Property modification of jatropha oil biodiesel by blending with other biodiesels or adding antioxidants

The feasibility of biodiesel production from jatropha (Jatropha curcas) oil was investigated with respect to the biodiesel blending properties and its oxidation stability with antioxidants. The JME (jatropha oil methyl esters) had the cetane number of 54, cold filter plugging point of −2 °C, density of 881 kg/m³ at 15 °C, ester content of 99.4 wt.%, iodine value of 96.55 g I₂/100 g, kinematic viscosity of 4.33 mm²/s at 40 °C, and oxidation stability of 3.86 h. Furthermore, the JME was blended with palm oil biodiesel and soybean oil biodiesel at various weight ratios and evaluated for fuel properties as compared to the relevant specifications. In addition, several antioxidants at concentrations between 100 and 1000 ppm were studied for their potential to improve the oxidation stability of the JME. The relationship between the IP (induction period) in the measurement of the oxidation stability associated with the antioxidant consumption in the JME was described by first-order reaction rate kinetics. Moreover, the ln IP (natural logarithm of the IP) at various concentrations of pyrogallol showed a linear relationship with the test temperature. The oxidation stability at ambient temperatures was predicted on the basis of an extrapolation of the temperature-dependent relationship.     

Castor oil biodiesel and its blends as alternative fuel

Intensive production and commercialization of biodiesel from edible-grade sources have raised some critical environmental concerns. In order to mitigate these environmental consequences, alternative oilseeds are being investigated as biodiesel feedstocks. Castor (Ricinus communis L.) is one of the most promising non-edible oil crops, due to its high annual seed production and yield, and since it can be grown on marginal land and in semi-arid climate. Still, few studies are available regarding its fuel-related properties in its pure form or as a blend with petrodiesel, many of which are due to its extremely high content of ricinoleic acid. In this study, the specifications in ASTM D6751 and D7467 which are related to the fatty acid composition of pure castor methyl esters (B100) and its blend with petrodiesel in a 10% vol ratio (B10) were investigated. Kinematic viscosity and distillation temperature of B100 (15.17 mm² s⁻¹ and 398.7 °C respectively) were the only two properties which did not meet the appropriate standard limits. In contrast, B10 met all the specifications. Still, ASTM D7467 requires that the pure biodiesel meets the requirements of ASTM D6751. This can limit the use of a wide range of feedstocks, including castor, as alternative fuel, especially due to the fact that in practice vehicles normally use low level blends of biodiesel and petrodiesel. These issues are discussed in depth in the present study.     

Hydrogen production from diluted and raw sugarcane vinasse under thermophilic anaerobic conditions

Two continuous anaerobic fluidized bed reactors (AFBRs) were operated under thermophilic (55 °C) temperature for 150 days to investigate the effect of dark H₂ fermentation of diluted and raw sugarcane vinasse on H₂ production using mixed seed sludge. Although effective H₂ production (52.8% of H₂; 0.80 L H₂ h⁻¹ L⁻¹; 0.79 mmol gCOD_added⁻¹) was observed using an elevated substrate concentration (30,000 mg COD L⁻¹), the optimal operational conditions were found for the AFBR₁ (10,000 mg COD L⁻¹) fed with diluted sugarcane vinasse (HRT 6 h; OLR 40 kg COD m⁻³ d⁻¹), achieving a H₂ yield of 2.86 mmol H₂ g COD_added⁻¹. H₂ production was inhibited by elevated volatile fatty acid (VFA) concentrations (butyric and acetic acids = 3.7 and 3.0 g L⁻¹, respectively) in the raw feedstock. Denaturing gradient gel electrophoresis (DGGE) analyses revealed changes in the bacterial population of the expanded clay biofilm as a function of the substrate concentration.     

Kapok oil methyl esters

The increased need for biodiesel feedstocks has caused various vegetable oils to be examined for this purpose. In the present work, the methyl esters of kapok (Ceiba pentandra) oil were prepared. The essential fuel properties were comprehensively determined and evaluated in comparison to specifications in biodiesel standards and some prior results. The kinematic viscosity of kapok oil methyl esters was greater than expected, an observation traced to the elevated amounts of methyl esters with cyclic moieties. Overall, kapok oil is a potential biodiesel feedstock. The ¹H and ¹³C NMR spectra of kapok methyl esters are reported.     

