Zeitschriften und Ausgaben

Volumen 33 (2022): Heft 2 (July 2022)

Volumen 33 (2022): Heft 1 (January 2022)

Volumen 32 (2021): Heft 2 (July 2021)

Volumen 32 (2021): Heft 1 (January 2021)

Volumen 31 (2020): Heft 2 (July 2020)

Volumen 31 (2020): Heft 1 (January 2020)

Volumen 30 (2019): Heft 2 (July 2019)

Volumen 30 (2019): Heft 1 (January 2019)

Volumen 29 (2018): Heft 2 (July 2018)

Volumen 29 (2018): Heft 1 (January 2018)

Volumen 28 (2017): Heft 2 (September 2017)

Volumen 28 (2017): Heft 1 (February 2017)

Volumen 27 (2016): Heft 2 (December 2016)

Volumen 27 (2016): Heft 1 (June 2016)

Volumen 26 (2015): Heft 2 (December 2015)

Volumen 26 (2015): Heft 1 (June 2015)

Volumen 25 (2014): Heft 2 (December 2014)

Volumen 25 (2014): Heft 1 (June 2014)

Volumen 24 (2013): Heft 2 (December 2013)

Volumen 24 (2013): Heft 1 (June 2013)

Volumen 23 (2012): Heft 2 (December 2012)

Volumen 23 (2012): Heft 1 (June 2012)

Zeitschriftendaten
Format
Zeitschrift
eISSN
2286-038X
ISSN
1223-7221
Erstveröffentlichung
22 Mar 2013
Erscheinungsweise
2 Hefte pro Jahr
Sprachen
Englisch

Suche

Volumen 24 (2013): Heft 1 (June 2013)

Zeitschriftendaten
Format
Zeitschrift
eISSN
2286-038X
ISSN
1223-7221
Erstveröffentlichung
22 Mar 2013
Erscheinungsweise
2 Hefte pro Jahr
Sprachen
Englisch

Suche

11 Artikel
Uneingeschränkter Zugang

Synthesis and evaluation of possible mechanism of anti nociceptive potential of novel 2-quinolone fused 3,5-pyrazolidinedione derivatives in experimental animal models

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 5 - 12

Zusammenfassung

Abstract

In the present synthesis a series of 1-(1-methyl-2-oxo-1,2-dihydroquinolin-4-yl)-2-substituted phenylpyrazolidine-3,5-diones were prepared. By the reaction of N-methylbenzenamine with diethyl malonoate 4-hydroxy-1-methylquinolin-2(1H)-one were prepared, which on treatment with posphoryl chloride converted into 4-chloro-1-methylquinolin-2(1H)-one. Subsequently with substituted phenyl hydrazines 1-methyl-4-(2- substitutedphenylhydrazinyl)quinolin-2(1H)-one were obtained, which on reaction with diethyl malonate gave 1- (1-methyl-2-oxo-1,2-dihydroquinolin-4-yl)-2-substituted phenylpyrazolidine-3,5-diones. All structures were characterized by IR, 1HNMR & mass spectrometry. Further all the synthesized compounds were evaluated for their anti-nociceptive activity in mice by Eddy’s hot plate and acetic acid induced writhing response. All compounds have shown the activity. In hot plate model compounds QAA-04c and QAA-04d have given more activity than standard, whereas in case of acetic acid induced writhing model compounds QAA-04a and QAA- 04d have given significant analgesic activity which is comparable with the standard drug. Compound QAA-04b has shown least analgesic activity. Compound QAA-04a was almost equal in activity to the standard drug diclofenac sodium and was considered as the lead molecule.

