RESUMO
The reindustrialization of acetone-butanol-ethanol (ABE) fermentation is hampered by its significant production cost, linked to high product inhibition and low product yield. ABE fermentation can be significantly enhanced by integrating in situ liquid-liquid extraction. In this study, hybrid simulations using Excel® and ASPEN Plus® were performed based on solvent-dependent experimental data (product titer, yield and productivity) to consider the physiological response of the microorganism in specific extractive ABE fermentations, and to quantify the energy requirements and the economic improvement of the overall process. Four scenarios, based on two different solvents (2-butyl-1-octanol, 2B1O, and a vegetable oil, VO) applied in batch or fed-batch operation, were compared with the batch conventional process. Total energy demand decreased in all extractive configurations and the greatest energy savings (61%) were reached with the VO-based fed-batch operation. However, the highest profit increase was achieved with 2B1O in fed-batch mode, reducing the minimum butanol selling price by 29% over the base case, along with 34% savings in raw materials and 80% wastewater reduction. The techno-economical solvent-based comparative evaluation is a useful tool to identify key challenges to be tackled when revisiting ABE extractive fermentation.
Assuntos
Acetona/química , Butanóis/química , Etanol/química , Microbiologia Industrial/economia , Solventes/química , Poluentes Químicos da Água/análise , 1-Butanol , Reatores Biológicos , Biotecnologia , Fermentação , Microbiologia Industrial/métodos , Extração Líquido-Líquido , Software , Águas Residuárias , Purificação da Água/métodosRESUMO
In the EU, chemicals with a production or import volume in quantities of one metric ton per year or more have to be tested for skin sensitizing properties under the REACH regulation. The murine Local Lymph Node Assay (LLNA) and its modifications are widely used to fulfil the data requirement, as it is currently considered the first-choice method for in vivo testing to cover this endpoint. This manuscript describes a case study highlighting the importance of understanding the chemistry of the test material during testing for 'skin sensitization' of MCDA (mixture of 2,4- and 2,6-diamino-methylcyclohexane) with particular focus on the vehicle used. While the BrdU-ELISA modification of the LLNA using acetone/olive oil (AOO) as vehicle revealed expectable positive results. However, the concentration control analysis unexpectedly revealed an instability of MCDA in the vehicle AOO. Further studies on the reactivity showed MCDA to rapidly react with AOO under formation of various imine structures, which might have caused the positive LLNA result. The repetition of the LLNA using propylene glycol (PG) as vehicle did not confirm the positive results of the LLNA using AOO. Finally, a classification of MCDA as skin sensitizer according to the Globally Harmonized System (GHS) was not justified.
Assuntos
Alérgenos , Cicloexilaminas , Excipientes/química , Haptenos , Acetona/química , Alérgenos/química , Alérgenos/classificação , Alérgenos/toxicidade , Animais , Cicloexilaminas/química , Cicloexilaminas/classificação , Cicloexilaminas/toxicidade , Dermatite Alérgica de Contato , Feminino , Haptenos/química , Haptenos/classificação , Haptenos/toxicidade , Ensaio Local de Linfonodo , Camundongos Endogâmicos CBA , Azeite de Oliva/química , Propilenoglicol/química , Sensibilidade e EspecificidadeRESUMO
Gastrointestinal nematodes are compromising productivity of grazing sheep and goats. Therefore, scientists have been looking for cost-effective alternative options. Forage legumes (Fabacea Family) contain tannins that could improve livestock performance and their health as well. The present study aimed to (i) determine the in vitro anthelmintic (AH) activity of 19 acetonic extracts of Hedysarum carnosum Desf on Haemonchus contortus by a larval exsheathment assay (LEA); (ii) test the anthelmintic activity of condensed tannins using a deactivating reagent, polyvinylpolypyrrolidone (PVPP); (iii) study the effect of location and the phenological stage on the percentage of exsheathment. The LEA was used at different concentrations (150, 300, 600, 1200 µg mL-1 of acetonic extract/mL of purified buffer solution (PBS)). The larval exsheathment is concentration, location, phenological stage dependent. All extracts, caused a delay of the percentage of exsheathment over 50% so the AH activity of H. carnosum was confirmed. After addition of PVPP, the % exsheathment was similar to the 150 µg mL-1 concentration. The biplot showed that Loc1(S), Loc4(B), Loc 5(PF), Loc 6(BM) and Loc 6(PF) were isolated from other plant extract sample. Our in vitro study showed that H. carnosum seems to be a promising alternative to AH drugs.
