Egusi seed shells (ESS) were used as precursor for the preparation of two activated carbons (ACs) following H3PO4 and ZnCl2 activation. The effect of factors controlling the preparation of ACs such as chemical activat...Egusi seed shells (ESS) were used as precursor for the preparation of two activated carbons (ACs) following H3PO4 and ZnCl2 activation. The effect of factors controlling the preparation of ACs such as chemical activating agent concentration (2 - 10 M), activation temperature (400°C - 700°C) and residence time (30 - 120 min) were optimized using the Box-Behnken Design (BBD). The optimized activated carbons based H3PO4 (ACP) and ZnCl2 (ACZ) were characterized by N2 adsorption, elemental analysis, atomic force microscopy (AFM), Boehm titration and Fourier transformed infrared (FTIR) techniques. The specific surface area was found to be 1053.91 and 1009.89 m2·g-1 for ACP and ACZ respectively. The adsorbents had similar surface functionalities and were both microporous. The effect of various parameters such as initial pH, concentration, and contact time on the adsorption of nitrate ions on ACP and ACZ in aqueous solution was studied. ACZ demonstrated better adsorption capacity (8.26 mg·g-1) compared to ACP (5.65 mg·g-1) at the same equilibrium time of 20 min. The adsorption process was governed by a “physical interactions” phenomenon for both adsorbents.展开更多
Oleuropein content in olive leaves dried at ambient temperature, and at elevated temperature (50°C) from Palestinian olive trees collected from West Bank in the middle of November was determined by HPLC and co...Oleuropein content in olive leaves dried at ambient temperature, and at elevated temperature (50°C) from Palestinian olive trees collected from West Bank in the middle of November was determined by HPLC and compared to naturally dry olive leaves (collected dry from the tree). Results showed that higher concentration was obtained from olive leaves dried at room temperature (10.0 mg per gram of dry olive leaves), compared to those dried at 50°C (1.7 mg/g), and those that collected dry from the tree (2.5 mg/g). Oleuropein content of dried olive leaves was compared with leaves that chopped and extracted fresh, and results show that fresh leaves showed the lowest oleuropein content (<0.1 mg/g) denoting that drying of leaves is required for high oleuropein recovery.展开更多
X-ray fluorescence (XRF) analysis utilizes particle size which is resulted from milling of a material. The milling ensures uniform and fine grained powder. The finer and more uniform the particle size is, the better t...X-ray fluorescence (XRF) analysis utilizes particle size which is resulted from milling of a material. The milling ensures uniform and fine grained powder. The finer and more uniform the particle size is, the better the result and easier it is for material quality control. To ensure uniformity in particle size and finer powder, a comparative analysis was conducted with different grinding aids and pressed pellet method was used in obtaining analysis results. Pressed pellets of cement raw meal sample milled with different grinding aids (graphite, aspirin and lithium borate) were subjected to XRF. Graphite produced better particle size uniformity with a corresponding standard deviation that made quality control of raw meal easier and better than aspirin and lithium borate.展开更多
The World Health Organization (WHO), Environmental Protection Agency (EPA), and International Atomic Energy Agency (IAEA) have recommended the use of hair for worldwide environmental monitoring. Mercury exposure to th...The World Health Organization (WHO), Environmental Protection Agency (EPA), and International Atomic Energy Agency (IAEA) have recommended the use of hair for worldwide environmental monitoring. Mercury exposure to the inhabitants of Karachi was assessed by using hair as bioindicator. Hair samples of 200 residents of Karachi were collected and analyzed through cold vapor atomic absorption spectroscopy (CVAA) technique for mercury concentration. The effects of age, gender, working status, location, food and smoking habit were investigated. Control region showed a positive correlation between HHg and age of donor while no such correlation was observed for polluted regions. Mercury exposure through cosmetic usage in female was only pronounced in control region. These results indicate that environmental pollution dominates other potential factors. Age and smoking habit were not found to be the influencing factors while an elevated mean level of mercury was noticed for regular fish consumers than rarely fish consumers. 95.33% of the samples contained HHg greater than the permissible level of 2 μg?g?1 set by WHO. An apparently healthy male donor had HHg concentration (28.24 μg?g?1) closer to the high risk concentration of 30 μg?g?1 based on WHO criteria. Whereas, two female donors of the age group of 41-50 years had HHg concentrations (10.82 and 11.84 μg?g?1) higher than the NOAEL (no observed adverse affects level) value (10 μg?g?1) for females which is associated with fetus neurotoxicity. However, no symptoms of mercury toxicity were visible. The results indicate the alarming condition of pollution in the city which should be taken into further consideration.展开更多
Through this study, the humus produced in the breeding place of Universidad Autonoma de Occidente was thermally characterized. The humus was submitted to a heating program controlled by the Differential Scanning Calor...Through this study, the humus produced in the breeding place of Universidad Autonoma de Occidente was thermally characterized. The humus was submitted to a heating program controlled by the Differential Scanning Calorimetry (DSC) technique to characterize the type of transition, Thermogravimetry (TGA) to study the equilibrium of phasesand Mass Spectrometry (MS) coupled to TGA to identify detached elements in a temperature range. The temperature range used in this study was 30℃ ℃. The energy required for the water desorption in the humus has been found in this study. The humus showed a quick desorption between 30℃ ≤ TDesorption ≤ 110℃ at a heating rate of 10℃/min and presented decomposition around 250℃. Moreover, the kinetics of the desorption of the humus was studied to obtain the activation energy three TGA measures for three different heating rates. The average activation energy was about 26 kJ/Mol. This result was carried out to obtain an estimation of the desorption time of water in the range from room temperature to the decomposition temperature around 350℃.展开更多