Net energy balance of small-scale on-farm biodiesel production from canola and soybean

One necessary criterion for a biofuel to be a sustainable alternative to the petroleum fuels it displaces is a positive net energy balance. This study estimated the net energy ratio (NER), net energy balance (NEB), and net energy yield (NEY) of small-scale on-farm production of canola [Brassica napus (L.)] and soybean [Glycine max (L.)] biodiesel in the upper Midwest. Direct and embodied energy inputs based on well-defined system boundaries and contemporary data were used to estimate the energy requirement of crop production, oil extraction, and biofuel processing. The NER of canola biodiesel was 1.78 compared with 2.05 for soybean biodiesel. Canola biodiesel had a NEB of 0.66 MJ MJ⁻¹ of biofuel compared with 0.81 MJ MJ⁻¹ for soybean biodiesel. The NEY of soybean biodiesel was 10,951 MJ ha⁻¹, less than canola biodiesel which had a NEY of 11,353 MJ ha⁻¹. Use of soybean as a biodiesel feedstock was more energetically efficient than canola primarily due to reduced nitrogen fertilizer requirement. In terms of energetic productivity, canola was a more productive biodiesel feedstock than soybean due to its higher oil content. A best-case scenario based on optimal feedstock yields, reduced fertilizer input, and advanced biofuel processing equipment suggested that potential gains in energetic efficiency was greater for canola than soybean. According to our results, small-scale on-farm biodiesel production using canola and soybean can be an energetically efficient way to produce energy for on-farm use.     

Genetic variability in Cynara cardunculus L. domestic and wild types for grain oil production and fatty acids composition

This paper aimed to study the genetic variability within different types of Cynara cardunculus L., domestic and wild types, for their grain oil amount and oil fatty acid composition.The grain oils were extracted from 8 domestic cardoons and 4 wild cardoons, by Soxhlet method, and obtained oils were characterized for palmitic, stearic, oleic and linoleic acids by gas chromatography.The oil amount, resulted on average of accessions 216 g kg⁻¹ DM with a good range of variability (CV = 11.7%). Unsaturated acids (oleic and linoleic) predominated over saturated ones (stearic and palmitic acids), the chemical characterization of extracted oil, showed the main compound (as % of analysed fatty acids), averaged for all populations, was linoleic acid (44.5%), followed by oleic acid (42.6%), palmitic acid (9.8%) and stearic acid (3.1%). In particular referring the oleic acid wild cardoon populations showed a mean value of 289 g kg⁻¹ oil, against a mean value of 472 g kg⁻¹ oil showed by domestic cardoon accessions. Three of the studied domestic cardoon (‘DC1’, ‘DC3’ and ‘DC7’) showed values higher than 795 g kg⁻¹ oil, while all the other accessions had concentration lower than 370 g kg⁻¹ oil.The three types of domestic cardoon ‘DC1’, ‘DC3’ and ‘DC7’ showed a fatty acids profile similar to genetic modified sunflower oil, representing new genetic material that potentially could be used for high quality biodiesel production, characterised by a low Iodine Number.     

Assessment of tree seed oil biodiesel: A comparative review based on biodiesel of a locally available tree seed

