Catalytic wet peroxide oxidation of vanillic acid as a lignin model compound towards the renewable production of dicarboxylic acids

tLignin can be depolymerised and used as a feedstock to obtain renewable raw-materials,providing a green alternative to fossil counterparts. Among others, C4dicarboxylic acids(DCA), like succinic, malic, maleic and fumaric acids, which can find applications in phar-maceuticals, food industry, and act as solvents, can be obtained from lignin oxidation. Toinvestigate their formation, the oxidation of vanillic acid (VA), a lignin model compound, wasstudied under catalytic wet peroxide oxidation (CWPO) conditions, using titanium silicalite-1 (TS-1) as the catalyst. The effect of temperature, pH, and reaction time were studied. Ina second phase, catalyst modification with transition metal oxides (Fe, Co, Cu) was tested.Results showed that oxidation under pH = 10.5 gives rise to complete VA conversion withhydroxylated DCA, namely malic (15 mol%) and tartaric (5 mol%) acids, as the main products.At pH = 4.0, the production of succinic acid was improved (7.4 mol%), with VA conversionachieving 78% after 2.0 h of reaction. At alkaline pH, H2O2reactivity is higher, leading to C4-DCA degradation to low-molecular weight compounds. Catalyst desilication was observed,pointed out for the convenience of using neutral and acidic pH. In acidic pH, Fe and Cu cat-alysts enhanced VA conversion, and Fe catalyst was more selective towards succinic acidproduction.The authors gratefully acknowledge support from Fundac¸ãopara a Ciência e a Tecnologia (FCT), Portugal, Grant num-bers: UID/EQU/50020/2019, UID/AGR/00690/2019; European Cooperation in Science and Technology, Grant numbers: Lig-noCOST (CA17128) and Costa Rican Science, Technology andTelecommunications Ministry, Costa Rica. Scholarship num-ber: MICITT-PINN-CON-2-1-4-17-1-002.info:eu-repo/semantics/publishedVersio

Lignin conversion into C4 dicarboxylic acids by catalytic wet peroxide oxidation using titanium silicalite-1

Lignin valorisation towards added-value products has become a relevant topic to consolidate a future circular bioeconomy. In this context lignin oxidation to C4 dicarboxylic acids (C4-DCA) by catalytic wet peroxide oxidation is emerging as a value-added strategy, supported by the extensive use of these building blocks in several industrial fields. In this work, lignins from different sources and processes (Indulin AT, Lignol, alkali and E. globulus kraft lignins) were oxidised using H2O2 and titanium silicalite-1 catalyst (TS-1) under different operating conditions (temperature, pH, time, H2O2, and TS-1 load). Indulin AT was the lignin leading to the highest succinic acid yield (11.3 wt%), and TS-1 catalyst enhanced its production four times over the noncatalysed reaction. Malic acid was also produced at high yields, especially for Lignol lignin. The other lignins (E. globulus kraft, and alkali lignins) also produced these C4 acids but at lower yields. The catalyst remained stable at the used experimental conditions, and showed potential to be reused for several cycles without being deactivated. Overall, the catalytic conversion of lignin to C4-DCA can help to guide the pathway to renewable chemicals production.This work was financially supported by: Base Funding - UIDB/50020/2020 of the Associate Laboratory LSRE-LCM - funded by national funds through FCT/MCTES (PIDDAC); Base Funding - UIDB/00690/2020 of CIMO - Centro de Investigação de Montanha—funded by national funds through FCT/MCTES (PIDDAC). COST Action LignoCOST (CA17128). Carlos Vega-Aguilar thanks the Costa Rica Science, Technology and Telecommunications Ministry for the PhD. Scholarship MICITT-PINN-CON-2-1-4-17-1-002. The authors thank Dr. Maria José Sampaio and Prof. Dr. Joaquim Faria (LA LSRE-LCM) for the help with the ATR measurements.info:eu-repo/semantics/publishedVersio

Effect of methoxy substituents on wet peroxide oxidation of lignin and lignin model compounds: understanding the pathway to c4 dicarboxylic acids

