Hasil untuk "Chemistry"

Nei Pereira Junior

Lignocellulosic biomass is one of the most abundant renewable carbon resources available, currently used predominantly for energy generation through direct combustion, yet still underutilized as a feedstock for higher-value biochemical conversion. Its structural complexity and intrinsic recalcitrance continue to challenge efficient biological processing. Overcoming these barriers requires an integrated understanding of plant cell-wall architecture, pretreatment chemistry, enzymatic mechanisms, and process engineering. This review provides a clear and conceptually grounded synthesis of these elements, illustrating how they converge to enable the development of second-generation (2G) lignocellulosic biorefineries. This review examines the hierarchical organization of cellulose, hemicelluloses, and lignin; the principles and performance of modern pretreatment technologies; the synergistic action of cellulolytic systems, including lytic polysaccharide monooxygenases (LPMOs) and non-hydrolytic proteins such as swollenins; advances in C5/C6 sugar fermentation; and emerging strategies for lignin upgrading. In addition to a comprehensive analysis of the literature, representative industrial and experimental case studies reported in the literature are discussed to illustrate practical process behavior and design considerations. By integrating mechanistic insight with industrially relevant examples, this review highlights the technical feasibility, current maturity, and remaining challenges of lignocellulosic biorefineries, underscoring their strategic role in enabling a competitive, low-carbon bioeconomy.

Yamada Kazuya, Matahira Yoshiharu, Takuwa Nagisa et al.

Nicotine consumption is known to be a risk factor for cardiovascular disease. β-Caryophyllene (BCP), a sesquiterpene with anti-inflammatory properties, was investigated in a randomized, double-blind, placebo-controlled trial to see if smoking cigarettes with BCP-containing capsules could improve aortic stiffness. In this study, 84 adult smokers were randomly assigned to either a BCP group or a placebo group. They smoked capsule-loaded cigarettes for 12 weeks, and various health parameters were measured every 4 weeks. The primary focus was on changes in brachial-ankle pulse wave velocity (baPWV), which measures arterial stiffness. The results showed that blood BCP levels increased only in the BCP group, while nicotine levels rose in both groups. For participants with a high baseline baPWV (≥ 1,400 cm/s), significant reductions in baPWV were observed in the BCP group at weeks 4 and 8. Additionally, baPWV at week 4 was significantly lower in the BCP group compared to the placebo group. No adverse effects were reported. In conclusion, smoking BCP-containing cigarettes improved arterial stiffness in participants with high baseline baPWV without causing any adverse effects.

Ruicheng Bai, Pei Zhang, Xihai Wang et al.

In this work, bilayer nanocoatings were designed and constructed on high-performance aromatic polysulfonamide (PSA) fibers for robust electric conduction and electromagnetic interference (EMI) shielding. More specifically, PSA fibers were first endowed with necessary electric conductivity via electroless nickel (Ni) or nickel alloy (Ni-P-B) plating. Afterward, silver electroplating was carried out to further improve the performance of the composite. The morphology, microstructure, environmental stability, mechanical properties, and EMI shielding performance of the proposed cladded fibers were thoroughly investigated to examine the effects of electrodeposition on both amorphous Ni-P-B and crystalline Ni substrates. The acquired results demonstrated that both PSA@Ni@Ag and PSA@Ni-P-B@Ag composite fibers had high environment stability, good tensile strength, low electric resistance, and outstanding EMI shielding efficiency. This indicates that they can have wide application prospects in aviation, aerospace, telecommunications, and military industries. Furthermore, the PSA@Ni-P-B@Ag fiber configuration seemed more reasonable because it exhibited smoother and denser silver surfaces as well as stronger interfacial binding, leading to lower resistance (185 mΩ cm⁻¹) and better shielding efficiency (82.48 dB in the X-band).

Cecilia Benazzato, Fernando Lojudice, Felizia Pöehlchen et al.