The present investigation is undertaken to investigate prospect of seeds of a locally available tree (koroch) for biodiesel production. The middle-size, evergreen koroch tree with spreading branches are available in Assam. The characteristics of koroch biodiesel and engine performance fueled by koroch biodiesel are also analyzed reviewing similar results available in the literature so as to ascertain its status. Twelve number of different tree seed oils, reported earlier, are considered for making the present comparative assessment. Though transesterification has been the common process for converting tree seed oil into biodiesel, as evidenced from the literature consulted in this study, but there have been variations of the chemical processes. Variations of the transesterification are attributed to (i) types of catalysis viz., acid (H₂SO₄) or base (KOH, NaOH, and NaOCH₃), (ii) reaction temperature, (iii) molar ratio, (iv) nature of reaction viz., single stage or multi-stage. The outputs of the reaction have also been found varying in terms of yield as well as quality. Quality of biodiesel, however, was found to influence by the nature of feedstock. The assessment of quality parameters was made either by ASTM D 6751 or EN 14214 standards. The major fuel properties such as calorific value, kinematic viscosity, cetane number and cloud point of the reference biodiesel (koroch biodiesel) are compared with the properties of five biodiesel obtained from non-edible tree seed (karanja, mahua, polonga, jatropha and rubber seed) and then ranked them in order of desirable property. No single biodiesel type could be found at top rank with reference to more than one property. With regards to viscosity, except rubber seed biodiesel, all other biodiesels (karanja, mahua, polonga, jatropha and koroch) fulfilled the ASTM D 6751 (1.9-6 cSt) as well as EN14214 (3.5-5) standards. Koroch biodiesel ranks 3rd, 3rd and 6th in case of kinematic viscosity, cetane number and calorific value amongst the biodiesel types considered for the present study. Cloud point of koroch, polanga, mahua, rubber, karanja and jatropha biodiesels are 4, 13.2, 5, 4, 12 and 4 °C. Further, properties of biodiesel were found to have influencing correlation with the fatty acid characteristics of the feedstock. Therefore, biodiesel with desirable properties could be expected form optimum mixing of different feedstock.Eleven number of different engine performance results pertaining to uses of biodiesel are also reviewed in this paper. Varying test conditions with reference to fuel types and blends, engine size and loading pattern are discussed. Engine performance results of koroch biodiesel were then compared with five similar tree-based biodiesel. It is observed that tree seed oil with more unsaturated fatty acids exhibits lower thermal efficiency compared to biodiesel having more saturated acids.     

Methyl ester of peanut (Arachis hypogea L.) seed oil as a potential feedstock for biodiesel production

The peanut (Arachis hypogea L.) seed oil was extracted from the seeds of the peanut that grows in SE Anatolia of Turkey. Oil was obtained in 50 wt/wt.%, by solvent extraction. Peanut (A. hypogea L.) seed oil was investigated as an alternative feedstock for the production of a biodiesel fuel. Biodiesel was prepared from peanut by transesterification of the crude oil with methanol in the presence of NaOH as catalyst. A maximum oil to ester conversion was 89%. The viscosity of biodiesel oil is nearer to that of petroleum diesel and the calorific value is about 6% less than that of diesel. Peanut seed oil have about 8.3% less heating value than that of diesel oil due to the oxygen content in their molecules. The quality of biodiesel is most important for engine part of view and various standards have been specified to check the quality. The important properties of peanut oil and its methyl ester (biodiesel) such as density, kinematic viscosity, flash point, iodine number, neutralization number, pour point, cloud point, cetane number are found out and compared to those of no. 2 petroleum diesel, ASTM and EN biodiesel standards. The comparison shows that the methyl ester has relatively closer fuel properties to diesel than that of raw peanut seed oil.     

Pyrolysis of black cumin seed cake in a fixed-bed reactor

The black cumin seed cake (BCSC) is a by-product obtained from the black cumin seeds with cold pressing. This by-product can be utilized as a biomass feedstock for conversion to bio-oil with pyrolysis process. The BCSC samples were initially pyrolyzed on a lab-scale pyrolysis system at different values in the ranges of 300-800 °C and 0.050-0.300 L min⁻¹ to determine the effects of operation temperature and N₂ flow rate on the yields on products, respectively. Then, the bio-oil in the highest yield (wB = 44.37%) which was obtained at pyrolysis final temperature (450 °C) temperature, heating rate (35 °C min⁻¹), particle size (dp > 850 ??m), and sweeping flow rate of 0.200 L min⁻¹ was characterized by Fourier Transform infra-red (FT-IR) spectroscopy, gas chromatography/mass spectrometry (GC-MS) and column chromatography. Consequently, it was shown that the operating temperature and N₂ gas flow rate parameters were effective on the product yields. Also, the important some physico-chemical properties of the pyrolytic oil obtained in high yield were determined as the calorific value of 38.48 MJ kg⁻¹, the empirical formula of CH_1.651O_0.105N_0.042S_0.001, the rich chemical content containing many different chemical groups, and the density of 970.25 kg m⁻³, and the viscosity of 63.42 mm² s⁻¹. Based on the determined properties of the pyrolytic oil, it was decided that the use of pyrolytic oil derived from the BCSC may possible be for the production of the alternative liquid fuels and finely chemicals after the necessary improvements.     

