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1.
Molecules ; 29(5)2024 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-38474449

RESUMO

In this work, a novel sustainable approach was proposed for the integral valorisation of Arctium lappa (burdock) seeds and roots. Firstly, a preliminary recovery of bioactive compounds, including unsaturated fatty acids, was performed. Then, simple sugars (i.e., fructose and sucrose) and phenolic compounds were extracted by using compressed fluids (supercritical CO2 and propane). Consequently, a complete characterisation of raw biomass and extraction residues was carried out to determine the starting chemical composition in terms of residual lipids, proteins, hemicellulose, cellulose, lignin, and ash content. Subsequently, three alternative ways to utilise extraction residues were proposed and successfully tested: (i) enzymatic hydrolysis operated by Cellulases (Thricoderma resei) of raw and residual biomass to glucose, (ii) direct ethanolysis to produce ethyl levulinate; and (iii) pyrolysis to obtain biochar to be used as supports for the synthesis of sulfonated magnetic iron-carbon catalysts (Fe-SMCC) to be applied in the dehydration of fructose for the synthesis of 5-hydroxymethylfurfural (5-HMF). The development of these advanced approaches enabled the full utilisation of this resource through the production of fine chemicals and value-added compounds in line with the principles of the circular economy.


Assuntos
Arctium , Arctium/química , Lignina/química , Extratos Vegetais/química , Celulose , Frutose
2.
J Sci Med Sport ; 27(3): 172-178, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38218663

RESUMO

OBJECTIVES: This study investigated relationships between isometric trunk and hip extensor strength, lumbar muscle morphology, and the risk of hamstring and knee ligament injuries in Australian Football League and National Rugby League players. DESIGN: Prospective cohort study. METHODS: Trunk and hip extensor strength, multifidus and quadratus lumborum cross-sectional area were measured during the 2020 pre-season. Logistic regressions and decision trees were employed to explore associations between maximum strength, strength endurance, multifidus and quadratus lumborum cross-sectional area, age, previous injuries, and hamstring and knee ligament injury risk. RESULTS: Greater strength endurance [odds ratio = 0.42 (0.23-0.74), p = 0.004] and maximum strength [odds ratio = 0.55 (0.31-0.94), p = 0.039] reduced hamstring injury risk. Increased risk of knee ligament injuries was associated with larger multifidus [odds ratio = 1.66 (1.14-2.45), p = 0.008] and higher multifidus to quadratus lumborum ratio (odds ratio = 1.57 (1.13-2.23), p = 0.008]. Decision tree models indicated that low strength endurance (< 99 Nm) characterised hamstring strains, while high (≥ 1.33) multifidus to quadratus lumborum ratio mitigated risk. Knee ligament injuries were associated with larger (≥ 8.49 cm2) multifidus, greater (≥ 1.25) multifidus to quadratus lumborum ratio, and lower maximum strength (< 9.24 N/kg). CONCLUSIONS: Players with lower trunk and hip extensor maximum strength and strength endurance had increased risk of hamstring injuries, while knee ligament injury risk was elevated with larger multifidus cross-sectional area, higher multifidus to quadratus lumborum ratio, and lower maximum trunk and hip extensor strength.


Assuntos
Traumatismos em Atletas , Músculos Isquiossurais , Traumatismos do Joelho , Traumatismos da Perna , Humanos , Austrália , Estudos Prospectivos , Rugby , Traumatismos em Atletas/epidemiologia , Força Muscular , Músculos Paraespinais/fisiologia
3.
ACS Omega ; 8(22): 19374-19384, 2023 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-37305320

RESUMO

The conversion of ethanol into petrochemicals, such as ethyl and butyl acetate, butanol, hexanol, and so forth was studied. The conversion was catalyzed by Mg-Fe mixed oxide modified with a second transition metal (Ni, Cu, Co, Mn, or Cr). The main aim was to describe the influence of second transition metal on (i) the catalyst itself and (ii) reaction products such as ethyl acetate, butanol, hexanol, acetone, and ethanal. Moreover, the results were compared with the results of pure Mg-Fe. The reaction was carried out in the gas phase in a flow reactor with a weight hour space velocity of 4.5 h-1 for 32 h at three reaction temperatures (280, 300, and 350 °C). The metals Ni and Cu in Mg-Fe oxide enhanced the ethanol conversion due to the population of active dehydrogenation sites. Despite the lower acido-basicity, Cu, Co, and Ni supported the yield of ethyl acetate, and Cu and Ni also promoted the yield of higher alcohols. Ni was related to the extent of the gasification reactions. Moreover, long-term stability (by leaching of metals) test was carried out for all catalysts (128 h).

