Sm Activity Research Articles

Photocatalytic Activity of Sm, Zr Co-Doped TiO<sub>2</sub> Synthesized by Ultrasonic Assisted Sol-Gel Method

Sm, Zr doped nanocrystalline TiO2 powers were prepared successfully by a facile ultrasonic assisted sol-gel method. The products were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. X-ray diffraction peaks could be assigned to anatase TiO2, which confirms the crystallinity of the as-prepared samples. The SEM images demonstrated that the crystalinity is formed with spherical aggregates with average diameters ranging from 10 to 20 nm. The photocatalytic activity was studied on the photocatalytic degradation of methyl orange (MO) aqueous solution irradiated with UV-visible light. Under UV-visible light irradiation, the photocatalytic performances of the doped samples were much better than that of pure TiO2, and the co-dopant showed highest. It demonstrated that a strong Sm-Zr synergistic interaction might play a decisive role in driving the excellent photocatalytic performance of TiO2.

Electrochemical extraction of samarium from molten chlorides in pyrochemical processes

This work concerns the electrochemical extraction of samarium from molten chlorides. In this way, the electrochemical behaviour of samarium ions has been investigated in the eutectic LiCl–KCl at the surface of tungsten, aluminium and aluminium coated tungsten electrodes. On a W inert electrode the electro-reduction of Sm(III) takes place in only one soluble–soluble electrochemical step Sm(III)/Sm(II). The electrochemical system Sm(II)/Sm(0) has not been observed within the electrochemical window, because of the prior reduction of Li(I) ions from the solvent, which inhibits the electro-extraction of Sm species from the salt on such a substrate. Sm metal in contact with the melt react to give Li(0) according to the reaction: Sm(0) + 2Li(I) ↔ Sm(II) + 2Li(0). On the contrary, on reactive Al electrodes the electrochemical system Sm(II)/Sm(0) was observed within the electroactive range. The potential shift of the redox couple is caused by the decrease of Sm activity in the metal phase due to the formation of Sm–Al alloys at the interface. The formation mechanism of the intermetallic compounds was studied in a melt containing: (i) both Sm(III) and Al(III) ions, using W and Al coated tungsten electrodes, and (ii) Sm(III) ions using an Al electrode. Analysis of the samples after potentiostatic electrolysis by X-ray diffraction and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), allowed the identification of Al 3Sm and Al 2Sm.

Silymarin nanoparticle prevents paracetamol-induced hepatotoxicity

Silymarin (Sm) is a polyphenolic component extracted from Silybum marianum. It is an antioxidant, traditionally used as an immunostimulant, hepatoprotectant, and dietary supplement. Relatively recently, Sm has proved to be a valuable chemopreventive and a useful antineoplastic agent. Medical success for Sm is, however, constrained by very low aqueous solubility and associated biopharmaceutical limitations. Sm flavonolignans are also susceptible to ion-catalyzed degradation in the gut. Proven antihepatotoxic activity of Sm cannot therefore be fully exploited in acute chemical poisoning conditions like that in paracetamol overdose. Moreover, a synchronous delivery that is required for hepatic regeneration is difficult to achieve by itself. This work is meant to circumvent the inherent limitations of Sm through the use of nanotechnology. Sm nanoparticles (Smnps) were prepared by nanoprecipitation in polyvinyl alcohol stabilized Eudragit RS100® polymer (Rohm Pharma GmbH, Darmstadt, Germany). Process parameter optimization provided 67.39% entrapment efficiency and a Gaussian particle distribution of average size 120.37 nm. Sm release from the nanoparticles was considerably sustained for all formulations. Smnps were strongly protective against hepatic damage when tested in a paracetamol overdose hepatotoxicity model. Nanoparticles recorded no animal death even when administered after an established paracetamol-induced hepatic necrosis. Preventing progress of paracetamol hepatic damage was traced for an efficient glutathione regeneration to a level of 11.3 μmol/g in hepatic tissue due to Smnps.

