Fluid Solvent Research Articles

Energy-saving aspects of the process of extraction of bioactive compounds from plant raw materials with supercritical fluid solvents

THE PURPOSE. Study of extraction processes of plant raw materials with a wide range of biologically active properties, supercritical carbon dioxide used as a solvent, as well as with the addition of ethanol, used as a co-solvent, to supercritical carbon dioxide in a ratio of 5% to the total consumption at a temperature of 313 K and pressure 30 MPa. METHODS. The study of extraction processes was carried out by the method of supercritical fluid extraction, which is effective and environmentally friendly compared to traditional methods for obtaining extracts. The experimental setup, equipped with two plunger pumps, allowed the implementation of a dynamic extraction method with both supercritical carbon dioxide and carbon dioxide with the addition of ethanol. RESULTS. The final extract yields were obtained for Valeriána officinális, Hypericum, Matricaria and Salvia at a temperature of 313 K and a pressure of 30 MPa using pure carbon dioxide and a carbon dioxide/ethanol mixture as a solvent. Based on the results of experimental data, the dependence of the mass yield of the extract on the extraction time was plotted. This determines the extraction rate of each sample. CONCLUSION. The experimental data obtained indicate that for each of the samples of plant raw materials, the use of supercritical carbon dioxide modified with ethanol in a ratio of 95 and 5%, respectively, leads to an increase in the yield of the extract. This, in turn, leads to a reduction in energy costs when implementing the extraction process using the proposed method on an industrial scale.

Alternative Solvents for Life: Framework for Evaluation, Current Status, and Future Research.

Life is a complex, dynamic chemical system that requires a dense fluid solvent in which to take place. A common assumption is that the most likely solvent for life is liquid water, and some researchers argue that water is the only plausible solvent. However, a persistent theme in astrobiological research postulates that other liquids might be cosmically common and could be solvents for the chemistry of life. In this article, we present a new framework for the analysis of candidate solvents for life, and we deploy this framework to review substances that have been suggested as solvent candidates. We categorize each solvent candidate through the following four criteria: occurrence, solvation, solute stability, and solvent chemical functionality. Our semiquantitative approach addresses all the requirements for a solvent not only from the point of view of its chemical properties but also from the standpoint of its biochemical function. Only the protonating solvents fulfill all the chemical requirements to be a solvent for life, and of those only water and concentrated sulfuric acid are also likely to be abundant in a rocky planetary context. Among the nonprotonating solvents, liquid CO2 stands out as a planetary solvent, and its potential as a solvent for life should be explored. We conclude with a discussion of whether it is possible for a biochemistry to change solvents as an adaptation to radical changes in a planet's environment. Our analysis provides the basis for prioritizing future experimental work to explore potential complex chemistry on other planets. Key Words: Habitability-Alternative solvents for life-Alternative biochemistry. Astrobiology 24, 1231-1256.

Comprehensive analysis of oils and remaining solid matrices from supercritical fluid extraction of salmon side streams: Fatty acids, bioactive peptides, minerals, and heavy metals

Atlantic salmon (Salmo salar) side streams (head, backbone, and viscera) are nutrient-rich and offer potential for valorization. This study evaluates supercritical fluid extraction (SFE) and solvent extraction (SE) methods for recovering oils, fatty acids, bioactive peptides, minerals, heavy metals, and antioxidants from these byproducts. Both the oil and the remaining solid resulting from the extraction process were analyzed. SFE was more effective in extracting fatty acids from heads and backbones. However, SE yielded a higher peptide content, with SE backbone solids containing 281 peptides, and SE viscera and heads containing 220 peptides each. In contrast, SFE-derived solids had significantly fewer peptides: 9 in heads, 129 in backbones, and 130 in viscera. The identified peptides exhibit potential functional properties, including antioxidant, anti-inflammatory, antithrombotic, immunomodulating, anticancer, and hypolipidemic effects. Mineral and heavy metal content in all extracts met safety standards. SFE-derived matrices had the highest calcium levels (49.7 mg/g in heads, 24.2 mg/g in backbones) and lower heavy metal concentrations than SE. Arsenic, cadmium, mercury, and lead levels were 1.8 mg/kg, 1.8 μg/kg, 55.0 μg/kg, and 25.7 μg/kg, respectively, for SFE, compared to SE's higher values (e.g., 3.5 mg/kg for arsenic). Both methods produced extracts with promising antioxidant activity.