The present study analyzed the volatile compounds of three mango varieties (Tommy Atkins, Rosa and Espada) using the static headspace technique with SPME coupled to CG-MS. Multivariate methodologies, such as factorial...The present study analyzed the volatile compounds of three mango varieties (Tommy Atkins, Rosa and Espada) using the static headspace technique with SPME coupled to CG-MS. Multivariate methodologies, such as factorial design and response surface methodology, were used to optimize the conditions of adsorption and desorption of these substances. The data were evaluated by using principal components analysis (PCA) and hierarchical grouping analysis, in order to visualize grouping tendencies of volatile compounds. Thirty-seven volatile compounds belonging to different chemical classes, such as esters, terpenes, alcohols and others, were tentatively identified in the three varieties of mango. Amongst them, twenty-three presented chromatographic peaks with relative areas larger than 2%. The multivariate analysis made it possible to visualize the grouping tendencies of the mango samples, according to the presence of their respective volatile substances, and enabled the identification of the groups of substances responsible for the discrimination among the three varieties.展开更多
It is well known that seawater that migrates deep into the Earth’s crust will pass into its supercritical domain at temperatures above 407°C and pressures above 298 bars. In the oceanic crust, these pressures ar...It is well known that seawater that migrates deep into the Earth’s crust will pass into its supercritical domain at temperatures above 407°C and pressures above 298 bars. In the oceanic crust, these pressures are attained at depths of 3 km below sea surface, and sufficiently high temperatures are found near intruding magmas, which have temperatures in the range of 800°C to 1200°C. The physico-chemical behaviour of seawater changes dramatically when passing into the supercritical domain. A supercritical water vapour (ScriW) is formed with a density of 0.3 g/cc and a strongly reduced dipolar character. This change in polarity is causing the ScriW to lose its solubility of the common sea salts (chlorides and sulphates) and a spontaneous precipitation of sea salts takes place in the pore system. However, this is only one of many cases where the very special properties of ScriW affect its surroundings. The objective of this paper is to increase awareness of the many geological processes that are initiated and governed by ScriW. This includes interactions between ScriW and its geological surroundings to initiate and drive processes that are of major importance to the dynamics and livelihood of our planet. ScriW is the driver of volcanism associated with subduction zones, as ScriW deriving from the subduction slab is interacting with the mantle rocks and reducing their melting point. ScriW is also initiating serpentinization processes where olivines in the mantle rocks (e.g. peridotite) are transformed to serpentine minerals upon the uptake of OH-groups from hydrolysed water. The simultaneous oxidation of Fe2+ dissolved from iron-bearing pyroxenes and olivines leads to the formation of magnetite and hydrogen, and consequently, to a very reducing environment. ScriW may also be the potential starter and driver of the poorly understood mud and asphalt volcanism;both submarine and terrestrial. Furthermore, the lack of polarity of the water molecules in ScriW gives the ScriW vapour the potential to dissolve organic matter and petroleum. The same applies to supercritical brines confined in subduction slabs. If these supercritical water vapours migrate upwards to reach the critical point, the supercritical vapour is condensed into steam and dissolved petroleum is partitioned from the water phase to become a separate fluid phase. This opens up the possibility of transporting petroleum long distances when mixed with ScriW. Therefore, we may, popularly, say that ScriW drives a gigantic underground refinery system and also a salt factory. It is suggested that the result of these processes is that ScriW is rejuvenating the world’s ocean waters, as all of the ocean water circulates into the porous oceanic crust and out again in cycles of less than a million years. In summary, we suggest that ScriW participates in and is partly responsible for: 1) Ocean water rejuvenation and formation;2) Fundamental geological processes, such as volcanism, earthquakes, and meta-morphism (including serpentinization);3) Solid salt production, accumulation, transportation, and (salt) dome formation;4) The initiation and driving of mud, serpentine, and asphalt volcanoes;5) Dissolution of organic matter and petroleum, including transportation and phase separation (fractionation), when passing into the subcritical domain of (liquid) water.展开更多
Mass spectrometry was used for studying of non-covalent complexes of bioflavonoids with cyclotriveratrylene (CVT). The complexes of cyclotriveratrylene (CVT) with the bioflavonoids (quercetin or dihydroquercetin) have...Mass spectrometry was used for studying of non-covalent complexes of bioflavonoids with cyclotriveratrylene (CVT). The complexes of cyclotriveratrylene (CVT) with the bioflavonoids (quercetin or dihydroquercetin) have been synthesized in subcritical water. The complexe formation was carried out at different temperatures of subcritical water (from 120℃ to 230℃). The structure of the inclusion compounds was confirmed by the data of ESI MS spectroscopy. The mass spectrometry results showed the presence of mixed adducts of CTV monomer, dimer, trimer and tetramer with quercetin and dihydroquercetin. Composition of the CTV complexes with the bioflavonoids, which were obtained in subcritical water medium and by traditional method, was compared.展开更多