Schlüsselwörter

  • - N-methylbenzenamine
  • diethyl malonoate
  • Eddy’s hot plate
  • anti-nociceptive activity
Uneingeschränkter Zugang

Alpha-tocopherol and ergocalciferol contents of some macroalgae from Bulgarian Black Sea coast

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 13 - 16

Zusammenfassung

Abstract

The aim of the present study was to determine and compare _-tocopherol and ergocalciferol content in four macroalgae from Bulgarian Black sea coast. Ulva rigida, Cladophora vagabunda, Cystoseira barbata and Cystoseira crinita were used for evaluation of corresponding fat soluble vitamins content. The sample preparation procedure includes alkaline saponification, followed by liquid-liquid extraction. Ergocalciferol (vitamin D2) and α-tocopherol (vitamin E) were analyzed simultaneously using HPLC/UV/FL system (Thermo Scientific Spectra SYSTEM) equipped with RP analytical column. The mobile phase was composed of 97:3 = MeOH:H2O. Ergocalciferol was monitored by UV detection at λmax = 265nm, while α-tocopherol was detected by fluorescence at λex=288nm and λem=332nm. Alpha-tocopherol content in algal tissues ranged from 1.68±0.38mg/100g d.w. in Cladophora vagabunda to 29.13±1.08mg/100g d.w. in Cystoseira barbata. Ergocalciferol was detected only in Ulva rigida samples.

Schlüsselwörter

  • macroalgae
  • ergocalciferol
  • α-tocopherol
  • HPLC
Uneingeschränkter Zugang

Influence of dietary fiber addition on some properties of yoghurt

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 17 - 20

Zusammenfassung

Abstract

The objective of this work was to study the effect of different dietary fibers on rheological properties of yoghurts fortified with these fibers [1, 2, 3]. Commercial fibers from apple and inulin were used. The effect of addition of dietary fibers in yoghurt [4, 5] was investigated by a rotational viscometer, Brookfield viscometer (Brookfield Engineering Inc., Model RV-DV I Prime) with RV spindles. The Brookfield viscometer DV I Prime with disk spindles represents an easy and cheap method for rheological characterization of non-Newtonian fluids, in this case of yoghurt. Syneresis and pH did not show any difference, while only apple fiber yoghurt showed colour differences compared to control.

Schlüsselwörter

  • rheology
  • syneresis
  • dietary fiber
  • colour
Uneingeschränkter Zugang

Nitrite determination in spices

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 21 - 23

Zusammenfassung

Abstract

The aim of this study is to determine the nitrite content in some spices: basil, pepper, dill, thyme, oregano, bay leaves, cinnamon, mint, mustard and cumin. The nitrite content was measured using UV-VIS spectrometric method with Griess reagent. The method was tested and partial validated. The nitrite content varied from 0.23 to 7.7 mg/Kg and these values are lower than those encountered in the literature.

Schlüsselwörter

  • nitrite
  • spices
  • UV -VIS spectrometry
  • validation
Uneingeschränkter Zugang

Estimation of the refractive index of diesel fuel+biodiesel blends

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 24 - 26

Zusammenfassung

Abstract

For now, biodiesel is the commonly accepted biofuel as a substitute for diesel fuel in internal combustion engines. Diesel fuel blends with up to 20% biodiesel can be used in diesel engines without any modification. A lot of studies regarding diesel fuel+biodiesel blends properties are presented in the literature. Some of the important properties of diesel fuel+biodiesel blends can be evaluated from other blends properties. For example, density and viscosity of biodiesel blends can be predicted based on blend refractive index. More than that, refractive index can be used as a reliable physical property to predict transesterification reaction progress. As a result, the refractive index of diesel fuel+biodiesel blends is important in order to characterize these blends or to monitor the evolution of transesterification process of vegetable oils or animal fats. The refractive index of diesel fuel+biodiesel blends can be experimentally determined or evaluated based on refractive indices of diesel fuel and biodiesel. The aim of this study was to estimate the accuracy of refractive index of diesel fuel +biodiesel blends calculation, using models initially proposed to evaluate the refractive index of a binary liquid mixture. It was shown that the refractive index of diesel fuel+biodiesel blends can be accurately predicted from refractive indices of the components of the blend. Wiener, Heller and Edward equations can be recommended to predict with a great accuracy the refractive index of diesel fuel+biodiesel blends.

