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Allantoin possesses numerous beneficial properties for the skin, like anti-irritant effects, wound healing, skin hydration, and epithelization. In this paper, we investigated a suitable preparation method for an allantoin hydrogel using the Semi-Solid Control Diagram (SSCD) method and characterized its rheological and consistency behavior. To accomplish this, xanthan gum (XG) was selected as a model gelling agent. Briefly, four hydrogels were prepared, two without allantoin (coded M01 and M02) and two with allantoin (M1 and M2). Similarly, the formulations were either prepared through magnetic stirring (M01 and M1) or homogenization in a mortar (M02 and M2). The prepared hydrogels were evaluated using the SSCD for specific parameters and indexes. The Good Quality Index (GQI) shows a higher value for the formulation, M1 = 6.27, compared to M2 = 5.45. This result is also underlined by the value of M01 = 6.45, which is higher than M02 = 6.38. Considering the consistency, the formulation M01 possessed the highest spreadability, followed by M02 and then the allantoin hydrogels M1 and M2. The rheological behavior had a thixotropic pseudoplastic flow for all the formulations. The use of SSCD pictographs outlined the rheological properties that need improvement, the method that is suitable to prepare the allantoin hydrogels, and the influence of the allantoin suspended in the XG hydrogel. [ABSTRACT FROM AUTHOR]

The corrosion of steel in post-tensioned tendons has been associated with deficient grout materials containing high free sulfate ion concentrations. In a Florida bridge in 2011, tendon corrosion failures occurred for a prepackaged thixotropic grout that had developed material segregation. However, the available grout and corrosion testing prescribed in material specifications, such as grout bleed water testing, was not able to identify the propensity or modality for the grout deficiencies and the associated steel corrosion that was observed in the field. It was of interest to identify corrosion testing methods that could prescribe grout resistance to segregation-related deficiencies that can form by aberrations in construction. The objectives of the work presented here included (1) characterizing the development of physical and chemical grout deficiencies due to excess mix water and water volume displacement, (2) developing small scale test methodologies that identify deficient grout, and (3) developing test methodologies to identify steel corrosion in deficient grout. The inverted-tee test (INT) and a modified incline-tube (MIT) test were assessed and both were shown to be useful to identify the robustness of grout materials to adverse mixing conditions (such as overwatering and pre-hydration) by parameters such as sulfate content, moisture content, electrical resistance, and steel corrosion behavior. It was shown that the different grout products have widely different propensities for segregation and accumulation of sulfate ions but adverse grout mixing practices promoted the development of grout deficiencies, including the accumulation of sulfate ions. Corrosion potentials of steel < −300 mVCSE developed in the deficient grout with higher sulfate concentrations. Likewise, the corrosion current density showed generally high values of >0.1 μA/cm2 in the deficient grouts. The values produced from the test program here were consistent with historical data from earlier research that indicated corrosion conditions of steel in deficient grout with >0.7 mg/g sulfate, further verifying the adverse effects of elevated sulfate ion concentrations in the segregated grout. [ABSTRACT FROM AUTHOR]

Oil-based drilling fluids are widely used in challenging wells such as those with large displacements, deepwater and ultra-deepwater wells, deep wells, and ultra-deep wells due to their excellent temperature resistance, inhibition properties, and lubrication. However, there is a challenging issue of rheological deterioration of drilling fluids under high-temperature conditions. In this study, a dual-amphiphilic segmented high-temperature-resistant gelling agent (HTR-GA) was synthesized using poly fatty acids and polyether amines as raw materials. Experimental results showed that the initial decomposition temperature of HTR-GA was 374 °C, indicating good thermal stability. After adding HTR-GA, the emulsion coalescence voltage increased for emulsions with different oil-to-water ratios. HTR-GA could construct a weak gel structure in oil-based drilling fluids, significantly enhancing the shear-thinning and thixotropic properties of oil-based drilling fluids under high-temperature conditions. Using HTR-GA as the core, a set of oil-based drilling fluid systems with good rheological properties, a density of 2.2 g/cm3, and temperature resistance up to 220 °C were constructed. After aging for 24 h at 220 °C, the dynamic shear force exceeded 10 Pa, and G′ exceeded 7 Pa, while after aging for 96 h at 220 °C, the dynamic shear force exceeded 4 Pa, and G″ reached 7 Pa. The synthesized compound HTR-GA has been empirically validated to significantly augment the rheological properties of oil-based drilling fluids, particularly under high-temperature conditions, showcasing impressive thermal stability with a resistance threshold of up to 220 °C. This notable enhancement provides critical technical reinforcement for progressive exploration endeavors in deep and ultra-deep well formations, specifically employing oil-based drilling fluids. [ABSTRACT FROM AUTHOR]