Tembotrione is herbicide which belongs to the triketone group of herbicides. It’s registered as a selective, post-emergence herbicide developed for the control of a broad spectrum broadleaf and grassy weeds in corn. ...Tembotrione is herbicide which belongs to the triketone group of herbicides. It’s registered as a selective, post-emergence herbicide developed for the control of a broad spectrum broadleaf and grassy weeds in corn. There is little information about tembotrione because of his short presence in the market. Due to its ever wider application, it is important to know the details of its chemical characteristics and redox processes, including biogeochemical transformation and migration after application to agricultural land, which could contribute to its efficient and safer application. In this paper we examined voltammetric behavior of tembotrione using Silver/Amalgam (Ag/Hg) electrode. For the investigation of electrochemical behavior we used the cyclic voltammetry technique, with conventional three-electrode cell and electrochemical workstation. During the experiment pH values of solution varieties while constant concentration of tembotrione was maintained. Cyclic voltammograms were recorded at pH values 6, 8, 10 and 12, at which tembotrione was electrochemically active. At this pH values two signals were observed. Optimum pH value, at which the current intensity was greatest, was 12. Obtained results provide relevant information on the electrochemical behavior of tembotrione, which can serve as a basis for the development of electrochemical techniques for the removal and degradation of this pesticide in the environment.展开更多
Complex formation of 1,6-anhydro-β-maltose and sodium ions was characterized using single-crystal X-ray crystallography and solution- and solid-state NMR spectroscopy. The 7-coordination structure, comprising two 1,6...Complex formation of 1,6-anhydro-β-maltose and sodium ions was characterized using single-crystal X-ray crystallography and solution- and solid-state NMR spectroscopy. The 7-coordination structure, comprising two 1,6-anhydro-β-maltoses, a thiocyanate ion and a sodium ion, was identified in the crystal of the complex, where a sodium ion was positioned in the center of the pentagon. In the NMR study, the line broadening of 23Na signals and the decrease of the spin-lattice relaxation times (T1) of 23Na were observed in CD3OD in the presence of 1,6-anhydro-β-maltose, indicating complex formation.展开更多
A simple protocol has been developed for the quantification of trace level arsenic through methyl red bromination. The proposed method is based on the oxidation of arsenic(III) to arsenic(V) by the bromine and the res...A simple protocol has been developed for the quantification of trace level arsenic through methyl red bromination. The proposed method is based on the oxidation of arsenic(III) to arsenic(V) by the bromine and the residual bromine’s reaction with methyl red to form colorless bromo methyl red. As the concentration of arsenic increases, the bleaching of the dye decreases due to bromine consumption. Measuring the intensity of the unreacted methyl red at 515 nm forms the basis of arsenic quantification. The molar absorptivity of this method has been found to be 2.25 × 103 L/mol/cm. The method obeys Beer’s law in the concentration range 0 - 0.25 μg/mL. The Sandell sensitivity and the limit of detection (LOD) were found to be 0.03 μg/mL/cm2 and 0.03 μg/mL respectively. The relative standard deviation has been found to be 0.35% at 1.0 μg/mL. The reaction conditions have been optimized and the interference due to various common cations and anions were studied. The proposed method has been successfully applied to the determination of trace level arsenic in various environmental samples like water, soil and vegetable samples.展开更多
The distribution of pesticide by-product in tissues of wistar rats were analyzed using high pressure liquid chromatography. The limit of detection of the HPLC was 0.1 μg. Results show bioaccumulation factor of pestic...The distribution of pesticide by-product in tissues of wistar rats were analyzed using high pressure liquid chromatography. The limit of detection of the HPLC was 0.1 μg. Results show bioaccumulation factor of pesticide “Raid?” in lipid, up to three times that of the feed at the first concentration and gradually decreased as the concentration increased in the muscle > (0.7), brain > (0.5) and liver > (0.3) as indicated in the text. At higher concentration of 961 μg/g, bioaccumulation factor decreased in the lipid to 1.2 and 0.6 in the muscle, 0.03 in the brain and 0.08 in the liver respectively. High Pressure Liquid Chromatography (HPLC) analysis of raid extract suggests the presence of micprothrin and palethrin. The implications are numerous, but simply put that accidental ingestion of chlorinated hydrocarbon as in “Raid?” may involve convulsions, collapse and coma after only brief excitation and ataxia at the onset.展开更多
This research investigates the potential of near infrared spectroscopy (NIRS) for the detection and quantification of pesticides in aqueous solution. Standard solutions of Alachlor and Atrazine (ranging in concentrati...This research investigates the potential of near infrared spectroscopy (NIRS) for the detection and quantification of pesticides in aqueous solution. Standard solutions of Alachlor and Atrazine (ranging in concentration from 1.25 - 100 ppm) were prepared by dilution in a Methanol/water solvent (1:1 methanol/water (v/v)). Near infrared transmission spectra were obtained in the wavelength region 400 - 2500 nm;however, the wavelength regions below 1300 nm and above 1900 nm were omitted in subsequent analysis due to the poor signal repeatability in these regions. Partial least squares analysis was applied for discrimination between pesticide and solvent and for prediction of pesticide concentration. Limits of detection of 12.6 ppm for Alachlor and 46.4 ppm for Atrazine were obtained.展开更多
C. bonariensis (L.) Cronq. known as hairy fleabane was first described in Argentina but it is now widely spread through most warmer regions of Europe, Africa, Asia, the Caribbean and Central America. In this work, a c...C. bonariensis (L.) Cronq. known as hairy fleabane was first described in Argentina but it is now widely spread through most warmer regions of Europe, Africa, Asia, the Caribbean and Central America. In this work, a chemical analysis by liquid and gas chromatography coupled with mass spectrometry of the whole plant, aerial part, flowers and roots extracts of C. bonariensis harvested in Togo (West Africa) was carried out. Two acetylenic compounds Lachnophyllum ester and limonene were identified as the main components of essential oils while Lachnophyllum and Matricaria lactones were dominant in chloroform extracts. Based on the plant chemical compositions, essential oils and chloroform extracts were tested on cowpea weevil Callosobruchus maculatus adults which are considered as one of the most cosmopolitan pests of stored beans, and on freshly hatched second-stage juveniles of root-knot nematode Meloidogyne incognita. Results showed that the whole plant essential oil demonstrated an LC<sub>50/24h</sub> value of 1.75 μL oil/L air on C. maculatus while at 3.91 μL oil/L air, it showed 100% mortality. Furthermore, the plant root chloroform extracts partitioned in diethyl ether-hexane mixture showed the strongest nematicidal activity with an LC<sub>50/72h</sub> value of 0.47 mg/mL. Our findings suggest that the widely diffused plant C. bonariensis and its acetylenic constituents could be considered as potent botanical insecticidal and nematicidal agents.展开更多