Economics of small-scale on-farm use of canola and soybean for biodiesel and straight vegetable oil biofuels

While the cost competitiveness of vegetable oil-based biofuels (VOBB) has impeded extensive commercialization on a large-scale, the economic viability of small-scale on-farm production of VOBB is unclear. This study assessed the cost competitiveness of small-scale on-farm production of canola- [Brassica napus (L.)] and soybean-based [Glycine max (L.)] biodiesel and straight vegetable oil (SVO) biofuels in the upper Midwest at 2007 price levels. The effects of feedstock type, feedstock valuation (cost of production or market price), biofuel type, and capitalization level on the cost L⁻¹ of biofuel were examined. Valuing feedstock at the cost of production, the cost of canola-based biodiesel ranged from 0.94 to 1.13 $ L⁻¹ and SVO from 0.64 to 0.83 $ L⁻¹ depending on capitalization level. Comparatively, the cost of soybean-based biodiesel and SVO ranged from 0.40 to 0.60 $ L⁻¹ and from 0.14 to 0.33 $ L⁻¹, respectively, depending on capitalization level. Valuing feedstock at the cost of production, soybean biofuels were cost competitive whereas canola biofuels were not. Valuing feedstock at its market price, canola biofuels were more cost competitive than soybean-based biofuels, though neither were cost competitive with petroleum diesel. Feedstock type proved important in terms of the meal co-product credit, which decreased the cost of biodiesel by 1.39 $ L⁻¹ for soybean and 0.44 $ L⁻¹ for canola. SVO was less costly to produce than biodiesel due to reduced input costs. At a small scale, capital expenditures have a substantial impact on the cost of biofuel, ranging from 0.03 to 0.25 $ L⁻¹.     

Hydrothermal conversion of water lettuce biomass at 473 or 523 K

The high moisture content of an aquatic biomass was used advantageously in a hydrothermal process. Reducing sugars, amino acids, proteins, and crude oil were extracted from water lettuce (Pistia stratiotes L.) using subcritically heated water. The highest yields of reducing sugars and amino acids were obtained after treatment at 473 K for 30 min (23.70 ± 0.52 g kg⁻¹ and 4.35 ± 0.09 g kg⁻¹ dry mass respectively), while protein was obtained at 3.60 ± 0.04 g kg⁻¹ feedstock after treatment at 523 K for 60 min. The greatest solubilization occurred at 523 K after 60 min. The solid residues could be applied as fertilizers as hemicellulose and cellulose were hydrothermally converted to humus. The crude oil components that were extracted from the liquid residues differed markedly between the two treatment temperatures. The conversion of furan compounds to cyclopentenone and its derivatives only occurred at the higher reaction temperature and was increased by a longer reaction time.     

Okra (Hibiscus esculentus) seed oil for biodiesel production

Biodiesel was derived from okra (Hibiscus esculentus) seed oil by methanol-induced transesterification using an alkali catalyst. Transesterification of the tested okra seed oil under optimum conditions: 7:1 methanol to oil molar ratio, 1.00% (w/w) NaOCH₃ catalyst, temperature 65 °C and 600 rpm agitation intensity exhibited 96.8% of okra oil methyl esters (OOMEs) yield. The OOMEs/biodiesel produced was analyzed by GC/MS, which showed that it mainly consisted of four fatty acids: linoleic (30.31%), palmitic (30.23%), oleic (29.09%) and stearic (4.93%). A small amount of 2-octyl cyclopropaneoctanoic acid with contribution 1.92% was also established. Fuel properties of OOMEs such as density, kinematic viscosity, cetane number, oxidative stability, lubricity, flash point, cold flow properties, sulfur contents and acid value were comparable with those of ASTM D 6751 and EN 14214, where applicable. It was concluded that okra seed oil is an acceptable feedstock for biodiesel production.     

The influence of free fatty acid intermediate on biodiesel production from soybean oil by whole cell biocatalyst

The whole cell of lipase-producing Rhizopus oryzae was employed as biocatalyst for transesterification of soybean oil containing oleic acid. The free fatty acid (FFA) intermediate, playing an important role in the kinetics of transesterification of soybean oil, was thoroughly investigated and characterized. The conversion was more than 97% at the initial FFA content of 5.5%. A high content of FFA could protect the lipase from denaturation. The 34.6 percent of FFA with the optimal 26-mg mL⁻¹ methanol resulted in a specific reaction rate of 420 mg h⁻¹g-dry cell⁻¹. In addition, the methanol/FFA ratio at 0.83-1.7 provides a good indication of the fatty acid methyl esters conversions for different initial FFA contents. In the transesterification process, more FFA intermediate present would become beneficial to conversion of retrograde feedstock to biodiesel. The immediately generated and original FFA content become the major rate-determining factor in the FFA-mixed transesterification process.     

