Influence of using hydrochloric acid for measuring the concentration of total carnitine in human plasma by Tandem mass spectrometry

The present study establishes whether the pH of samples is crucial for measuring total carnitine in human plasma by tandem mass spectrometry and if it is necessary to neutralize the samples after alkaline hydrolysis of acylcarnitines. Free and total carnitine of ten plasma samples were measured by a radioenzymatic assay as a reference method, and forward there were analyzed by tandem mass spectrometry divided into two groups: treated with hydrochloric acid and without hydrochloric acid measuring each sample five times for both variables. Free and total carnitine concentrations were similar for the radioenzymatic essay and tandem mass spectrometry. There was no significant difference between the two analyzed variables (treated with hydrochloric acid and without hydrochloric acid). It could be concluded that the pH of samples is no crucial for measuring total carnitine in plasma by tandem mass spectrometry, and it is not necessary to neutralize the samples after alkaline hydrolysis of acylcarnitines, then the shorter method, without adding hydrochloric acid can be used for total carnitine measurement in plasma by tandem mass spectrometryEl presente estudio establece, si el pH al cual se procesan las muestras, condiciona la determinación de la carnitina total en plasma, mediante el uso de espectrometría de masas en tándem; así mismo analiza, si es necesario neutralizar las muestras luego de la hidrólisis alcalina de las acilcarnitinas. Carnitina libre y total de 10 muestras de plasma fueron medidas mediante el ensayo radioenzimático, como método de referencia. Posteriormente fueron medidas cinco veces cada muestra, mediante espectrometría de masas en tándem utilizando ácido hidroclorhídrico y sin usar ácido hidroclorhídrico. Las concentraciones de carnitina libre y total, fueron similares utilizando ensayo radioenzimático y espectrometría de masas en tándem. No se encontró diferencias significativas entre las dos variables analizadas (con ácido hidroclorhídrico, o sin ácido hidroclórhídrico). Puede concluirse que el pH de las muestras no es crucial para medir carnitina total en plasma por espectrometría de masas en tandem y no es necesario neutralizar las muestras luego de la hidrólisis alcalina de las acilcarnitinas. El método más corto puede ser utilizado para tal fin

Application of emulsified acids on sandstone formation at elevated temperature conditions: an experimental study

Emulsified acid has attracted considerable attention of the oil and gas industry due to its delayed nature that allows deeper penetration of acid into the formation which essentially facilitate further enhancing the well productivity, and at the same time minimizes the corrosion issues. However, emulsified acid has only been extensively studied and applied on carbonate formations. Considering more than half of the reservoirs worldwide are sandstone reservoirs, studying the effects of emulsified acid on sandstone under high-temperature conditions would unlock the potential of emulsified acid and help generate more value for the oil and gas industry by improving the well productivity from sandstone reservoirs. To ensure the applicability of the emulsified acid on the real sandstone reservoir, which usually has a temperature higher than ambient conditions, the stability of emulsified acids is investigated under 300 °F. Then, the stable emulsified acid samples are developed and their impact on the properties of Berea sandstone core samples, including porosity, pore-size distribution, permeability and wettability, are investigated. The core samples have undergone pre-flush (10% HCl:5% CH3COOH) before the main flush (emulsified acid). The emulsified acids are prepared using hydrofluoric acid, hydrochloric acid, phosphoric acid, cationic surfactant and chelating agent. Fourteen core samples are saturated with different emulsified acids under vacuum conditions for 3 days to ensure maximum saturation. The porosity, permeability and wettability of each core sample are measured before and after the reaction with acid. Nuclear magnetic resonance analysis has been applied to evaluate the change in pore size distribution. This study has demonstrated that the emulsified acids are capable of improving the porosity and permeability of Berea sandstone core sample. The pore size distribution has also been affected by the application of emulsified acid, where more large pores have been evolved to the core samples due to the reaction of acids with the sandstone which ultimately helps in improving the productivity of hydrocarbons. This indicates less precipitation of the secondary reaction products resulting better enhancement in sandstone flow properties. These results demonstrate the potential of emulsified acid during sandstone acidizing as emulsified acid significantly improved the sandstone properties which can essentially enhance the well productivity

Investigating the Effectiveness of Emulsified Acid on Sandstone Formation under High Temperature Conditions