Background: In the context of a nuclear reactor accident, thyroid is the main target organ of radioactive iodines. To avoid as much as possible thyroid disorders or even cancer development, it is recommended to admini...Background: In the context of a nuclear reactor accident, thyroid is the main target organ of radioactive iodines. To avoid as much as possible thyroid disorders or even cancer development, it is recommended to administer a single dose of potassium iodide to people at risk of exposure. Nevertheless, the Fukushima Dai-ichi disaster has pointed out many questions about the conditions of stable iodine prophylaxis implementation highlighting the need for reflection further revision of the actual “iodine doctrine”. Therefore, providing useful data is required notably through the implementation of animal experiments to strengthen current knowledge and to edit new recommendations. Methods: Urinary iodine constitutes a very good indicator to investigate the function of thyroid, its interpretation demands reliable analyses. Prior to perform animal experiments, two calibration methods were designed by our lab and compared together (standard addition and external calibration) to assess the urinary concentration of stable iodine in urine by ICP-MS. They were validated based on several key parameters especially linearity, accuracy and limits of detection (LOD) and quantification (LOQ). Results: The results were nicely satisfying. Indeed, both calibration methods have indicated very good coefficients of correlations, accuracies with low expanded relative uncertainties were obtained. The estimated LOD in the sample for standard addition method and external calibration were fully acceptable, 0.39 μg·L-1 and 0.35 μg·L-1, respectively. All performance criteria have been thus fulfilled successfully. The established methods were proven to be accurate, robust and sensitive. Once validated, both calibration methods were applied to rat urine samples and the results of z-score and Wilcoxon W test concluded that there were no statistically significant differences between both methods.展开更多
In recent years, photosynthetic microalgae regained attention for biodiesel production. For efficient utilization of microalgae, a number of criteria including a strain with high biomass and lipid productivities and e...In recent years, photosynthetic microalgae regained attention for biodiesel production. For efficient utilization of microalgae, a number of criteria including a strain with high biomass and lipid productivities and employment of effective and reliable methods for oil extraction from the obtained biomass should be met. Recently, we have isolated and identified three thermo-resistant green microalgae strains, namely;Scenedesmus sp. ME02, Hindakia tetrachotoma ME03 and Mic-ractinium sp. ME05. In this study, we compared percent lipid content of thermos-tolerant mic-roalgal strains using the following solvent extraction methods: Soxhlet, Bligh and Dyer and Folch methods with or without assisted cell disruption techniques including lyophilization, homogenization, ultrasonication, bead and microwave-assisted. The highest increase in lipid yield was obtained with a combination of lyophilization and ultrasonication techniques together with Soxhlet method: 27% of total dry weight for Micractinium sp. ME05. We conclude that lyophilization and ultrasonication are effective assistance methods for lipid extraction from thermo-resistant microalgae.展开更多
The purpose of this study was to determine the effects of skin pigmentation regarding Near Infrared Spectroscopy (NIRS) tissue oxygen saturation values (StO2). The study examined NIRS values in individuals with varyin...The purpose of this study was to determine the effects of skin pigmentation regarding Near Infrared Spectroscopy (NIRS) tissue oxygen saturation values (StO2). The study examined NIRS values in individuals with varying skin pigmentation on the anterior compartment of the lower leg and volar forearm to determine if correlation exists among three NIRS devices, the EQUANOX, Casmed, and INVOS. Skin pigmentation was measured on the anterior lower leg (AL) and volar forearm (VF) of participants using a noninvasive colorimeter that employed reflective spectroscopy to produce a quantitative value for erythema (skin “redness”) and melanin (skin pigment). Muscle oxygenation was measured using three oximetry devices with sensors placed in the same areas. The EQUANOX device showed no significant correlation with skin pigmentation, while the Casmed and INVOS devices showed moderate and significant correlation with skin pigmentation, respectively. Different devices have different abilities to remove confounding variables, such as skin pigmentation and erythema, which may affect clinical decision-making, and affect the use of NIRS technology.展开更多
A capillary zone electrophoresis method was developed for determination of melamine in food samples, such as quail egg and milk products. The CE procedure was performed on fused silica capillary (41 cm × 75 μm I...A capillary zone electrophoresis method was developed for determination of melamine in food samples, such as quail egg and milk products. The CE procedure was performed on fused silica capillary (41 cm × 75 μm I.D.) at 17 kV using pH3.1 60mmol/L phosphate buffer as run buffer and detecting at 200 nm. The proposed method showed good linearity (0.5 - 10.0 μmol/L) and low LOD (0.5 μmol/L) with good reproducibility (RSD% was 2.4 and 3.2 for migration time and peak area respectively), which made it suitable for quantity control of the related food product.展开更多