Sm-promoted alumina supported Ru catalysts for ammonia synthesis: Effect of the preparation method and Sm promoter

Abstract Sm promoted Ru/Al 2 O 3 catalysts were prepared by different preparation methods. The samples were characterized by XRF, TEM, CO chemisorption and H 2 -TPD. It is found that chlorine-free Ru/Al 2 O 3 catalyst could be prepared by precipitation method. The presence of residual chlorine restricted the adsorbed hydrogen, which corresponded to the desorption peak in the temperature range of 150 to 325 °C. The addition of Sm significantly decreased the amount of adsorbed hydrogen. Sm promoted the precipitated Ru/Al 2 O 3 catalysts showed higher ammonia synthesis activities than those samples obtained by hydrogen treatment or hydrazine reduction. The activity of Sm promoted Ru/Al 2 O 3 catalysts increased up to a certain value and then decreased with the increase in Sm loading.

Synthesis, Crystal Structure, Interaction with BSA and Antibacterial Activity of La(III) and Sm(III) Complexes with Enrofloxacin

Two new La(III) and Sm(III) complexes with enrofloxacin (HER, 1-cyclopropyl-7-(4-ethyl-1-piperazinyl)-6-fluoro-1,4-dihydro-4-oxo-3-quinoline carboxylic acid, C(19)H(21)FN(3)O(3)), [La(2)(ER)(6)(H(2)O)(2)]·14H(2)O(1) and [Sm(2)(ER)(6)(H(2)O)(2)]·14H(2)O(2) have been synthesized and characterized by elemental analysis, FT-IR, TG-DTG and X-ray single crystal diffraction. Both of the complexes are triclinic system with space group Pī. The structure of the complexes show that each rare earth atom in both complexes was nine-coordinated. Two of the enrofloxacin ions acted as tridentate chelate and bridging ligands, while the others as bidentate chelate ligands. The binding reaction between the complexes and bovine serum albumin (BSA) was studied by UV-vis absorption spectra and fluorescence spectroscopy. The results indicated that the two complexes had a quite strong ability to quench the fluorescence from BSA and the binding reaction was mainly a static quenching process. The binding constants K ( A )/(L·mol(-1)) were 1.46 × 10(5)(1) and 8.59 × 10(6)(2) and one binding site was formed. The synchronous spectroscopy suggested that tryptophan residues were placed in BSA. It was also found that the two complexes exhibited greater antimicrobial activity than enrofloxacin at given concentrations.

Effects of lemon peel extracts on lactate dehydrogenase and sucrase activity of Streptococcus mutans

To investigate the effect of lemon peel extracts (LPE) on the activity of lactate dehydrogenase and sucrase of Streptococcus mutans (Sm). After serial dilution with trypticase soy broth (TSB) medium containing 2% glucose, LPE was used as the experimental group, and TSB without LPE as the control group. Sm was added to each group, which was then cultured for 6, 18, 24 and 48 hours in the anaerobic tank. The activity of lactate dehydrogenase(LDH) was measured with the method of oxidation of reduction coenzymeIand the pH value of the culture solution was also detected. The activity of the sucrose was determined with the method of coloration of 3,5-dinitrosalicylic acid. The activity of LDH, sucrase and the changes of solution pH were decreased with the increase of the concentration of LPE (P < 0.01). The activity of LDH were declined from (0.8025 ± 0.0913) × 10(3) U/L to (0.2099 ± 0.0283) × 10(3) U/L; the activity of sucrase were declined from (-0.0107 ± 0.0003) × 10(3) U/L to (-0.0078 ± 0.0002) × 10(3) U/L; the ΔpH were declined from (2.8067 ± 0.0404) to (2.5033 ± 0.0416) (24 h results). The differences were significant between experimental groups and the control group (P < 0.01), and there were also significant differences among experimental groups with different LPE concentration (P < 0.01). The inhibitory effect of acid generation and lactate dehydrogenas' activity of Sm were positively correlated (P < 0.01). LPE can inhibit the activity of lactate dehydrogenase, sucrase and the acid production capacity of the Sm in a dose dependent manner. The inhibitory effects in logarithmic phase is stronger than that in other phases of growth cycle.