Acid stimulation supports the oil and gas industry as a versatile mean in enhanced oil recovery to fulfill the world energy demand. Although hydrochloric acid can significantly improve the reservoir permeability, its rapid reaction rate at high temperature has created a barrier for acid penetration. Subsequently, emulsified acid has slowly gain its popularity due to its retardation effect which allows deeper penetration of acid into the formation and achieves minimal corrosion issues. Nonetheless, emulsified acid has rarely applied on sandstone formation. Since a large portion of reservoirs are made up of sandstone, the effects of emulsified acid on sandstone under high temperature conditions should be studied to unlock the effective usage of emulsified acid in restoring the hydrocarbon recovery from the potential sandstone reservoirs. Besides, it is also crucial to explore cheaper and greener substitute to formulate innovative emulsified acid in minimizing the high acidizing budget along with environmental concerns. In this project, 10 different emulsified acid combinations are prepared using hydrofluoric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid, cationic surfactant, diesel and waste oil. The pre-flush treatment (5 % CH3COOH: 10 % HCl) is followed by the main flush (emulsified acids) saturation for 3 days. The thermal stability of emulsified acids and their effect on the Berea sandstone properties are evaluated. Major outcome is that the emulsified acids have the capability to remain stable at 275 °F up to 6 hours with uniform and fine droplet size. It is also proven that most of the emulsified acids can improve the porosity and permeability of Berea sandstone core samples except for HF: H3PO4. Regardless of the types of oil used for emulsified acid formulation, HF: HCl acid combination shows the best performance enhancement for both diesel-based and waste oil-based emulsified acids. In sandstone acidizing, emulsified acid dissolves the minerals and create acid transport pathway with close connectivity between pore spaces, causing the formation of large and conductive channels within the rock. Hence, these positive results clearly reflect on the feasibility of emulsified acid application in sandstone matrix acidizing and the effectiveness of waste oil as a replacement fluid for diesel

Hydration Behaviour and Characteristics of Binary Blended Metakaolin Cement Pastes

Cement production consume large amount of energy to form clinker and carbon dioxide (CO2) emitted into the atmosphere causing global warming. To mitigate this challenge, the use of Metakaolin (MK) as supplementary cementitious material cannot be over emphasized. This study evaluated the use of Metakaolin (MK) on hydration development of MK--PC blended cements and strength of Mortars. The MK with a Blaine fineness of 7883 cm2/g was used to replace Portland Cement (PC) at a level of 0, 5, 10, 15, 20, 25 and 30 % by mass of PC at a constant w/b ratio of 0.50 to prepare blended cements. Hydration development of blended cement and compressive strength of Mortars were investigated using chemically bond water and free-lime contents and strength tests respectively. X – Ray diffraction (XRD) and scanning electron Microscopy (SEM) techniques were also utilised in the analysis of Pozzolanic reaction and hydration products. Test results indicates that Water of consistency, setting times for the mixes increased with increase in MK contents, influence of MK on the chemically bond water and free Lime contents of the blended cements were due to its filler and dilution effects and Pozzolanic reaction. The cumulative non-evaporable water and free-lime contents increased by partial replacement of PC with MK due to PC hydration and Pozzolanic reaction. The tested Mortar prepared with blended cements with 30 % PC replacement with MK shows a retardation of strength development with a low value at early ages (7 days) and increased in growth at later ages (28 days). The compressive strength of tested mortar for 90 days curing age for the blended mortar is 31 N/mm2 close to that of control Mortar (35 N/mm2). The results obtained from XRD and SEM analysis indicated increase in Calcium Hydroxide (CH) consumption and Calcium Silicate hydrate (C-S-H) formation in blended cement pastes with curing time. The PC replacement with MK induced changes in Microstructures of blended cement paste and chemical composition of hydration products. These results are potentials for modelling the behaviour of MK-PC blended cements

Occupational exposure to zinc oxide

"A standard is recommended for occupational exposure to zinc-oxide (1314132), including information on environmental standards, medical surveillance, labeling, personal protective equipment, informing employees of hazards, work practices, sanitation, monitoring and recordkeeping requirements. Biological effects of exposure, environmental data, and development of the standard are discussed." - NIOSHTIC-2Douglas L. Smith had NIOSH program responsibility for development of this document.Tabershaw-Cooper Associates, inc., developed the basic information for consideration by the NIOSH staff under contract no. HSM-99-73-50.John M. Fajen of Stanford Research Institute developed the final document for consideration by the NIOSH staff and consultants under contract no. CDC-99-94-313CurrentPrevention and ControlEnvironmental HealthHSM-99-73-50CDC-99-94-31

Synthesis and characterisation of metal chelators: Mannich bases of hydroxy-pyrones and hydroxy-pyridones