The Navier-Stokes equation and a fully developed turbulence

In fairly general conditions we give explicit (smooth) solutions for the potential flow. We show that, rigorously speaking, the equations of the fluid mechanics have not rotational solutions. However, within the usual approximations of an incompressible fluid and an isentropic flow, the Navier-Stokes equation has approximate vorticial (rotational) solutions, generated by viscosity. However, in general, these vortices are unstable, and a discrete distribution of vorticial solutions is not in me chanical equilibrium; it forms an unstable vorticial liquid. On the other hand, these solutions may exhibit turbulent, fluctuating instabilities for large variations of the velocity over short distances. We represent a fully developed turbulence as a homogeneous, isotropic and highly-fluctuating distribution of singular centres of turbulence. A regular mean flow can be included. In these circumstances the Navier-Stokes equation exhibits three time scales. The equations of the mean flow can be disentangled from the equations of the fluctuating part, which is reduced to a vanishing inertial term. This latter equation is not satisfied after averaging out the temporal fluctuations. For a homogeneous and isotropic distribution of non-singular turbulence centres the equation for the inertial term is satisfied trivially, i.e. both the average fluctuating velocity and the average fluctuating inertial term are zero. If the velocity is singular at the turbulence centres, we are left with a quasi-ideal classical gas of singularities, or a solution of singularities (solute) in quasi thermal equilibrium in the background fluid (solvent). This is an example of an emergent dynamics. We give three examples of vorticial liquids.

Methods for Making a Nanosuspension of Poorly Soluble Medications

Class II prescriptions are known to dissolve ineffectively in both natural and fluid solvents, making them a significantly more challenging challenge. When it comes to these kinds of high log P synthetic compounds that are insoluble in water, the nanosuspension structure is desired. The overall bioavailability of nanosuspensions is influenced by an increase in surface area and a decrease in molecule size. Sometimes the oral dosage forms of water-soluble drugs that are slowly absorbed and inefficient show insufficient bioavailability. A drug's permeability and solubility have a significant impact on how bioavailable it is. To create sub-micron-sized particles, a suitable emulsifier and a pharmaceutical mixture are fed through a high-pressure homogenization or milling procedure. Both classic milling and precipitation processes are commonly used to create particles larger than one millimetre. In this investigation, the techniques was used to prepare the nanosuspension for improving the solubility of poorly soluble drugs.

Evaluation of Moringa oleifera seed oil extracted with different extraction methods

Moringa seed oil composition extracted with different methods such as supercritical fluid extraction (SFE), soxhlet extraction (SOXE) and solvent extraction (SE) was evaluated and compared. The oil yield obtained by SFE, SE and SOXE was 25.25, 27.53 and 29.81%, respectively. There were slightly significant differences among SFE, SOXE and SE oils in their refractive indices, peroxide values, tocopherols, carotenoids, β-sitosterol and campesterol contents. However, SOXE and SE oils showed no significant differences in their TBA, unsaponifiable matter, phenols, flavonoids, oxidative stability, oleic acid, stigmasterol, Δ7- avenasterol and Δ5-avenasterol contents. Furthermore, SFE oil showed significantly higher unsaponifiable matter, phenols, flavonoids, tocopherols, carotenoids, oleic acid, unsaturated fatty acids to saturated fatty acids ratio, sterols contents and oxidative stability. The high content of tocopherol, phenols, and flavonoids of the Moringa oils could be attributed to the higher resistance to oxidation, especially extracted by SFE. These results promote the use of SFE for the extraction of high quality Moringa oil. extraction of high quality.

Towards a Greener Approach for Biomass Valorization: Integration of Supercritical Fluid and Deep Eutectic Solvents.