Schlüsselwörter

  • Biodiesel
  • diesel fuel
  • refractive index
  • models
Uneingeschränkter Zugang

Fatty acid and fat soluble vitamins composition of raw and cooked Black Sea horse mackerel

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 27 - 34

Zusammenfassung

Abstract

The fat soluble vitamins, as well as n3 and n6 fatty acids (FA) are essential compounds of fish lipids and exclusively provided by the diet. Fish is sometimes eaten raw, but it is usually thermal processed before consumption. Temperature processing of fish tissue enhances its taste, inactivates pathogenic microorganisms and increases its shelf life. The fat soluble vitamins (vitamins A, D3 and E) and fatty acids are considered to be susceptible to oxidation during heating (cooking) process. The aim of the present study was to evaluate the effect of steaming (10 min at 90°C) and frying (5 min on the each side with sunflower oil) on fat soluble vitamins and fatty acids composition in Horse mackerel (Trahurus mediterraneus) fish fillets. Vitamins A, D3 and E were analyzed simultaneously using RP-HPLC. The fatty acid composition was analyzed by GC-MS. The amounts of vitamin A (retinol) in cooked fish fillets (for both heat treatments) decreased significantly, compared to their content in the raw samples. In contrast vitamin D3 (cholecalciferol) content affects only by steaming, while changes on vitamin E (alpha-tocopherol) was observed solely after frying process. The highest content of monounsaturated fatty acids (MUFA) were observed after steaming, whereas fried samples presented higher values of polyunsaturated fatty acids (PUFA) due to significant increase in linoleic acid (C18:2n6). During steaming did not reduce significant n3 and n6 PUFA levels, while frying caused a large reduction of n3 PUFAs. The ratio of n3/n6 was markedly lower in fried samples than in raw and steamed mackerel. In conclusion the Black Sea Horse Mackerel is a good source of vitamin D3, vitamin E and n3 PUFAs. After steaming and frying process there were minimum losses in the contents of cholecalciferol and alpha-tocopherol, while retinol was reduced nearly a half. The process of frying affects most significantly three fatty acids groups, whereas after steaming was observed little influence on fatty acids profile.

Schlüsselwörter

  • Trahurus mediterraneus
  • steaming
  • frying
  • vitamins
  • fatty acids
  • human health
Uneingeschränkter Zugang

Effect of thermal treatment on antioxidant activity and colour of carrot purées

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 35 - 38

Zusammenfassung

Abstract

Total antioxidant activity, levels of bio-active compound groups and instrumental colour of carrot purée subjected to thermal treatment (70°C/2 min) were measured. The method applied to the dosage of ascorbic acid was with 2,6-diclorophenolindophenol. Total phenols (TP) in purée were determined using the Folin- Ciocalteau method and antioxidant activity by the use of DPPH free radical method. The colour of the samples was measured using a Hunter-Lab colour meter. Heat treatment caused a rapid decrease in ascorbic acid. Phenolic contents were in general unaffected by thermal treatment. Colour parameters were significantly affected by thermal treatment. This provides a helpful tool for understanding the effect of processing on colour variation of carrot purée in a broader spectrum. Industrial relevance: This research paper provides scientific evidence of the influence of thermal treatments in retaining important bioactive compounds.

Schlüsselwörter

  • antioxidant activity
  • carrot
  • total phenols
  • colour
Uneingeschränkter Zugang

Trace element levels of three mushroom species

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 39 - 42

Zusammenfassung

Abstract

The aim of this study was to determine Cu, Fe and Cr contents of three species of fresh mushrooms and canned mushrooms: white and brown champignon (Agaricus bisporus) and Pleurotus Ostreatus. Were analyzed various plant parts: stem, cap and cuticle of fresh mushrooms and only stem and cap for canned mushrooms. The levels of trace metals of mushroom samples collected from regions of Romania, Poland and Turkey were determined by UV/Visible spectrometry - standard addition method after digestion method. The contents of investigated trace metals in mushroom samples were found to be in the range of 0.01 - 2.26 mg/Kg for chromium, 2.02 - 430.67 mg/Kg for copper and 240.40 - 7952.89 mg/Kg for iron. The iron content was found to be higher than those of the other two minerals in all the samples. Mushrooms species in the highest levels of trace elements were found white champignon for Cu and Fe and brown champignon for Cr.