Kojic acid (5-hydroxy-2-hydroxymethy1-4(1H)-pyrone) undergoes a rapid Mannich reaction with formaldehyde and morpholine, under aqueous conditions at 25 °C. The implications of the kinetic analysis on the mechanism of the Mannich reaction were discussed. The kinetics was conveniently monitored spectrophotometrically (280nm) under pseudo first-order conditions, with respect to kojic acid. The kinetics was not consistent with the reaction between kojic acid and a freely diffusing iminium ion, a mechanism which appears widely in the literature. Instead, the kinetics requires a rate limiting reaction between kojic acid and both hemi-aminal and bis-aminal. A rate equation was formulated which expresses the equilibrium concentrations of the condensation species of formaldehyde and morpholine, as well as the ionisation of kojic acid. The equation which follows was shown to be valid over a wide range of pH and concentration of reagents. Rate = (kojic acid]. 1 / (1 + Ka / [H+]) . [formaldehyde]. [amine]. (k1 . β1 + k2 . β2 . [amine]) Ka is the acid dissociation constant of kojic acid, β1 and β2 are the formation constants and k1 and k2 the rate constants for the hemi- and bis-aminal, respectively. With values of logβ1 = 2.898 and logβ2 = 4.192, pKa = 7.534 and the optimised values of k1 and k2 are 0.65 (±0.04) and 0.77 (±0.05) M-1S-1, respectively. The bell-shaped pH dependence of kobs was correctly modeled and the pH giving maximum kobs was predicted within 0.05 pH units. This occurs at pH 7.1 (kobs = 1.0 x 10-2 sec-1) with formaldehyde at 30 mM and morpholine at 147 mM. However, the pH of maximum rate was predicted to rise to 7.3 while kobs falls to 0.31 x 10-2 sec-1 at the lower morpholine concentration of 14.7 mM. 3-Hydroxy-2 (1H)-pyridinone (3HP) was covalendy coupled to the condensation product(s) of formaldehyde and poly(ethyleneimine) via a Mannich reaction and form novel metal chelating polymeric resins, called poly-Mannich bases. Poly-Mannich bases (e.g.. MKP-DP9-4) with random orientation of 3-hydroxy-2(1H)-pyridinone chelating moieties on the organic polymeric backbone were isolated by method of precipitation, using an aqueous solution of mineral acid and acetone. Rapid uptake of Fe3+ accompanied by a spontaneous colour reaction was observed on addition of aqueous solution of iron (III) nitrate to the poly-Mannich base (MKP-DP9-4). The amount of iron bound per gram of poly-Mannich base was 40 m g and showed 4 times or more affinity for F e3+ compared with other ion-exchange resins. The site of aminomethylation of N-unsubstituted 3-hydroxy-2(1H)-pyridinones and 3-hydroxy-4(1H)-pyridinones, under Mannich reaction conditions was directed by the unprotected hydroxyl group or by the keto group, when the hydroxyl was protected as an ether. This offered a convenient route to a variety of Mannich base synthons useful in the synthesis of derivatives of these clinically important, bidentate, metal-ion chelators. This was exemplified by the reactions of 3-hydroxy-2(1H)-pyridinones, 3-methoxy-2(1H)-pyridinone and 3-benzyloxy-2-methyl-4(1H)-pyridinone

Continuous culture of sulphur-oxidizing microorganisms for metal recovery

Màster d'Enginyeria Ambiental, Facultat de Química, Universitat de Barcelona, Curs: 2019-2020, Tutor:Joan Dosta ParrasNowadays heavy metal contamination has become a global problem. So, it is necessary to find a way to remove heavy metals and biological extraction can be a good alternative from physical or chemical. Biological extraction ahs low energy demand and it is considered a green and environment friendlier technique. The most commonly biological method used in metal recovery is called bioleaching. An example of bioleaching could be use sulphur oxidizing bacteria (SOB) to oxidized elemental sulphur to sulphuric acid, lowering pH and improving heavy metals solubilization. The present work aims to study copper recovery and to enrich sulphur oxidizing microorganisms in a reactor to obtain an effluent to be able to carry out the bioleaching process. A continuous stirred tank reactor with mixed of Acidithiobacillus thiooxidans and sulphur-oxidizing microorganisms to achieved the effluent, had been tested. Also, a bioleaching Jar-Test in order to assess copper solubilization as a function of sulphuric acid dose, total solids content and stirring time. After activating the microorganisms, the reactor was able to start up properly, achieving an effluent with a 0.06 M of sulphuric acid concentration. In addition, Jar-Test was reached a copper solubilization between 148.25 mg Cu/kg sludge and 203.86 mg Cu/kg sludge. The factor combination that obtained the best copper solubilization was: 2% total solids content, 6 days of stirring time and 3 g S°/L transformed in sulphuric acid dose

