Aflatoxins occurrence through the food chain in Costa Rica: Applying the One Health approach to mycotoxin surveillance

Aflatoxins (AFs) are toxic metabolites produced by Aspergillus spp. and commonly found in crops, grains, feedstuff, and forages. Exposure to AFs has been associated with increased risk of liver cancer and growth retardation in humans, liver damage, immunosuppression, embryotoxicity in both animals and humans, and decreased milk, egg and meat production in animals. For the first time, the Costa Rican national mycotoxin surveillance programs for animal feed and food are considered as a whole, applying the One Health approach to the mycotoxin epidemiological research. Therefore, the aim of this study was to determine the occurrence of AFs in cereals, nuts, grains intended for animal and human consumption in Costa Rica.In animal feed and feed ingredients, 970 samples were analyzed for AFs from 2010 to 2016 with an overall prevalence of positive samples of 24.0% (ranging from 0.01 to 290 μg kg⁻¹). Only 2.5% of the samples failed to comply the regulation for total AFs (20 μg kg⁻¹ feed). From 5493 samples of agricultural commodities intended for human consumption analyzed from 2003 to 2015, there was an overall prevalence of AF positive samples of 10.8% (ranging from 0.48 to 500 μg kg⁻¹), and 2.8% did not comply the regulation for AFs (20 μg kg⁻¹). In both feed and food, the highest AF prevalence corresponded to corn ingredients (27.8%) and white corn (38.6%), respectively. Among the commodities intended for human consumption, red beans had the highest aflatoxin concentrations (500 μg kg⁻¹).     

PCDD,PCDF and PCB contamination in Atherina boyeri (Risso, 1810) from Turkey

The levels of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (DL-PCBs) and indicator polychlorinated biphenyls were measured in Atherina boyeri (Risso, 1810) samples collected from Hirfanl? Dam Lake, Turkey in 2008 and 2009.Concentrations of PCDDs–PCDFs were detected as 0.16 and 0.17 pg TEQ₍₁₉₉₈₎ g^?1 wet weight while contamination levels of DL-PCBs were found as 0.42 and 0.38 pg TEQ₍₁₉₉₈₎ g^?1 wet weight in fish samples. The concentrations of total indicator PCBs in fish samples were found as 1.5 ng g^?1 and 0.9 ng g^?1 wet weight. Concentrations of PCDDs–PCDFs and DL-PCBs were below the EU regulation limits.     

Scope extension validation of a LC-MS method for the inspection of preservatives in butter

Butters are considered as “natural products” by many consumers, once they are obtained from milkfat without adding of any additive, except sodium chloride, starter cultures and natural dyes. The main goals of this study were to extend the scope of a previously developed method, including a new analyte (benzoic acid) and new matrices (butter and margarine), and thus evaluate the content of preservatives in national and imported butters traded in Brazil. Samples (n = 51) from inspected establishments in Argentina (n = 2), Brazil (n = 40), France (n = 7) and Uruguay (n = 2) were assessed by liquid chromatography-tandem mass spectrometry. Two screening inspection rounds were carried out between November, 2015 and January, 2016. Non-compliance rates were 36.4% in 2015 and 22.2% in 2016 for Brazilian butters. It was shown that preservatives are irregularly added to butters by many factories, contrary to regulation, and without proper declaration on labeling. The limits of quantitation (LOQ) were set to 25.00 mg kg⁻¹ (benzoic acid), 1.25 mg kg⁻¹ (natamycin), 3.13 mg kg⁻¹ (nisin) and 2.50 mg kg⁻¹ (sorbic acid). Except nisin, any of the researched preservatives was detected in a total of 12 samples, in concentrations that ranged from <LOQ–235.67 mg kg⁻¹ (benzoic acid), 8.26–35.60 mg kg⁻¹ (natamycin) and 4.52–1007.17 mg kg⁻¹ (sorbic acid). The method was also checked on margarine samples, revealing concentrations that ranged from 43.72 to 359.17 mg kg⁻¹ (benzoic acid) and from 509.00 to 1102.67 mg kg⁻¹ (sorbic acid), respectively. Our findings demonstrate that there is a need for stricter control in butter processing, with the aim to ensure food safety and to safeguard consumers.     