Assuntos
Fabaceae/química , Haemonchus/efeitos dos fármacos , Extratos Vegetais/farmacologia , Acetona/química , Animais , Anti-Helmínticos/isolamento & purificação , Anti-Helmínticos/farmacologia , Larva/efeitos dos fármacos , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Povidona/análogos & derivados , Povidona/farmacologia , TunísiaRESUMO
BACKGROUND: The anthocyanin and tannin concentration and composition of Vitis vinifera L. cv. Sangiovese berries were investigated from post-veraison to harvest. Exhaustive extraction with methanol and acetone was performed to determine the total flavonoid concentration, while a model hydroalcoholic solution was used to prepare extracts representing the winemaking process. The aim of this study was to improve the knowledge of the phenolic maturity of Sangiovese grape. RESULTS: The total anthocyanin concentration increased during ripening, but the quantity of extractable anthocyanins increased more rapidly than the total. The total skin tannin concentration declined from post-veraison to harvest, whereas the extractable portion increased, with little difference in the composition of the fractions. Both the total and extractable seed tannin concentration diminished rapidly just after veraison, and only small fluctuations were detected until harvest. CONCLUSION: These results indicate that the extractability of anthocyanins and skin tannins increases during ripening, whereas there is no clear trend for seed tannins during the same period. This is the first survey to study the behavior of phenolic compounds during different steps of ripening of Sangiovese grape. © 2016 Society of Chemical Industry.
Assuntos
Produtos Agrícolas/química , Flavonoides/análise , Frutas/química , Epiderme Vegetal/química , Sementes/química , Vitis/química , Acetona/química , Produção Agrícola , Produtos Agrícolas/crescimento & desenvolvimento , Produtos Agrícolas/metabolismo , Flavonoides/biossíntese , Flavonoides/economia , Flavonoides/isolamento & purificação , Indústria de Processamento de Alimentos/economia , Frutas/crescimento & desenvolvimento , Frutas/metabolismo , Concentração de Íons de Hidrogênio , Resíduos Industriais/análise , Resíduos Industriais/economia , Itália , Metanol/química , Epiderme Vegetal/crescimento & desenvolvimento , Epiderme Vegetal/metabolismo , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Estações do Ano , Sementes/crescimento & desenvolvimento , Sementes/metabolismo , Solubilidade , Solventes/química , Taninos/análise , Taninos/biossíntese , Taninos/isolamento & purificação , Vitis/crescimento & desenvolvimento , Vitis/metabolismo , Vinho/análiseRESUMO
BACKGROUND: Banana is grown worldwide and consumed as ripe fruit or used for culinary purposes. Peels form about 18-33% of the whole fruit and are discarded as a waste product. With a view to exploiting banana peel as a source of valuable compounds, this study was undertaken to evaluate the effect of different extraction parameters on the antioxidant activities of the industrial by-product of banana waste (peel). METHODS: Influence of different extraction parameters such as types of solvent, percentages of solvent, and extraction times on total phenolic content (TPC) and antioxidant activity of mature and green peels of Pisang Abu (PA), Pisang Berangan (PB), and Pisang Mas (PM) were investigated. The best extraction parameters were initially selected based on different percentages of ethanol (0-100% v/v), extraction time (1-5 hr), and extraction temperature (25-60°C) for extraction of antioxidants in the banana peels. Total phenolic content (TPC) was evaluated using Folin-Ciocalteu reagent assay while antioxidant activities (AA) of banana peel were accessed by DPPH, ABTS, and ß-carotene bleaching (BCB) assays at optimum extraction conditions. RESULTS: Based on different extraction solvents and percentages of solvents used, 70% and 90% of acetone had yielded the highest TPC for the mature and green PA peels, respectively; 90% of ethanol and methanol has yielded the highest TPC for the mature and green PB peels, respectively; while 90% ethanol for the mature and green PM peels. Similar extraction conditions were found for the antioxidant activities for the banana peel assessed using DPPH assay except for green PB peel, which 70% methanol had contributed to the highest AA. Highest TPC and AA were obtained by applying 4, 1, and 2 hrs extraction for the peels of PA, PB and PM, respectively. The best extraction conditions were also used for determination of AAs using ABTS and ß-carotene bleaching assays. Therefore, the best extraction conditions used have given the highest TPC and AAs. CONCLUSIONS: By-products of banana (peel) can be considered as a potential source of antioxidants in food and pharmaceutical industry.
