Molecular Engineering of Zinc Phthalocyanines with Phosphinic Acid Anchoring Groups

Ló,pez‐,Duarte, Ismael,Wang, Mingkui,Humphry‐,Baker, Robin,Ince, Mine,Martí,nez‐,Dí,az, M. Victoria,Nazeeruddin, Mohammad K.,Torres, Tomá,s,Grä,tzel, Mich WILEY‐VCH Verlag 2012 Angewandte Chemie Vol.124 No.8

<P><B>Zwei Zinkphthalocyanin‐Photosensibilisatoren</B> mit verschiedenen Phosphinsäure‐Ankergruppen (siehe Schema) wurden synthetisiert. Solarzellen mit diesen Verbindungen verfügen über eine Photostromdichte von (7.6±0.2) mA cm<SUP>−2</SUP> bei geschlossenem Stromkreis, eine Spannung von (559±30) mV bei offenem Stromkreis und einen Füllfaktor von 0.76±0.03; dies entspricht einem Gesamtwirkungsgrad von 3.24 % unter 1 sun.</P>

Emission-line activity in type 2 quasars from the Sloan Digital Sky Survey

Villar-Martí,n, M.,Humphrey, A.,Martí,nez-Sansigre, A.,Pé,rez-Torres, M.,Binette, L.,Zhang, X. G. Blackwell Publishing Ltd 2008 Monthly notices of the Royal Astronomical Society Vol.390 No.1

<P>ABSTRACT</P><P>We have compared the optical emission-line ratios of type 2 quasars from Zakamska et al. with standard active galactic nucleus (AGN) photoionization model predictions, type 2 Seyfert galaxies, H <SMALL>II</SMALL> galaxies and narrow-line Fanaro–Riley type II radio galaxies. Moderate to high-ionization narrow-line radio galaxies and type 2 Seyfert galaxies are indistinguishable from type 2 quasars based on their optical line ratios. The standard AGN photoionization models, widely discussed for other type 2 AGN, can reproduce successfully the loci and trends of type 2 quasars in some of the main diagnostic diagrams. These models are not exempt of problems, and the discrepancies with the data are the same encountered for other type 2 AGN. As for these, realistic models must take into account a range of cloud properties, as widely demonstrated in the literature.</P><P>The Zakamska et al. sample is strongly biased towards objects with high line luminosities (L[O <SMALL>III</SMALL>] >10<SUP>42</SUP> erg s<SUP>−1</SUP>). We have found that stellar photoionization is obvious in a fraction of objects (3 out of 50) which are characterized by low [O <SMALL>III</SMALL>] luminosities compared with most type 2 quasars in the sample. We suggest that if the sample were expanded towards lower line luminosities (∼10<SUP>40–42</SUP> erg s<SUP>−1</SUP>) stellar photoionization might be evident much more frequently.</P><P>We explore an alternative scenario to pure AGN photoionization in which a varying contribution of stellar ionized gas contributes to the line fluxes. Although the models presented here are rather simplistic and not strong quantitative results can be extracted regarding the relative contribution of stellar versus AGN photoionization, our results suggest that adding a varying contribution of stellar photoionized gas works in the right direction to solve most of the problems affecting the standard AGN photoionization models. The ‘temperature problem’ on the other hand remains.</P>

Rheology and gel point of the enzymatic hydrolysis of urea in the presence of urease

R. Serrato-Millán,L. Medina-Torres,F. Calderas,B.L. España-Sánchez,M. Estevez,A.R. Hernandez-Martínez,M. Cruz-Soto,I.C. Sánchez,R. Gómez-García,I. Sánchez-Betancourt,M.C. Velasquillo-Martínez,G. Luna- 한국유변학회 2017 Korea-Australia rheology journal Vol.29 No.1

This study reports on the rheology of the gelation kinetics of raw chitosan (CTS) solutions (2% w/v) produced by enzymatic hydrolysis of urea at different urea concentrations (40, 50, 60, 80, and 100 mM) in the presence of urease at 1 U/mL. Viscoelastic parameters and pH values were evaluated during gelation process and the rheological properties of CTS hydrogels produced were monitored after 24 h at 37°C to simulate human body temperatures. pH measurements suggest that above some critical urea concentration (50 mM) the time required (tgel) to reach the critical pH gelation shows no dependence on urea concentration (tgel was ca. 70 minutes). Above 50 mM of urea concentration, CTS hydrogels exhibit an elastic modulus G' higher than the viscous modulus G'' with no frequency dependence characteristic of a gel behavior. Gelation kinetics analyzed by rheology suggest that the G' (i.e., structure) development depends on urea concentration during solution neutralization.