Abstract Zika virus (ZIKV) infection was first reported in 2015 in Brazil as causing microcephaly and other developmental abnormalities in newborns, leading to the identification of Congenital Zika Syndrome (CZS). Viral infections have been considered an environmental risk factor for neurodevelopmental disorders outcome, such as Autism Spectrum Disorder (ASD). Moreover, not only the infection per se, but maternal immune system activation during pregnancy, has been linked to fetal neurodevelopmental disorders. To understand the impact of ZIKV vertical infection on brain development, we derived induced pluripotent stem cells (iPSC) from Brazilian children born with CZS, some of the patients also being diagnosed with ASD. Comparing iPSC-derived neurons from CZS with a control group, we found lower levels of pre- and postsynaptic proteins and reduced functional synapses by puncta co-localization. Furthermore, neurons and astrocytes derived from the CZS group showed decreased glutamate levels. Additionally, the CZS group exhibited elevated levels of cytokine production, one of which being IL-6, already associated with the ASD phenotype. These preliminary findings suggest that ZIKV vertical infection may cause long-lasting disruptions in brain development during fetal stages, even in the absence of the virus after birth. These disruptions could contribute to neurodevelopmental disorders manifestations such as ASD. Our study contributes with novel knowledge of the CZS outcomes and paves the way for clinical validation and the development of potential interventions to mitigate the impact of ZIKV vertical infection on neurodevelopment.

Hayet Elkolli, Meriem Elkolli, Farid S. Ataya et al.

<i>Eucalyptus</i>, a therapeutic plant mentioned in the ancient Algerian pharmacopeia, specifically two species belonging to the <i>Myrtaceae</i> family, <i>E</i>. <i>radiata</i> and <i>E</i>. <i>cinerea</i>, were investigated in this study for their antibacterial, antioxidant, and anti-inflammatory properties. The study used aqueous extracts (AE) obtained from these plants, and the extraction yields were found to be different. The in vitro antibacterial activity was evaluated using a disc diffusion assay against three typical bacterial strains. The results showed that the two extracts were effective against all three strains. Both extracts displayed significant antioxidant activity compared to BHT. The anti-inflammatory impact was evaluated using a protein (BSA) inhibition denaturation test. The <i>E</i>. <i>radiata</i> extract was found to inhibit inflammation by 85% at a concentration of 250 µg/mL, significantly higher than the Aspirin. All phytoconstituents present good pharmacokinetic characteristics without toxicity except very slight toxicity of terpineol and cineol and a maximum binding energy of −7.53 kcal/mol for its anti-TyrRS activity in silico. The study suggests that the extracts and their primary phytochemicals could enhance the efficacy of antibiotics, antioxidants, and non-steroidal anti-inflammatory drugs (NSAIDs). As pharmaceutical engineering experts, we believe this research contributes to developing natural-based drugs with potential therapeutic benefits.

Salam S Alsharari, Muneefah A. Alenezi, Mona S. Al Tami et al.

A critical milestone in nano-biotechnology is establishing reliable and ecological friendly methods for fabricating metal oxide NPs. Because of their great biodegradable, electrical, mechanical, and optical qualities, zirconia NPs (ZrO2NPs) attract much interest among all zirconia NPs (ZrO2NPs). Zirconium oxide (ZrO2) has piqued the interest of researchers throughout the world, particularly since the development of methods for the manufacture of nano-sized particles. An extensive study into the creation of nanoparticles utilizing various synthetic techniques and their potential uses has been stimulated by their high luminous efficiency, wide bandgap, and high exciton binding energy. Zirconium dioxide nanoparticles may be used as antimicrobial and anticancer agents in food packaging. In response to the growing interest in nano ZrO2, researchers invented and developed methods for synthesizing nanoparticles. ZrO2 nanocomposites with various morphologies have recently been created using biological (green chemistry) methods. Microbes and plants both contribute to the production of zirconia in the laboratory. Capping and stabilizing agents are provided by the biomolecules found in plant extracts, whereas microorganisms provide enzymes as capping and stabilizing agents (intracellular or extracellular). It is possible to analyze the nanoparticles produced using a variety of analytical approaches, including ultraviolet-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). When applied to bacteria (both Gram-positive and Gram-negative) and fungi, ZrO2NPs show promising antibacterial capabilities. Normal and malignant cells are sensitive to ZrO2 nanoparticles, which can be explained by the generation of reactive oxygen (ROS). This work discusses and describes many ways of producing ZrO2 nanoparticles, their properties, and various application possibilities.