Lignin depolymerization through peroxide oxidation produces dicarboxylic acids (DCA), especially C4-DCA, like succinic acid. In this work, the effect of methoxy substituents on C4-DCA production using peroxide oxidation of lignin model compounds (p-hydroxybenzoic acid, vanillic acid, and syringic acid) and hardwood and softwood lignin samples was studied. It was concluded that methoxy substituents increased the reactivity toward peroxide oxidation. The succinic acid yield was higher for the model compounds with fewer methoxy groups, achieving 5.8 wt % of succinic acid for p-hydroxybenzoic acid. For Eucalyptus globulus kraft lignin (hardwood lignin with guaiacyl and syringyl units), an increased reactivity was verified, and more succinic acid (3.5 wt %) was produced in a shorter time, comparatively with Indulin AT lignin (softwood lignin, with only guaiacyl units), which produced 2.7 wt %. This evidence suggests that E. globulus kraft lignin might be a better raw material than Indulin AT for succinic acid production by peroxide oxidation.This work was financially supported by Base Funding − UIDB/50020/2020 of the Associate Laboratory LSRE-LCM − funded by national funds through FCT/MCTES (PIDDAC); Base Funding−UIDB/00690/2020 of CIMO, Centro de Investigação de Montanha−funded by national funds through FCT/MCTES (PIDDAC); COST Action LignoCOST (CA17128). C.A.V.-A. thanks the Costa Rican Science, Technology and Telecommunications Ministry for the Ph.D. Scholarship MICITT-PINN-CON-2-1-4-17-1-002.info:eu-repo/semantics/publishedVersio

Globular Clusters: DNA of Early-Type galaxies?

This paper explores if the mean properties of Early-Type Galaxies (ETG) can be reconstructed from "genetic" information stored in their GCs (i.e., in their chemical abundances, spatial distributions and ages). This approach implies that the formation of each globular occurs in very massive stellar environments, as suggested by some models that aim at explaining the presence of multi-populations in these systems. The assumption that the relative number of globular clusters to diffuse stellar mass depends exponentially on chemical abundance, [Z/H], and the presence of two dominant GC sub-populations blue and red, allows the mapping of low metallicity halos and of higher metallicity (and more heterogeneous) bulges. In particular, the masses of the low-metallicity halos seem to scale up with dark matter mass through a constant. We also find a dependence of the globular cluster formation efficiency with the mean projected stellar mass density of the galaxies within their effective radii. The analysis is based on a selected sub-sample of galaxies observed within the ACS Virgo Cluster Survey of the {\it Hubble Space Telescope}. These systems were grouped, according to their absolute magnitudes, in order to define composite fiducial galaxies and look for a quantitative connection with their (also composite) globular clusters systems. The results strengthen the idea that globular clusters are good quantitative tracers of both baryonic and dark matter in ETGs.Comment: 20 pages, 28 figures and 5 table

CORRIGENDUM: Surface wave damping in a brimful circular cylinder

As pointed out to us by Mr T. Heath, the following printing errors can be quite misleading when using the formulas in the paper to obtain eigenfrequencies and damping rates to compare with experiments: in (A 13) 1 should read −1 on the right-hand side; in (A 22) and (A 26) Ω20 should read Ω−20; in (A 25) the factor Ω40 must be omitted on the right-hand side. When revising again the printed version of the paper, we discovered several additional misprints: A factor C was omitted in the first two integrals in the expression for J2, immediately following equation (2.9). The sign of the second expression for I1 in (2.23) should be changed. The expression (W0Wz +3WW0z)z=0 should read 2(W0Wz +WW0z)z=0 in equation (2.24). The expression W0(1, z)W0z(1, z) in (2.26) should read W0(r, 0)W0z(r, 0). None of the misprints above affect the results of the paper, which were obtained with the correct expressions

Added-value chemicals from lignin oxidation

Lignin is the second most abundant component, next to cellulose, in lignocellulosic biomass. Large amounts of this polymer are produced annually in the pulp and paper industries as a coproduct from the cooking process-most of it burned as fuel for energy. Strategies regarding lignin valorization have attracted significant attention over the recent decades due to lignin’s aromatic structure. Oxidative depolymerization allows converting lignin into added-value compounds, as phenolic monomers and/or dicarboxylic acids, which could be an excellent alternative to aromatic petrochemicals. However, the major challenge is to enhance the reactivity and selectivity of the lignin structure towards depolymerization and prevent condensation reactions. This review includes a comprehensive overview of the main contributions of lignin valorization through oxidative depolymerization to produce added-value compounds (vanillin and syringaldehyde) that have been developed over the recent decades in the LSRE group. An evaluation of the valuable products obtained from oxidation in an alkaline medium with oxygen of lignins and liquors from different sources and delignification processes is also provided. A review of C4 dicarboxylic acids obtained from lignin oxidation is also included, emphasizing catalytic conversion by O2 or H2O2 oxidation.This work was financially supported by Base Funding—UIDB/50020/2020 and Programmatic- UIDP/50020/2020 Funding of the Associate Laboratory LSRE-LCM—funded by national funds through FCT/MCTES (PIDDAC) and Base Funding—UIDB/00690/2020 of CIMO— Centro de Investigação de Montanha—funded by national funds through FCT/MCTES (PIDDAC). COST Action LignoCOST (CA17128). Carlos Vega-Aguilar thanks the Costa Rican Science, Technology and Telecommunications Ministry for the PhD. Scholarship MICITT-PINN-CON-2-1-4-17-1-002.info:eu-repo/semantics/publishedVersio