4.
Molecules ; 28(6)2023 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-36985791

RESUMO

The paper is focused on the epoxidation of methyl esters prepared from oil crops with various profiles of higher fatty acids, especially unsaturated, which are mainly contained in the non-edible linseed and Camelina sativa oil (second generation). The novelty consists in the separation and identification of all products with oxirane ring formed through a reaction and in the determination of time course. Through the epoxidation, many intermediates and final products were formed, i.e., epoxides with different number and/or different position of oxirane rings in carbon chain. For the determination, three main methods (infrared spectroscopy, high-pressure liquid chromatography and gas chromatography with mass spectrometry) were applied. Only gas chromatography enables the separation of individual epoxides, which were identified on the base of the mass spectra, molecule ion and time course of products. The determination of intermediates enables: (i) control of the epoxidation process, (ii) determination of the mixture of epoxides in detail and so the calculation of selectivity of each product. Therefore, the epoxidation will be more environmentally friendly especially for advanced applications of non-edible oil crops containing high amounts of unsaturated fatty acids.


Assuntos
Ésteres , Ácidos Graxos Insaturados , Cromatografia Gasosa-Espectrometria de Massas/métodos , Ésteres/análise , Ácidos Graxos Insaturados/química , Ácidos Graxos/química , Compostos de Epóxi/química , Óleos de Plantas/química
5.
Med Sci Sports Exerc ; 54(5): 814-820, 2022 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-34935708

RESUMO

INTRODUCTION: Noncontact lower limb injuries are common within the Australian Football League (AFL) and National Rugby League (NRL). Smaller (<8.5 cm2) lumbar multifidus at the fifth vertebra (LM L5) and larger (>8.2 cm2) quadratus lumborum (QL) cross-sectional area (CSA) have been associated with increased noncontact lower limb injury risk in AFL players. These associations have not been explored in an NRL cohort. This study will attempt to replicate previous research findings by confirming that muscle morphology is associated with noncontact lower limb injury. METHODS: AFL (n = 87) and NRL (n = 151) players underwent LM L2-L5 and QL CSA ultrasound measures during preseason. Each club's medical staff reported all noncontact lower limb injuries sustained in the subsequent regular season. LM and QL CSA, age, body mass index, and noncontact lower limb injuries were analyzed using multivariable logistic regression. RESULTS: Seventy-two players sustained a noncontact lower limb injury in the 2020 regular season (AFL = 21, NRL = 51). The multivariable logistic regression (odds ratio (OR) = 1.36; 95% confidence interval (CI), 1.02-1.85; P = 0.038) identified AFL players with larger QL CSA at increased risk of sustaining a noncontact lower limb injury during the regular season, but no relationship was found for LM CSA and noncontact lower limb injuries in the AFL (OR = 1.01; 95% CI, 0.36-2.78; P = 0.591) or NRL (OR = 0.63; 95% CI, 0.29-1.33; P = 0.149). CONCLUSIONS: AFL players who sustained regular season noncontact lower limb injuries had larger QL CSA in preseason tests. No significant associations between either LM L5 CSA or LM L5 to QL ratio and regular season noncontact lower limb injuries were found.


Assuntos
Traumatismos em Atletas , Traumatismos da Perna , Rugby , Esportes de Equipe , Humanos , Traumatismos em Atletas/diagnóstico por imagem , Austrália , Traumatismos da Perna/diagnóstico por imagem , Extremidade Inferior/diagnóstico por imagem , Extremidade Inferior/lesões
6.
ACS Omega ; 5(49): 32040-32050, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33344858

RESUMO

This paper is focused on the heterogeneously catalyzed transesterification (in a batch reactor) of vegetable oil, including the determination of leached metals. The oil was obtained from the short-season crop Camelina sativa. The reaction was catalyzed by mixed oxides, which were synthesized from Mg/Al hydrotalcites with built-in different types of divalent cations such as Mn, Ca, Co, Ni, and Fe. The various physicochemical properties like the structure by X-ray diffraction, acidity, basicity, and textural properties were measured and the effect of the added cation type on catalyst properties and activity was compared. A noticeable relationship between the cation type and catalytic activity in the transesterification reaction was observed. The highest ester content of 96.6 wt % after 7 h of transesterification was observed for catalysts with nickel and iron. The statistical analysis of results showed that the catalyst activity was mainly influenced by middle-temperature basic sites. The novelty lies in transesterification over five different heterogeneous catalysts-mixed oxides with added divalent metals at the same reaction conditions of C. sativa oil.