Molecular oleogels have the potential to be used as materials in healthcare applications. However, their design and synthesis are complex, thus requiring simple and effective methods for their preparation. This paper reports on alkylanilides that are low molecular-weight organogelators, which when appropriately mixed with different alkyl chain lengths could result in the formation of mixed molecular gels that exhibit excellent gel-forming ability and mechanical properties. In addition, the single and mixed molecular organogel systems were found to be applicable as single and mixed molecular oleogel systems capable of gelling oils such as olive oil and squalane. This has been found to be true, especially in molecular oleogel systems consisting of squalane, which is used as solvents in healthcare. The mixed squalene-molecular oleogel systems showed an increase in the critical (minimum) gelation concentration from 1.0 to 0.1 wt.% in the single system and an improvement in the thixotropic behavior recovery time. The thixotropic behavior of the molecular oleogels in the mixed system was quantitatively evaluated through dynamic viscoelasticity measurements; however, it was not observed for the single-system molecular oleogels. Scanning electron microscopy of the xerogels suggested that this behavior is related to the qualitative improvement of the network owing to the refinement of the mesh structure. These mixed molecular oleogels, composed of alkylanilides displaying such thixotropic behavior, could be used as candidates for ointment-base materials in the healthcare field. [ABSTRACT FROM AUTHOR]

This article discusses the issue of poor platelet counts in platelet-rich plasma (PRP) kits that use a thixotropic gel separator. The authors conducted a study to understand the cause of this problem and found that a large portion of platelets were getting trapped in the gel separator during the PRP preparation process. They compared the traditional inversion method with a patented agitation method and found that the agitation method resulted in higher platelet counts and platelet capture efficiency. The authors suggest that using the agitation method can increase the yield of platelets in PRP preparation and potentially enhance the regenerative properties of PRP in dermatologic applications. [Extracted from the article]

Chitosan‐based hydrogels are prepared via the formation of polypseudorotaxanes (PPR), by selectively threading α‐cyclodextrin (α‐CD) macrocycles onto polymeric chains, which, through the formation of microcrystalline domains, act as junction points for the network. Specifically, host–guest inclusion complexes are formed between α‐CD and PEGylated chitosan (PEG‐Ch), resulting in the formation of supramolecular gels. PEG‐grafted chitosan is obtained with a reaction yield of 79.8%, a high degree of grafting (50.9% GW) and water solubility (≈16 mg mL−1), as assessed by turbidimetry. A range of compositions for mixtures of PEG‐Ch solutions (0.2–0.8% w/w) and α‐CD solutions (2−12% w/w, or 0.04–0.2% mol) are studied. Regardless of PEG content, gels are not formed at low α‐CD concentrations (<4%). Dynamic rheology measurements reveal stiff gels (G' above 15k) and a narrow linear viscoelastic region, reflecting their brittleness. The highest elastic modulus is obtained for a hydrogel composition of 0.4% PEG‐Ch and 6% α‐CD. Steady‐state measurements, cycling between low and high shear rates, confirm the thixotropic nature of the gels, demonstrating their capacity to fully recover their mechanical properties after being exposed to high stress, making them good candidates to use as in‐situ gel‐forming materials for drug delivery to topical or parenteral sites. [ABSTRACT FROM AUTHOR]