Assuntos
Antioxidantes/isolamento & purificação , Produtos Agrícolas/química , Frutas/química , Resíduos Industriais/análise , Musa/química , Extratos Vegetais/isolamento & purificação , Solventes/química , Acetona/química , Antioxidantes/química , Produtos Agrícolas/economia , Produtos Agrícolas/crescimento & desenvolvimento , Etanol/química , Aditivos Alimentares/química , Aditivos Alimentares/economia , Aditivos Alimentares/isolamento & purificação , Indústria de Processamento de Alimentos/economia , Frutas/economia , Frutas/crescimento & desenvolvimento , Temperatura Alta , Resíduos Industriais/economia , Malásia , Metanol/química , Musa/crescimento & desenvolvimento , Fenóis/análise , Fenóis/química , Fenóis/economia , Fenóis/isolamento & purificação , Extratos Vegetais/química , Fatores de TempoRESUMO
The distribution behaviors of metals in bio-oils derived from sewage sludge (SS) by liquefaction with different solvents (ethanol, methanol, or acetone) and by pyrolysis at different temperatures (550-850 °C) were investigated. The concentrations of crust metals (K, Na, Ca, Mg, Fe, and Al) in bio-oils were much higher than those of the anthropogenic metals (Cu, Zn, Pb, Cd, Cr, Ni, V, Mn, Ba, Co, Ti, Sn, As, and Hg), but the anthropogenic metals were more inclined to distribute in bio-oil phase compared with crust metals. The anthropogenic metals in bio-oils can be divided in three groups in terms of the distribution similarities according to Cluster analysis: (A) Cu, Co, Ni, V, and Sn; (B) Cr, Ti, Mn, and Ba; (C) Pb, Cd, As, Hg, and Zn. Cu, Cr, Hg, Cd, V, Co, and Sn distributed in the liquefaction/pyrolysis bio-oils accounted for as high as 5-20% of the metals in SS and were evaluated "moderate enrichment" by the enrichment factors method. According to the potential ecological risk index (PERI) method, Hg presented very high risk, Cu presented moderate risk, and Cd presented low to moderate risk; and the overall risk levels of these bio-oils were very high risk (except P550, presented considerable risk).
Assuntos
Metais/análise , Óleos/análise , Esgotos/química , Acetona/química , Etanol/química , Mercúrio , Metais Pesados , Metanol/química , Óleos/química , Medição de Risco , Solventes/químicaRESUMO
The coherence between occupational exposure limits (OELs) and their corresponding biological limit values (BLVs) was evaluated for 2-propanol and acetone. A generic human PBPK model was used to predict internal concentrations after inhalation exposure at the level of the OEL. The fraction of workers with predicted internal concentrations lower than the BLV, i.e. the 'false negatives', was taken as a measure for incoherence. The impact of variability and uncertainty in input parameters was separated by means of nested Monte Carlo simulation. Depending on the exposure scenario considered, the median fraction of the population for which the limit values were incoherent ranged from 2% to 45%. Parameter importance analysis showed that body weight was the main factor contributing to interindividual variability in blood and urine concentrations and that the metabolic parameters Vmax and Km were the most important sources of uncertainty. This study demonstrates that the OELs and BLVs for 2-propanol and acetone are not fully coherent, i.e. enforcement of BLVs may result in OELs being violated. In order to assess the acceptability of this "incoherence", a maximum population fraction at risk of exceeding the OEL should be specified as well as a minimum level of certainty in predicting this fraction.
