Deep control of linear oligomerization of glycerol using lanthanum catalyst on mesoporous silica gel

The valorization of glycerol (1), a waste of biodiesel production of Fatty Acid Methyl Esters (FAMEs), adopting a “green” approach, represents an important goal of sustainable chemistry. While the polymerization of 1 to hyperbranched oligomers is a well-established process, the linear analogues are difficult to obtain. In this context, we explore the reaction without the solvent of heterogeneous hybrid La(III)O-KIT-6 catalyst (2), which is based on lanthanum oxide on mesoporous silica gel, showing a superior linear selectivity compared to most of the analogous catalysts recently reported

Electronic nose and isotope ratio mass spectrometry in combination with chemometrics for the characterization of the geographical origin of Italian sweet cherries

Sweet cherries from two Italian regions, Apulia and Emilia Romagna, were analysed using electronic nose (EN) and isotope ratio mass spectrometry (IRMS), with the aim of distinguishing them according to their geographic origin. The data were elaborated by statistical techniques, examining the EN and IRMS datasets both separately and in combination. Preliminary exploratory overviews were performed and then linear discriminant analyses (LDA) were used for classification. Regarding EN, different approaches for variable selection were tested, and the most suitable strategies were highlighted. The LDA classification results were expressed in terms of recognition and prediction abilities and it was found that both EN and IRMS performed well, with IRMS showing better cross-validated prediction ability (91.0%); the EN–IRMS combination gave slightly better results (92.3%). In order to validate the final results, the models were tested using an external set of samples with excellent results

Valorization of cigarette butts for synthesis of levulinic acid as top value-added chemicals

Unprecedented in the literature, levulinic acid (LA), one of the top value-added intermediates of chemical industry, is obtained from cigarette butts as cellulose feedstock by means of a one-pot hydrothermal process carried out at 200 °C for 2 h and catalysed by phosphoric acid. The protocol avoids the use of more aggressive and toxic H2SO4 and HCl, that are generally employed on several cellulose sources (e.g. sludge paper), thus minimizing corrosion phenomena of plants. Neither chemical pre-treatment of butts nor specific purification procedure of LA are required. Notably, by simply modifying acid catalyst (e.g. using CH3COOH), another top value-added fine chemical such as 5-hydroxymethylfuraldehyde (HMF) is obtained, thus widening the scope of the method. Being cigarette filters a waste available in quantities of megatonnes per year, they represent an unlimited at no cost source of cellulose, thus enabling the up-scale to an industrial level of LA production

Concerning synthesis of new biobased polycarbonates with curcumin in replacement of bisphenol a and recycled diphenyl carbonate as example of circular economy

Curcumin (CM) is a natural polyphenol well-known for its antioxidant and pharmaceutical properties, that can represent a renewable alternative to bisphenol A (BPA) for the synthesis of biobased polycarbonates (PC). In the presented strategy, preparation of the CM-based PC was coupled with chemical recycling of the fossil-based BPA polycarbonate (BPA-PC) conducting a two-steps trans-polymerization that replaces BPA monomer with CM or its tetrahydrogenated colorless product (THCM). In the first step of synthetic strategy, depolymerization of commercial BPA-PC was carried out with phenol as nucleophile, according to our previous procedure based on zinc derivatives and ionic liquids as catalysts, thus producing quantitatively diphenyl carbonate (DPC) e BPA. In the second step, DPC underwent a melt transesterification with CM or THCM monomers affording the corresponding bio-based polycarbonates, CM-PC and THCM-PC, respectively. THCM was prepared by reducing natural bis-phenol with cyclohexene as a hydrogen donor and characterized by 1H-NMR and MS techniques. Polymerization reactions were monitored by infrared spectroscopy and average molecular weights and dispersity of the two biobased polymers THCM-PC and CM-PC were determined by means of gel permeation chromatography (GPC). Optical properties of the prepared polymers were also measured

Multifunctional halloysite and hectorite catalysts for effective transformation of biomass to biodiesel

Halloysite surface was modified with tetrabutylammonium iodide, and then the obtained nanomaterial was used as support for ZnO nanoparticles. After characterization, the nanomaterial was used as a catalyst for fatty acid methyl esters (FAMEs) production. The recyclability of the nanomaterial was also investigated, and the optimization of reaction conditions by the design of experiments approach was performed as well. In addition, the synthesized nanomaterial was tested as a catalyst for FAME production from a series of waste lipids affording biodiesel in moderate to good yields (35–95%), depending on the matrix. To fully exploit the feasibility of clay minerals as catalysts in biodiesel formation, a screening of different clays and clay minerals with different morphologies and compositions, such as sepiolite, palygorskite, bentonite, and hectorite was also performed in the esterification of FFAs (a mixture of 1:1 palmitic and stearic acids). Finally, hectorite, chosen as a model of 2:1 clay minerals, was covalently modified, and tested as a catalyst in the esterification of FFAs

Análisis del discurso científico: una nueva organización categorial

Resumen: En el presente ensayo abordamos el tema del análisis del discurso científico presentando nuevas categorías y formas de organización para la descripción del mismo. Su aplicación facilita la transmisión de las prácticas metodológicas y clarifica la comprensión de los conceptos involucrados en la producción de propuestas de investigación, tesis y artículos científicos. Se hace uso principalmente de adverbios de posición en lengua latina ya que los mismos dan una indicación clara de la relación entre las partes del discurso propio de este género

Validation of a continuous-wave, single-distance NIRS oxymeter for the determination of muscle oxygenation during cycling.

