Pharmacological evidences for the extracts and secondary metabolites from plants of the genus Hibiscus

The scientific basis for the statement that plants and their active constituents play an important role in the prevention of chronic and degenerative diseases is continuously advancing. In fact, the origin of many therapeutic substances is due to secondary metabolism in the plant. The genus Hibiscus contains 220 species distributed around the world. It is an interesting source of potential bioactive molecules, as phenolic compounds, triterpene derivatives, phytosteroids, with antioxidant, cardioprotective, antihypertensive and antiproliferative activities. This work reviews the pharmacological evidence of extracts of plants from the genus Hibiscus, giving an overview of the most studied biological effects and the known phytochemical composition. Although more studies are necessary, Hibiscus spp. exhibits proven potential to become of important pharmacological interest.     

Influence of water and aluminium powder content on the properties of waste-containing geopolymer foams

The production of low thermal conductivity geopolymers has attracted increasing attention over the past years due to their low cost and green processing technology. In this work, light and porous geopolymers were produced by the proper association of aluminium content and solid-to-liquid ratio. This allowed the production of very low thermal conductivity geopolymers (78.6 mW/m K) exhibiting homogeneous pore size distribution which suggests their use in thermal insulating applications. Moreover this study also reduced the existing knowledge gap concerning the fresh-state characterization of foamed geopolymer slurries. The influence of aluminium powder, curing temperature and solid-to-liquid ratio on the calorimetric response of biomass fly ash-containing geopolymer slurries was evaluated. The calorimetric response of geopolymer slurries shows that the time needed to reach the maximum temperature decreases when the aluminium powder rises, thus shortening the open time before in situ application. It was also found that the geopolymerization rate is governed by the curing temperature.     

Exploitation of Chemical Signaling by Parasitoids: Impact on Host Population Dynamics

Chemical information mediates species interactions in a wide range of organisms. Yet, the effect of chemical information on population dynamics is rarely addressed. We designed a spatio-temporal parasitoid—host model to investigate the population dynamics when both the insect host and the parasitic wasp that attacks it can respond to chemical information. The host species, Drosophila melanogaster, uses food odors and aggregation pheromone to find a suitable resource for reproduction. The larval parasitoid, Leptopilina heterotoma, uses these same odors to find its hosts. We show that when parasitoids can respond to food odors, this negatively affects fruit fly population growth. However, extra parasitoid responsiveness to aggregation pheromone does not affect fruit fly population growth. Our results indicate that the use of the aggregation pheromone by D. melanogaster does not lead to an increased risk of parasitism. Moreover, the use of aggregation pheromone by the host enhances its population growth and enables it to persist at higher parasitoid densities.     

超高效液相色谱-电喷雾串联质谱法测定戊唑醇、肟菌酯及代谢物肟菌酸在西瓜和土壤中的残留

[目的]建立同时测定西瓜和土壤中戊唑醇、肟菌酯及代谢物肟菌酸残留量的超高效液相色谱串联质谱法(UPLC-MS/MS)。[方法]样品中的待测农药组分采用乙腈-水(体积比4∶1)提取,硅藻土液液萃取小柱净化,采用UPLC-MS/MS法,ESI(+)电离方式,多反应监测(MRM)定量测定。[结果]仪器最低检测量为戊唑醇5.0×10-13g,肟菌酯4.0×10-13g,肟菌酸2.5×10-13g;3种农药的最低检出质量分数均为0.02 mg/kg,在西瓜和土壤中的添加回收率为81.8%～94.2%,变异系数为3.67%～7.04%。[结论]该方法快速、准确、灵敏度高,适合西瓜与土壤样品中戊唑醇、肟菌酯及肟菌酸的残留量测定。     

Magnetoelectricity in CoFe2O4 nanocrystal-P(VDF-HFP) thin films

Transition metal ferrites such as CoFe₂O₄, possessing a large magnetostriction coefficient and high Curie temperature (T_c > 600 K), are excellent candidates for creating magnetic order at the nanoscale and provide a pathway to the fabrication of uniform particle-matrix films with optimized potential for magnetoelectric coupling. Here, a series of 0–3 type nanocomposite thin films composed of ferrimagnetic cobalt ferrite nanocrystals (8 to 18 nm) and a ferroelectric/piezoelectric polymer poly(vinylidene fluoride-co-hexafluoropropene), P(VDF-HFP), were prepared by multiple spin coating and cast coating over a thickness range of 200 nm to 1.6 μm. We describe the synthesis and structural characterization of the nanocrystals and composite films by XRD, TEM, HRTEM, STEM, and SEM, as well as dielectric and magnetic properties, in order to identify evidence of cooperative interactions between the two phases. The CoFe₂O₄ polymer nanocomposite thin films exhibit composition-dependent effective permittivity, loss tangent, and specific saturation magnetization (M_s). An enhancement of the effective permittivity and saturation magnetization of the CoFe₂O₄-P(VDF-HFP) films was observed and directly compared with CoFe₂O₄-polyvinylpyrrolidone, a non-ferroelectric polymer-based nanocomposite prepared by the same method. The comparison provided evidence for the observation of a magnetoelectric effect in the case of CoFe₂O₄-P(VDF-HFP), attributed to a magnetostrictive/piezoelectric interaction. An enhancement of M_s up to +20.7% was observed at room temperature in the case of the 10 wt.% CoFe₂O₄-P(VDF-HFP) sample.     