As Oneok Drew Regulatory Line for Gas,So Does EPSA for Electricity

Quite recently in these pages, we discussed a then-new Supreme Court decision carefully parsing the respective boundaries of federal oversight compared to state regulation of the natural gas industry. ¹ 1 Sabino, M. A. (2016, January). Supreme Court clarifies federal versus state authority over natural gas. Natural Gas & Electricity, 32 (6), 1–7 (discussing Oneok, Inc. v. Learjet, Inc., 575 U.S. ____ 135 S. Ct. 1591 (2015).
But what about the electricity industry? Does not that segment of the energy sector deserve equal consideration from the Supreme Court on the crucial matter of who is authorized to regulate its operations?     

Levels of polychlorinated dibenzo-p-dioxins,dibenzo-p-furans and polychlorinated biphenyls in farmed sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata) from Turkey

Farmed European sea bass and Gilthead sea bream were obtained from four different fish farms in Turkey during 2008–2009, for determination of 17 2,3,7,8-Cl-substituted PCDDs and PCDFs, and coplanar and indicator PCBs.Concentrations of ∑PCDD/Fs and DL-PCBs, as TEQ, in fish samples, ranged from 0.14 to 0.70 pg TEQ₍₁₉₉₈₎ g⁻¹ wet weight and from 0.46 to 4.51 pg TEQ₍₁₉₉₈₎ g⁻¹ wet weight, respectively. The concentrations of total indicator PCBs in fish samples ranged from 3.1 ng g⁻¹ to 22.1 ng g⁻¹ wet weight. Concentrations of PCDD/Fs and DL-PCBs were below the EU regulation (EC No. 1881/2006) limits.     

Evaluation of dispersive liquid–liquid microextraction for the determination of patulin in apple juices using micellar electrokinetic capillary chromatography

Patulin (PAT) is a mycotoxin naturally found in fruits, including apples. Its occurrence as a natural contaminant of fruit juices is indicative of fruit quality in production. The European Union has set the maximum content of patulin in 50 μg kg⁻¹ for fruit juices and 10 μg kg⁻¹ for infant fruit juices. In this paper, dispersive liquid–liquid microextraction (DLLME) has been proposed for the extraction and preconcentration of PAT in apple juice, followed by its determination by micellar electrokinetic chromatography (MEKC) with diode-array detection. PAT has been analyzed in the presence of 5-hydroxymethylfurfural (HMF), which is the main interference in this kind of matrix. Variables affecting DLLME efficiency were optimized and the calibration curve was established for PAT in analyte standard solutions, applying the DLLME–MEKC procedure. The limit of detection was 0.6 μg L⁻¹ and recoveries obtained for spiked freshly-made apple juice samples at four different concentration levels (5, 20, 50 and 75 μg L⁻¹), were above 75% with RSD lower than 9%. This method can be classified as a green alternative, being successfully applied to the measurement of 19 apple juice samples obtained from different suppliers and supermarkets. The optimized DLLME–MEKC method is free from matrix effects and avoids the tedious matrix-matched or standard addition calibration method. Almost fifty percent of the samples were contaminated with a PAT content greater than the maximum content established by the European regulation.     

In-house method validation,estimating measurement uncertainty and the occurrence of fumonisin B1 in samples of Brazilian commercial rice