Hydrogen production by steam reforming of acetic acid: Comparison of conventional supported metal catalysts and metal-incorporated mesoporous smectite-like catalysts

The activities of various metal catalysts were tested in steam reforming of acetic acid for the production of H 2, using conventional metal oxides and transition metal-incorporated mesoporous smectite-like materials as supports. It has been found that Pt is superior to Ni, Co, and Fe among Al 2O 3 supported catalysts, Al 2O 3 is more effective than ZrO 2 and SiO 2 as support for Pt, Ni incorporated smectite (SM(Ni)) support is more effective than Fe and Co incorporated ones for Pt, and SM(Ni) is also active in the absence of Pt. The total activity for the conversion of acetic acid is in the order of Pt/Al 2O 3 > Pt/SM(Ni) > SM(Ni) but the ability of H 2 production is comparable among these catalysts. These catalysts (and the other ones) were observed to lose their activities during the reforming reactions. The activity of Pt/Al 2O 3 decreased during the whole course of reaction up to 10 h. In contrast, the activity of SM(Ni) also decreased within 2 h but it showed a stable activity in the following stage of reaction. The initial activity of the used Pt/SM(Ni) and SM(Ni) was able to be almost completely restored by thermal treatment with H 2 but less effectively for the used Pt/Al 2O 3. The catalyst deactivation was shown to occur by the formation and deposition of carbon materials on the catalysts (XRD, TEM, thermal analysis). The properties of carbon deposits formed on Pt/Al 2O 3 and SM(Ni) catalysts should be different and this may be responsible for the differences in the extent of deactivation and in the regeneration behavior between the two catalysts.

Synthesis, characterization and cytotoxic/cytostatic activity of Sm(III) and Gd(III) complexes

New Sm(III) and Gd(III) complexes of deprotonated 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (Acenocoumarol) were synthesized and characterized using FT-IR, FT-Raman, NMR spectra, and elemental analyses. The vibrational study gave evidence for the coordination of ligand to lanthanide ions. The ligand and its lanthanide(III) complexes were tested for their cytotoxic/cytostatic activity against two tumor cell lines and peritoneal mouse macrophages. The Sm(III) and Gd(III) complexes exhibit good activity against melanoma B16 and fibrosarcoma L929 and are stronger inhibitors of tumor cell proliferation than the ligand. Besides their cytotoxicity to tumor cells, Acenocoumarol and its gadolinium(III) and samarium(III) complexes modulate NO generation in activated macrophages.

High performance Ni–Sm2O3 cermet anodes for intermediate-temperature solid oxide fuel cells

Abstract A novel anode consisting of Ni and Sm 2 O 3 with negligible oxygen-ion conductivity was developed for intermediate-temperature solid oxide fuel cells (SOFCs). Its triple phase boundary length is pretty small compared with the conventional Ni-samaria doped ceria (SDC) anode, of which SDC is one of the electrolytes having high oxygen-ion conductivity. Even so, single cells with Ni–Sm 2 O 3 anodes generated peak power density of 542 mW cm −2 at 600 °C, comparable to, if not higher than those with the Ni–SDC anodes when the same cathodes and electrolytes were applied. In addition, Ni–Sm 2 O 3 exhibited lower interfacial polarization resistance than Ni–SDC. The high electrochemical performance, which might be related to the high catalytic activity of Sm 2 O 3 and the unique microstructures of the Ni–Sm 2 O 3 , suggests a viable alternative to the conventional anodes for SOFCs.

Hypoglycaemic activity of Nauclea latifolia Sm. (Rubiaceae) in experimental animals.