Asprich: A novel aspartic acid-rich protein family from the prismatic shell matrix of the bivalve Atrina rigida

Almost all mineralized tissues contain proteins that are unusually acidic. As they are also often intimately associated with the mineral phase, they are thought to fulfill important functions in controlling mineral formation. Relatively little is known about these important proteins, because their acidic nature causes technical difficulties during purification and characterization procedures. Much effort has been made to overcome these problems, particularly in the study of mollusk-shell formation. To date about 16 proteins from mollusk-shell organic matrices have been sequenced, but only two are unusually rich in aspartic and glutamic acids. Here we screened a cDNA library made from the mRNA of the shell-forming cells of a bivalve, Atrina rigida, using probes for short Asp-containing repeat sequences, and identified ten different proteins. Using more specific probes designed from one subgroup of conserved sequences, we obtained the full sequences of a family of seven aspartic acid-rich proteins, which we named "Asprich"; a subfamily of the unusually acidic shell-matrix proteins. Polyclonal antibodies raised against a synthetic peptide of the conserved acidic1 domain of these proteins reacted specifically with the matrix components of the calcitic prismatic layer, but not with those of the aragonitic nacreous layer. Thus the Asprich proteins are constituents of the prismatic layer shell matrix. We can identify different domains within these sequences, including a signal peptide characteristic of proteins destined for extracellular secretion, a conserved domain rich in aspartic acid that contains a sequence very similar to the calcium-binding domain of Calsequestrin, and another domain rich in aspartic acid, that varies between the seven sequences. We also identified a domain with DEAD repeats that may have Mg-binding capabilities. Although we do not know, as yet, the function of these proteins, their generally conserved sequences do indicate that they might well fulfill basic functions in shell formation.     

Reactive Hot Pressing and Properties of Zr1−xTixB2–ZrC Composites

Reactive hot pressing was used to prepare Zr_1?xTi_xB₂–ZrC composites with advantageous microstructure and mechanical properties from ZrB₂–TiC powders. The reaction mechanisms and the effects of different levels of TiC on the physical and mechanical properties of the resulting composite were explored in detail and compared to conventionally hot‐pressed ZrB₂ and ZrB₂–ZrC. Incorporation of 10 to 30 vol% TiC enabled full densification and restrained grain growth, reducing the final average grain size from 5.6 μm in pure ZrB₂ to a minimum of 1.4 μm in samples with 30 vol% TiC. The flexural strengths and hardnesses of the composites sintered with TiC were consequently greater than the conventionally processed ZrB₂–ZrC materials, increasing from 440 MPa and 17.4 GPa to a maximum of 670 MPa and 24.2 GPa at 10 vol% TiC. However, despite a decrease in the total average grain size, the flexural strength at higher TiC levels was limited by an increase in ZrC grain growth, which was observed to determine the flexural strength of the reaction sintered composites similar to the case of ZrB₂–SiC.     

海泡石和稀土对镍催化剂性能的影响

本文研究了海泡石和稀土Sm镍催化剂的苯加氢活性及CO_２甲烷化活性的影响，并用XPS、活性比表面积及CS_２中毒等方法表征了催化剂的表面性质。结果表明，海泡石和稀土Sm能提高镍催化剂的加氢活性和抗毒性，并能增大活性镍的比表面及镍上的电子云密度，降低CO_２甲烷化反应的活化能。     

Partially fluorinated polymer networks: Synthesis and structural characterization

Functionalizacion of epoxy‐based networks by the preferential surface enrichment of perfluorinated tails to achieve hydrophobic surface is described. The selected fluorinated epoxies (FE) were: 2,2,3,3,4,4,5,5,6,6,7,7,8,9,9,9‐hexadecafluoro‐8‐trifluoromethyl nonyloxirane (FED3) and 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9‐heptadecafluoro nonyloxirane (FES3). Two series of crosslinked fluorinated epoxy‐based materials containing variable fluorine contents (from 0 to 5 wt % F) were prepared using formulations based on partially fluorinated diamine, epoxy monomer and a curing agent. The epoxy monomer was based on diglycidyl ether of bisphenol A (DGEBA) while the curing agents were either propyleneoxide diamine (JEFFAMINE) or 4,4′‐methylenebis(3‐chloro 2,6‐diethylaniline) (MCDEA). It was found that depending on the curing agent employed, homogeneous distribution of fluorine or phase separation distinguishable at micrometer or nanometer scale was obtained when curing blends initially homogeneous. The morphology and composition of partially fluorinated networks were investigated on a micrometer scale combining scanning electron microscopy and X‐ray analysis. When curing with JEFFAMINE, samples were homogeneous for all fluorine proportions. In contrast, MCDEA‐cured blends showed fluorine‐rich zones dispersed in a continuous epoxy‐rich phase. A completely different morphology, characterized by a distribution of irregular fluorine‐rich domains dispersed in an epoxy‐rich phase, was obtained when curing blends initially immiscible. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Facile functionalization by π-stacking of macroscopic substrates made of vertically aligned carbon nanotubes: Tracing reactive groups by electrochemiluminescence

We report a simple, fast and reliable non-covalent route of functionalization of macroscopic carbon nanotubes (CNTs) surfaces based on the π-stacking of CNTs sidewall with fluorescein derivatives (i.e., amino- and isothiocyanate-). The electrochemiluminescent emission of Ru(bpy)₃²⁺ labels bearing –COOH and –NH₂ side groups coupled with colorimetric and XPS measurements allowed to estimate the quantity of –NH₂ and –NCS functions obtained. The evaluation of reactivity suggests that functionalized CNTs substrates, in particular those carrying –NCS groups, are suitable to covalently bind probe molecules such as proteins and oligonucleotides, thus opening up the possibility of future application in genomics and proteomics fields.