Stefan Dolder

Teaching and learning chemical formulas and structures is challenging. In many cases students understand chemical formulas only at a superficial level and poorly comprehend and retain the underlying chemical processes. Teaching methods still follow historically evolved principles, which are briefly summarized in this article. Difficulties and misconceptions that students encounter are presented and discussed. Didactic principles are proposed to help overcome the main challenge of connecting learned concepts and models to chemical formulas. The macOS and iPadOS application MoleculeSketch for drawing chemical structures is presented.

Radostina Palcheva, Luděk Kaluža, Tanya Petrova et al.

Tri-metallic NiMoW catalysts prepared by impregnating mesoporous aluminas (pore sizes of ~9 nm and surface areas of ~225 m²/g) obtained by sol-gel (NiMoW/Al) and hydrothermal (NiMoW/Al_HYDT) processes were investigated in the hydrodesulfurization (HDS) of thiophene and 4,6-dimethyldibenzothiophene (4,6-DMDBT) at H₂ pressures of 1 MPa and 5.0 MPa, respectively. The supports and catalysts were characterized by N₂ physisorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM). The NiMoW/Al_HYDT catalyst, which was the most active in both test HDS reactions, was characterized by a pore size of 7.5 nm, whereas the pore size of the catalyst on sol-gel alumina (NiMoW/Al) was only 4.8 nm. Moreover, the NiMoW/Al_HYDT catalyst exhibited reduction peaks shifted to a lower temperature during TPR, indicating weaker metal support interactions, a higher degree of Mo (79%) and W (48%) sulfidation, and an optimal layer slab length distribution of Mo(W)S₂ nanocrystals preferentially between 2–4 nm with an average layer stacking of 1.7 compared to the NiMoW/Al counterpart.

Xiongye Zhang, Lixin Zhang, Xue Hu et al.

The rotary tillage knife roller, as one of the typical soil-touching parts of the tillage equipment cutting process, is in direct contact with the soil. During the cutting process, there are problems related to structural bending, deformation, and high power consumption, caused by impact and load, and it is difficult to observe the micro-change law of the rotary tillage tool and soil. In view of the above problems, we took the soil of the cotton experimental field in Shihezi, Xinjiang, and the soil-contacting parts of the rotary tillage equipment, specifically the rotary tiller roller, as the research subject. Using the finite-element method (FEM) to simulate the structure of the rotary tiller with different bending angle parameters, we obtained its average stress and deformation position information, and obtained a range linear relationship between the bending angle and the structural performance of the rotary tiller tool. Using discrete element method (DEM)-based simulation to build the corresponding contact model, soil particle model, and soil–rotary tillage knife roll interaction model to simulate the dynamic process of a rotary tillage knife roll cutting soil, we obtained the change rules of the soil deformation area, cutting process energy, cutting resistance, and soil particle movement. By using the orthogonal simulation test and the response surface method, we optimized the kinematic parameters of the rotary tiller roller and the key design parameters of a single rotary tiller. Taking the reduction of cutting power consumption as the optimization goal and considering the influence of the bending angle on its structural performance, the optimal parameter combination was obtained as follows: the forward speed was 900 m/h, the rotation speed was 100 rad/min, the bending angle was 115°, and the minimum power consumption of the cutter roller was 0.181 kW. The corresponding average stress and deformation were 0.983 mm and 41.826 MPa, which were 15.8%, 13%, and 7.9% lower than the simulation results of power consumption, stress, and deformation under the initial parameter setting, respectively. Finally, the effectiveness of the simulation optimization model in reducing power consumption and the accuracy of the soil-cutting simulation were verified by a rotary tilling inter-field test, which provided theoretical reference and technical support for the design and optimization of other typical soil-touching parts of tillage and related equipment, such as disc harrow, ploughshare, and sub-soiling shovel.

Danga Rallet, Abba Paltahe, Cornelius Tsamo et al.