A green and sustainable procedure for obtaining Lavandula stoechas extracts with antioxidant and antimicrobial properties was investigated. Green solvents, supercritical CO2, and natural deep eutectic solvents (NADES) together with ultrasound-assisted extraction were used for the sequential extraction of terpene and polyphenols fractions. After the CO2 extraction of the terpene fraction, the residue material was used in an extraction with different NADES (betaine-ethylene glycol (Bet:EG), betaine-glycerol (Bet:Gly), and glycerol-glucose (Gly:Glu)), intensified with an ultrasound-assisted method (at 30 and 60 °C). In the CO2 extract, the major group of components belonged to oxygenated monoterpenes, while the highest polyphenol content with the dominant rutin (438.93 ± 4.60 µg/mL) was determined in Bet:EG extracts (60 °C). Bet:EG extracts also exhibited the most potent antioxidant activity according to DPPH, ABTS, and FRAP assays. Moreover, Bet:EG extracts showed significant inhibitory activity against Gram-positive and Gram-negative bacteria, with minimum inhibitory activity of 0.781-3.125 and 1.563-6.250 mg·mL-1, respectively. By comparing the polyphenolic content and antioxidant and antimicrobial activities of Bet:EG extracts with extracts obtained with conventional solvents (water and ethanol), the superiority of NADES was determined. The established environmentally friendly procedure unifies the requirements of green and sustainable development and modern pharmacognosy because it combines the use of safe alternative solvents, the absence of solvent waste generation, more rational use of resources, and the attainment of safe and quality extracts.

Towards a greener approach for biomass valorization: Integration of supercritical fluid and deep eutectic solvents

Towards a greener approach for biomass valorization: Integration of supercritical fluid and deep eutectic solvents

Ultrasound assisted extraction of oils from apple seeds: A comparative study with supercritical fluid and conventional solvent extraction

The aim of this study was to optimize the processing conditions for the extraction of apple seed oil by applying ultrasounds (UAE) using hexane as solvent. A response surface methodology with a central composite design identified the following optimized parameters: 56 W of power (64% amplitude), 30 min at 30 °C. The obtained oil presented a fatty acids profile rich in linoleic acid (35.5 ± 2.8 g/100 g) with an antioxidant activity equal to 0.22 ± 0.1 mg Trolox/g oil and a total phenolic content of 0.16 ± 0.1 mg GAE/o oil. The chemical characteristics of the UAE oil were then compared with those obtained for the oils extracted with Soxhlet (SE) and supercritical fluid (SFE). UAE gave similar yields (17.20 ± 2.3%) compared to SFE (19.3 ± 2.1%), and SE (19.1 ± 1.5%). Fatty acid profiles were also not significantly different (p < 0.05). The UAE oil was richer in antioxidants like phloretin and phloridzin. Amygdalin was detected in UAE and SE oils but not in SFE oil. The comparison among the processes showed that the UAE was a more efficient and time-saving technique, while SFE was able to provide an oil free from amygdalin suitable for possible further food applications.

Inertial effects on rectification and diffusion of active Brownian particles in an asymmetric channel.

Micro- and nano-swimmers, moving in a fluid solvent confined by structures that produce entropic barriers, are often described by overdamped active Brownian particle dynamics, where viscous effects are large and inertia plays no role. However, inertial effects should be considered for confined swimmers moving in media where viscous effects are no longer dominant. Here, we study how inertia affects the rectification and diffusion of self-propelled particles in a two-dimensional, asymmetric channel. We show that most of the particles accumulate at the channel walls as the masses of the particles increase. Furthermore, the average particle velocity has a maximum as a function of the mass, indicating that particles with an optimal mass Mop * can be sorted from a mixture with particles of other masses. In particular, we find that the effective diffusion coefficient exhibits an enhanced diffusion peak as a function of the mass, which is a signature of the accumulation of most of the particles at the channel walls. The dependence of Mop * on the rotational diffusion rate, self-propulsion force, aspect ratio of the channel, and active torque is also determined. The results of this study could stimulate the development of strategies for controlling the diffusion of self-propelled particles in entropic ratchet systems.

Quality comparison of camellia (Camellia oleifera C.Abel) seed oil with different extraction methods

The quality of camellia seed oil (CSO) varies with the oil extraction methods. In the present work, the oil yield, physicochemical properties, bioactive compounds, fatty acid composition, and Fourier transform infrared spectra of CSOs prepared by supercritical fluid, aqueous, pressing, and solvent extraction were explored systematically. Additionally, the microstructure of camellia seed cake after oil extraction was observed by scanning electron microscopy. Results showed that supercritical fluid extraction had the highest oil yield (92.42%), and the extracted oil was also superior to the other methods in the contents of polyphenol, β-sitosterol, and squalene, which were 89.34, 3173.23, and 6.20 mg/kg, respectively. Moreover, CSO extracted by supercritical fluid extraction had lower peroxide value and better colour indexes. In terms of fatty acid composition, CSOs extracted by supercritical fluid, pressing, and solvent extraction were similar, while CSO extracted by aqueous extraction had higher saturated fatty acid contents and lower unsaturated fatty acid contents than the other samples. Fourier transform infrared spectra analysis showed that the extraction methods had no significant effect on the chemical functional groups of CSOs. Scanning electron microscopy revealed that supercritical fluid extraction and solvent extraction could more effectively promote the release of oil from camellia seeds. In general, the quality of CSOs extracted by different methods had significant differences, and supercritical fluid extraction could be a promising extraction method for CSO.