7.
J Environ Manage ; 262: 110295, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32250784

RESUMO

The paper describes transesterification of oil by methanol with use of cosolvents such as ethyl acetate, tetrahydrofuran, hexane, acetone and diethyl ether at catalyst homogeneous (potassium hydroxide) and heterogeneous (mixed oxides). The cosolvents dissolve oil and methanol to form a single (homogeneous) phase, which increases the reaction rate. Therefore, the biodiesel production will be environmentally friendly because less energy is consumed, which increases sustainability. The whole binodal curve of ternary plots of oil, methanol and cosolvent was determined to find the molar ratio, in which the reaction mixture forms a single phase. The ethyl acetate and tetrahydrofuran have relatively small heterogeneous region, because of the similarity of their electric dipole moment with methanol. After transesterification, the detailed analysis of ester and also glycerol phase was carried out. For homogeneous catalyst, the highest esters content in the ester phase was achieved with tetrahydrofuran. For heterogeneous catalyst, the ester content was lower with cosolvent than without cosolvent, probably due to dilution of reaction components by cosolvent or bonding of cosolvent to the active sites of the catalyst.


Assuntos
Biocombustíveis , Ésteres , Catálise , Esterificação , Metanol , Óleos de Plantas
8.
J Environ Manage ; 218: 555-561, 2018 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-29709823

RESUMO

Biodiesel is a mixture of esters of fatty acids (most often palmitic, stearic and oleic) and lower alcohols (in our work butanol) produced by transesterification. It is a renewable source of energy, prepared from triacylglycerides, which are contained in vegetable oils and animal fats. This work focuses on alkaline catalyzed transesterification of rapeseed oil with butanol and comparison of two catalysts (potassium hydroxide and potassium tert-butoxide). In industry is usually transesterification of rapeseed oil carried out like reaction catalyzed by potassium hydroxide. Potassium hydroxide have high content of K2CO3, KHCO3 and water. Moreover water is formed by neutralization of potassium hydroxide with free fatty acids contained in oil. In cause of tert-butoxide catalyzed reaction, it is not possible because tert-butoxide have not a OH- aniont, which is needed for water forming. The influence of various conditions (addition of water, temperature of separation, intensity of stirring and type of catalyst) on butanolysis process was studied for both catalysts. For both catalysts dependence of conversions on time were plotted. When tert-butoxide was used, satisfactory phase separation was not achieved. The only way was separation of hot crude reaction mixture without adding water. Ester formed by this method had high content of free glycerol and soaps, but reached higher conversion. The best results were obtained with KOH and subsequent separation of cold crude reaction mixture with the addition of water and slow stirring. The difference between reactions catalyzed by potassium hydroxide and potassium tert-butoxide was described.


Assuntos
Biocombustíveis , Butanóis , Hidróxidos , Compostos de Potássio , Animais , Catálise , Ácidos Graxos Monoinsaturados , Óleos de Plantas , Óleo de Brassica napus
9.
Gait Posture ; 53: 179-184, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28171844

RESUMO

In human motion analysis predictive or functional methods are used to estimate the location of the hip joint centre (HJC). It has been shown that the Harrington regression equations (HRE) and geometric sphere fit (GSF) method are the most accurate predictive and functional methods, respectively. To date, the comparative reliability of both approaches has not been assessed. The aims of this study were to (1) compare the reliability of the HRE and the GSF methods, (2) analyse the impact of the number of thigh markers used in the GSF method on the reliability, (3) evaluate how alterations to the movements that comprise the functional trials impact HJC estimations using the GSF method, and (4) assess the influence of the initial guess in the GSF method on the HJC estimation. Fourteen healthy adults were tested on two occasions using a three-dimensional motion capturing system. Skin surface marker positions were acquired while participants performed quite stance, perturbed and non-perturbed functional trials, and walking trials. Results showed that the HRE were more reliable in locating the HJC than the GSF method. However, comparison of inter-session hip kinematics during gait did not show any significant difference between the approaches. Different initial guesses in the GSF method did not result in significant differences in the final HJC location. The GSF method was sensitive to the functional trial performance and therefore it is important to standardize the functional trial performance to ensure a repeatable estimate of the HJC when using the GSF method.