In this work, Clay-Biochar composite was synthesized from local Clay and local cotton wood, and applied for removal of glyphosate from aqueous solutions by adsorption. The Clay, Biochar and Clay-Biochar composite were characterized using X-ray diffraction, scanning electron microscope, fourier transform infrared spectroscopy, and thermal analysis. The adsorption studies of glyphosate were investigated by batch process at laboratory temperature. Adsorption experiments showed that the composite exhibited much better adsorption capability than both Clay and Biochar. The adsorption kinetics of glyphosate obeyed pseudo-second-order model according to their high coefficient R2 = 0.996, 0.995, 0.999 for Clay, Biochar and Clay-Biochar composite, respectively. The equilibrium adsorption data was best described by Langmuir model with R2 values of 0.937, 0.989, and 0.993 and Temkin model with R2 values of 0.982, 0.909, and 0.983, each for Clay, Biochar and Clay-Biochar respectively. Therefore, Clay-Biochar composite could be applied in the remediation of glyphosate in contaminated aqueous media.

Violeta Dediu, Mariana Busila, Vasilica Tucureanu et al.

Annually, antimicrobial-resistant infections-related mortality worldwide accelerates due to the increased use of antibiotics during the coronavirus pandemic and the antimicrobial resistance, which grows exponentially, and disproportionately to the current rate of development of new antibiotics. Nanoparticles can be an alternative to the current therapeutic approach against multi-drug resistance microorganisms caused infections. The motivation behind this work was to find a superior antibacterial nanomaterial, which can be efficient, biocompatible, and stable in time. This study evaluated the antibacterial activity of ZnO-based nanomaterials with different morphologies, synthesized through the solvothermal method and further modified with Au nanoparticles through wet chemical reduction. The structure, crystallinity, and morphology of ZnO and ZnO/Au nanomaterials have been investigated with XRD, SEM, TEM, DLS, and FTIR spectroscopy. The antibacterial effect of unmodified ZnO and ZnO/Au nanomaterials against <i>Escherichia coli</i> and <i>Staphylococcus aureus</i> was investigated through disc diffusion and tetrazolium/formazan (TTC) assays. The results showed that the proposed nanomaterials exhibited significant antibacterial effects on the Gram-positive and Gram-negative bacteria. Furthermore, ZnO nanorods with diameters smaller than 50 nm showed better antibacterial activity than ZnO nanorods with larger dimensions. The antibacterial efficiency against <i>Escherichia coli</i> and <i>Staphylococcus aureus</i> improved considerably by adding 0.2% (<i>w</i>/<i>w</i>) Au to ZnO nanorods. The results indicated the new materials’ potential for antibacterial applications.

Thobile Masinga, Malvin Moyo, Vusumzi Emmanuel Pakade

Contamination of water by hexavalent chromium generated from man–made activities remains one of the challenges for environmental pollution. Activated carbon impregnated with diluted polyethyleneimine (PEI) solutions was investigated as a possible adsorbent for the remediation of water contaminated with toxic Cr(VI). The activated carbon adsorbents were characterized using Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Parameters that influence the adsorptive removal of Cr(VI) were evaluated, and it was observed that high removal efficiency was achieved at pH 3 with a contact time of 120 min and 1 g L−1 dosage concentration. The data were analyzed by kinetic and isotherm models. The data fitted well into the Elovich and Langmuir models, the latter yielding a maximum adsorption capacity of 114 mg g−1. Overall, the MAC-PEI showed promise as a potential adsorbent to remove noxious Cr(VI) in aqueous solution.

Elena Alfaya-Lamas, Menchu Garrote Espantoso

The concept of representativeness is the main distinguishing characteristic of specialised corpora in comparison to other sets of texts. The Coruña Corpus of English Scientific Writing currently comprises four published subcorpora (astronomy, life sciences, history, and philosophy) plus three others under compilation (physics, chemistry and linguistics). In this paper we aim to assess the lexical density of the text samples in CETA, the Corpus of English Texts on Astronomy, by means of the ReCor tool, a posteriori. The study is motivated by the following question: does quantitative representativeness analysis using ReCor provide, in the form of a cross-check, further validation of previous research on the representativeness of CETA? Previous work (Crespo and Moskowich, 2010) has indicated that the CETA corpus is well designed and valid for the purposes for which it was intended. We will here suggest metrics to measure these findings. The most important contribution of this study is to offer quantitative data collection results using the ReCor tool, which allows data triangulation and consequently ensures overall data quality. Results show that data analysis with the ReCor tool supports previous findings, and thus we are able to verify that CETA is indeed representative of the language of its time and register.