Effect of a physical education-based dynamic stretching program on hamstring extensibility in female high-school students

The purpose of the present study was to examine the effects of a dynamic stretching development program followed by a four-week detraining period and maintenance program on hamstring extensibility in a physical education setting. A sample of 108 female high-school students aged 16-17 years from four classes were clustered randomly and assigned to either an experimental or a control group. During physical education sessions, the experimental group students performed a dynamic stretching program twice a week for eight weeks. Subsequently, after a four-week period of detraining, the experimental group students completed a maintenance program twice a week during four weeks. The results of the two-way analysis of variance showed that the physical education-based development program significantly improved students’ hamstring extensibility (p.05), the gains obtained previously were recovered after a four-week maintenance program (p<.001). Hence, a physical education-based dynamic stretching intervention is effective in improving and maintaining hamstring extensibility among female high-school students. However, after four weeks of detraining, students’ flexibility reverts to its baseline levels. These findings could help and guide teachers to design programs that guarantee a feasible and an effective development of flexibility in a physical education setting

¿Cómo cambian los niveles de extensibilidad isquiosural de los estudiantes durante un año académico? Un estudio longitudinal

The main purpose of the present study was to examine the students’ hamstring extensibility levels through an academic year. A sample of 128 11th-grade students from a high school center was assessed by the classic sit-and-reach test in pre-, mid- and post-academic year. The results showed that students’ hamstring extensibility level statistically significantly decreased from pre-academic year (22.1 ± 8.5 cm) to mid- (19.9 ± 8.6 cm; d = -0.26) and post-academic year (18.6 ± 9.3 cm; d = -0.41) (p < 0.001) and from mid-academic year to post-academic year (d = -0.16) (p < 0.001). The results of the McNemar’s test indicated that there was a statistically significant decrease on the proportion of students with normal hamstring extensibility level from pre-academic year to post-academic year (p < 0.05). In conclusion, high-school students lost hamstring extensibility levels during an academic year. As a result of this decrease, the number of students with hamstring extensibility shortening increased by 10.9%. Physical education teachers should implement stretching programs to avoid students’ hamstring extensibility shortening.El objetivo principal del presente estudio fue examinar los niveles de extensibilidad isquiosural de los estudiantes durante un curso académico. Una muestra de 128 estudiantes de 1º de bachillerato de un centro de educación secundaria se evaluó mediante la prueba de classic sit-and-reach al comienzo, mediados y final del curso académico. Los resultados mostraron que el nivel de extensibilidad de isquiosural de los estudiantes disminuyó estadísticamente significativamente desde el comienzo (22,1 ± 8,5 cm) a mediados (19,9 ± 8,6 cm, d = -0,26) y final del año académico (18,6 ± 9,3 cm; d = -0,41) (p < 0,001), y desde mediados al final (d = -0.16) (p < 0,001). Los resultados de la prueba de McNemar indicaron que hubo una disminución estadísticamente significativa en la proporción de estudiantes con un nivel de extensibilidad isquiosural normal desde el comienzo al final del curso académico (p < 0,05). En conclusión, los estudiantes de educación secundaria perdieron niveles de extensibilidad isquiosural durante un curso académico. Como resultado de esta disminución, el número de estudiantes con acortamiento de los músculos isquiosurales aumentó un 10,9%. Los profesores de educación física deberían implementar programas de estiramiento para prevenir el acortamiento de extensibilidad isquiosural de los estudiantes.Facultad de Humanidades y Ciencias de la Educació

Delving into Android Malware Families with a Novel Neural Projection Method

[Abstract] Present research proposes the application of unsupervised and supervised machine-learning techniques to characterize Android malware families. More precisely, a novel unsupervised neural-projection method for dimensionality-reduction, namely, Beta Hebbian Learning (BHL), is applied to visually analyze such malware. Additionally, well-known supervised Decision Trees (DTs) are also applied for the first time in order to improve characterization of such families and compare the original features that are identified as the most important ones. The proposed techniques are validated when facing real-life Android malware data by means of the well-known and publicly available Malgenome dataset. Obtained results support the proposed approach, confirming the validity of BHL and DTs to gain deep knowledge on Android malwar