Fumonisin B₁ was investigated in samples of rice intended for human consumption, including polished parboiled rice, whole grain rice and whole grain parboiled rice. Until the present, no studies on the occurrence of fumonisin B₁ have been performed on these types of rice that are commercially available in the south-eastern region of Brazil. A careful intralaboratory validation was carried out to demonstrate the fitness-of-purpose of the applied method for determining fumonisin B₁ in the three studied rice types. The performance criteria – selectivity, reliable limits of detection (50 μg kg⁻¹) and quantification (100 μg kg⁻¹), linearity (range 100–2500 μg kg⁻¹), precision (RSD values ≤ 17.0%) and recovery (71.7–112.0 %) were evaluated, and the expanded measurement uncertainty was estimated by using the data obtained from precision and recovery experiments. Matrix-matched calibration standards were employed to quantify the mycotoxin levels in the rice samples, in which the residual normality, homoscedasticity and independence were confirmed. In addition, the measurement uncertainty values are consistent with the maximum acceptable uncertainty established by European Union regulation for analytical methods for controlling mycotoxins in foodstuffs. Among the thirty-one commercial samples of rice analysed in the present study, five samples presented detectable levels of the mycotoxin, and these levels ranged from 64.8 to 163.0 μg kg⁻¹.     

Survey of aflatoxins and ochratoxin a contamination in food products imported in Italy

In this study the levels of aflatoxins (AF B₁, B₂, G₁ and G₂) and ochratoxin A (OTA) were monitored in several food products imported in Italy with a high contamination risk. A total of 345 samples were collected from the Maritime Authority of Salerno Customs Port during the period from January 2008 to December 2009 and analyzed by immunoaffinity chromatography as clean-up, high performance liquid chromatography with fluorescence detection for quantification and tandem mass spectrometry for confirmation. The analytical methods were validated on different food matrices and meet the performance criteria set by EC Regulation No. 401/2006 for mycotoxin analysis. The results obtained in this survey showed that 7% of the total samples contained detectable levels of AFs and OTA, and 1.2% had AFs concentrations exceeding the maximum limits set by EU regulation. OTA was the most prevalent mycotoxin, with an incidence of 17.6% of samples analyzed for OTA. The highest detected levels were 23.70 μg kg^?1 of OTA in a green coffee sample and 70.69 μg kg^?1 of AFs in an apricot kernels sample. Among the food products analyzed, hazelnuts paste and dried vine fruits were the commodities mainly contaminated with AFs and OTA, respectively.     

An assessment of L. monocytogenes transfer from wooden ripening shelves to cheeses: Comparison with glass and plastic surfaces

Food contact surfaces are subject to contamination by pathogens, which can lead to cross-contamination by transfer to other food products. However, the European regulation specifies that materials intended for safe food contact must not interfere with foodstuff characteristics. Considered a traditional and natural material, wooden boards are used as a “technological tool” during the cheese-ripening process. In France, wood is authorized for food-contact.The aim of this study was to determine the behavior of deliberately contaminated wooden surfaces in direct contact with foodstuffs. The model studied consisted of spruce ripening shelves experimentally inoculated with a well-known potential hazard throughout the production chain of some dairy products: Listeria monocytogenes. Then, the transfer from deliberately inoculated wood to cheese was analyzed and compared with plastic and glass inoculated surfaces.For this purpose, a protocol was developed and first-use spruce boards were inoculated with L. monocytogenes solution at a concentration of 10⁵ CFU/cm² then the microbial transfer to pressed non-cooked cheeses was studied. Factors such as cheese contact time, wood and cheese moisture contents, were tested. We compared the transfer rate with glass plates and plastic sheets with inclined meshes, commonly used throughout the cheese production chain, in the same conditions.The results showed a transfer yield below 3% (CFU/cm²) in the first hour of contact for all surfaces tested and was 0.55% for the wooden boards. No differences were found for drier cheeses or for higher wood moisture content. The wooden porous surface in contact with cheeses was not a factor that increased the L. monocytogenes direct transfer rates. In conclusion, wooden shelves have the lowest transfer rate of L. monocytogenes to pressed non-cooked cheeses compared to glass and polypropylene surfaces. This results contribute to the suitability of use of wooden material for direct contact with food.     