Effect of Silica Fume on Metakaolin Geopolymers’ Sulfuric Acid Resistance

To demonstrate the importance of the Si/Al ratio in terms of geopolymer mix designs for acid resistance, a metakaolin-based geopolymer was modified by replacing the aforementioned precursor with different percentages of silica fume. Durability tests were performed by exposing geopolymers with varying amounts of silica fume (up to 9%) to sulfuric acid solution (pH 1) over a period of 84 days. Geopolymer samples were analyzed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) before and after 7, 14, 28, 56 and 84 days of exposure. To show the time-dependent change of the elemental composition in the corroded layer after sulfuric acid attack, SEM-EDX elemental mappings were conducted and divided into 100 µm segments to generate element-specific depth profiles. The results show that above a critical silica fume content, the erosion of the sample surface by complete dissolution can be prevented and higher amounts of silica fume lead to a significant densification of large (protective) areas of the corroded layer, which delays the progress of corrosion

Nutritional evaluation of fermented palm kernel cake using red tilapia

The use of palm kernel cake (PKC) and other plant residues in fish feeding especially under extensive aquaculture have been in practice for a long time. On the other hand, the use of microbial-based feedstuff is increasing. In this study, the performance of red tilapia raised on Trichoderma longibrachiatum fermented PKC (TL-PKC) was evaluated. Seven isonitrogenous and isocaloric diets were formulated. Reference diet, D1 had no PKC, while the other diets, D2 to D5 contained 10, 20, 30and 40% fermented PKC (TL-PKC), respectively. All diets contained 1% chromic oxide as an inert marker. Red tilapias of average weight of 2.5 g were fed on these six diets for a period of 8 weeks. The fish were fed at 4% of their body weight, twice a day. There was no difference in mortality rate of fish on the various diets used. However, weight gain decreased with an increase of TL-PKC in diets. There were significant (P £ 0.05) differences in the apparent digestibility coefficient (ADC) of protein and drymatter between the reference diet and diet containing TL-PKC. The ADC of both protein and dry matter generally decrease when the percentage TL-PKC was increased in the test diets. There was also no significant difference in carcass protein content among fish on the various diets. However, there was a significant (P £ 0.05) increase in the levels of phosphorus, calcium and copper in the carcass of fish raised on TL-PKC, but the level of lipids was significantly reduced. Decreasing dry matter and protein digestibility with corresponding weight reduction may have resulted from increased crude fibre content of diets with TL-PKC

Levels of heavy metals in deposited dust and soil from selected primary schools in Dar es Salaam

The objective of this study was to examine the levels of heavy metals, lead, manganese, nickel, copper, chromium and cadmium in standard one and kindergarten classroom dusts and playing ground soils from selected primary schools along Morogoro road highway (Kimara, Mbezi, Kibamba and Kiluvya primary schools) and away from Morogoro road highway (Makabe, Msumi and Mbopo primary schools) as well as in the Dar es Salaam city center (Uhuru, Mzimuni, Dr. Omari Ali Juma, Manzese and Ubungo National House primary schools), Tanzania. The samples were acid digested and the supernatant analyzed using inductively coupled plasma optical emission spectrometer (ICP-OES). The mean concentrations (mg/kg) range of heavy metals in kindergarten and standard one classroom dust samples were bdl – 3.2 ± 0.2 (Cd), 14.7 ± 0.5 – 30.1 ± 2.2 (Cr), 6701 ± 1201– 277775 ± 32632 (Mn), 5.18 ± 0.59 – 122 ± 145 (Cu), 6.95 ± 1.57 – 30.3 ± 31.1 (Ni) and 17.67 ± 3.56 – 104.9 ± 94.7 (Pb). Similarly, the mean concentrations (mg/kg) range of heavy metals in kindergarten and standard one playing ground soil samples were bdl – 1.86 ± 0.06 (Cd), 5.8 ± 0.8 – 105 ± 124 (Cr), 7176 ± 226 – 191779 ± 82776 (Mn), 1.64 ± 0.01 – 11.51 ± 6.5 (Cu), 1.11 ± 0.2 – 37.5 ± 45.9 (Ni) and 8.9 ± 2.4 – 34.04 ± 1.9 (Pb). The present results, which indicate significantly high levels of heavy metals in school classroom dusts and playing ground soils, signify an important advancement towards shedding light on the alarming threat to school children’s health since classrooms and playing grounds are their immediate environments where they spend significant amount of their early life time.Keywords: Heavy metals, lead, manganese, nickel, copper, chromium, cadmium, classrooms dusts, Tanzani