Y. Wang, M. Hu, M. Hu et al.

<p>Nitro-aromatic compounds (NACs), as important contributors to the light absorption by brown carbon, have been widely observed in various ambient atmospheres; however, their formation in the urban atmosphere was little studied. In this work, we report an intensive field study of NACs in summer 2016 at an urban Beijing site, characterized by both high-<span class="inline-formula">NO_<i>x</i></span> and anthropogenic VOC dominated conditions. We investigated the factors that influence NAC formation (e.g., <span class="inline-formula">NO₂</span>, VOC precursors, RH and photolysis) through quantification of eight NACs, along with major components in fine particulate matter, selected volatile organic compounds, and gases. The average total concentration of the quantified NACs was 6.63&thinsp;ng&thinsp;m<span class="inline-formula">⁻³</span>, higher than those reported in other summertime studies (0.14–6.44&thinsp;ng&thinsp;m<span class="inline-formula">⁻³</span>). 4-Nitrophenol (4NP, 32.4&thinsp;%) and 4-nitrocatechol (4NC, 28.5&thinsp;%) were the top two most abundant NACs, followed by methyl-nitrocatechol (MNC), methyl-nitrophenol (MNP), and dimethyl-nitrophenol (DMNP). The oxidation of toluene and benzene in the presence of <span class="inline-formula">NO_<i>x</i></span> was found to be a more dominant source of NACs than primary biomass burning emissions. The <span class="inline-formula">NO₂</span> concentration level was found to be an important factor influencing the secondary formation of NACs. A transition from low- to high-<span class="inline-formula">NO_<i>x</i></span> regimes coincided with a shift from organic- to inorganic-dominated oxidation products. The transition thresholds were <span class="inline-formula">NO₂ ∼ 20</span>&thinsp;ppb for daytime and <span class="inline-formula">NO₂∼25</span>&thinsp;ppb for nighttime conditions. Under low-<span class="inline-formula">NO_<i>x</i></span> conditions, NACs increased with <span class="inline-formula">NO₂</span>, while the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NO</mi><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="c5e3e0772eea57309f236de17ca43cb8"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-7649-2019-ie00001.svg" width="25pt" height="16pt" src="acp-19-7649-2019-ie00001.png"/></svg:svg></span></span> concentrations and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mo>(</mo><msubsup><mi mathvariant="normal">NO</mi><mn mathvariant="normal">3</mn><mo>-</mo></msubsup><mo>)</mo><mo>/</mo><mi mathvariant="normal">NACs</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="66pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="b11e1e5398608eb8df751ed83b541a68"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-7649-2019-ie00002.svg" width="66pt" height="16pt" src="acp-19-7649-2019-ie00002.png"/></svg:svg></span></span> ratios were lower, implying organic-dominated products. Under high-<span class="inline-formula">NO_<i>x</i></span> conditions, NAC concentrations did not further increase with <span class="inline-formula">NO₂</span>, while the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M18" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NO</mi><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="7dd3c683c0655cd2a5c1ed2d08ea01e9"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-7649-2019-ie00003.svg" width="25pt" height="16pt" src="acp-19-7649-2019-ie00003.png"/></svg:svg></span></span> concentrations and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M19" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mo>(</mo><msubsup><mi mathvariant="normal">NO</mi><mn mathvariant="normal">3</mn><mo>-</mo></msubsup><mo>)</mo><mo>/</mo><mi mathvariant="normal">NACs</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="66pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="c4832a949e671b238f8731d693d75742"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-7649-2019-ie00004.svg" width="66pt" height="16pt" src="acp-19-7649-2019-ie00004.png"/></svg:svg></span></span> ratios showed increasing trends, signaling a shift from organic- to inorganic-dominated products. Nighttime enhancements were observed for 3M4NC and 4M5NC, while daytime enhancements were noted for 4NP, 2M4NP, and DMNP, indicating different formation pathways for these two groups of NACs. Our analysis suggested that the aqueous-phase oxidation was likely the major formation pathway of 4M5NC and 3M5NC, while photo-oxidation of toluene and benzene in the presence of <span class="inline-formula">NO₂</span> could be more important for the formation of nitrophenol and its derivatives. Using the (3M4NC<span class="inline-formula">+</span>4M5NC)&thinsp;<span class="inline-formula">∕</span>&thinsp;4NP ratios as an indicator of the relative contribution of aqueous-phase and gas-phase oxidation pathways to NAC formation, we observed that the relative contribution of aqueous-phase pathways increased at elevated ambient RH and remained constant at RH&thinsp;&gt;&thinsp;30&thinsp;%. We also found that the concentrations of VOC precursors (e.g., toluene and benzene) and aerosol surface area acted as<span id="page7650"/> important factors in promoting NAC formation, and photolysis as an important loss pathway for nitrophenols.</p>