Loop-mediated isothermal amplification (LAMP) coupled with bioluminescence for the detection of Listeria monocytogenes at low levels on food contact surfaces

A commercial loop-mediated isothermal amplification (LAMP) based system with bioluminescence, named as 3M™ Molecular Detection Assay (MDA), was validated for the detection of Listeria monocytogenes (3-strain cocktail) at low levels (10⁰, 10¹, 10² CFU/100 cm²) inoculated on stainless steel (SS) and polyethylene (PE) surfaces, with and without (w/o) organic load (OL) of cold-smoked salmon homogenate by comparing with a standard ISO method as reference. The results of this study revealed that a commercial LAMP-based method performed equally effective compared with ISO method at inoculum levels of 10⁰ and 10²/100 cm², showing 100% specificity and sensitivity, respectively. At 10¹ CFU/100 cm², a slight reduction in the effectiveness of LAMP-based method was observed most likely due to the use of single enrichment step in the procedure of LAMP-based method. The LAMP-based method was shown to be rapid and reliable detection technique for L. monocytogenes present at low numbers on food processing surfaces, regardless of organic residues, and can be applicable in seafood industry.     

Oxidation of alcohols involving two types of peroxyl radicals

Liquid-phase oxidation of alcohols (R¹R²CHOH) occurs as a chain reaction involving two peroxyl radicals, namely, R¹R²C(OH)O ₂ ^· and HO ₂ ^· . Using the model of crossing parabolas, the activation energy and the rate constant were calculated for the reactions of α-hydroperoxyl radicals with four alcohols. A kinetic analysis of this reaction as a two-center chain process in which two peroxyl radicals that differ in reactivity (R¹R²C(OH)O ₂ ^· and HO ₂ ^· ) participate in chain propagation was performed. The relative amounts of the peroxyl radicals and their contribution to chain propagation under different oxidation conditions (temperature, alcohol concentration) were calculated for the oxidation of four alcohols: ethanol, 2-propanol, cyclohexanol, and α-phenylethanol. A change in the ratio between radicals due to the accumulation of a carbonyl compound and the fast addition of hydroperoxyl radicals to the carbonyl group during alcohol oxidation was considered and its effect on the chain propagation step in the oxidation reaction was discussed.     

Base-catalyzed oxidation of poly (ethylene glycol) by alkaline permanganate: Part I. Kinetics and mechanism of formation of coordination intermediate complex

A spectrophotometric investigation has been applied to study the kinetics of oxidation of poly (ethylene glycol) (PEG) as a synthetic polymer by alkaline permanganate at a constant ionic strength of 1.0 mol.dm^?3. The reaction was found to proceed through two distinct measurable stages. The first stage was relatively fast and corresponding to the formation of coordination polymer intermediate complexes involving blue hypomanganate (V) and/or green manganate (VI) transient species. The influence of variable factors on the oxidation rates such as the concentration of permanganate ion and PEG substrate concentrations as well as the pH and ionic strength have been examined. Under the pseudo-first-order reaction conditions of [PEG] ? [MnO₄^?], the experimental results showed a first-order dependence in [MnO₄^?] and fractional first-order kinetics in each of [PEG] and alkali concentration. The oxidation process was of base-catalyzed nature where the oxidation rates were increased with increasing the alkali concentration. The observed first-order rate constant was found to be 1.1 ×10^?3 s^?1 with deprotonation constant of 0.72 dm³ mol^?1 at 45 °C. Blue hypomanganate (V) was detected for the first time by using a conventional spectrophotometer. The oxidation process has proceeded without the intervention of a free-radical mechanism. Colloidal manganese (IV) and the acid derivatives of PEG were identified as final oxidation products. The activation parameters of the second-order reaction have been calculated and found to be ΔH^≠ = 40.66 kJmol^?1; ΔS^≠ = ? 145.41 Jmo^l?K^?1 and ΔG^≠ = 83.99 kJmol^?1. A plausible reaction mechanism for oxidation based on the evaluated activation parameters and in good consistent with the observed kinetic data was suggested and discussed.     