Aqueous, ethanolic and hexane extracts of the leaves of Nauclea latifolia (Rubiaceae) were assessed for their fasting blood glucose lowering effect in normoglycaemic and streptozotocin-diabetic rats. Wistar strain albino rats were given different doses of the extracts after 18 hrs fast and their blood glucose measured at 0, 1, 2, 4 and 6 hours after treatment. The aqueous and ethanolic extracts significantly lowered the fasting blood glucose levels of the STZ-diabetic rats in a dose-dependent manner. The highest dose administered (400 mg/kg) lowered the fasting blood glucose of the diabetic rats by 31.7% (aqueous) and 36.1% (ethanolic) extracts. The aqueous extract did not significantly lower the glucose levels of normoglycaemic rats (maximum 6.6%), nor was any significant decrease seen in the rats administered with the hexane (maximum of 4.0% for normoglycaemic and 2.4% for diabetics) extract. The hypoglycaemic and antihyperglycaemic potentials of the aqueous and ethanolic extracts were comparable to that of glibenclamide (1 mg/kg).These results further support the traditional use of the plant in the treatment of diabetes mellitus.

Correlation and Prediction of Activity and Osmotic Coefficients of Aqueous Electrolytes at 298.15 K by the Modified TCPC Model

The modification and extension of a three-characteristic-parameter correlation model for calculating the thermodynamic properties including osmotic and mean activity coefficients of aqueous electrolytes at 298.15 K have been presented in this paper. The model can be reduced with two parameters: b, the approaching parameter, and S, the solvation parameter. Although the model adequately describes the thermodynamics with these two parameters, the third parameter, n, which is related to the distance between an ion and a solvent molecule, also can be regarded as an adjustable parameter. The two sets of parameters for 283 single salts in aqueous solutions up to saturation have been obtained from the regression of experimental values. Mean activity or osmotic coefficients of RbNO2, MgCl2, Sm(ClO4)3, and ZnSO4, with these two sets of parameters, have been compared with the smoothed experimental data, which show good agreement. When the model with three parameters is employed, it gives a more accurate result, especially in case of high concentration. The comparison with Pitzer and the original TCPC model also illustrates the excellent performance of this modified model.

Sol–gel auto-combustion synthesis of samarium-doped TiO 2 nanoparticles and their photocatalytic activity under visible light irradiation

High photocatalytic activity of Sm 3+-doped TiO 2 nanocrystalline under visible light has been successfully prepared by sol–gel auto-combustion technique. The samples were characterized by X-ray diffraction, UV–vis diffuse reflectance spectroscopy and photoluminescence (PL) spectra. UV–vis diffuse reflectance spectra showed a slight shift to longer wavelengths and an extension of the absorption in the visible region for almost all the samarium-doped samples, compared to the non-doped sample. The results of photocatalytic decomposition of methylene blue (MB) over 0.5 mol% Sm 3+-TiO 2 prepared at various calcinations temperatures show that the sample calcinated at 600 °C consists of mixed phases with 51.61% rutile shows the highest photocatalytic activity, which suggests the existence of a synergistic effect between anatase and rutile powders under visible light. Doping with the samarium ions significantly enhanced the overall photocatalytic activity for MB degradation under visible light irradiation because the larger specific surface area and the higher separation efficiency of electron–hole pairs were obtained simultaneously for Sm 3+-doped TiO 2 nanocrystalline. It was found that there were certain relationships between PL spectra and photocatalytic activity, namely, the stronger the PL intensity, the larger the content of oxygen vacancies and defects, the higher the photocatalytic activity. Therefore, in this study, 0.5 mol% may be the most suitable content of Sm 3+ in the titania, at which the recombination of photoinduced electrons and holes could be effectively inhibited and thereby the highest photocatalytic activity is formed.