The rheological behavior of gel propellants is crucial for their practical applications, especially in the rocket engine and ramjet fields. The thixotropic characteristics of gel propellants are an important component of their rheological properties and have a notable impact on their flow and injection process. However, most gel propellants contain rich, dynamic cross-linked network structures, which impart complex non-Newtonian fluid properties, and it is difficult to establish a unified mathematical model. In view of this, this study addresses the thixotropy of a prepared RP-3 kerosene gel and determines the mathematical model and model parameters describing its thixotropy. Experiments show that the kerosene gel exhibits shear-thinning properties as well as thixotropy. To describe the microstructural changes in the gel, three thixotropic constitutive models are introduced to analyze the rheological data, and the constitutive equation parameters are optimized. The three models are all structural dynamic models, which can be used to describe microstructural changes within the material. In addition, the fitting of the constitutive equation is a multiparameter optimization problem, and an appropriate optimization method must be used for parameter fitting. Therefore, the Bayesian optimization method combined with Gaussian process regression and the upper confidence bound (UCB) acquisition function is used in the multiparameter fitting of the constitutive models. Both experiments and numerical results show that the thixotropic model, which introduces a pre-factor with shear strain and assumes that the breakdown of the gel structure is related to energy dissipation rather than the shear rate, has a better fitting effect and prediction ability with regard to the gel. Combined with transient experiments at different shear rates, the model parameters of the constitutive law can be determined quickly by applying the Bayesian optimization method. [ABSTRACT FROM AUTHOR]

Zinc oxide nanoparticles (ZnO NPs) modified by oxopyrymidine alcohol, also known as xymedone (Xym), were obtained and studied using FTIR, UV-vis, and fluorescent spectroscopy, and SEM, BET, powder XRD, and DLS analysis. A formulation of thixotropic hydrophilic gels containing Carbopol-based Xym and ZnO NPs was developed. A vertical Franz cell with a cellulose acetate membrane was used as a model to investigate the passive diffusion of the gel components by AAS. The gel components—Xym and ZnO NPs—were shown to penetrate through acetyl cellulose membrane within 5–7 h depending on an initial amount, and its values were in the range of 56–77%. The penetration of modified ZnO NPs by Xym was more effective in contrast to ZnO NPs without modification. The burn wound healing activity of ZnO NPs–Xym gel was demonstrated on a thermal burn wound model on rats. SOD and GR activity was increased by 30–35% during ZnO NPs–Xym gel treatment, the burn area on 10 postburn day decreased by 10% in contrast to a positive control, Methyluracyl®® ointment. [ABSTRACT FROM AUTHOR]

The author reported molecular organogels using N-alkylhydantoins as new low-molecular-weight gelators for the first time, and thixotropic mixed molecular organogels using a set of N-alkylhydantoin gelators with different alkyl chain lengths. These homologous compounds with different alkyl chains are found to form macroscopic crystals or solution states in polar solvents, but form homogeneous organogels in non-polar solvents, such as n-octane and squalane. Although there is no significant increase in the minimum gelation concentration of the mixed molecular gels using squalane as a solvent, these mixed molecular organogels show improved mechanical properties, especially in their thixotropic behavior, which is not observed in the single N-alkylhydantoin gels. Furthermore, they exhibit reversible thixotropic behavior with quick recovery of the gel state in a minute by quantitatively measuring dynamic viscoelasticity measurements of rheometry of mixed molecular gels. Based on the morphological observations of the xerogels, the self-assembling fibers of the gelators become finer, indicating an increase in the density of the mesh structure inside the gel, which could explain its thixotropic behavior. These thixotropic mixed molecular gels may be applicable to ointment base materials, because they are gelled with squalane oil. [ABSTRACT FROM AUTHOR]