CHARACTERIZATION OF COAL CHARS FROM A FLASH PYROLYSIS PROCESS BY CROSS POLARIZATION/MAGIC ANGLE SPINNING 13C NMR

ABSTRACT

Chars from the Illinois Springfield (No. 5) Coal are prepared by flash pyrolysis at progressively higher charring temperatures. The results of a study of these chars by ¹³C NMR with CP/MAS indicate that the initial stage of heating (300^°C) produces a char with aromatic carbon fraction (f_ar) of 68%, and successive heating gives chars with f_ar of 70% (400^°C), 73% (500^°C), 89% (600^°C), 95% (700^°C), and 96% (800^°C). However, the actual amount of aromatic and aliphatic carbon in the char can be calculated by using the NMR measurements, the organic carbon content of the char, and the weight of the char. The calculated values show that the amount of aromatic carbon in char remains relatively constant at each temperature, but the amount of aliphatic carbon in char is reduced during higher temperature charring. At 600^°C, both a large reduction of the aliphatic carbon content and a maximum weight loss occur. Evidently, the aliphatic-bond carbon in coal is the principal source of volatiles derived from coal. The apparent increase in aromaticity (f_ar) of the char heated to progressively higher temperatures is due to the loss of aliphatic-bond moieties and reduction in volume of materials.     

CONSTRAINING THE TIMING AND DEPOSITIONAL CONDITIONS OF THE MAIKOP FORMATION WITHIN THE KURA BASIN,EASTERN AZERBAIJAN,THROUGH THE APPLICATION OF RE‐OS GEOCHRONOLOGY AND CHEMOSTRATIGRAPHY

The Oligocene – Miocene Maikop Formation is the key source rock in the South Caspian and Kura Basins. The Maikop is composed of a thick (up to 3 km) succession of clay‐rich mudstones containing up to 15% total organic carbon (TOC). Despite decades of study, the mudstones often lack precise age control – Maikop strata rarely contain diagnostic microfaunal assemblages which can be used for dating, stratigraphic correlation, or constraining the depositional setting. Using rhenium‐osmium geochronology, this study adds important numerical age data for the Maikop Formation. Of five sample suites analysed from the Kura Basin, eastern Azerbaijan, one Re‐Os data‐set produced a significant range in ¹⁸⁷Re/¹⁸⁸Os versus ¹⁸⁷Os/¹⁸⁸Os space to yield an isochron of 17.2 ± 3.2 Ma (Early Miocene). Other sample suites yielded imprecise Re‐Os age constraints as a result of variable initial ¹⁸⁷Os/¹⁸⁸Os values and a limited range in ¹⁸⁷Re/¹⁸⁸Os versus ¹⁸⁷Os/¹⁸⁸Os space. The initial ¹⁸⁷Os/¹⁸⁸Os values of these data‐sets were compared with the known ¹⁸⁷Os/¹⁸⁸Os values of seawater for the past 70 Ma to provide more qualitative age constraints. Pre‐Maikopian strata from the Perikeshkul locality were found to coincide in ¹⁸⁷Os/¹⁸⁸Os values with an isotope excursion at the Eocene – Oligocene Transition (EOT), therefore indicating that deposition of Maikopian strata began around the EOT. While values such as this match well with global values, there are several ¹⁸⁷Os/¹⁸⁸Os values that are not easily explained by global ratios. Intervals with initial ¹⁸⁷Os/¹⁸⁸Os values that deviate significantly from global ¹⁸⁷Os/¹⁸⁸Os values suggest periodic basin restriction and the development of anoxia at discrete times as the basin transitioned towards a closed system. High Os abundances outside of expected global values are often coupled with enrichment in detrital elements (Al, Ti, Ga, Sc and La) and changes in basin circulation, suggesting changing basinal conditions and sediment routing dynamics related to the initial uplift of the Greater Caucasus Mountains, changes in sediment provenance, or changing proximity to the sediment source. Through generation of isochron age dates and imprecise Re‐Os age constraints from the Maikop Formation, we gain a better understanding of the timing and nature of the evolution of the South Caspian Basin during this critical time period. Better age constrains will also help to better constrain the wealth of geochemical information already gathered within this petroleum‐rich basin.     