Assuntos
Articulação do Quadril/fisiologia , Aumento da Imagem , Movimento/fisiologia , Caminhada , Adulto , Fenômenos Biomecânicos , Feminino , Marcha , Articulação do Quadril/diagnóstico por imagem , Humanos , Masculino , Valor Preditivo dos Testes , Amplitude de Movimento Articular , Valores de Referência , Reprodutibilidade dos Testes
10.
Bioresour Technol ; 110: 288-91, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22349194

RESUMO

The effects of phase separation temperatures (5-90°C) on losses of higher fatty acid (C(16) and C(18)) ethyl esters in the glycerol phase were investigated. Losses of ethyl esters produced from ethanolysis of rapeseed oil were 30-60% higher when NaOH rather than KOH was used as homogeneous catalyst. The losses decreased with an increase in separation temperature, resulting in an increase in the yield of the ester phase. The concentration of impurities (e.g. alkali metals, free glycerol and glycerides) in the ester phase increased with increasing separation temperature due reversible transesterification and reciprocal solubility of the compounds. Carbonates formed during neutralization of the catalysts are also transesterification catalysts and they cause reverse reaction. The ethyl ester bound in the glycerol phase during NaOH-mediated catalysis can be extracted by heating the separated glycerol phase to 60-90°C. The ester yield is increasing with increasing separation temperature, however with decreasing quality.


Assuntos
Etanol/química , Hidróxidos/química , Óleos de Plantas/química , Compostos de Potássio/química , Hidróxido de Sódio/química , Temperatura , Catálise , Ésteres , Ácidos Graxos Monoinsaturados , Óleo de Brassica napus
11.
Talanta ; 82(1): 283-5, 2010 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-20685468

RESUMO

In biodiesel production, glycerol is formed as a side product and it is contained in the glycerol phase. This phase contains (besides glycerol): water, soaps, alcohol, traces of catalyst and glycerides and the remaining esters. In this paper, a new method for the determination of esters in the glycerol phase is introduced. The determination enables the minimization of the losses of biodiesel within the production process. It is based on the gradient RP-LC method (water and acetonitrile) with refractometric detection. The analysis is easy and the samples do not need any treatment (only dilution by water) and has a low detection limit. The results of this method were compared with the results of two other published methods: isocratic HPLC and GC. The disadvantage of these two methods is that they need extensive treatment of the sample, which takes many hours, and they are able to determine only the sum of esters. The new method is reliable, much faster and able to differentiate esters of almost each higher fatty acid (e.g. linoleic, linolenic, strearic alkyl ester) in the glycerol phase.


Assuntos
Ésteres/análise , Glicerol/química , Óleos de Plantas/química , Cromatografia Gasosa , Cromatografia Líquida de Alta Pressão , Esterificação , Ésteres/química
12.
Bioresour Technol ; 101(19): 7397-401, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20537532

RESUMO

Many samples of rapeseed oil ethyl ester were prepared by alkaline-catalyzed transesterification at various conditions (reaction time, temperature, amount of catalyst, the molar ratio of ethanol to oil, the rotations of a disperser and the purification by water). The concentrations of the key impurities for biodiesel quality (the concentrations of monoglycerides, diglycerides, triglycerides, free glycerol, ethanol, free fatty acids, water) and some qualitative parameters (flash point, carbon residue, kinematics viscosity at 40 degrees C) were determined and then the relationships among them were found out. The relationships were characterized by the linear or non-linear statistical models. The found models enable the better understanding of the significance of the qualitative parameters and estimate them from the concentrations of impurities. The temperature dependence was also measured in the case of the viscosity of ethyl ester and used rapeseed oil.