Microbial lipid production by the oleaginous yeast Cryptococcus curvatus O3 grown in fed-batch culture

This study investigates the capability of the oleaginous yeast Cryptococcus curvatus O3 to synthesize microbial lipids using glucose as its sole carbon source. Both glucose concentration and varying nitrogen sources have a significant effect on cell growth and microbial lipid accumulation in batch and fed-batch cultures. When cultivated in a shaking flask at 30 °C with glucose as sole carbon source, the cellular biomass and lipid content reached 51.8 kg m⁻³ and 651 g kg⁻¹, respectively. The fed-batch culture in a 30 × 10⁻³ m³ stirred-tank fermentor run for 185 h produced a cellular biomass, lipid content, and lipid productivity rate of up to 104.1 kg m⁻³, 827 g kg⁻¹, and 0.47 kg m⁻³ h⁻¹, respectively. These data indicate that C. curvatus O3 can be used as an ideal oleaginous yeast for microbial lipid production. Gas chromatography analysis of the synthesized microbial lipids revealed that the major constituents are long-chain fatty acids, such as palmitic acid, stearic acid, oleic acid, and linoleic acid. The results suggest that the microbial lipids produced by C. curvatus O3 can be used to produce biodiesel.     

Production of microbial oil with high oleic acid content by Trichosporon capitatum

Microbial oils with high unsaturated fatty acids content, especially oleic acid content, are good feedstock for high quality biodiesel production. Trichosporon capitatum was found to accumulate lipid with around 80% oleic acid and 89% total unsaturated fatty acids content on nitrogen-limited medium. In order to improve its lipid yield, effects of medium components and culture conditions on cell growth and lipid accumulation were investigated. Optimization of media resulted in a 61% increase in the lipid yield of T. capitatum after cultivation at 28 °C and 160 rpm for 6 days. In addition, T. capitatum could grow well on cane molasses and afford a lipid yield comparable to that on synthetic nitrogen-limited medium. The biodiesel from the microbial oil produced by T. capitatum on cane molasses displayed a low cold filter plugging point (−15 °C), and so T. capitatum might be a promising strain to provide lipid suitable for high quality biodiesel production.     

Utilization of waste freshwater mussel shell as an economic catalyst for biodiesel production

An economic and environmentally friendly catalyst derived from waste freshwater mussel shell (FMS) was prepared by a calcination-impregnation-activation method, and it was applied in transesterification of Chinese tallow oil. The as-prepared catalyst exhibits a “honeycomb” -like structure with a specific surface area of 23.2 m² g⁻¹. The newly formed CaO crystals are major active phase of the catalyst. The optimal calcination and activity temperature are 900 °C and 600 °C, respectively. When the reaction is carried out at 70 °C with a methanol/oil molar ratio of 12:1, a catalyst concentration of 5% and a reaction time of 1.5 h, the FMS-catalyst is active for 7 reaction cycles, with the biodiesel yield above 90%. The experimental results indicate that the FMS can be used as an economic catalyst for the biodiesel production.     

Reduction of tars by dolomite cracking during two-stage gasification of olive cake

The effective implementation of biomass gasification has to overcome some difficulties such as the minimization of tars. On the other hand, with a proper design of experimental conditions, biomass gasification can be directed towards the production of hydrogen. The aim of the present study was to investigate the use of dolomite as catalyst to improve tar removal and hydrogen production by a two-stage steam gasification process, using olive cake as raw material. Fixing the olive cake gasification conditions on the first reactor (900 °C, steam flow rate of 190 mg min⁻¹, O₂ flow rate of 7.5 cm³ min⁻¹), the cracking of tars was prompted by: a) steam gasification (steam flow rate in the range 40-190 mg min⁻¹) at 1000 °C, b) catalytic gasification, using dolomite (5% wt.). It was found that increasing steam flow rate up to 110 mg min⁻¹ involves an increase in hydrogen fraction due to the enhancement of water gas and water gas shift reactions. Also, the influence of dolomite was studied at 800 and 900 °C in a second reactor, finding better results at 800 °C, which gave an hydrogen fraction of 0.51.     