Schlüsselwörter

  • Cu
  • Fe
  • Cr
  • mushrooms
  • UV/VIS spectrometry
Uneingeschränkter Zugang

Field testing of a magnesium oxide-lime-calcium chloride hydrochloric acid based filter

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 43 - 50

Zusammenfassung

Abstract

Field trials of a MgO-Lime-CaCl2-HCl filter has been carried out to test the operation of the filter during actual user conditions. Water quality parameters like pH, TDS, Ca, Mg hardness, total alkalinity, SO4-2, Cl- were found to be within permissible limits in the water obtained from the filter except nitrate, whose concentration was above permissible limits in the raw ground water itself. The dosage of HCl had to be adjusted and fixed in the field trials. In comparison to the laboratory trials conducted earlier it was found that during the field trials there was on an average 6% reduction in the fluoride removal efficiency of the filter. Operational user problems of filter were found and were addressed in the village.

Schlüsselwörter

  • magnesium oxide,water quality parameters
  • removal fluoride efficiency
Uneingeschränkter Zugang

A study of rheological behavior for refined rapeseed oil

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 51 - 54

Zusammenfassung

Abstract

The refined rapeseed oil were carefully studied in recent years because they may constitute a raw material for biodegradable lubricants getting organic. These oils are an alternative to synthetic mineral oils. This article presents rheological behavior of refined rapeseed oil. The dynamic viscosity of refined rapeseed oil was determined at temperatures range between 313 - 363 K and shear rates range from 3.3 - 120 s-1. For temperature ranging between 313 - 363 K refined rapeseed oil has a Bingham fluid behavior.

Schlüsselwörter

  • rheological behaviour
  • refined rapeseed oil
Uneingeschränkter Zugang

High temperature PEM fuel cell steady-state transport modeling

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 55 - 60

Zusammenfassung

Abstract

A fuel cell is a device that can directly transfer chemical energy to electric and thermal energy. Proton exchange membrane fuel cells (PEMFC) are highly efficient power generators, achieving up to 50-60% conversion efficiency, even at sizes of a few kilowatts. There are several compelling technological and commercial reasons for operating H2/air PEM fuel cells at temperatures above 100 °C; rates of electrochemical kinetics are enhanced, water management and cooling is simplified, useful waste heat can be recovered, and lower quality reformed hydrogen may be used as the fuel. All of the High Temperature PEMFC model equations are solved with finite element method using commercial software package COMSOL Multiphysics. The results from PEM fuel cell modeling were presented in terms of reactant (oxygen and hydrogen) concentrations and water concentration in the anode and cathode gases; the polarization curve of the cell was also displayed.

Schlüsselwörter

  • Maxwell-Stefan equation
  • molar concentration
  • polarization curve
11 Artikel
Uneingeschränkter Zugang

Synthesis and evaluation of possible mechanism of anti nociceptive potential of novel 2-quinolone fused 3,5-pyrazolidinedione derivatives in experimental animal models

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 5 - 12

Zusammenfassung

Abstract

In the present synthesis a series of 1-(1-methyl-2-oxo-1,2-dihydroquinolin-4-yl)-2-substituted phenylpyrazolidine-3,5-diones were prepared. By the reaction of N-methylbenzenamine with diethyl malonoate 4-hydroxy-1-methylquinolin-2(1H)-one were prepared, which on treatment with posphoryl chloride converted into 4-chloro-1-methylquinolin-2(1H)-one. Subsequently with substituted phenyl hydrazines 1-methyl-4-(2- substitutedphenylhydrazinyl)quinolin-2(1H)-one were obtained, which on reaction with diethyl malonate gave 1- (1-methyl-2-oxo-1,2-dihydroquinolin-4-yl)-2-substituted phenylpyrazolidine-3,5-diones. All structures were characterized by IR, 1HNMR & mass spectrometry. Further all the synthesized compounds were evaluated for their anti-nociceptive activity in mice by Eddy’s hot plate and acetic acid induced writhing response. All compounds have shown the activity. In hot plate model compounds QAA-04c and QAA-04d have given more activity than standard, whereas in case of acetic acid induced writhing model compounds QAA-04a and QAA- 04d have given significant analgesic activity which is comparable with the standard drug. Compound QAA-04b has shown least analgesic activity. Compound QAA-04a was almost equal in activity to the standard drug diclofenac sodium and was considered as the lead molecule.