Assuntos
Biocombustíveis/análise , Carbono/análise , Etanol/química , Óleos de Plantas/química , Fenômenos Biomecânicos , Ácidos Graxos Monoinsaturados , Glicerol/análise , Hidrólise , Potássio/análise , Óleo de Brassica napus , Temperatura , Triglicerídeos/análise , Viscosidade
13.
Eur J Hum Genet ; 18(8): 915-23, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20234393

RESUMO

The Tuareg presently live in the Sahara and the Sahel. Their ancestors are commonly believed to be the Garamantes of the Libyan Fezzan, ever since it was suggested by authors of antiquity. Biological evidence, based on classical genetic markers, however, indicates kinship with the Beja of Eastern Sudan. Our study of mitochondrial DNA (mtDNA) sequences and Y chromosome SNPs of three different southern Tuareg groups from Mali, Burkina Faso and the Republic of Niger reveals a West Eurasian-North African composition of their gene pool. The data show that certain genetic lineages could not have been introduced into this population earlier than approximately 9000 years ago whereas local expansions establish a minimal date at around 3000 years ago. Some of the mtDNA haplogroups observed in the Tuareg population were involved in the post-Last Glacial Maximum human expansion from Iberian refugia towards both Europe and North Africa. Interestingly, no Near Eastern mtDNA lineages connected with the Neolithic expansion have been observed in our population sample. On the other hand, the Y chromosome SNPs data show that the paternal lineages can very probably be traced to the Near Eastern Neolithic demic expansion towards North Africa, a period that is otherwise concordant with the above-mentioned mtDNA expansion. The time frame for the migration of the Tuareg towards the African Sahel belt overlaps that of early Holocene climatic changes across the Sahara (from the optimal greening approximately 10 000 YBP to the extant aridity beginning at approximately 6000 YBP) and the migrations of other African nomadic peoples in the area.


Assuntos
População Negra/genética , Cromossomos Humanos Y/genética , DNA Mitocondrial/genética , Etnicidade/genética , Marcadores Genéticos , Variação Genética , África Subsaariana , África do Norte , Ásia Ocidental , Mapeamento Cromossômico , Emigração e Imigração , Europa (Continente) , Feminino , Pool Gênico , Haplótipos , Humanos , Masculino , Polimorfismo de Nucleotídeo Único , Migrantes
14.
Bioresour Technol ; 101(9): 3242-5, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20074939

RESUMO

Glycerol is a by-product of biodiesel produced by transesterification and is contained in the glycerol phase together with many other materials such as soaps, remaining catalyst, water, and esters formed during the process. The content of glycerol is approximately 30-60 wt.%. In this paper, treatments of the glycerol phase to obtain glycerol with a purity of 86 wt.% (without distillation) and a mixture of fatty acids with esters (1:1) or only a mixture of fatty acids with a purity of 99 wt.% are presented. The treatment was carried out by removing of alkaline substances and esters. Fatty acids were produced by saponification of the remaining esters and subsequent neutralization of alkaline substances by phosphoric, sulfuric, hydrochloric, or acetic acids. Salts are by-products and, in the case of phosphoric acid can be used as potash-phosphate fertilizer. The process of treatment is easy and environmentally friendly, because no special chemicals or equipment are required and all products are utilizable.


Assuntos
Biocombustíveis , Gasolina , Glicerol/isolamento & purificação , Ácidos/química , Precipitação Química , Esterificação , Metanol/química
15.
Bioresour Technol ; 101(9): 3121-5, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20045635

RESUMO

This paper deals with the effect of water and catalyst (KOH) amount on the quantity and quality of transesterification products of rapeseed oil by methanol, the methyl ester phase (i.e. yield, conversion), and the side-product, the glycerol phase (i.e. density, viscosity, the mass fraction of glycerol, esters, soaps). The dependencies were described by statistical models. The transesterification was carried out at constant reaction conditions (90 min reaction time, 400 rpm, 60 degrees Celsius). Twelve experiments with the independent factors, amount of potassium hydroxide (0.65-0.9 mg per gram of oil) and total amount of water (0.24-1.42 mg per gram of oil) naturally present in the reaction components or formed by the neutralisation reaction of free fatty acids and of added water. The data were analyzed by linear regression with respect to regression triplet (complex critical analysis of the model, data and regression method). The analysis resulted in a set of linear and/or quadratic models consisting of statistically proven terms at a statistical significance level of 0.05 and demonstrated that ester in the glycerol phase increases with increasing amount of soaps.