Assuntos
2-Propanol/efeitos adversos , 2-Propanol/química , Acetona/efeitos adversos , Acetona/química , Exposição por Inalação/análise , Exposição Ocupacional/análise , Administração por Inalação , Peso Corporal/efeitos dos fármacos , Humanos , Modelos Biológicos , Método de Monte Carlo , Níveis Máximos Permitidos , IncertezaRESUMO
Acetone was investigated and found to be an appropriate alternative to Triton X-100 as a solvent of essential oils in bioassays aimed to investigate their effects on pinewood nematode (Bursaphelenchus xylophilus) mortality. Therefore it was used as dilution agent to screen the effectiveness of fifty two essential oils against this pest. Thirteen essential oils were highly effective, resulting in more than 90% pinewood nematode mortality at 2 mg/mL, with six of them resulting in 100% mortality. LC100 values ranged between 0.50 mg/mL and 0.83 mg/mL for the essential oils of Origanum vulgare and Satureja montana, respectively. Essential oils were submitted to gas chromatography and gas chromatography-mass spectrometry analysis and their chemical composition established. Data from essential oils with 100% mortality at 2 mg/mL and other essential oils previously found to have LC100 ≤ 2 mg/mL was combined, their chemical profiles investigated by correspondences analysis plus automatic classification.
Assuntos
Antinematódeos/farmacologia , Nematoides/efeitos dos fármacos , Óleos Voláteis/farmacologia , Testes de Toxicidade/métodos , Acetona/química , Animais , Antinematódeos/química , Octoxinol/química , Óleos Voláteis/química , Origanum/química , Testes de Sensibilidade Parasitária/métodos , Óleos de Plantas/química , Óleos de Plantas/farmacologia , Satureja/química , Solventes/químicaRESUMO
UNLABELLED: Mango biowastes, obtained after processing, contain large amounts of compounds with antioxidant activity that can be reused to reduce their environmental impact. The present study evaluates the effect of solvent (methanol, ethanol, acetone, water, methanol:water [1:1], ethanol:water [1:1], and acetone:water [1:1]), and temperature (25, 50, and 75 °C) on the efficiency of the extraction of antioxidants from mango peel and seed. Among the factors optimized, extraction solvent was the most important. The solvents that best obtained extracts with high antioxidant capacity were methanol, methanol:water, ethanol:water, and acetone:water (ß-carotene test, antioxidant activity coefficient 173 to 926; thiobarbituric acid reactive substances test, inhibition ratio 15% to 89%; 2,2'-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid ABTS(·+); and 2,2-diphenyl-1-picrylhydrazyl DPPH· scavenging, 7 to 22 and 8 to 28 g trolox equivalent antioxidant capacity [TE] per 100 g mango biowaste on a dry matter basis [DW]). Similarly, the flavonoid (0.21 to 1.4 g (+)-catechin equivalents per 100 g DW), tannin (3.8 to 14 g tannic acid equivalents per 100 g DW), and proanthocyanidin (0.23 to 7.8 g leucoanthocyanidin equivalents per 100 g DW) content was highest in the peel extracts obtained with methanol, ethanol:water, or acetone:water and in the seed extracts obtained with methanol or acetone:water. From the perspective of food security, it is advisable to choose ethanol (which also has a notable antioxidant content), ethanol:water, or acetone:water, as they are all solvents that can be used in compliance with good manufacturing practice. In general, increasing temperature improves the capacity of the extracts obtained from mango peel and seed to inhibit lipid peroxidation; however, its effect on the extraction of phytochemical compounds or on the capacity of the extracts to scavenge free radicals was negligible in comparison to that of the solvent. PRACTICAL APPLICATION: There are many antioxidant compounds in mango peel and seed, and they could be used as a natural and very inexpensive alternative to synthetic food additives. However, the conditions in which the antioxidants are extracted must be optimized. This work proves that conditions such as extraction solvent or temperature have a crucial impact on obtaining extracts rich in antioxidants from mango biowastes.