Schlüsselwörter

  • - N-methylbenzenamine
  • diethyl malonoate
  • Eddy’s hot plate
  • anti-nociceptive activity
Uneingeschränkter Zugang

Alpha-tocopherol and ergocalciferol contents of some macroalgae from Bulgarian Black Sea coast

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 13 - 16

Zusammenfassung

Abstract

The aim of the present study was to determine and compare _-tocopherol and ergocalciferol content in four macroalgae from Bulgarian Black sea coast. Ulva rigida, Cladophora vagabunda, Cystoseira barbata and Cystoseira crinita were used for evaluation of corresponding fat soluble vitamins content. The sample preparation procedure includes alkaline saponification, followed by liquid-liquid extraction. Ergocalciferol (vitamin D2) and α-tocopherol (vitamin E) were analyzed simultaneously using HPLC/UV/FL system (Thermo Scientific Spectra SYSTEM) equipped with RP analytical column. The mobile phase was composed of 97:3 = MeOH:H2O. Ergocalciferol was monitored by UV detection at λmax = 265nm, while α-tocopherol was detected by fluorescence at λex=288nm and λem=332nm. Alpha-tocopherol content in algal tissues ranged from 1.68±0.38mg/100g d.w. in Cladophora vagabunda to 29.13±1.08mg/100g d.w. in Cystoseira barbata. Ergocalciferol was detected only in Ulva rigida samples.

Schlüsselwörter

  • macroalgae
  • ergocalciferol
  • α-tocopherol
  • HPLC
Uneingeschränkter Zugang

Influence of dietary fiber addition on some properties of yoghurt

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 17 - 20

Zusammenfassung

Abstract

The objective of this work was to study the effect of different dietary fibers on rheological properties of yoghurts fortified with these fibers [1, 2, 3]. Commercial fibers from apple and inulin were used. The effect of addition of dietary fibers in yoghurt [4, 5] was investigated by a rotational viscometer, Brookfield viscometer (Brookfield Engineering Inc., Model RV-DV I Prime) with RV spindles. The Brookfield viscometer DV I Prime with disk spindles represents an easy and cheap method for rheological characterization of non-Newtonian fluids, in this case of yoghurt. Syneresis and pH did not show any difference, while only apple fiber yoghurt showed colour differences compared to control.

Schlüsselwörter

  • rheology
  • syneresis
  • dietary fiber
  • colour
Uneingeschränkter Zugang

Nitrite determination in spices

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 21 - 23

Zusammenfassung

Abstract

The aim of this study is to determine the nitrite content in some spices: basil, pepper, dill, thyme, oregano, bay leaves, cinnamon, mint, mustard and cumin. The nitrite content was measured using UV-VIS spectrometric method with Griess reagent. The method was tested and partial validated. The nitrite content varied from 0.23 to 7.7 mg/Kg and these values are lower than those encountered in the literature.