Ion selective electrodes based on methyl 6-(hydroxymethyl) picolinate ionophore for electrochemical determination of Fe(III) in petroleum water samples

A potentiometric method was described for the determination of iron(III) in petroleum water samples using modified carbon paste and screen-printed sensors. These sensors were embodied with multi-walled carbon nanotubes (MWCNTs) since it improved the performance of the sensors in presence of (methyl 6-(hydroxymethyl) picolinate) ionophore. The fabricated sensors can be applied successfully for the potentiometric determination of iron(III) ions in the concentration range of 1.0 × 10^?6–1.0 × 10^?2 mol L^?1 with a detection limit of 1.0 × 10^?6 mol L^?1 for modified carbon paste electrodes (MCPEs) and 2.6 × 10^?7–1 × 10^?2 mol L^?1 with a detection limit of 2.6 × 10^?7 mol L^?1 for the modified screen-printed electrode (MSPEs). The slopes of the calibration graphs were 19.9 ± 0.41 and 19.0 ± 0.16 for MCPEs with tricresylphosphate (TCP; electrode I) and dioctylsebacate (DOS; electrode II) as plasticizers, respectively. Also, the MSPEs showed good potentiometric slopes of 20.4 ± 0.30 and 19.6 ± 0.28 mV decade^?1 with tricresylphosphate (TCP; electrode III) and dioctylsebacate (DOS; electrode IV) as plasticizers, respectively. The sensors were successfully applied for the determination of Fe(III) in petroleum water samples. The results obtained applying these potentiometric sensors were comparable with those obtained using atomic absorption spectrometry (AAS).     

Kinetics and Selectivity of Asphaltene Thermal Cracking,Thermal Hydrocracking,and Catalytic Hydrocracking

Abstract

A pentane-insoluble asphaltene was processed by thermal cracking, thermal hydrocracking, and catalytic hydrocracking in a microbatch reactor at 430°C. The experimental data of asphaltene conversion fit second-order kinetics adequately to give the apparent rate constants of 1.704 × 10^?2, 2.435 × 10^?2, and 9.360 × 10^?2 wt frac^?1 min^?1 for the above three cracking processes, respectively. A three-lump kinetic model is proposed and solved to obtain rate constants of parallel reactions of asphaltenes to produce liquid oil (k₁) and gas + coke (k₃) and a consecutive reaction from liquid to gas + coke (k₂). The value of k₁ is 1.697 × 10^?2, 2.430 × 10^?2, and 9.355 × 10^?2 wt frac^?1 min^?1; k₂ is 3.605 × 10^?2, 2.426 × 10^?2, and 6.347 × 10^?3 min^?1; and k₃ is 6.934 × 10^?5, 5.416 × 10^?5, and 4.803 × 10^?5 wt frac^?1 min^?1 for asphaltenes thermal cracking, thermal hydrocracking, and catalytic hydrocracking, respectively. Analysis of selectivity shows that the catalytic hydrocracking process provides the highest liquid production, and the coking process provides the highest coke formation, as expected. An induction period of coke formation was found to increase from thermal cracking to thermal hydrocracking to catalytic hydrocracking process.     

Synthesis and characterization of Schiff base ligand as a carrier and its application for construction of new Mn(II) sensors and their use in petroleum water samples

The ligand (PBABMDP: 2,2′-((1E,1′E)-(1,3-phenylene bis(azanylylidene)) bis(methanyly-lidene))-diphenol was synthesized in a reasonable yield from 2-hydroxybenzaldehyde and m-phenylenediamine and studied using IR, mass, and ¹H NMR spectroscopy. PBABMDP has been used as a neutral carrier to make a new carbon paste (CPS) and screen-printed sensors (SPS) that are highly selective to Mn(II) ions. They revealed linear concentration ranges from 1.0 × 10^-7 to 1.0 × 10^-1 mol L^-1 for CPS (sensor I) and from 3.7 × 10^-8 to 1.0 × 10^-1 mol L^-1 for SPS (sensor II), respectively, with Nernstian slopes of 29.01 ± 0.97 and 29.96 ± 0.57 mV decade^-1. For sensor I and sensor II, the detection limit, and the response time of the sensors were: 1.0 × 10^-7 and 3.7 × 10^-8 mol L^-1 and 9 and 6 s, respectively. Without observe a divergence, the paste may be used for more than 95 or 182 days and the sensors can be used between 4.0 and 7.5 pH and 3.0 to 8.5 pH. For sensor I and II, the isotherm coefficient of the sensors was 0.000105 and 0.000168 V/^oC. The proposed sensors were applied to the determination of Mn(II) ions in real petroleum water samples. The results achieved using this potentiometric method and those obtained with AAS were well agreed.     