Assuntos
Antioxidantes/química , Frutas/química , Resíduos Industriais/análise , Mangifera/química , Extratos Vegetais/química , Sementes/química , Solventes/química , Acetona/química , Antioxidantes/análise , Antioxidantes/economia , Antioxidantes/isolamento & purificação , Etanol/química , Flavonoides/análise , Flavonoides/química , Flavonoides/economia , Flavonoides/isolamento & purificação , Indústria de Processamento de Alimentos/economia , Temperatura Alta , Resíduos Industriais/economia , Extratos Vegetais/economia , Extratos Vegetais/isolamento & purificação , Proantocianidinas/análise , Proantocianidinas/química , Proantocianidinas/economia , Proantocianidinas/isolamento & purificação , Taninos/análise , Taninos/química , Taninos/economia , Taninos/isolamento & purificação , Substâncias Reativas com Ácido Tiobarbitúrico/análise , Água/químicaRESUMO
Large-scale nuclear magnetic resonance (NMR) tube cleaning is currently a bottleneck in high-throughput NMR ligand affinity screens. Expensive alternatives include discarding the NMR tubes after a single use (~US $2-$8/tube), using commercial NMR tube cleaners (~$15,000), and abandoning NMR tubes for flow probe technology (~$75,000). Instead, we describe a relatively inexpensive (~$400) and easily constructed apparatus that can clean 180 NMR tubes per hour while using a modest amount of solvent. The application of this apparatus significantly shortens the time to recycle NMR tubes while avoiding cross-contamination and tube damage.
Assuntos
Espectroscopia de Ressonância Magnética/instrumentação , Reciclagem/métodos , Solventes/química , Acetona/química , Espectroscopia de Ressonância Magnética/economia , Metanol/química , Ácido Nítrico/química , Reciclagem/economia , Bicarbonato de Sódio/química , Água/químicaRESUMO
A novel environmentally friendly solution-based method for preparing dispersed silver particles is described. The simple and convenient approach consists in heating silver oxide particles dispersed in a highly alkaline water/acetone mixture. The data presented clearly show that acetone reduces completely and rapidly Ag(2)O particles to metallic silver at 60°C. A mechanism explaining the provenance of the electrons responsible for the reduction of silver is proposed.
Assuntos
Acetona/química , Precipitação Química , Química Verde/métodos , Substâncias Redutoras/química , Prata/química , Química Verde/economia , Calefação , Oxirredução , Óxidos/química , Compostos de Prata/químicaRESUMO
Sample preparation is one of the major issues in 2-DE for the separation of proteins. Although a 100% representation of cellular proteins onto a 2-DE is virtually impossible, maximum representation of cellular proteins compared with the original cell lysate is important in the subsequent analysis. We demonstrate that lysis of cells in urea/thiourea solution with subsequent sonication to disrupt the nucleic acids and concentration of the lysate using centri-con led to enrichment of proteins. The procedure resulted in minimal nucleic acid contamination with better resolution of spots. 2-DE spot patterns of proteins prepared using urea-thiourea solubilization/centri-con method to other protein enrichment methods such as phenol/chloroform/isoamyl alcohol extraction, methanol/ammonium acetate precipitation, acetone precipitation and ethanol precipitation were compared. Urea-thiourea solubilization combined with centri-con method of protein enrichment represented higher number/unique spots particularly in the 50-250 kDa M(r) compared with others. Lysis of cells in urea/thiourea from the beginning of lysate preparation preserves the proteins from protease activity due to denaturation of proteases. Thus, we demonstrate that the centri-con methodology is simple and effective for the preparation of high-quality sample that can be used for a qualitative representation of cellular proteins on a 2-DE for proteomic analysis.