Schlüsselwörter

  • nitrite
  • spices
  • UV -VIS spectrometry
  • validation
Uneingeschränkter Zugang

Estimation of the refractive index of diesel fuel+biodiesel blends

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 24 - 26

Zusammenfassung

Abstract

For now, biodiesel is the commonly accepted biofuel as a substitute for diesel fuel in internal combustion engines. Diesel fuel blends with up to 20% biodiesel can be used in diesel engines without any modification. A lot of studies regarding diesel fuel+biodiesel blends properties are presented in the literature. Some of the important properties of diesel fuel+biodiesel blends can be evaluated from other blends properties. For example, density and viscosity of biodiesel blends can be predicted based on blend refractive index. More than that, refractive index can be used as a reliable physical property to predict transesterification reaction progress. As a result, the refractive index of diesel fuel+biodiesel blends is important in order to characterize these blends or to monitor the evolution of transesterification process of vegetable oils or animal fats. The refractive index of diesel fuel+biodiesel blends can be experimentally determined or evaluated based on refractive indices of diesel fuel and biodiesel. The aim of this study was to estimate the accuracy of refractive index of diesel fuel +biodiesel blends calculation, using models initially proposed to evaluate the refractive index of a binary liquid mixture. It was shown that the refractive index of diesel fuel+biodiesel blends can be accurately predicted from refractive indices of the components of the blend. Wiener, Heller and Edward equations can be recommended to predict with a great accuracy the refractive index of diesel fuel+biodiesel blends.

Schlüsselwörter

  • Biodiesel
  • diesel fuel
  • refractive index
  • models
Uneingeschränkter Zugang

Fatty acid and fat soluble vitamins composition of raw and cooked Black Sea horse mackerel

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 27 - 34

Zusammenfassung

Abstract

The fat soluble vitamins, as well as n3 and n6 fatty acids (FA) are essential compounds of fish lipids and exclusively provided by the diet. Fish is sometimes eaten raw, but it is usually thermal processed before consumption. Temperature processing of fish tissue enhances its taste, inactivates pathogenic microorganisms and increases its shelf life. The fat soluble vitamins (vitamins A, D3 and E) and fatty acids are considered to be susceptible to oxidation during heating (cooking) process. The aim of the present study was to evaluate the effect of steaming (10 min at 90°C) and frying (5 min on the each side with sunflower oil) on fat soluble vitamins and fatty acids composition in Horse mackerel (Trahurus mediterraneus) fish fillets. Vitamins A, D3 and E were analyzed simultaneously using RP-HPLC. The fatty acid composition was analyzed by GC-MS. The amounts of vitamin A (retinol) in cooked fish fillets (for both heat treatments) decreased significantly, compared to their content in the raw samples. In contrast vitamin D3 (cholecalciferol) content affects only by steaming, while changes on vitamin E (alpha-tocopherol) was observed solely after frying process. The highest content of monounsaturated fatty acids (MUFA) were observed after steaming, whereas fried samples presented higher values of polyunsaturated fatty acids (PUFA) due to significant increase in linoleic acid (C18:2n6). During steaming did not reduce significant n3 and n6 PUFA levels, while frying caused a large reduction of n3 PUFAs. The ratio of n3/n6 was markedly lower in fried samples than in raw and steamed mackerel. In conclusion the Black Sea Horse Mackerel is a good source of vitamin D3, vitamin E and n3 PUFAs. After steaming and frying process there were minimum losses in the contents of cholecalciferol and alpha-tocopherol, while retinol was reduced nearly a half. The process of frying affects most significantly three fatty acids groups, whereas after steaming was observed little influence on fatty acids profile.

Schlüsselwörter

  • Trahurus mediterraneus
  • steaming
  • frying
  • vitamins
  • fatty acids
  • human health
Uneingeschränkter Zugang

Effect of thermal treatment on antioxidant activity and colour of carrot purées

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 35 - 38

Zusammenfassung

Abstract

Total antioxidant activity, levels of bio-active compound groups and instrumental colour of carrot purée subjected to thermal treatment (70°C/2 min) were measured. The method applied to the dosage of ascorbic acid was with 2,6-diclorophenolindophenol. Total phenols (TP) in purée were determined using the Folin- Ciocalteau method and antioxidant activity by the use of DPPH free radical method. The colour of the samples was measured using a Hunter-Lab colour meter. Heat treatment caused a rapid decrease in ascorbic acid. Phenolic contents were in general unaffected by thermal treatment. Colour parameters were significantly affected by thermal treatment. This provides a helpful tool for understanding the effect of processing on colour variation of carrot purée in a broader spectrum. Industrial relevance: This research paper provides scientific evidence of the influence of thermal treatments in retaining important bioactive compounds.