Very long chain fatty acids (VLCFAs) are accumulated in cells and blood in patients with peroxisomal diseases, such as adrenoleukodystrophy (ALD) and Zellwger Syndrome (ZS). The purpose of this study is to investigate...Very long chain fatty acids (VLCFAs) are accumulated in cells and blood in patients with peroxisomal diseases, such as adrenoleukodystrophy (ALD) and Zellwger Syndrome (ZS). The purpose of this study is to investigate usefulness of Fourier transform infrared spectroscopy (FTIR) with attenuated total reflection (ATR) analysis method for clinical diagnosis of those diseases, thereby we measured the infrared spectra of the sera of patients and healthy controls. Correlation coefficients between 2nd derivative FTIR spectra of the serum samples and the VLCFA content ratio which is used as a clinical parameter to date were comprehensively calculated to investigate which wavenumber showed high correlation with the VLCFA ratio. Multiple regression analysis using the serum FTIR spectra showed that high correlations were observed with VLCFA ratios (C26:0/C22:0 ratio), and we could construct a suitable regression model (R2 = 0.97, p ﹣19). In addition, the model system using various VLCFAs in newborn bovine serum also showed that several FTIR peaks in 800 ~ 900 cm﹣1 region were found to have good correlation with VLCFA ratios. Our results support that FTIR analysis is useful for diagnosis of peroxisomal diseases.展开更多
The objectives of the study were to find the type and species of zeolite which gives optimum adsorption of copper, provide an explanation of the mechanism involved in the adsorption process and establish the selectivi...The objectives of the study were to find the type and species of zeolite which gives optimum adsorption of copper, provide an explanation of the mechanism involved in the adsorption process and establish the selectivity sequence among zeolites. Adsorption of Cu onto zeolites and mont-morillonite as a reference was conducted at an initial Cu concentration range of 0 - 0.60 mM in the presence of 100 mM NH4NO3 at initial pH of 5. Langmuir and Freundlich models were used in analyzing the equilibrium data and a selectivity sequence derived from the Langmuir calculation was A4 > faujasite X > modernite > Na-P1 ≈montmorillonite ≈faujasite Y > clinoptilolite. Zeolites A4 and faujasite X had high adsorptive capacities of 1429 mmol·kg﹣1 and 909 mmol·kg﹣1, respectively. Zeolite A4 has the highest CEC among all the samples (6150 mmol·kg﹣1), and the adsorption capacity of Cu was largely influenced by the CEC of the samples. The adsorption mechanism was based on the exchange of Cu from solution with mostly Na which was the main exchangeable cation available. These results are important in selecting the most effective and suitable adsorbent for Cu removal from polluted environments.展开更多
文摘Egusi seed shells (ESS) were used as precursor for the preparation of two activated carbons (ACs) following H3PO4 and ZnCl2 activation. The effect of factors controlling the preparation of ACs such as chemical activating agent concentration (2 - 10 M), activation temperature (400°C - 700°C) and residence time (30 - 120 min) were optimized using the Box-Behnken Design (BBD). The optimized activated carbons based H3PO4 (ACP) and ZnCl2 (ACZ) were characterized by N2 adsorption, elemental analysis, atomic force microscopy (AFM), Boehm titration and Fourier transformed infrared (FTIR) techniques. The specific surface area was found to be 1053.91 and 1009.89 m2·g-1 for ACP and ACZ respectively. The adsorbents had similar surface functionalities and were both microporous. The effect of various parameters such as initial pH, concentration, and contact time on the adsorption of nitrate ions on ACP and ACZ in aqueous solution was studied. ACZ demonstrated better adsorption capacity (8.26 mg·g-1) compared to ACP (5.65 mg·g-1) at the same equilibrium time of 20 min. The adsorption process was governed by a “physical interactions” phenomenon for both adsorbents.
文摘Oleuropein content in olive leaves dried at ambient temperature, and at elevated temperature (50°C) from Palestinian olive trees collected from West Bank in the middle of November was determined by HPLC and compared to naturally dry olive leaves (collected dry from the tree). Results showed that higher concentration was obtained from olive leaves dried at room temperature (10.0 mg per gram of dry olive leaves), compared to those dried at 50°C (1.7 mg/g), and those that collected dry from the tree (2.5 mg/g). Oleuropein content of dried olive leaves was compared with leaves that chopped and extracted fresh, and results show that fresh leaves showed the lowest oleuropein content (<0.1 mg/g) denoting that drying of leaves is required for high oleuropein recovery.
文摘X-ray fluorescence (XRF) analysis utilizes particle size which is resulted from milling of a material. The milling ensures uniform and fine grained powder. The finer and more uniform the particle size is, the better the result and easier it is for material quality control. To ensure uniformity in particle size and finer powder, a comparative analysis was conducted with different grinding aids and pressed pellet method was used in obtaining analysis results. Pressed pellets of cement raw meal sample milled with different grinding aids (graphite, aspirin and lithium borate) were subjected to XRF. Graphite produced better particle size uniformity with a corresponding standard deviation that made quality control of raw meal easier and better than aspirin and lithium borate.
文摘The World Health Organization (WHO), Environmental Protection Agency (EPA), and International Atomic Energy Agency (IAEA) have recommended the use of hair for worldwide environmental monitoring. Mercury exposure to the inhabitants of Karachi was assessed by using hair as bioindicator. Hair samples of 200 residents of Karachi were collected and analyzed through cold vapor atomic absorption spectroscopy (CVAA) technique for mercury concentration. The effects of age, gender, working status, location, food and smoking habit were investigated. Control region showed a positive correlation between HHg and age of donor while no such correlation was observed for polluted regions. Mercury exposure through cosmetic usage in female was only pronounced in control region. These results indicate that environmental pollution dominates other potential factors. Age and smoking habit were not found to be the influencing factors while an elevated mean level of mercury was noticed for regular fish consumers than rarely fish consumers. 95.33% of the samples contained HHg greater than the permissible level of 2 μg?g?1 set by WHO. An apparently healthy male donor had HHg concentration (28.24 μg?g?1) closer to the high risk concentration of 30 μg?g?1 based on WHO criteria. Whereas, two female donors of the age group of 41-50 years had HHg concentrations (10.82 and 11.84 μg?g?1) higher than the NOAEL (no observed adverse affects level) value (10 μg?g?1) for females which is associated with fetus neurotoxicity. However, no symptoms of mercury toxicity were visible. The results indicate the alarming condition of pollution in the city which should be taken into further consideration.