Assuntos
Eletroforese em Gel Bidimensional/métodos , Proteínas/isolamento & purificação , Proteômica/métodos , Acetona/química , Linhagem Celular , Precipitação Química , Eletroforese em Gel Bidimensional/economia , Etanol/química , Humanos , Proteômica/economia , Tioureia/química , Ureia/químicaRESUMO
Acetonitrile as a solvent used in liquid chromatography/mass spectrometry (LC/MS) of peptides and proteins is a relatively toxic solvent (LD50 oral; rat; 2,460 mg/kg) compared to alternatives like methanol (LD50 oral; rat; 5,628 mg/kg) and acetone (LD50 oral; rat; 5,800 mg/kg). Strategies to minimize its consumption in LC are either to reduce the inner diameter of the column or replace acetonitrile with a suitable alternative. Methanol is often recommended to replace acetonitrile in peptide analysis. In this study however, the main focus lies on another alternative solvent for LC/MS of peptides; acetone. A number of model proteins were tryptically digested and the peptide solutions were analyzed on a linear trap quadrupole (LTQ) mass spectrometer. The performances of acetonitrile, methanol and acetone were compared according to the quality of the chromatograms obtained and identification of the peptides using the BioWorks software developed by Thermo Scientific. In accordance to the elutropic series, acetone was found to significantly reduce the retention times of peptides separated by C18 column material with regard to acetonitrile while methanol led to increased retention times. Acetone was the superior solvent to methanol for most of the tested model proteins reaching similar sequence coverage and numbers of identified peptides as acetonitrile. We therefore propose acetone as an alternative to acetonitrile in LC/MS of peptides.
Assuntos
Acetona/química , Acetonitrilas/química , Cromatografia Líquida/métodos , Espectrometria de Massas/métodos , Peptídeos/química , Animais , Bovinos , Cromatografia Líquida/instrumentação , Cavalos , Espectrometria de Massas/instrumentaçãoRESUMO
Solvents should be properly evaporated after application to dental substrates. The aim of this study was to assess the evaporation of commercial, experimental and neat solvents. The tested null hypotheses were that there are no differences in solvent evaporation regardless of its formulation and over time. Evaporation from commercial adhesive systems (Scotchbond Multipurpose Primer, Scotchbond Multipurpose Adhesive, Prime & Bond NT, Multi Bond, Excite, Single Bond 2, Adhese Primer, Adhese Bond, Xeno III A and Xeno III B) and experimental primers (35% HEMA plus 65% acetone or ethanol or water v/v) were compared to neat solvents (acetone, ethanol and water). Samples (10 microL) of these products were dripped into glass containers placed on a digital precision balance. Evaporation was assessed at 0, 5, 10, 15, 30, 60, 120, 300 and 600 s times to calculate mass loss. Data were analyzed statistically by ANOVA and Bonferroni's correction (a=0.05). Acetone-based products exhibited a remarkable capacity to evaporate spontaneously over time. Neat acetone evaporated significantly more than the HEMA-mixtures and the commercial formulations (p<0.05). The incorporation of monomers and other ingredients in the commercial formulations seem to reduce the evaporation capacity. Solvent evaporation was time and material-dependent.
Assuntos
Adesivos Dentinários/química , Cimentos de Resina/química , Solventes/química , Acetona/química , Etanol/química , Teste de Materiais , Fatores de Tempo , Volatilização , Água/químicaRESUMO
The objective of the present study was to screen various solvent extracts of Polyalthia longifolia var. pendula (Annonaceae) leaf for anti-inflammatory activity and to evaluate the anti-inflammatory and hepatoprotective potency of the potent solvent extract. Successive extraction was performed with six different solvents, viz. petroleum ether, hexane, toluene, chloroform, acetone and methanol. Toluene, chloroform, acetone and methanol were used in acute inflammatory studies; the results revealed methanol as most potent extract. Hence three concentrations of methanolic extract (300, 600, 900 mg/kg) were used to evaluate its potential as an anti-inflammatory and hepatoprotective agent. Diclofenac sodium was used as the toxicant in hepatoprotective studies, in which various serum biochemical parameters and liver glycogen were assessed. The three concentrations of methanol showed anti-inflammatory activity comparable to that of the control (Diclofenac sodium). All the serum biochemical parameters studied revealed the hepatoprotective nature of the methanol extract, but a concentration effect was not observed. The results indicated that the methanolic extract of Polyalthia longifolia var. pendula leaf possesses significant anti-inflammatory and hepatoprotective activity. However, the appropriate effective concentration needs to be determined.