Schlüsselwörter

  • antioxidant activity
  • carrot
  • total phenols
  • colour
Uneingeschränkter Zugang

Trace element levels of three mushroom species

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 39 - 42

Zusammenfassung

Abstract

The aim of this study was to determine Cu, Fe and Cr contents of three species of fresh mushrooms and canned mushrooms: white and brown champignon (Agaricus bisporus) and Pleurotus Ostreatus. Were analyzed various plant parts: stem, cap and cuticle of fresh mushrooms and only stem and cap for canned mushrooms. The levels of trace metals of mushroom samples collected from regions of Romania, Poland and Turkey were determined by UV/Visible spectrometry - standard addition method after digestion method. The contents of investigated trace metals in mushroom samples were found to be in the range of 0.01 - 2.26 mg/Kg for chromium, 2.02 - 430.67 mg/Kg for copper and 240.40 - 7952.89 mg/Kg for iron. The iron content was found to be higher than those of the other two minerals in all the samples. Mushrooms species in the highest levels of trace elements were found white champignon for Cu and Fe and brown champignon for Cr.

Schlüsselwörter

  • Cu
  • Fe
  • Cr
  • mushrooms
  • UV/VIS spectrometry
Uneingeschränkter Zugang

Field testing of a magnesium oxide-lime-calcium chloride hydrochloric acid based filter

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 43 - 50

Zusammenfassung

Abstract

Field trials of a MgO-Lime-CaCl2-HCl filter has been carried out to test the operation of the filter during actual user conditions. Water quality parameters like pH, TDS, Ca, Mg hardness, total alkalinity, SO4-2, Cl- were found to be within permissible limits in the water obtained from the filter except nitrate, whose concentration was above permissible limits in the raw ground water itself. The dosage of HCl had to be adjusted and fixed in the field trials. In comparison to the laboratory trials conducted earlier it was found that during the field trials there was on an average 6% reduction in the fluoride removal efficiency of the filter. Operational user problems of filter were found and were addressed in the village.

Schlüsselwörter

  • magnesium oxide,water quality parameters
  • removal fluoride efficiency
Uneingeschränkter Zugang

A study of rheological behavior for refined rapeseed oil

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 51 - 54

Zusammenfassung

Abstract

The refined rapeseed oil were carefully studied in recent years because they may constitute a raw material for biodegradable lubricants getting organic. These oils are an alternative to synthetic mineral oils. This article presents rheological behavior of refined rapeseed oil. The dynamic viscosity of refined rapeseed oil was determined at temperatures range between 313 - 363 K and shear rates range from 3.3 - 120 s-1. For temperature ranging between 313 - 363 K refined rapeseed oil has a Bingham fluid behavior.

Schlüsselwörter

  • rheological behaviour
  • refined rapeseed oil
Uneingeschränkter Zugang

High temperature PEM fuel cell steady-state transport modeling

Online veröffentlicht: 20 Oct 2013
Seitenbereich: 55 - 60

Zusammenfassung

Abstract

A fuel cell is a device that can directly transfer chemical energy to electric and thermal energy. Proton exchange membrane fuel cells (PEMFC) are highly efficient power generators, achieving up to 50-60% conversion efficiency, even at sizes of a few kilowatts. There are several compelling technological and commercial reasons for operating H2/air PEM fuel cells at temperatures above 100 °C; rates of electrochemical kinetics are enhanced, water management and cooling is simplified, useful waste heat can be recovered, and lower quality reformed hydrogen may be used as the fuel. All of the High Temperature PEMFC model equations are solved with finite element method using commercial software package COMSOL Multiphysics. The results from PEM fuel cell modeling were presented in terms of reactant (oxygen and hydrogen) concentrations and water concentration in the anode and cathode gases; the polarization curve of the cell was also displayed.

Schlüsselwörter

  • Maxwell-Stefan equation
  • molar concentration
  • polarization curve

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