Disminuir el impacto ambiental derivado del uso de combustibles fósiles necesita el desarrollo de fuentes de energía renovables, y la producción sostenible de combustibles líquidos. Los éteres de ...oximetileno (OMEs), son compuestos oxigenados que han surgido como una potencial alternativa para sustituir el combustible Diesel. El uso de estos éteres en los motores disminuye la formación de hollín y óxidos de nitrógeno (NOx) durante la combustión. Dentro de esta familia de compuestos, el 1,1-dimetoximetano (OME1) tiene especial interés, no solo por su uso como solvente industrial o como intermediario químico, sino, también porque puede ser usado como materia prima para la producción de OMEs de cadena larga. La síntesis directa de OME1 involucra la oxidación selectiva de metanol sobre catalizadores bifuncionales, los cuales han sido objeto de estudio durante las últimas décadas. Este trabajo resume las principales características de los distintos sistemas catalíticos desarrollados, los cuales juegan un papel fundamental para la producción comercial del 1,1-dimetoximetano.
Tithonia diversifolia se distribuye en trópico y subtrópico de México y es una valiosa fuente de compuestos bioactivos. Existen varios métodos para la extracción de compuestos bioactivos, sin ...embargo, su rendimiento depende de varios factores, por lo que es importante seleccionar las mejores condiciones.
PtCo based nanoparticles in alloy structure were synthesized using the microwave-assisted reduction method. These nanoparticles were deposited on different carbon supporting materials. Here, these ...supporting materials such as rGO (reduced graphene oxide), rGO-VC (vulcan carbon) and AC-VC (activated carbon-vulcan carbon) were used and the methanol oxidation reaction (MOR) activity of single carbon support and hybrid carbon support material in the presence of PtCo nanoparticles were investigated at the same molar concentration. The average particle size of the PtCo nanoparticles detected in the TEM analysis was found to be 3.55 ± 0.64 nm. The MOR activity of the PtCo@rGO, PtCo@rGO-VC and PtCo@AC-VC catalysts was determined, where the anodic peak current of PtCo@AC-VC was determined as 73 mA/cm2. It has been observed that PtCo nanoparticles with carbon hybrid support structures are more advantageous than single support structures due to the synergistic effect between carbon support structures and providing a larger surface area. Compared to previous studies, the MOR activity of PtCo@AC-VC is quite high. It can be stated that PtCo@AC-VC has comparable catalytic activity compared to the commercial available anode catalyst.
•PtCo nanoparticles were synthesized using the microwave-assisted reduction method.•The average particle size of the PtCo nanoparticles was found to be 3.55 nm.•The anodic peak potential of PtCo@AC-VC was determined as 73 mA/cm2.•PtCo@AC-VC is a highly efficient catalyst in direct methanol fuel cells.
The Abraham solvation parameter model, a linear free energy relationship (LFER) approach, has been used to characterize a polymeric zwitterionic (sulfobetaine) column in HILIC mode. When acetonitrile ...(MeCN) is used in the preparation of mobile phases the main solute characteristics affecting the chromatographic behavior of analytes are the molecular size and the hydrogen-bonding (both acidity and basicity) interactions. The former property is more favorable in the acetonitrile-rich mobile phase, reducing thus the retention, but the latter reveals a higher affinity for the water layer adsorbed on the stationary phase, enhancing retention. However, if the aprotic acetonitrile is replaced by methanol, a hydrogen-bond acidic solvent, solute hydrogen-bond basicity does not contribute any more to retention, quite the opposite. Thus, a slightly different selectivity is observed in methanol/water than in acetonitrile/water. Normal-phase mode and HILIC-MeCN share the same main factors affecting retention. For reversed-phase and immobilized artificial membrane (IAM) chromatography, the solute molecular size increase retention because of the lower amount of energy required in the formation of a cavity in the solvated stationary phase. On the contrary, the analyte hydrogen-bond basicity favors interactions with the hydroorganic mobile phase and reduces retention. The determined parameters justify the reversed selectivity commonly observed in HILIC in reference to reversed-phase. In most instances, the least retained solutes in reversed-phase are the most retained in HILIC.
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•The Abraham model is used for the characterization of a HILIC column.•Selectivity depends on the organic solvent used, acetonitrile or methanol.•HILIC is compared to normal-phase, reversed-phase and IAM retention selectivity.
Future ships need to operate with low or possibly zero greenhouse gas (GHG) emissions while ensuring low influence on other environmental impacts and that the operation is economically feasible. This ...study conducts a life-cycle evaluation of potential decarbonization solutions involving selected energy carriers (electrolytic hydrogen, electro-ammonia, electro-methanol, and electricity) in different propulsion system setups (engines, fuel cells, and carbon capture technologies) in terms of environmental impact and costs. The results of the study show that the assessed decarbonization options are promising measures to reduce maritime GHG emissions with low-carbon-intensive electricity. The same order of GHG reduction is shown to be possible independent of the propulsion system and energy carrier used onboard. However, the carbon abatement cost ranges from 300 to 550 €/tCO2eq, and there is a trade-off with environmental impacts such as human toxicity (cancer and non-cancer effects) and freshwater ecotoxicity mainly linked with the wind infrastructure used for electricity production. Electro-ammonia in fuel cells is indicated to be effective in terms of the carbon abatement cost followed by the so-called HyMethShip concept. The higher abatement cost of all options compared to current options indicates that major incentives and policy measures are required to promote the introduction of alternative fuel and propulsion systems.