A Biomimetic Emitter Inspired from Green Fluorescent Protein.

The unique tripeptide structure of green fluorescent protein (GFP), a Ser-Tyr-Gly motif, generates the mature chromophore in situ to define the emission profiles of GFP. Here, we describe the rational design and discovery of a biomimetic fluorescent emitter, MBP, by mimicking the key structure of the Ser-Tyr-Gly motif. Through systematically tailoring the tripeptide, a family of four chromophores were engineered, while only MBP exhibited bright fluorescence in different fluid solvents with highly enhanced quantum yields. Distinct to previous hydrogen-bonding-induced fluorescence quenching of GFP chromophore analogues, the emission of MBP was only slightly decreased in protic solvents. Heteronuclear multiple bond correlation techniques demonstrated the fundamental mechanism for enhanced fluorescence emission owing to the synergy of the formation of the intramolecular hydrogen-bonding-ring structure and the self-restricted effect, which was further illustrated via theoretical calculations. This work puts forward an extraordinary approach toward highly emissive biomimicking fluorophores, which gives new insights into the emission mechanisms and photophysics of GFP-like chromophores.

Turbulent entrainment in viscoelastic fluids

Direct numerical simulations (DNS) of turbulent fronts spreading into an irrotational flow region are used to analyse the turbulent entrainment mechanism for viscoelastic fluids. The simulations use the FENE-P fluid model and are initiated from DNS of isotropic turbulence with Weissenberg and turbulence Reynolds numbers varying in the ranges $1.30 \le Wi \le 3.46$ and $206 \le Re_{\lambda }^{0} \le 404$, respectively. The enstrophy dynamics near the turbulent/non-turbulent interface (TNTI) layer, that separates regions of turbulent and irrotational flow, includes a new mechanism – the viscoelastic production – caused by the interaction between the vorticity field and the polymer stresses. This term can be a sink or a source of enstrophy in the turbulent core region of the flow, depending on the Weissenberg number, and contributes to the initial growth of the enstrophy in the viscous superlayer, together with the viscous diffusion, which is the only mechanism present for Newtonian fluids. For low and moderate Weissenberg numbers the scaling of the TNTI layer is similar to the scaling of TNTI layers for Newtonian fluids, but this is no longer the case at high Weissenberg numbers where the enstrophy tends to be concentrated into thin vortex sheets instead of vortex tubes. Finally, it is shown that the substantial decrease of the entrainment rates observed in turbulent flows of viscoelastic fluids, compared with Newtonian fluids, is caused by a reduction of the surface area and fractal dimension of the irrotational boundary, originated by the depletion of ‘active’ scales of motion in the fluid solvent caused by the viscoelasticity.

A technology review of recycling methods for fiber-reinforced thermosets

The rapidly rising demand for fiber-reinforced plastics (FRPs) has led to large volumes of manufacturing and end-of-life waste. Recycling fiber-reinforced thermosets is very difficult owing to their complex structure and heterogeneity. Landfill and incineration have become the most commonly used methods for eliminating non-degradable FRP waste, which adversely affects the environment and ecology. The purpose of this review is to evaluate end-of-life FRP recycling technologies in terms of optimizing the reuse/recycling of resources and eliminating waste, thereby improving FRP waste management. The technical progress made in the recycling of thermosetting composites is reviewed, including mechanical, thermal (pyrolysis and fluidized-bed), and chemical (critical fluid and low-temperature solvent) methods. The technical feasibility of each method was compared, and the economic and environmental impacts were considered. The challenges and opportunities facing the establishment of a composite recycling market in the future are examined. Finally, we provide a comprehensive summary of the scope of each recycling method.

Validation UV Spectrophotometric Method to Determine Entrapment Efficiency of Ocular Polymeric Nanoparticle Levofloxacin Hemihydrate

Simple, easy, and economical UV spectrophotometric methods have been developed using simulated tear fluid (STF) solvent to determine levofloxacin hemihydrate (LEVH) levels in ocular nanoparticles, as indicated by the % entrapment efficiency. A maximum wavelength of levofloxacin at 288nm, with a 4.0-12.0µg/mL concentration, shows linear results with a correlation coefficient (r) of 0.9997 and an average % recovery of 99.920 –100.804%. The developed method is able to use for the analysis of levofloxacin hemihydrate in nanoparticle preparations.