Validation of a continuous-wave, single-distance NIRS oxymeter for the determination of muscle oxygenation during cycling. Silvia Pogliaghi1, Lorenzo Casiello1, Andrea Bandera2 1 Faculty of Kinesiology, University of Verona, Italy; 2 Nirox srl, Brescia, Italy An Italian company recently developed a relatively inexpensive continuous-wave (CW), single-distance near-infrared spectroscopy (NIRS) oxymeter that allows the calculation of absolute values of deoxygenated haemoglobin (deoxyHb). This absolute quantification is made possible by an in-vivo estimate of the scattering coefficient (based on direct measures of the scattering at the water absorption peak and on its linear extrapolation to the near-infrared range). The calculated scattering coefficient is assumed not to change over the time of the experiment. PURPOSE: We tested the possible correspondence between non-invasive measures of muscle deoxyHb obtained using this CW device and a frequency-domain (FD) multi-distance NIRS system, used as a reference method. METHODS: 11 healthy sedentary males (27\ub15 years, 176\ub11 cm , 73\ub18 kg, 54\ub14 ml*kg-1*min-1 VO2max) performed an incremental cycling test. Following a 3-min rest, subjects pedaled at 50 watt for 3 min. Thereafter, the workload was increased stepwise, 20 watt per minute, up to voluntary exhaustion. During the tests, muscle deoxyHb was monitored continuously on the vastus lateralis of the right leg, using the reference FD device (FDdeoxyHb), and on the right leg, using the CW instrument (CWdeoxyHb). The average values of the last 30s of rest and warm-up cycling, and the last 10 s of each stage were used for statistical analysis. Agreement between the two instruments was tested by Bland Altman analysis (significance 640.05). RESULTS: Resting CWdeoxyHb and FDdeoxyHb were 27\ub16 and 29\ub15 mmol*l-1 respectively (not different). As expected, deoxyHb increased as a function of exercise intensity reaching 43\ub19 (CWdeoxyHb) and 44\ub110 mmol*l-1 (FDdeoxyHb) upon exhaustion (not different). At all exercise intensities, CWdeoxyHb was not significantly different from FDdeoxyHb (bias 0.93, not different from 0; precision 7.6 mmol*l-1). CONCLUSIONS: The main finding of this study is that there is a very good agreement between muscle deoxyHb values measured by the evaluated CW device and the reference FD oxymeter. Compared to the reference device, the new, relatively inexpensive oxymeter yields unbiased and precise deoxyHb values during incremental cycling exercises in healthy sedentary males. The study was supported by Nirox srl, Ital

El desarrollo sustentable desde la perspectiva de las relaciones multimodales

Resumen: Se revisan en este trabajo los métodos clásicos para abordar el problema de la sustentabilidad, tales como los análisis de impacto ambiental, el uso de indicadores ambientales y los métodos de decisión con objetivos inconmensurables, para ilustrar la necesidad de una visión más amplia orientada hacia la comprensión, donde las explicaciones son significativas en la medida en que favorezcan la anterior. Dado que la metodología multimodal se ajusta a esta perspectiva, se revisan sus suposiciones básicas con relación a la estructura de la realidad y al concepto de modalidad. Debido a que la metodología mencionada se construye sobre estos elementos básicos, se muestran cuáles son los problemas abiertos tales como el tratamiento de las relaciones entre diferentes modalidades, así como la necesidad de comenzar por las dos primeras modalidades en la jerarquía: la ética y la estética. También se desarrolla una ilustración de la aplicación de la metodología a una situación específica.Abstract: Current methods for dealing with sustainability, like environmental impact analysis, environmental indicator systems and decision methods for incommensurables objectives, are critically reviewed in this essay to illustrate the need for broader view oriented toward understanding , where explanations are meaningful as long as they favor the latter. Since multimodal methodology fits within this perspective, its basic propositions regarding the structure of reality and the concept of modality are reviewed. Because the former methodology is built upon these basic elements, open problems like dealing with relations among different modalities are shown, as well as the need to start with the study of the relation between the two modalities in the higher hierarchy: the ethical and the aesthetical ones. An illustration of the application of the methodology to specific situations is also outlined