Characterization and photocatalytic activity of Sm 3+-doped TiO 2 nanocrystalline prepared by low temperature combustion method

Sm 3+-doped TiO 2 nanocrystalline has been successfully prepared by low temperature combustion synthesis (LCS). Results showed that the samarium doping was found to be able to significantly inhibit the anatase–rutile phase transformation. Photocatalytic degradation experiments indicated that doping samarium ions in TiO 2 could enhance photocatalytic activity in photocatalytic degradation of methylene blue. The increase in photocatalytic activity is probably due to prevention of electron–hole recombination and the existence of a synergistic effect between anatase and rutile. The highest enhancement in photoreactivity was obtained at 0.5 mol% samarium ions doping, which may be in favor of the most efficient separation of the charge carriers. It has been found that the photocatalytic activity is drastically increased under the presence of a small amount of anatase phase (only 5.9% anatase) compared to pure rutile, and the sample calcined at 600 °C with 51.61% rutile shows the highest photocatalytic activity, which suggests the existence of a synergistic effect between anatase and rutile powders in the Sm 3+-doped TiO 2, which is similar to that of undoped TiO 2.

Correlation between phenol structure and catalytic activity of samarium(III) phenolates in polymerization of ɛ-caprolactone: Part 2. Tertbutyl's electronic and steric effects

Six Sm(III) phenolates were firstly synthesized with un-substituted phenol (P), 2-tertbutylphenol (2B), 4-tertbutylphenol (4B), 4-methylphenol (4M), 2-tertbutyl-4-methylphenol (2B4M) and 2,6-ditertbutyl-4-methylphenol (26B4M) separately. All the phenolates were used as single component catalyst for the ring-opening polymerization (ROP) of ɛ-caprolactone (CL). The experimental results showed that, with phenols substituted by single or double tertbutyls at different sites, Sm(III) phenolates resulted in ordered variations both in their catalytic activities and in ROP characteristics. In order to find the correlation between these ordered variations and tertbutyl substituents’ electronic and steric effects, data describing phenols’ geometric and charge distribution parameters were obtained with quantum chemical (QC) calculation and discussed with experimental results in organized groups. It was found that, single tertbutyl on phenol, especially ortho one, would induce mixed electronic effect but positive steric effect, latter of which induce easier ROP under mild conditions, increased catalytic activity while more inter- and intramolecular transesterifications, resulting in PCL with wider molecular weight distribution (MWD). Two ortho tertbutyls induce not only positive steric effect but also positive electronic effect, which induce the highest catalytic activity of Sm(26B4M) 3, most transesterifications and the resultant widest MWD of PCL.

Novel Synthesis and Photocatalytic Activity of Oxysulfide Sm2Ti2S2O5.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Novel Function for the Sm Proteins in Germ Granule Localization during C. elegans Embryogenesis

General mRNA processing factors are traditionally thought to function only in the control of global gene expression. Here we show that the Sm proteins, core components of the splicesome, also regulate germ granules during early C. elegans development. Germ granules are large cytoplasmic particles that localize to germ cells and their precursors during embryogenesis of diverse organisms [1]. In C. elegans, germ granules, called P granules, are segregated to the germline precursor cells during embryogenesis by asymmetric cell division, and they remain in germ cells at all stages of development [2]. We found that at least some Sm proteins are components of P granules. Moreover, disruption of Sm activity caused defects in P granule localization to the germ cell precursors during early embryogenesis. In contrast, loss of other splicing factor activities had no effect on germ granule control in the embryo. These observations suggest that the Sm proteins control germ granule integrity and localization in the early C. elegans embryo and that this role is independent of pre-mRNA splicing. Thus, a highly conserved splicing factor may have been adapted to control both snRNP biogenesis and the localization of components important for germ cell function.

Epstein-Barr virus immediate-early protein BRLF1 interacts with CBP, promoting enhanced BRLF1 transactivation.

The Epstein-Barr virus (EBV) immediate-early protein BRLF1 is a transcriptional activator that mediates the switch from latent to lytic viral replication. Many transcriptional activators function, in part, due to an interaction with histone acetylases, such as CREB-binding protein (CBP). Here we demonstrate that BRLF1 interacts with the amino and carboxy termini of CBP and that multiple domains of the BRLF1 protein are necessary for this interaction. Furthermore, we show that the interaction between BRLF1 and CBP is important for BRLF1-induced activation of the early lytic EBV gene SM in Raji cells.