Particle size effect of LiAlSiO₄on the thermal expansion of SiC porous materials

I. Juárez-Ramírez,K. Matsumaru,K. Ishizaki,L.M. Torres-Martínez 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.5

This paper reports the effect of the particle size of LiAlSiO4 on the thermal expansion and Young’s modulus of low thermal expansion (LTE) coefficient of porous materials using silicon carbide (SiC), vitrified bonding material (VBM) and lithium aluminum silicate (LiAlSiO4) at 850 oC. According to the XRD results, there is no reaction between the raw materials during the sintering process. SEM analysis revealed the presence of an internal porous structure with a pore size less than 4 micrometers. It was found that decreasing the particle size of LiAlSiO4 by almost 4 times reduces the porosity, keeping a low thermal expansion coefficient, but the Young’s modulus increases 50%. This paper reports the effect of the particle size of LiAlSiO4 on the thermal expansion and Young’s modulus of low thermal expansion (LTE) coefficient of porous materials using silicon carbide (SiC), vitrified bonding material (VBM) and lithium aluminum silicate (LiAlSiO4) at 850 oC. According to the XRD results, there is no reaction between the raw materials during the sintering process. SEM analysis revealed the presence of an internal porous structure with a pore size less than 4 micrometers. It was found that decreasing the particle size of LiAlSiO4 by almost 4 times reduces the porosity, keeping a low thermal expansion coefficient, but the Young’s modulus increases 50%.

Effect of the In₂O₃ content on the photodegradation of the alizarin dye using TiO₂-In₂O₃ nanostructured semiconductors

V. Rodríguez-González,F. Paraguay-Delgado,X. García-Montelongo,L.M. Torres-Martínez,R. Gómez 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

The photocatalytic degradation of the synthetic red mordant dye alizarin on TiO2-In2O3 semiconductors as a function of the In2O3 content (1-12 wt%) was studied. High specific surface areas varying from 122 to 178 m2 g−1, depending on the In2O3 content, were obtained. A modification of the Eg band gap from 3.12 to 3.50 eV was obtained for low and high In2O3 contents. The XRD spectral patterns of the solids showed that anatase is the main crystalline titania phase. STEM-EDX chemical maps show that the In2O3 was found highly dispersed on the surface of the TiO2-In2O3 mixed oxide. By means of TEM images, nanostructured materials with crystallite sizes between 8 and 12 nm were identified. The photocatalytic activity for the alizarin degradation showed a maximum with the catalyst with 3.0 wt% of In2O3. The role of the In2O3 developing an optimal alizarin adsorption on the TiO2-In2O3 semiconductors is discussed. The photocatalytic degradation of the synthetic red mordant dye alizarin on TiO2-In2O3 semiconductors as a function of the In2O3 content (1-12 wt%) was studied. High specific surface areas varying from 122 to 178 m2 g−1, depending on the In2O3 content, were obtained. A modification of the Eg band gap from 3.12 to 3.50 eV was obtained for low and high In2O3 contents. The XRD spectral patterns of the solids showed that anatase is the main crystalline titania phase. STEM-EDX chemical maps show that the In2O3 was found highly dispersed on the surface of the TiO2-In2O3 mixed oxide. By means of TEM images, nanostructured materials with crystallite sizes between 8 and 12 nm were identified. The photocatalytic activity for the alizarin degradation showed a maximum with the catalyst with 3.0 wt% of In2O3. The role of the In2O3 developing an optimal alizarin adsorption on the TiO2-In2O3 semiconductors is discussed.