Effective Utilization of Pineapple Waste

India is the largest fruit and vegetable producer. Until fruit is eaten, fruit peel stays waste. Phenolic acids, ascorbic acid, β-carotenes, and flavonoids are the most bioactive components of pineapples. This is one of the secondary plant metabolites abundantly present in pineapple skins in this sample, ferulic acid. Ferulic acid is a low-toxic phenolic acid widely used in diet and cosmetics. Ferulic acid is extracted using different conventional and non-conventional methods such as Soxhlet extraction, Supercritical fluid extraction and Solvent extraction and the amount of ferulic acid is quantified using High performance liquid chromatography (HPLC). The study also evaluated the presence of total phenolic content (Gallic acid equivalent/GAE)and antioxidant activity. Soxhlet extraction using methanol and petroleum ether was the best solvent, methanol showed maximum ferulic acid concentration (0.7696 g/100g), phenolic content (2.365 mg g/GAE), antioxidant activity (45%) and percentage yield (90.5% mg). This study also analysed micronutrients such as vitamins (A, B, B1, B2, B6, B12 and C), calcium, potassium, phosphorus, iron, manganese, zinc and dietary fibre in the pineapple peel

Early warning of citric acid overdose and timely adjustment of regional citrate anticoagulation based on machine learning methods

BackgroundRegional citrate anticoagulation (RCA) is an important local anticoagulation method during bedside continuous renal replacement therapy. To improve patient safety and achieve computer assisted dose monitoring and control, we took intensive care units patients into cohort and aiming at developing a data-driven machine learning model to give early warning of citric acid overdose and provide adjustment suggestions on citrate pumping rate and 10% calcium gluconate input rate for RCA treatment.MethodsPatient age, gender, pumped citric acid dose value, 5% NaHCO3 solvent, replacement fluid solvent, body temperature value, and replacement fluid PH value as clinical features, models attempted to classify patients who received regional citrate anticoagulation into correct outcome category. Four models, Adaboost, XGBoost, support vector machine (SVM) and shallow neural network, were compared on the performance of predicting outcomes. Prediction results were evaluated using accuracy, precision, recall and F1-score.ResultsFor classifying patients at the early stages of citric acid treatment, the accuracy of neutral networks model is higher than Adaboost, XGBoost and SVM, the F1-score of shallow neutral networks (90.77%) is overall outperformed than other models (88.40%, 82.17% and 88.96% for Adaboost, XGBoost and SVM). Extended experiment and validation were further conducted using the MIMIC-III database, the F1-scores for shallow neutral networks, Adaboost, XGBoost and SVM are 80.00%, 80.46%, 80.37% and 78.90%, the AUCs are 0.8638, 0.8086, 0.8466 and 0.7919 respectively.ConclusionThe results of this study demonstrated the feasibility and performance of machine learning methods for monitoring and adjusting local regional citrate anticoagulation, and further provide decision-making recommendations to clinicians point-of-care.

Karakteristik Fisik Serbuk Ekstrak Buncis (Pheseolus vulgaris L) dengan Variasi Lama Penyimpanan

Research has been carried out on the analysis of physic properties of green bean extract powder (Phaseolus vulgaris L). This study aims to determine the physical characteristics of the bean extract powder that has been stored in a predetermined time variation. The physic properties tested included water content, solubility and organoleptic tests. The results of the sample water content test with storage variations of less than 1, 1, 2 and 3 months respectively were 5.55%, 2.86%, 3.83% and 3.54% and the solubility was 42.67%, 33, 84%, 44.51% and 34.33% for Artificial Gastrid Fluid (AGF) solvents and 31.79%, 35.08%, 43.24 and 34.52% for Water solvents. The results of the organoleptic test showed that the color of the bean extract powder sample with a storage time of ± 2 months was the most preferred by the panelists, Fresh samples had the highest average scores for taste and aroma, of the panelist samples preferred the samples that had been stored for ± 3 months

The hydrothermal alkaline alteration of potassium feldspar: A nanometer-scale investigation of the orthoclase interface