Assuntos
Hidróxidos/farmacologia , Metano/metabolismo , Óleos de Plantas/metabolismo , Compostos de Potássio/farmacologia , Água/farmacologia , Bicarbonatos/farmacologia , Fenômenos Biomecânicos , Carbonatos/farmacologia , Fracionamento Químico , Esterificação/efeitos dos fármacos , Ésteres/metabolismo , Ácidos Graxos Monoinsaturados , Glicerol/farmacologia , Hidrólise/efeitos dos fármacos , Modelos Químicos , Potássio/farmacologia , Óleo de Brassica napus , Sabões , Viscosidade/efeitos dos fármacos
16.
Bioresour Technol ; 101(4): 1213-9, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19800222

RESUMO

The alkaline-catalyzed (KOH) ethanolysis of rapeseed oil with the help of a mechanical disperser was researched in this study. The effects of chosen reaction conditions (independent variables: the reaction temperature and time, the amount of catalyst, the molar ratio ethanol to oil and the rotation frequency of the disperser) on the ethanolysis process and ways for the improvement of the transesterification and separation process were studied. The transesterification of oil, the separation of the ester phase from the glycerol phase and qualitative properties of the ester phase were monitored by many dependent variables (e.g. the yield of the ester phase, the weight concentration of glycerides, the content of potassium ions, etc.). The measured data was analyzed by multi-linear regression with the help of many statistical tests (significance of parameters, exclusion of outliers, etc.). The created mathematical models describing the relations between the independent and dependent variables were verified by several independent experiments.


Assuntos
Biotecnologia/métodos , Etanol/química , Óleos de Plantas/química , Catálise , Esterificação , Ésteres/química , Ácidos Graxos Monoinsaturados , Hidróxidos/química , Modelos Lineares , Compostos de Potássio/química , Óleo de Brassica napus , Reprodutibilidade dos Testes
17.
Bioresour Technol ; 101(7): 2071-5, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20005094

RESUMO

The distribution of ethyl esters, triglycerides, diglycerides, monoglycerides, and glycerol between the ester and glycerol phase was investigated after the ethanolysis of rapeseed oil at various reaction conditions. The determination of these substances in the ester and glycerol phases was carried out by the GC method. The amount of ethyl esters in the glycerol phase was unexpectedly high and therefore the possibility of the reduction of this amount was investigated. The distribution coefficients and the weight distributions of each investigated substance were calculated and compared mutually. The distribution coefficients between the ester and glycerol phase increase in this sequence: glycerol, monoglycerides, diglycerides, ethyl esters, and triglycerides. Soaps and monoglycerides in the reaction mixture cause a worse separation of ethyl esters from the reaction mixture. The existence of a non-separable reaction mixture was observed also, and its composition was determined.


Assuntos
Ésteres/análise , Etanol/química , Glicerídeos/análise , Glicerol/análise , Óleos de Plantas/química , Cromatografia Gasosa , Ácidos Graxos Monoinsaturados , Hidrólise , Peso Molecular , Óleo de Brassica napus
18.
Bioresour Technol ; 100(23): 5555-9, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19574043

RESUMO

The aim of this work is to study the transesterification of vegetable oil with a high acid number at unchanged reaction conditions. Rapeseed oil was used as the raw material and its acid number was changed by the addition of oleic acid (from 0.89 to 12.25 mg KOH/g). Methanol was used for transesterification (molar ratio of oil to methanol 1:6) and potassium hydroxide was used as a catalyst. After the reaction time, the residue of the catalyst was neutralised by gaseous carbon dioxide and the methanol excess was removed. After the separation of two phases, each of them was analyzed (in the ester phase: yield, content of methyl ester and acid number; in the glycerol phase: yield, density, viscosity, content of glycerol, soaps, methyl ester, potassium carbonate and hydrogen carbonate). The obtained data was compared with theoretical material balances and the effect on the saponification of oil was discussed. The results show that the yield of methyl ester (biodiesel) is significantly affected by a higher acid number, as well as enhanced soap formation. On the other hand, the conversion of the oil and acid number of the ester phase remain at constant values in studied borders.