文摘Through this study, the humus produced in the breeding place of Universidad Autonoma de Occidente was thermally characterized. The humus was submitted to a heating program controlled by the Differential Scanning Calorimetry (DSC) technique to characterize the type of transition, Thermogravimetry (TGA) to study the equilibrium of phasesand Mass Spectrometry (MS) coupled to TGA to identify detached elements in a temperature range. The temperature range used in this study was 30℃ ℃. The energy required for the water desorption in the humus has been found in this study. The humus showed a quick desorption between 30℃ ≤ TDesorption ≤ 110℃ at a heating rate of 10℃/min and presented decomposition around 250℃. Moreover, the kinetics of the desorption of the humus was studied to obtain the activation energy three TGA measures for three different heating rates. The average activation energy was about 26 kJ/Mol. This result was carried out to obtain an estimation of the desorption time of water in the range from room temperature to the decomposition temperature around 350℃.
文摘The present study analyzed the volatile compounds of three mango varieties (Tommy Atkins, Rosa and Espada) using the static headspace technique with SPME coupled to CG-MS. Multivariate methodologies, such as factorial design and response surface methodology, were used to optimize the conditions of adsorption and desorption of these substances. The data were evaluated by using principal components analysis (PCA) and hierarchical grouping analysis, in order to visualize grouping tendencies of volatile compounds. Thirty-seven volatile compounds belonging to different chemical classes, such as esters, terpenes, alcohols and others, were tentatively identified in the three varieties of mango. Amongst them, twenty-three presented chromatographic peaks with relative areas larger than 2%. The multivariate analysis made it possible to visualize the grouping tendencies of the mango samples, according to the presence of their respective volatile substances, and enabled the identification of the groups of substances responsible for the discrimination among the three varieties.
文摘It is well known that seawater that migrates deep into the Earth’s crust will pass into its supercritical domain at temperatures above 407°C and pressures above 298 bars. In the oceanic crust, these pressures are attained at depths of 3 km below sea surface, and sufficiently high temperatures are found near intruding magmas, which have temperatures in the range of 800°C to 1200°C. The physico-chemical behaviour of seawater changes dramatically when passing into the supercritical domain. A supercritical water vapour (ScriW) is formed with a density of 0.3 g/cc and a strongly reduced dipolar character. This change in polarity is causing the ScriW to lose its solubility of the common sea salts (chlorides and sulphates) and a spontaneous precipitation of sea salts takes place in the pore system. However, this is only one of many cases where the very special properties of ScriW affect its surroundings. The objective of this paper is to increase awareness of the many geological processes that are initiated and governed by ScriW. This includes interactions between ScriW and its geological surroundings to initiate and drive processes that are of major importance to the dynamics and livelihood of our planet. ScriW is the driver of volcanism associated with subduction zones, as ScriW deriving from the subduction slab is interacting with the mantle rocks and reducing their melting point. ScriW is also initiating serpentinization processes where olivines in the mantle rocks (e.g. peridotite) are transformed to serpentine minerals upon the uptake of OH-groups from hydrolysed water. The simultaneous oxidation of Fe2+ dissolved from iron-bearing pyroxenes and olivines leads to the formation of magnetite and hydrogen, and consequently, to a very reducing environment. ScriW may also be the potential starter and driver of the poorly understood mud and asphalt volcanism;both submarine and terrestrial. Furthermore, the lack of polarity of the water molecules in ScriW gives the ScriW vapour the potential to dissolve organic matter and petroleum. The same applies to supercritical brines confined in subduction slabs. If these supercritical water vapours migrate upwards to reach the critical point, the supercritical vapour is condensed into steam and dissolved petroleum is partitioned from the water phase to become a separate fluid phase. This opens up the possibility of transporting petroleum long distances when mixed with ScriW. Therefore, we may, popularly, say that ScriW drives a gigantic underground refinery system and also a salt factory. It is suggested that the result of these processes is that ScriW is rejuvenating the world’s ocean waters, as all of the ocean water circulates into the porous oceanic crust and out again in cycles of less than a million years. In summary, we suggest that ScriW participates in and is partly responsible for: 1) Ocean water rejuvenation and formation;2) Fundamental geological processes, such as volcanism, earthquakes, and meta-morphism (including serpentinization);3) Solid salt production, accumulation, transportation, and (salt) dome formation;4) The initiation and driving of mud, serpentine, and asphalt volcanoes;5) Dissolution of organic matter and petroleum, including transportation and phase separation (fractionation), when passing into the subcritical domain of (liquid) water.
文摘Mass spectrometry was used for studying of non-covalent complexes of bioflavonoids with cyclotriveratrylene (CVT). The complexes of cyclotriveratrylene (CVT) with the bioflavonoids (quercetin or dihydroquercetin) have been synthesized in subcritical water. The complexe formation was carried out at different temperatures of subcritical water (from 120℃ to 230℃). The structure of the inclusion compounds was confirmed by the data of ESI MS spectroscopy. The mass spectrometry results showed the presence of mixed adducts of CTV monomer, dimer, trimer and tetramer with quercetin and dihydroquercetin. Composition of the CTV complexes with the bioflavonoids, which were obtained in subcritical water medium and by traditional method, was compared.
基金This paper is supported by Serbian Ministry of Education and Science,project number 172030.