沥青质热裂解、临氢热裂解和临氢催化裂解反应动力学

 实验考察了1种正戊烷不溶解的沥青质在703 K下的热裂解、临氢热裂解和由 NiMo/γ-Al₂O₃催化的临氢裂解反应。3种沥青质转化反应都能较好地吻合二级反应动力学,得到的表观速率常数分别为1.704×10^-2、 2.435×10^-2和9.360×10^-2。建立三集总动力学模型,用于求解沥青质裂解转化生成液体油反应速率常数(k₁)和与之平行的生成焦炭＋气体反应速率常数（k₃）,以及由液体产物继续转化生成焦炭＋气体的反应速率常数（k₂）。对沥青质热裂解、临氢热裂解和临氢催化裂解反应,速率常数 k₁分别为1.697×10^-2、 2.430×10^-2和9.355×10^-2, k₂分别为3.605×10^-2、 2.426×10^-2和6.347×10^-3, k₃分别为6.934×10^-5、 5.416×10^-5和4.803×10^-5。     

The Effects of Weight Hour Space Velocity on the Products Distribution of Aromatization Reaction of Lanlian FCC Gasoline

Abstract

By using Lanlian fluid catalytic cracked (FCC) gasoline as a feedstock, the effects of weight hour space velocity (WHSV) on the product distribution, light oil compound, off-gas, and liquefied petroleum gas were researched in a confined fluidized bed reactor. The equation of off-gas yield, liquefied petroleum gas yield, coke yield, and light oil yield with increasing WHSV were established in the experimental data. The experimental result showed that with increasing WHSV, coke, off-gas, and liquefied petroleum gas yield decreased gradually, and light oil yield increased piece by piece; the amount of olefin was enhanced step by step, that of aromatics dropped slowly, and that of saturated hydrocarbon did not change. However, olefin conversion and increasing ratio of aromatics presented a slowly decreasing trend and increasing ratio of saturated hydrocarbon showed no change; hydrogen yield was low and did not change; i-butane and propane decreased, but n-butane increased gradually; C⁰ ₃/C⁼ ₃ and nC⁰ ₄/nC⁼ ₄ values did not change, iC⁰ ₄/iC⁼ ₄ variety had no order; C⁰ ₃/C⁼ ₃, C⁰ ₄/C⁼ ₄, and (C⁰ ₃ + C⁰ ₄)/(C⁼ ₃ + C⁼ ₄) values showed a decreasing trend.     

Synergism between MC-MA-MCNR<Superscript>2</Superscript> terpolymer and EVA as a cold flow improver in diesel fuel

A novel terpolymer, MC-MA-MCNR², derived from tetradecyl methacrylate (MC), maleic anhydride (MA), and methacrylamide (MCNR²) was synthesized. The ability of MC-MA-MCNR² was evaluated as a cold flow improver in diesel fuel, and the interactions of MC-MA-MCNR² with several kinds of copolymer were studied. To provide a better understanding of the synergistic mechanism, microscopy was used to study the crystal conformation when MC-MA-MCNR² and EVA (ethylene-vinyl acetate) are mixed into a diesel fuel. The results indicate that using blends of MC-MA-MCNR² and EVA, one can obtain a satisfactory cold filter plugging point depression. Based on the microscopy experiment, the synergism mechanism was discussed. Published in Khimiya i Tekhnologiya Topliv i Masel, No. 4, pp. 21–23, 2007.