Potassium feldspars (KAlSi3O8) are ubiquitous minerals in the Earth's upper crust. This family of minerals has been the subject of numerous experimental and theoretical investigations concerning their dissolution kinetics and the mechanisms controlling chemical alteration at acid and neutral pH, and at temperatures ranging from ambient to hydrothermal conditions. On the other hand, considerably less research on the dissolution behavior of K-feldspars has been carried out at alkaline conditions, in particular at pH > 9 and elevated temperatures. Filling in this gap in knowledge is the major motivation for this study. More specifically, we wanted to document and understand how the K-feldspar interface structurally and chemically evolves during alteration in order to determine the mechanism of dissolution. In this study we examined interfaces of orthoclase samples that were altered in separate experiments in a Ca(OH)2-H2O solution (pH25°C 12.4) at 190 °C for 24 h. We used a combination of focused ion beam (FIB) milling and advanced analytical transmission electron microscopy (TEM) techniques to investigate the structure and chemistry of the near surface region of post-reaction grains, with particular attention being given to the fluid-solid interface. Even though each grain diminishes in volume due to dissolution, high-resolution TEM imaging indicates that the feldspar structure itself remains completely intact and crystalline, as evidenced by lattice fringes that abruptly terminate at the grain edge. Nanometer-scale chemical composition measurements and mapping by TEM-EDXS (energy dispersive X-ray spectroscopy) and EFTEM (energy filtered TEM) show that the chemistry of the parent feldspar also remains unchanged at the interface. In particular, there is no evidence for the incursion of Ca from the fluid solvent into the structure, either by interdiffusion or by a replacement process. Taken together, the TEM observations point to a sharp chemical reaction front characterized by the congruent (i.e. stoichiometric) release of all elements from the feldspar structure.Nanometer-scale measurements by high resolution analytical TEM also reveal that a surface alteration layer (SAL) of amorphous material forms in situ at the expense of the feldspar structure. The interface demarcates a spatially coincident and nm-sharp chemical and structural discontinuity between the parent feldspar and the amorphous phase. The amorphous SAL has a variable thickness, from under 10 nm up to ~200 nm. This is likely one of the first observed occurrences of a significant surface amorphous layer on feldspar due to alteration in an alkaline solvent. The lack of a gap between the two phases points to an interfacial dissolution-reprecipitation process that continuously operates during hydrothermal alteration, and mostly likely right from the onset of contact with the fluid. After the initial formation of the amorphous layer, a 1–2 μm-thick porous amalgam of secondary crystalline phases comprised of calcite, tobermorite, and hydrogrossular, as well as other minor phases, precipitated over the SAL. These authigenic crystalline minerals formed during the experiment (hydrothermal alteration, followed by fluid loss due to evaporation) by a classical thermodynamically-controlled precipitation process as the reactor bulk fluid became increasingly concentrated.We propose that a coupled interfacial dissolution-reprecipitation (CIDR) mechanism best explains the chemical and structural properties of the interface and the formation of an amorphous surface layer. In fact, many recent studies postulate that a CIDR process controls feldspar dissolution and the formation of SALs at acid and circumneutral pH over a wide range of temperatures. Combining these previous results with our new observations supports the idea that a unique and unifying mechanism likely controls chemical alteration of feldspars in all aqueous fluids.

Direct numerical simulations of turbulent viscoelastic jets

Direct numerical simulations (DNS) of spatially evolving turbulent planar jets of viscoelastic fluids described by the FENE-P model, such as those consisting of a Newtonian fluid solvent carrying long chain polymer molecules, are carried out in order to develop a theory for the far field of turbulent jets of viscoelastic fluids. New evolution relations for the jet shear-layer thickness , centreline velocity and maximum polymer stresses are derived and validated by the new DNS data, yielding , , and , respectively, where is the coordinate in the streamwise direction. It is shown that, compared with a classical (Newtonian) turbulent jet, the effect of the polymers is to reduce the spreading rate, centreline velocity decay, Reynolds stresses and viscous dissipation rate. The self-preserving character of the flow is analysed and it is shown that profiles of mean velocity, Reynolds stresses and polymer stresses are self-similar provided the proper scales are used in the normalisation of these quantities. A fundamental difference from the Newtonian jet in this regard is the necessity for two, instead of only one, different velocity and length scales to properly characterise the evolution of the turbulent flow. These extra velocity and length scales are directly related to a time scale associated with the characteristic fading memory property of viscoelastic fluids.