Hydrodesulfurization of thiophene over synthetic cobalt-containing smectite-like mesoporous materials

Mesoporous smectite-like materials containing cobalt, SM(Co), were synthesized by a hydrothermal method under different conditions. The materials were used as catalysts for hydrodesulfurization (HDS) of thiophene. The SM(Co) sample is a new type of active HDS catalyst. The activity depends on the synthetic conditions used, but the product distribution does not change so much, giving trans-2-butene, cis-2-butene, and 1-butene with a minor product of n-butane. The high HDS activity of SM(Co) samples may be explained by higher degrees of cobalt dispersion due to the method of preparation used. In addition, the treatment of SM(Co) samples with ammonia solution is effective in enhancing their HDS activities, in particular for originally less active ones. The treatment removes Na + species involved and this may suppress structural changes of SM(Co) samples by HDS reactions. The ammonia-treated samples maintain high surface area and include much lower concentrations of Na + species, which would have a negative effect on the activity, and so they indicate enhanced HDS activity.

Association with the cellular export receptor CRM 1 mediates function and intracellular localization of Epstein-Barr virus SM protein, a regulator of gene expression.

Splicing and posttranscriptional processing of eukaryotic gene transcripts are linked to their nuclear export and cytoplasmic expression. Unspliced pre-mRNAs and intronless transcripts are thus inherently poorly expressed. Nevertheless, human and animal viruses encode essential genes as single open reading frames or in the intervening sequences of other genes. Many retroviruses have evolved mechanisms to facilitate nuclear export of their unspliced mRNAs. For example, the human immunodeficiency virus RNA-binding protein Rev associates with the soluble cellular export receptor CRM 1 (exportin 1), which mediates nucleocytoplasmic translocation of Rev-HIV RNA complexes through the nuclear pore. The transforming human herpesvirus Epstein-Barr virus (EBV) expresses a nuclear protein, SM, early in its lytic cycle; SM binds RNA and posttranscriptionally activates expression of certain intronless lytic EBV genes. Here we show that both the trans-activation function and cytoplasmic translocation of SM are dependent on association with CRM 1 in vivo. SM is also shown to be associated in vivo with other components of the CRM 1 export pathway, including the small GTPase Ran and the nucleoporin CAN/Nup214. SM is shown to be present in the cytoplasm, nucleoplasm, and nuclear envelope of transfected cells. Mutation of a leucine-rich region (LRR) of SM inhibited CRM 1-mediated cytoplasmic translocation and SM activity, as did leptomycin B, an inhibitor of CRM 1 complex formation. Surprisingly, however, leptomycin B treatment and mutation of the LRR both led to SM becoming more tightly attached to intranuclear structures. These findings suggest a model in which SM is not merely a soluble carrier protein for RNA but rather is bound directly to intranuclear proteins, possibly including the nuclear pore complex.

SYNTHESIS, CHARACTERIZATION AND ANTITUMOR ACTIVITY OF TERNARY COMPLEXES OF ALL-TRANS RETINOIC ACID WITH RARE EARTH METALS

Eight new ternary complexes of all-trans retinoic acid (HRA) with rare earth metals have been synthesized and characterized by elemental analysis, molar conductance, IR, TG-DTA, UV and 1HNMR. The general formula of the complexes is M(RA)2 Ac nH2O where M = Y, La, Nb, Sm, Eu,Gd, Er,Tm, n = 4–8. Antitumour activity of Sm(RA)2 Ac 4H2O and Y(RA)2 Ac 8H2O was tested with human bladder cancer line EJ cells. The results obtained indicated that the inhibitory rates of the two complexes were significantly greater than that of HRA itself (p < 0.05). Especially, Y(RA)2 Ac 8H2O effects on inducing differentiation, modulating the expressions of P21 and mutation of P53 genes in vitro.