文摘Tembotrione is herbicide which belongs to the triketone group of herbicides. It’s registered as a selective, post-emergence herbicide developed for the control of a broad spectrum broadleaf and grassy weeds in corn. There is little information about tembotrione because of his short presence in the market. Due to its ever wider application, it is important to know the details of its chemical characteristics and redox processes, including biogeochemical transformation and migration after application to agricultural land, which could contribute to its efficient and safer application. In this paper we examined voltammetric behavior of tembotrione using Silver/Amalgam (Ag/Hg) electrode. For the investigation of electrochemical behavior we used the cyclic voltammetry technique, with conventional three-electrode cell and electrochemical workstation. During the experiment pH values of solution varieties while constant concentration of tembotrione was maintained. Cyclic voltammograms were recorded at pH values 6, 8, 10 and 12, at which tembotrione was electrochemically active. At this pH values two signals were observed. Optimum pH value, at which the current intensity was greatest, was 12. Obtained results provide relevant information on the electrochemical behavior of tembotrione, which can serve as a basis for the development of electrochemical techniques for the removal and degradation of this pesticide in the environment.
文摘Complex formation of 1,6-anhydro-β-maltose and sodium ions was characterized using single-crystal X-ray crystallography and solution- and solid-state NMR spectroscopy. The 7-coordination structure, comprising two 1,6-anhydro-β-maltoses, a thiocyanate ion and a sodium ion, was identified in the crystal of the complex, where a sodium ion was positioned in the center of the pentagon. In the NMR study, the line broadening of 23Na signals and the decrease of the spin-lattice relaxation times (T1) of 23Na were observed in CD3OD in the presence of 1,6-anhydro-β-maltose, indicating complex formation.
文摘A simple protocol has been developed for the quantification of trace level arsenic through methyl red bromination. The proposed method is based on the oxidation of arsenic(III) to arsenic(V) by the bromine and the residual bromine’s reaction with methyl red to form colorless bromo methyl red. As the concentration of arsenic increases, the bleaching of the dye decreases due to bromine consumption. Measuring the intensity of the unreacted methyl red at 515 nm forms the basis of arsenic quantification. The molar absorptivity of this method has been found to be 2.25 × 103 L/mol/cm. The method obeys Beer’s law in the concentration range 0 - 0.25 μg/mL. The Sandell sensitivity and the limit of detection (LOD) were found to be 0.03 μg/mL/cm2 and 0.03 μg/mL respectively. The relative standard deviation has been found to be 0.35% at 1.0 μg/mL. The reaction conditions have been optimized and the interference due to various common cations and anions were studied. The proposed method has been successfully applied to the determination of trace level arsenic in various environmental samples like water, soil and vegetable samples.
文摘The distribution of pesticide by-product in tissues of wistar rats were analyzed using high pressure liquid chromatography. The limit of detection of the HPLC was 0.1 μg. Results show bioaccumulation factor of pesticide “Raid?” in lipid, up to three times that of the feed at the first concentration and gradually decreased as the concentration increased in the muscle > (0.7), brain > (0.5) and liver > (0.3) as indicated in the text. At higher concentration of 961 μg/g, bioaccumulation factor decreased in the lipid to 1.2 and 0.6 in the muscle, 0.03 in the brain and 0.08 in the liver respectively. High Pressure Liquid Chromatography (HPLC) analysis of raid extract suggests the presence of micprothrin and palethrin. The implications are numerous, but simply put that accidental ingestion of chlorinated hydrocarbon as in “Raid?” may involve convulsions, collapse and coma after only brief excitation and ataxia at the onset.
文摘This research investigates the potential of near infrared spectroscopy (NIRS) for the detection and quantification of pesticides in aqueous solution. Standard solutions of Alachlor and Atrazine (ranging in concentration from 1.25 - 100 ppm) were prepared by dilution in a Methanol/water solvent (1:1 methanol/water (v/v)). Near infrared transmission spectra were obtained in the wavelength region 400 - 2500 nm;however, the wavelength regions below 1300 nm and above 1900 nm were omitted in subsequent analysis due to the poor signal repeatability in these regions. Partial least squares analysis was applied for discrimination between pesticide and solvent and for prediction of pesticide concentration. Limits of detection of 12.6 ppm for Alachlor and 46.4 ppm for Atrazine were obtained.
文摘C. bonariensis (L.) Cronq. known as hairy fleabane was first described in Argentina but it is now widely spread through most warmer regions of Europe, Africa, Asia, the Caribbean and Central America. In this work, a chemical analysis by liquid and gas chromatography coupled with mass spectrometry of the whole plant, aerial part, flowers and roots extracts of C. bonariensis harvested in Togo (West Africa) was carried out. Two acetylenic compounds Lachnophyllum ester and limonene were identified as the main components of essential oils while Lachnophyllum and Matricaria lactones were dominant in chloroform extracts. Based on the plant chemical compositions, essential oils and chloroform extracts were tested on cowpea weevil Callosobruchus maculatus adults which are considered as one of the most cosmopolitan pests of stored beans, and on freshly hatched second-stage juveniles of root-knot nematode Meloidogyne incognita. Results showed that the whole plant essential oil demonstrated an LC<sub>50/24h</sub> value of 1.75 μL oil/L air on C. maculatus while at 3.91 μL oil/L air, it showed 100% mortality. Furthermore, the plant root chloroform extracts partitioned in diethyl ether-hexane mixture showed the strongest nematicidal activity with an LC<sub>50/72h</sub> value of 0.47 mg/mL. Our findings suggest that the widely diffused plant C. bonariensis and its acetylenic constituents could be considered as potent botanical insecticidal and nematicidal agents.
基金partly supported by the French National“Investment for the future”funding programme.