Biodiesel production from swine manure via housefly larvae (Musca domestica L.)

Although biodiesel is a sustainable and renewable diesel fuel, the current feedstock predominantly from edible oils limits the economic feasibility of biodiesel production and thus the development of a cost-effective non-food feedstock is really essential. In this study, approximately 21.6% of crude grease was extracted from housefly (Musca domestica L.) larvae reared on swine manure, and the extracted grease was evaluated for biodiesel production concerning the variables affecting the yield of acid-catalyzed production of methyl esters and the properties of the housefly larvae-based biodiesel. The optimized process of 8:1 methanol/grease (mol/mol) with 2 vol% H₂SO₄ reacted at 70 °C for 2 h resulted in a 95.7% conversion rate from free fatty acid (FFA) into methyl esters. A 90.3% conversion rate of triglycerides (crude grease) to its esters was obtained from alkaline trans-esterification using sodium hydroxide as catalyst. The major fatty acid components of this larvae grease were palmitic (29.1%), oleic (23.3%), palmitoletic (17.4%) and linoleic (17.2%). The housefly larvae-based biodiesel has reached the ASTM D6751-10 standard in density (881 kg/m³), viscosity (5.64 mm²/s), ester content (96.8%), flash point (145 °C), and cetane number (52). These findings suggest that the grease derived from swine manure-grown housefly larvae can be a feasible non-food feedstock for biodiesel production.     

Performance evaluation of artificial neural network coupled with generic algorithm and response surface methodology in modeling and optimization of biodiesel production process parameters from shea tree (Vitellaria paradoxa) nut butter

This work investigated the potential of shea butter oil (SBO) as feedstock for synthesis of biodiesel. Due to high free fatty acid (FFA) of SBO used, response surface methodology (RSM) was employed to model and optimize the pretreatment step while its conversion to biodiesel was modeled and optimized using RSM and artificial neural network (ANN). The acid value of the SBO was reduced to 1.19 mg KOH/g with oil/methanol molar ratio of 3.3, H₂SO₄ of 0.15 v/v, time of 60 min and temperature of 45 °C. Optimum values predicted for the transesterification reaction by RSM were temperature of 90 °C, KOH of 0.6 w/v, oil/methanol molar ratio of 3.5, and time of 30 min with actual shea butter oil biodiesel (SBOB) yield of 99.65% (w/w). ANN combined with generic algorithm gave the optimal condition as temperature of 82 °C, KOH of 0.40 w/v, oil/methanol molar ratio of 2.62 and time of 30 min with actual SBOB yield of 99.94% (w/w). Coefficient of determination (R²) and absolute average deviation (AAD) of the models were 0.9923, 0.83% (RSM) and 0.9991, 0.15% (ANN), which demonstrated that ANN model was more efficient than RSM model. Properties of SBOB produced were within biodiesel standard specifications.     

Biodiesel potential of the seed oils from some Brazilian native Euphorbiaceae species

In the present study, the oil content, fatty acid composition and physicochemical properties of seed oils and biodiesel from seven species of Euphorbiaceae were analyzed. The oil content from seven Brazilian native Euphorbiaceae species ranged from 25.4 to 48.5%. Nine primarily unsaturated fatty acids were identified in seed oils. Actinostemon concolor and Stillingia trapezoidea seeds accumulated mainly oleic and linoleic acids, whereas in the seeds of Croton floribundus, Croton nepetifolius, Euphorbia comosa and Microstachys corniculata, linoleic and linolenic acids were the main constituents identified. Palmitic and oleic acids were predominantly detected in the seeds of Sapium glandulosum. In general, the oils showed low acidity, viscosity and free fatty acids. The results suggest that the seed oils from A. concolor, S. glandulosum and S. trapezoidea might be a viable alternative for biodiesel production, while those from C. floribundus, C. nepetifolius, E. comosa and M. corniculata seeds have great potential for application in the paint, varnish and lubricant industries. Due to the high content of saturated fatty acids, the seeds of S. glandulosum could also be used to produce soaps and detergents. For most species analyzed, the biodiesel specifications are in accordance with EN 14214 and ASTM D6751 standards.