Venkata Rao Madduluri, Peddinti Nagaiah, Challa Prathap et al.

Co3O4/γ-Al2O3 catalysts with variable Co3O4 loadings (5–20 wt%) and deposition of 15% Co3O4 on La2O3/γ-Al2O3 were prepared by wet impregnation method. La2O3-γ-Al2O3 support with variable composition of La2O3 (2–6 wt%) were prepared by co-precipitation method. All the catalysts were tested for oxidative dehydrogenation of ethylbenzene with CO2 as soft oxidant. Among the Co3O4/γ-Al2O3 catalysts, 15% Co3O4/γ-Al2O3 has shown good performance and hence this catalyst has been chosen to investigate the effect of La2O3 species. CO2 pulse chemisorption data indicate more amount of CO2 uptake over 15% Co3O4/4%La2O3/γ-Al2O3 catalyst which clearly indicates that this catalyst exhibits good performance in ethylbenzene dehydrogenation with CO2 as soft oxidant because of reverse water gas shift reaction. Temperature programmed reduction studies indicate that the Co3O4 catalysts follow two step reduction mechanism from Co3O4 to CoO and then to Co and La2O3 promotional effect is visible through facile reduction of Co3O4 species. La2O3 doping has a vital influence in getting enhanced ethylbenzene conversion, styrene yield and alleviates catalyst deactivation compared to that of unpromoted Co3O4/γ-Al2O3 catalyst. TGA studies indicate the presence low amount coke deposition during time-on-stream over 15% Co3O4/4%La2O3/γ-Al2O3 catalyst compared to 15% Co3O4/γ-Al2O3 catalyst. Keywords: Ethylbenzene dehydrogenation, Co3O4/γ-Al2O3 catalysts, La2O3 promotion, CO2 as soft oxidant

Magda Ferreira, Melissa Schwanz, Gustavo Cosenza et al.

Vanilla planifolia (Orchidiaceae) is a species that is renowned globally and represents the largest source of vanillin flavoring used in the food, cosmetic and pharmaceutical industries. This study was carried out to analyze by TLC and HPLC-PDA vanillin in herbal drug and tincture from V. planifolia. The herbal drug was obtained with hydroalcoholic solution under reflux; and a kinetic reaction was performed by TLC. The influences of solvent and herbal drug concentration were studied through an experimental design. The solutions (herbal drug, tincture and standard – vanillin) were prepared and analyzed in HPLC coupled with DAD detector, using wavelength of 280 nm. The total extraction of vanillin was achieved after three extraction cycles, using 1.0 g of herbal material and Ethanol 50% (v/v) as solvent. The method was linear (R2> 0.99) and demonstrated repeatability (RSD < 0.90), intermediate precision (RSD < 1.09), recovery (93.12-113.74%), as well as robustness (RSD < 4.33). The total content of vanillin found was 1.82 g% and 0.21 g% for herbal drug and tincture, respectively. A simple and optimized method for sample preparation by reflux was able to provide the exhaustive extraction of vanillin and does not compromise the reliability of the HPLC-PDA method. The chromatographic procedure was validated to separate and quantify vanillin in herbal material and tincture from pods of V. planifolia.