Silver nanoparticles incorporated into Na₂Ti6O13 microfibers

V. Rodríguez-González,I. Juárez-Ramírez,R. Zanella,M.E. Zarazúa,L.M. Torres-Martínez 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

This research is concerned with novel semiconductor composites of sodium hexatitanate oxide (Na2Ti6O13), and silver metallic nanoparticles. The Na2Ti6O13 was prepared by two methods, a sol-gel process and a solid state reaction. The silver nanoparticles were incorporated into the titanate by a deposition-precipitation technique, using NaOH as precipitation agent in the dark. Ag/Na2Ti6O13 microfibers were obtained by the sol-gel method, meanwhile octagonal microbar agglomerates were the product of the solid state reaction. The SEM-TEM observations showed silver particles with a nanometric size (5-7 nm); and fibrillar structures in the sol-gel sodium titanates. The UV-Vis-RD spectroscopy showed a blue shift Eg from 3.3 to 3.4 nm; and a plasmon surface resonance in the visible region. These materials are proposed as potential photocatalysts for contaminated water purification. This research is concerned with novel semiconductor composites of sodium hexatitanate oxide (Na2Ti6O13), and silver metallic nanoparticles. The Na2Ti6O13 was prepared by two methods, a sol-gel process and a solid state reaction. The silver nanoparticles were incorporated into the titanate by a deposition-precipitation technique, using NaOH as precipitation agent in the dark. Ag/Na2Ti6O13 microfibers were obtained by the sol-gel method, meanwhile octagonal microbar agglomerates were the product of the solid state reaction. The SEM-TEM observations showed silver particles with a nanometric size (5-7 nm); and fibrillar structures in the sol-gel sodium titanates. The UV-Vis-RD spectroscopy showed a blue shift Eg from 3.3 to 3.4 nm; and a plasmon surface resonance in the visible region. These materials are proposed as potential photocatalysts for contaminated water purification.

Combination of Mn oxidation states improves the photocatalytic degradation of phenol with ZnAl LDH materials without a source of O₂ in the reaction system

Morales-Mendoza, Getsemani,Alvarez-Lemus, Mayra,Ló,pez, Rosendo,Tzompantzi, Francisco,Adhikari, Rajesh,Lee, Soo Wohn,Torres-Martí,nez, Leticia M.,Gó,mez, Ricardo Elsevier 2016 CATALYSIS TODAY - Vol.266 No.-

<P><B>Abstract</B></P> <P>Mn-doped Zn/Al layered double hydroxides (LDH) materials were synthesized by the co-precipitation method. X-ray diffraction (XRD) analysis confirmed the polytype structure of LDH materials obtained as well as the successful incorporation of Mn into the structure. Atomic absorption spectroscopy (AAS) and energy dispersive X-ray spectroscopy (EDS) studies showed a well dispersion of Mn and a good correlation between the nominal and experimental composition. Scanning electron microscopy (SEM) revealed the formation of grains close to 1μm length. Energy band gap (Eg) of the solids determined by UV–vis diffuse reflectance spectroscopy (DRS) showed high photoresponse in the ultraviolet (UV) region, which was increased with Mn incorporation into the LDH structure. The LDH materials were evaluated in the photocatalytic degradation of phenol in aqueous medium, under UV radiation with and without O<SUB>2</SUB> source in the reaction system. The results showed that the O<SUB>2</SUB> is not an effective electron scavenger as usually occurs in TiO<SUB>2</SUB> photocatalyst. The Mn effect in the photocatalytic activity was notably marked in anaerobic condition however in aerobic or anaerobic conditions the presence of Mn increases the photoactivity. The phenol mineralization reached in anaerobic conditions was 95% (1.5ppm) of the initial concentration (30ppm) and it is maintained constant after 6h of radiation while in aerobic conditions the TOC reaches only 55% (13.5ppm). The role of Mn as charges separator is discussed and a suitable mechanism is proposed. This study shows that the Mn doped-Zn/Al LDH materials could be a promising photocatalysts under anaerobic conditions for the removal of phenol from aqueous medium.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ZnAl LDH rebuilt in phenol solution have not capacity to open the interlayer space. </LI> <LI> A source of O<SUB>2</SUB> have not influence in the phenol photooxidation with ZnAl LDH. </LI> <LI> Mn doped-ZnAl LDH increases the optical properties of absorption. </LI> <LI> The role as electron and hole trap of Mn takes advantage to separate charge. </LI> <LI> The Mn incorporation in ZnAl LDH materials improves the photocatalytic activity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>