Assuntos
Anti-Inflamatórios/farmacologia , Hepatopatias/prevenção & controle , Extratos Vegetais/farmacologia , Folhas de Planta/química , Polyalthia/química , Acetona/química , Alanina Transaminase/sangue , Animais , Anti-Inflamatórios/química , Anti-Inflamatórios/isolamento & purificação , Aspartato Aminotransferases/sangue , Doença Hepática Induzida por Substâncias e Drogas , Clorofórmio/química , Diclofenaco , Relação Dose-Resposta a Droga , Feminino , Glicogênio/metabolismo , Hexanos/química , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Hepatopatias/sangue , Masculino , Metanol/química , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Ratos , Ratos Wistar , Tolueno/químicaRESUMO
Solvents should be properly evaporated after application to dental substrates. The aim of this study was to assess the evaporation of commercial, experimental and neat solvents. The tested null hypotheses were that there are no differences in solvent evaporation regardless of its formulation and over time. Evaporation from commercial adhesive systems (Scotchbond Multipurpose Primer, Scotchbond Multipurpose Adhesive, Prime & Bond NT, Multi Bond, Excite, Single Bond 2, Adhese Primer, Adhese Bond, Xeno III A and Xeno III B) and experimental primers (35 percent HEMA plus 65 percent acetone or ethanol or water v/v) were compared to neat solvents (acetone, ethanol and water). Samples (10 µL) of these products were dripped into glass containers placed on a digital precision balance. Evaporation was assessed at 0, 5, 10, 15, 30, 60, 120, 300 and 600 s times to calculate mass loss. Data were analyzed statistically by ANOVA and Bonferroni's correction (a=0.05). Acetone-based products exhibited a remarkable capacity to evaporate spontaneously over time. Neat acetone evaporated significantly more than the HEMA-mixtures and the commercial formulations (p<0.05). The incorporation of monomers and other ingredients in the commercial formulations seem to reduce the evaporation capacity. Solvent evaporation was time and material-dependent.
O solvente deve ser adequadamente evaporado após aplicação ao substratos dentários. O objetivo deste estudo foi avaliar a evaporação de formulações comerciais, primers experimentais e solventes puros. As hipóteses nulas testadas foram de que não há diferenças da quantidade evaporada independentemente do material e tempo. Evaporação dos sistemas adesivos comerciais (Scotchbond multipurpose primer, Scotchbond multipurpose adhesive, Prime & Bond NT, Multi Bond, Excite, Single Bond 2, Adhese Primer, Adhese Bond, Xeno III A e Xeno III B) e primers experimentais (35 por cento HEMA associado com 65 por cento acetona, etanol ou água v/v) foram comparadas a solventes puros (acetona, etanol e água). Amostras (10 µL) de cada produto foram dispensadas em balança de precisão digital. As massas nos tempos 0, 5, 10, 15, 30, 60, 120, 300 e 600 s foram registradas. Os dados foram analisados estatisticamente por ANOVA e Bonferroni (a=0,05). Produtos a base de acetona exibiram maior capacidade de evaporação espontânea ao longo do tempo. Acetona pura evaporou significantemente mais que as misturas de HEMA e formulações comerciais (p<0,05). A incorporação de monômeros e outros ingredientes nas formulações comerciais reduzem a capacidade de evaporação. A evaporação é dependente do produto e do tempo.
Assuntos
Adesivos Dentinários/química , Cimentos de Resina/química , Solventes/química , Acetona/química , Etanol/química , Teste de Materiais , Fatores de Tempo , Volatilização , Água/químicaRESUMO
We present a symmetry-reduced version of the dielectrically-consistent reference interaction site model (DRISM) equation and an adaptation of the Labík-Malijevský-Vonka hybrid algorithm for its numerical solution. This approach is used for the calculation of site-site correlation functions of water, acetone and a water-acetone mixture. Compared to the traditional Picard iteration of non-reduced DRISM theories, savings of more than 90% in computational time are obtained. The resulting site-site pair-correlation functions are in reasonable agreement with computer simulations.