Assuntos
Biotecnologia/métodos , Ésteres/química , Óleos de Plantas/química , Bicarbonatos/química , Dióxido de Carbono/química , Carbonatos/química , Catálise , Fontes Geradoras de Energia , Esterificação , Ácidos Graxos/química , Ácidos Graxos Monoinsaturados , Glicerol/química , Concentração de Íons de Hidrogênio , Hidróxidos/química , Metanol/química , Ácidos Oleicos/química , Potássio/química , Compostos de Potássio/química , Óleo de Brassica napus
19.
BMC Evol Biol ; 9: 63, 2009 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-19309521

RESUMO

BACKGROUND: Chad Basin, lying within the bidirectional corridor of African Sahel, is one of the most populated places in Sub-Saharan Africa today. The origin of its settlement appears connected with Holocene climatic ameliorations (aquatic resources) that started ~10,000 years before present (YBP). Although both Nilo-Saharan and Niger-Congo language families are encountered here, the most diversified group is the Chadic branch belonging to the Afro-Asiatic language phylum. In this article, we investigate the proposed ancient migration of Chadic pastoralists from Eastern Africa based on linguistic data and test for genetic traces of this migration in extant Chadic speaking populations. RESULTS: We performed whole mitochondrial genome sequencing of 16 L3f haplotypes, focused on clade L3f3 that occurs almost exclusively in Chadic speaking people living in the Chad Basin. These data supported the reconstruction of a L3f phylogenetic tree and calculation of times to the most recent common ancestor for all internal clades. A date ~8,000 YBP was estimated for the L3f3 sub-haplogroup, which is in good agreement with the supposed migration of Chadic speaking pastoralists and their linguistic differentiation from other Afro-Asiatic groups of East Africa. As a whole, the Afro-Asiatic language family presents low population structure, as 92.4% of mtDNA variation is found within populations and only 3.4% of variation can be attributed to diversity among language branches. The Chadic speaking populations form a relatively homogenous cluster, exhibiting lower diversification than the other Afro-Asiatic branches (Berber, Semitic and Cushitic). CONCLUSION: The results of our study support an East African origin of mitochondrial L3f3 clade that is present almost exclusively within Chadic speaking people living in Chad Basin. Whole genome sequence-based dates show that the ancestral haplogroup L3f must have emerged soon after the Out-of-Africa migration (around 57,100 +/- 9,400 YBP), but the "Chadic" L3f3 clade has much less internal variation, suggesting an expansion during the Holocene period about 8,000 +/- 2,500 YBP. This time period in the Chad Basin is known to have been particularly favourable for the expansion of pastoralists coming from northeastern Africa, as suggested by archaeological, linguistic and climatic data.


Assuntos
DNA Mitocondrial/genética , Emigração e Imigração , Genética Populacional , Haplótipos/genética , Idioma , Filogenia , África , Chade , Variação Genética , Geografia , Humanos
20.
Am J Phys Anthropol ; 138(4): 439-47, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19012329

RESUMO

The Soqotra archipelago is one of the most isolated landmasses in the world, situated at the mouth of the Gulf of Aden between the Horn of Africa and southern Arabia. The main island of Soqotra lies not far from the proposed southern migration route of anatomically modern humans out of Africa approximately 60,000 years ago (kya), suggesting the island may harbor traces of that first dispersal. Nothing is known about the timing and origin of the first Soqotri settlers. The oldest historical visitors to the island in the 15th century reported only the presence of an ancient population. We collected samples throughout the island and analyzed mitochondrial DNA and Y-chromosomal variation. We found little African influence among the indigenous people of the island. Although the island population likely experienced founder effects, links to the Arabian Peninsula or southwestern Asia can still be found. In comparison with datasets from neighboring regions, the Soqotri population shows evidence of long-term isolation and autochthonous evolution of several mitochondrial haplogroups. Specifically, we identified two high-frequency founder lineages that have not been detected in any other populations and classified them as a new R0a1a1 subclade. Recent expansion of the novel lineages is consistent with a Holocene settlement of the island approximately 6 kya.


Assuntos
Cromossomos Humanos Y , Variação Genética , Geografia , Isolamento Social , África , Antropologia Física , Arábia , DNA Mitocondrial/química , Efeito Fundador , Haplótipos , Humanos , Filogenia , Grupos Raciais/genética
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