Penggerek buah kopi (PBKo) (Hypothenemus hampei) adalah hama utama dan dapat menyebabkan kerugian ekonomi besar dan penurunan kualitas buah kopi yang signifikan. Upaya menekan populasi hama ini ...dibutuhkan pengendalian efektif, salah satunya penggunaan senyawa semiokimia berupa etanol dan metanol melalui perangkap botol yang digantung di ranting tanaman kopi. Penelitian ini bertujuan untuk mengetahui efektivitas komposisi rasio perbandingan etanol dan metanol yang efektif dalammenarik hama PBKo. Penelitian dilakukan dengan menggunakan metode rancangan acak kelompok (RAK) selama delapan minggu dan variabel pengamatan berupa populasi PBKo yang terperangkap selama satu minggu, intensitas buah kopi yang terserang PBKo, dan serangga lain yang terperangkap. Perlakuan etanol dan metanol 3:2 merupakan perlakuan terbaik dalam menangkap hama PBKo yaitu sebanyak 402 imago. Intensitas serangan hama PBKo menunjukkan penurunan intensitas serangan yang signifikan setelah pemasangan perangkap botol dengan kategori awal serangan sedang hingga sangat ringan.
The ethanol (active) and methanol (toxic) substances content were quantified for commercial sanitizing gels. The health emergency caused by the COVID-19 epidemic has motivated to production of ...sanitizing gels to cover higher demand. The analytical composition of 24 commercial gels is reported (15 produced by national and transnational companies, and 9 collected gels which were in use at public areas). From the results it was found, that only one brand of 15 gels meets the quality requirements regarding 70% (wt./wt.) of ethanol content. Concerning to the collected gels, none of them contains the minimum active compound required. The non-compliance of this requirement means that these gels present its sanitizing action diminished. A striking result is that 25% of commercially packaged gels contain methanol - a toxic substance - in alarming amounts, hundreds of times more than the FDA upper limits requirement.
In Aquaculture, the use of microalgae is fundamental in the first feeding of native fish species, since their optimal nutritional level favors survival. Successful production of microalgae under ...laboratory conditions depends on the culture medium used during the cryopreservation stage of production. Agricultural fertilizers can be used as a low-cost alternative culture media that promotes cell growth and cryopreservation. The objective was to evaluate the effect of two culture media on population growth (PG) and post-thawing viability (PTV) of three microalgal species (Chlorella sp., Desmodesmus sp., and Ankistrodesmus sp.). The PG and PTV were evaluated for F/2 Guillard and Nutrifoliar® culture media. Instantaneous growth rate (K), doubling time (dt), yield (y), and maximum density (md) were evaluated for PG in both culture media. For VCP, 5 and 10 % methanol was used in six treatments. The PTV was classified as no cell damage (NCD), cell damage (CD), and marked lesions (ML). Population growth did not differ among microalgae (p >0.05). T1 resulted in the lowest dt for Desmodesmus sp., (p <0.05). T2 showed the highest y and md for the three microalgae (p <0.05). Regarding post-thawing cell viability, the highest NCD for Chlorella sp. at day (d) 0 was similar between T3 and T4, and at d 5 it occurred in T6; for Desmodesmus sp., at d 0 it occurred in T6, and at d 5 it was similar between T6 and T1; for Ankistrodesmus sp., at d 0 and d 5 it occurred in T3. It is concluded that the culture medium Nutrifoliar®, is a viable alternative and of low cost for the culture and the cryopreservation of microalgae of fresh water.
The aim of this work was to compare the effect of solventsin the UAE on the content of total phenolic compounds (TPC) andin vitroantioxidant capacity DPPH and reducing power (RP) of the whole ...fruitB.alicastrum. The phenolic compounds of the freeze-dried fruit were extractedin an ultrasonic bath for 30 min at 30°C, 100% amplitude and 40 kHzfrequency. The solvents used were: ethanol (Et-OH), methanol (Met-OH),50% ethanol (50% Et-OH) and 50% methanol (50% Met-OH). The UAE ofphenolic compounds of the fruit was improved by adding distilled water tothe organic solvent. The highest TPC content and antioxidant capacity wereobtained with 50% Met-OH. There was a high positive correlation betweenTPC and antioxidant capacity (DPPH and PR). It is suggested to use 50%Met-OH as solvent for UAE of phenolic compounds of fruitB. alicastrum.
El trabajo tuvo como objetivo comparar el efecto de disol-ventes en la EAU sobre el contenido de compuestos fenólicos totales(CFT) y capacidad antioxidantein vitroDPPH y poder reductor (PR) delfruto completoB. alicastrum. Los compuestos fenólicos del fruto liofilizadofueron extraídos en un baño de ultrasonidos durante 30 min a 30°C, 100%de amplitud y 40 kHz de frecuencia. Los disolventes utilizados fueron:etanol (Et-OH), metanol (Met-OH), 50% de etanol (50% Et-OH) y 50% demetanol (50% Met-OH). La EAU de compuestos fenólicos del fruto mejoróadicionando agua destilada al disolvente orgánico. El mayor contenido CFTy la mayor capacidad antioxidante se obtuvieron con 50% Met-OH. Hubouna alta correlación positiva entre CFT y la capacidad antioxidante (DPPHy PR). Se sugiere utilizar 50% Met-OH como disolvente para la EAU decompuestos fenólicos del fruto completoB. alicastrum.
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