文摘Background: In the context of a nuclear reactor accident, thyroid is the main target organ of radioactive iodines. To avoid as much as possible thyroid disorders or even cancer development, it is recommended to administer a single dose of potassium iodide to people at risk of exposure. Nevertheless, the Fukushima Dai-ichi disaster has pointed out many questions about the conditions of stable iodine prophylaxis implementation highlighting the need for reflection further revision of the actual “iodine doctrine”. Therefore, providing useful data is required notably through the implementation of animal experiments to strengthen current knowledge and to edit new recommendations. Methods: Urinary iodine constitutes a very good indicator to investigate the function of thyroid, its interpretation demands reliable analyses. Prior to perform animal experiments, two calibration methods were designed by our lab and compared together (standard addition and external calibration) to assess the urinary concentration of stable iodine in urine by ICP-MS. They were validated based on several key parameters especially linearity, accuracy and limits of detection (LOD) and quantification (LOQ). Results: The results were nicely satisfying. Indeed, both calibration methods have indicated very good coefficients of correlations, accuracies with low expanded relative uncertainties were obtained. The estimated LOD in the sample for standard addition method and external calibration were fully acceptable, 0.39 μg·L-1 and 0.35 μg·L-1, respectively. All performance criteria have been thus fulfilled successfully. The established methods were proven to be accurate, robust and sensitive. Once validated, both calibration methods were applied to rat urine samples and the results of z-score and Wilcoxon W test concluded that there were no statistically significant differences between both methods.
文摘In recent years, photosynthetic microalgae regained attention for biodiesel production. For efficient utilization of microalgae, a number of criteria including a strain with high biomass and lipid productivities and employment of effective and reliable methods for oil extraction from the obtained biomass should be met. Recently, we have isolated and identified three thermo-resistant green microalgae strains, namely;Scenedesmus sp. ME02, Hindakia tetrachotoma ME03 and Mic-ractinium sp. ME05. In this study, we compared percent lipid content of thermos-tolerant mic-roalgal strains using the following solvent extraction methods: Soxhlet, Bligh and Dyer and Folch methods with or without assisted cell disruption techniques including lyophilization, homogenization, ultrasonication, bead and microwave-assisted. The highest increase in lipid yield was obtained with a combination of lyophilization and ultrasonication techniques together with Soxhlet method: 27% of total dry weight for Micractinium sp. ME05. We conclude that lyophilization and ultrasonication are effective assistance methods for lipid extraction from thermo-resistant microalgae.
文摘The purpose of this study was to determine the effects of skin pigmentation regarding Near Infrared Spectroscopy (NIRS) tissue oxygen saturation values (StO2). The study examined NIRS values in individuals with varying skin pigmentation on the anterior compartment of the lower leg and volar forearm to determine if correlation exists among three NIRS devices, the EQUANOX, Casmed, and INVOS. Skin pigmentation was measured on the anterior lower leg (AL) and volar forearm (VF) of participants using a noninvasive colorimeter that employed reflective spectroscopy to produce a quantitative value for erythema (skin “redness”) and melanin (skin pigment). Muscle oxygenation was measured using three oximetry devices with sensors placed in the same areas. The EQUANOX device showed no significant correlation with skin pigmentation, while the Casmed and INVOS devices showed moderate and significant correlation with skin pigmentation, respectively. Different devices have different abilities to remove confounding variables, such as skin pigmentation and erythema, which may affect clinical decision-making, and affect the use of NIRS technology.
文摘A capillary zone electrophoresis method was developed for determination of melamine in food samples, such as quail egg and milk products. The CE procedure was performed on fused silica capillary (41 cm × 75 μm I.D.) at 17 kV using pH3.1 60mmol/L phosphate buffer as run buffer and detecting at 200 nm. The proposed method showed good linearity (0.5 - 10.0 μmol/L) and low LOD (0.5 μmol/L) with good reproducibility (RSD% was 2.4 and 3.2 for migration time and peak area respectively), which made it suitable for quantity control of the related food product.
文摘Very long chain fatty acids (VLCFAs) are accumulated in cells and blood in patients with peroxisomal diseases, such as adrenoleukodystrophy (ALD) and Zellwger Syndrome (ZS). The purpose of this study is to investigate usefulness of Fourier transform infrared spectroscopy (FTIR) with attenuated total reflection (ATR) analysis method for clinical diagnosis of those diseases, thereby we measured the infrared spectra of the sera of patients and healthy controls. Correlation coefficients between 2nd derivative FTIR spectra of the serum samples and the VLCFA content ratio which is used as a clinical parameter to date were comprehensively calculated to investigate which wavenumber showed high correlation with the VLCFA ratio. Multiple regression analysis using the serum FTIR spectra showed that high correlations were observed with VLCFA ratios (C26:0/C22:0 ratio), and we could construct a suitable regression model (R2 = 0.97, p ﹣19). In addition, the model system using various VLCFAs in newborn bovine serum also showed that several FTIR peaks in 800 ~ 900 cm﹣1 region were found to have good correlation with VLCFA ratios. Our results support that FTIR analysis is useful for diagnosis of peroxisomal diseases.
文摘The objectives of the study were to find the type and species of zeolite which gives optimum adsorption of copper, provide an explanation of the mechanism involved in the adsorption process and establish the selectivity sequence among zeolites. Adsorption of Cu onto zeolites and mont-morillonite as a reference was conducted at an initial Cu concentration range of 0 - 0.60 mM in the presence of 100 mM NH4NO3 at initial pH of 5. Langmuir and Freundlich models were used in analyzing the equilibrium data and a selectivity sequence derived from the Langmuir calculation was A4 > faujasite X > modernite > Na-P1 ≈montmorillonite ≈faujasite Y > clinoptilolite. Zeolites A4 and faujasite X had high adsorptive capacities of 1429 mmol·kg﹣1 and 909 mmol·kg﹣1, respectively. Zeolite A4 has the highest CEC among all the samples (6150 mmol·kg﹣1), and the adsorption capacity of Cu was largely influenced by the CEC of the samples. The adsorption mechanism was based on the exchange of Cu from solution with mostly Na which was the main exchangeable cation available. These results are important in selecting the most effective and suitable adsorbent for Cu removal from polluted environments.