Tieqiang Zhao, Dong Wang, Sergey Y. Cheranov et al.

To investigate the mechanisms underlying 15(S)-HETE-induced angiogenesis, we have studied the role of the small GTPase, Rac1. We find that 15(S)-HETE activated Rac1 in human retinal microvascular endothelial cells (HRMVEC) in a time-dependent manner. Blockade of Rac1 by adenovirus-mediated expression of its dominant negative mutant suppressed HRMVEC migration as well as tube formation and Matrigel plug angiogenesis. 15(S)-HETE stimulated Src in HRMVEC in a time-dependent manner and blockade of its activation inhibited 15(S)-HETE-induced Rac1 stimulation in HRMVEC and the migration and tube formation of these cells as well as Matrigel plug angiogenesis. 15(S)-HETE stimulated JNK1 in Src-Rac1-dependent manner in HRMVEC and adenovirus-mediated expression of its dominant negative mutant suppressed the migration and tube formation of these cells and Matrigel plug angiogenesis. 15(S)-HETE activated ATF-2 in HRMVEC in Src-Rac1-JNK1-dependent manner and interference with its activation via adenovirus-mediated expression of its dominant negative mutant abrogated migration and tube formation of HRMVEC and Matrigel plug angiogenesis. In addition, 15(S)-HETE-induced MEK1 stimulation was found to be dependent on Src-Rac1 activation. Blockade of MEK1 activation inhibited 15(S)-HETE-induced JNK1 activity and ATF-2 phosphorylation. Together, these findings show that 15(S)-HETE activates ATF-2 via the Src-Rac1-MEK1-JNK1 signaling axis in HRMVEC leading to their angiogenic differentiation.

Gabriele Ballistreri, Biagio Fallico, Elena Arena

This paper highlights, for the first time, the changes in the phenolics fraction (anthocyanins, flavonoids and stilbenes) and tocopherols of unpeeled Pistacia vera L. var. bianca with ripening, and the effect of the sun-drying process. The total polyphenol levels in pistachios, measured as mg of Gallic Acid Equivalent (GAE), were: 201 ± 10.1, 349 ± 18.3 and 184.7 ± 6.2 mg GAE/100 g DM in unripe, ripe and dried ripe samples, respectively. Most phenolics in ripe pistachios were found to be anthocyanins. They increased with ripening, while the sun drying process caused a susbtantial loss. Flavonoids found in all pistachio samples were daidzein, genistein, daidzin, quercetin, eriodictyol, luteolin, genistin and naringenin, which decreased both with ripening and drying. Before the drying process both unripe and ripe pistachios showed a higher content of trans-resveratrol than dried ripe samples. γ-Tocopherol was the major vitamin E isomer found in pistachios. The total content (of α- and γ-tocopherols) decreased, both during ripening and during the drying process. These results suggested that unpeeled pistachios can be considered an important source of phenolics, particularly of anthocyanins. Moreover, in order to preserve these healthy characteristics, new and more efficient drying processes should be adopted.

Gerard Boyer, Florence Chatel, Jean-Pierre Galy

Filipović Miloš, Kilibarda Nikola

An adequate method for calculating chemical equilibrium in a predominantly gaseous, multi-component reactive mixture was investigated and successfully applied. This method involves the stated equilibrium reaction scheme, including, first, the formation of chemical species, of which concentrations prevail in the mixture, then the formation of gaseous atomic species by dissociation of previous ones, and, finally, the formation of complex chemical species from the atomic species. A computer program, which permits calculations of equilibrium compositions by the iteration procedure, has been developed. The results of calculations have been compared with data obtained by the programs OPHELIE, MICROPEP, and the program SPP, as documented in the NASA-Lewis Code, which is presently the world-wide standard. All comparisons gave satisfactory agreement.