ultimate tensile strength and quality index of the Al-Si-Cu-Mg alloy. In addition, the hardness value of Al-11Si-Cu increased by 7-8% with the increasing amount of La added.

Influence of La addition on the structural, magnetic and magnetocaloric properties in Sr2−xLaxFeMoO6 (0≤x≤0.3) double perovskite

We report the effect of carrier doping via partial substitution of La3+ for Sr2+ on the structural, magnetic and magnetocaloric properties of Sr2FeMoO6 double perovskite. Polycrystalline Sr2−xLaxFeMoO6 (x=0.0, 0.1, 0.2, 0.3) samples were prepared using the conventional solid state reaction method. Using the X-ray diffraction (XRD) analysis it was established that all the samples crystallized in a tetragonal structure with I4/mmm space group. An increase in the La doping lead to an increase in the lattice parameter ‘a’ and the volume of the unit cell. The lattice parameter ‘c’ however remained unchanged. The temperature variation in magnetization and Arrott analysis suggested a second order of ferromagnetic phase transition in all samples with Curie temperature, TC increasing from 358K for x=0.0–365K for x=0.3. A gradual increase in magnetization was also observed with the increasing La content up to x=0.2. The magnetic entropy change was calculated from the measurement of isothermal magnetization versus magnetic field at different temperatures. The tunability of magnetization and TC simply by adjusting the concentration of La and synthesis conditions makes Sr2FeMoO6 an attractive material for magnetic refrigeration at desired temperature.

Development of heat resistant Mg-Zn-Al-based magnesium alloys by addition of La and Ca: Microstructure and tensile properties

In order to clarify the potential of developing Mg-Zn-Al-RE-Ca-based heat resistant magnesium alloy, the influences of different La and Ca combinations on the microstructure and mechanical properties of Mg-4Zn-4Al-xLa-yCa (x + y = 4) alloys have been investigated. The results show that the high content of La and Ca additions promotes Al2LaZn2, Al4Ca and Ca2Mg6Zn3 isomorphous phases forming in the as-cast Mg-Zn-Al-La-Ca alloys, instead of the formation of low melting point Mg-Al and Mg-Zn-Al eutectics. Among all the secondary phases, the Al2LaZn2 phase is prior to form by consuming up La atoms, and then the Al reacts with Ca to form Al4Ca, and finally the surplus Zn reacts with Ca and Mg to form Ca2Mg6Zn3 phase. The Ca2Mg6Zn3 isomorphous phase contains a certain amount of Al, and its volume fraction is increased with increasing Ca content. The tensile strengths at both room temperature and 175 °C are increased with increasing Ca addition, while the ductility is decreased due to the increased formation of networked Ca2Mg6Zn3 phase. The Mg-4Zn-4Al-2La-2Ca alloy shows the optimal tensile properties at both room temperature and high temperature.

Lactic acid inhibits IL-33-mediated mast cell inflammatory responses via HIF-1α suppressing miR-155 expression

Abstract Lactic acid (LA) is elevated in tumors, asthma, and wound healing, environments that also include mast cells and IL-33. However, how LA affects mast cell function is unknown. Therefore we evaluated how LA modifies the IL-33-mediated mast cell response. When bone marrow derived mast cells were cultured with LA, we noted reduced IL-33-mediated cytokine production, an effect that was both monocarboxylate transporter (MCT)1- and pH-dependent. LA selectively decreased IL-33-induced TAK1, JNK, ERK, and NFkB phosphorylation, but not p38 activation. Additionally, LA increased HIF-1α expression. Since HIF-1α has been shown to regulate the pro-inflammatory microRNA miR-155, we examined miR-155 expression. miR-155-5p was reduced by LA, an effect that was reversed by HIF-1α antagonism. More importantly, miR-155-5p overexpression abolished the suppressive effects of LA. Additionally, the negative regulator SOCS1, a known miR-155 target, was elevated by LA addition. This suggests that LA employs HIF-1a to suppress miR-155, indirectly increasing SOCS-1 and limiting cytokine production. These data were recapitulated in vivo, since C57BL/6 mice injected with LA showed less IL-33-induced plasma cytokine levels than control mice. Lastly, LA suppressed IL-33-mediated human skin mast cell activation, an effect that was also MCT1-dependent. Our data demonstrate that lactic acid, present in inflammatory and malignant microenvironments, alters mast cell function to suppress inflammation.