Assuntos
Algoritmos , Simulação por Computador , Modelos Químicos , Método de Monte Carlo , Acetona/química , Fatores de Tempo , Água/químicaRESUMO
Removal of polycyclic aromatic hydrocarbons (PAHs) from petrochemical wastewater was investigated using various low-cost adsorbents of natural origin including sugar cane bagasse, green coconut shells, chitin, and chitosan. Adsorption experiments of mixtures of PAHs (5.0-15.0 mg/L) have been carried out at ambient temperature (28+/-2 degrees C) and pH 7.5. The adsorption isotherms of PAHs were in agreement with a Freundlich model, while the uptake capacity of PAHs followed the order: green coconut shells>sugar cane bagasse>chitin>chitosan. The adsorption properties of green coconut shells were comparable to those of some conventional adsorbents such as Amberlite T. The partition coefficients in acetone:water, the adsorption constants at equilibrium, and the molecular masses of the PAHs could be linearly correlated with octanol-water partition coefficients.
Assuntos
Hidrocarbonetos Policíclicos Aromáticos/isolamento & purificação , Poluentes do Solo/análise , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/métodos , Acetona/química , Adsorção , Quitina/química , Cocos/metabolismo , Recuperação e Remediação Ambiental , Concentração de Íons de Hidrogênio , Modelos Estatísticos , Peso Molecular , Hidrocarbonetos Policíclicos Aromáticos/análise , Temperatura , Água/química , Poluentes Químicos da Água/isolamento & purificaçãoRESUMO
Since advances in the ABE (acetone-butanol-ethanol) fermentation process in recent years have led to significant increases in its productivity and yields, the production of butanol and its use in motor vehicles have become an option worth evaluating. This study estimates the potential life-cycle energy and emission effects associated with using bio-butanol as a transportation fuel. It employs a well-to-wheels (WTW) analysis tool: the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model. The estimates of life-cycle energy use and greenhouse gas (GHG) emissions are based on an Aspen Plus(R) simulation for a corn-to-butanol production process, which describes grain processing, fermentation, and product separation. Bio-butanol-related WTW activities include corn farming, corn transportation, butanol production, butanol transportation, and vehicle operation. In this study, we also analyzed the bio-acetone that is coproduced with bio-butanol as an alternative to petroleum-based acetone. We then compared the results for bio-butanol with those of conventional gasoline. Our study shows that driving vehicles fueled with corn-based butanol produced by the current ABE fermentation process could result in substantial fossil energy savings (39%-56%) and avoid large percentage of the GHG emission burden, yielding a 32%-48% reduction relative to using conventional gasoline. On energy basis, a bushel of corn produces less liquid fuel from the ABE process than that from the corn ethanol dry mill process. The coproduction of a significant portion of acetone from the current ABE fermentation presents a challenge. A market analysis of acetone, as well as research and development on robust alternative technologies and processes that minimize acetone while increase the butanol yield, should be conducted.
Assuntos
Fontes de Energia Bioelétrica , Butanóis/análise , Butanóis/química , Efeito Estufa , Zea mays/química , Acetona/análise , Acetona/química , Veículos AutomotoresRESUMO
OBJECTIVE: To access the capability of 1H nuclear magnetic resonance (NMR) -based metabonomics in the evaluation of graft function in the perioperation period of liver transplantation. METHODS: Plasma samples of 15 male primary hepatic carcinoma patients were collected for clinical biochemical analysis and 1H NMR spectroscopy 1 day before operation, 1 day and 1 week after the operation. The NMR data were analyzed using principal component analysis. RESULTS: Metabonomic analysis indicated that, compared with those before operation, blood concentrations of valine, alanine, acetone, succinic acid, glutamine, choline, lactate, and glucose increased significantly 1 day after transplantation. One week later, the levels of lipids and choline increased notably, while those of glucose and amino acids decreased. Principal component analysis showed significant difference between metabolic profiles of plasma samples of variant periods of liver transplantation, due to the variation of the levels of glucose, lipids, lactate, and choline. A good agreement was observed between clinical chemistry and metabonomic data. CONCLUSIONS: Metabonomic analysis can clearly identify the difference between the plasma samples of primary hepatic carcinoma patients at different time during the perioperation period of liver transplantation. It therefore may be a promising new technology in predicting the outcomes of liver transplantation.