Zinc oxide nanoparticles (ZnO NPs) modified by oxopyrymidine alcohol, also known as xymedone (Xym), were obtained and studied using FTIR, UV-vis, and fluorescent spectroscopy, and SEM, BET, powder XRD, and DLS analysis. A formulation of thixotropic hydrophilic gels containing Carbopol-based Xym and ZnO NPs was developed. A vertical Franz cell with a cellulose acetate membrane was used as a model to investigate the passive diffusion of the gel components by AAS. The gel components—Xym and ZnO NPs—were shown to penetrate through acetyl cellulose membrane within 5–7 h depending on an initial amount, and its values were in the range of 56–77%. The penetration of modified ZnO NPs by Xym was more effective in contrast to ZnO NPs without modification. The burn wound healing activity of ZnO NPs–Xym gel was demonstrated on a thermal burn wound model on rats. SOD and GR activity was increased by 30–35% during ZnO NPs–Xym gel treatment, the burn area on 10 postburn day decreased by 10% in contrast to a positive control, Methyluracyl®® ointment.

A variable focus optical lens using a thixotropic gel and ultrasonic vibration is discussed. The surface profile of the gel could be deformed via acoustic radiation force generated by ultrasound. A thixotropic gel in which the viscosity was changed by shear stress was employed as a transparent lens material. The thixotropic gel allowed the lens to maintain shape deformation in the absence of continuous ultrasound excitation. The lens had a simple structure with no mechanical moving parts and included an annular piezoelectric transducer, a glass disk, and the thixotropic gel film. The axisymmetric concentric flexural vibration mode was generated on the lens at 71 kHz, which resulted in static surface deformation of the gel via the acoustic radiation force. The preservation rate was investigated after switching off the ultrasonic excitation. There was a trade-off between the preservation rate of the lens deformation and the response time for focusing. The focal length could be controlled via the input voltage to the lens, and a variable-focus convex lens could be realized; the change in the focal length with 4.0 Vpp was 0.54 mm. The optical transmittance of the lens was measured and the transmittance ranged 70%–80% in the visible spectral region. [ABSTRACT FROM AUTHOR]

Ultra Violet radiations induced skin damage and associated skin disorders are a widespread concern. The consequences of sun exposure include a plethora of dermal conditions like aging, solar urticaria, albinism and cancer. Sunscreens provide effective protection to skin from these damages. Besides FDA approved physical and chemical UV filters, phytoconstituents with their multi functionalities are emerging as frontrunners in Therapy of skin disorders. Objective of this study was to develop novel phyto-dermal gel (PDG) with dual action of sun protection and antioxidant potential using polymeric mixed micelles (PMMs) are nanocarriers. PMMs of Pluronic F127 and Pluronic F68 loaded with curcumin and quercetin were optimized by 32 factorial designs. Responses studied were vesicle size, SPF, entrapment efficiency of curcumin and quercetin and antioxidant activity. Droplet size ranged from 300 to 500 nm with PDI in between 0.248 and 0.584. Combination of curcumin and quercetin showed enhanced sun protection and antioxidant activity. Pluronics played a significant positive role in various parameters. In present studies vesicle size of factorial batches was found to be between 387 and 527 nm, and SPF was found to be between 18.86 and 28.32. Transmission electron microscopy revealed spherical morphology of micelles. Optimized micelles were incorporated into Carbopol 940. Optimized PDG was evaluated for pH, drug content, spreadability, rheology, syneresis, ex vivo permeation, and skin retention. Hysteresis loop in the rheogram suggested thixotropy of PDG. Syneresis for gels from day 0–30 days was found to be between 0% and 12.46% w/w. SPF of optimized PDG was 27±0.5. Optimized PDG showed no signs of erythema and edema on Wistar rats. PMMs thus effectively enhanced antioxidant and skin protective effect of curcumin and quercetin. [Display omitted] • Curcumin and quercetin loaded in mixed polymeric micelles. • Factorial design to study relationship between independent and dependent variables. • Phytoconstituents loaded micelles incorporated into thixotropic gel. • Gel exhibits enhanced antioxidant activity and sun protection factor. [ABSTRACT FROM AUTHOR]

The article is devoted to influence of the clay thixotropic solutions on the strength of resistance to movement of the earthmoving machines' working elements. The forces of resistance to the movement of a flat plate, a smooth cylinder and real working bodies in a clay solution for various modes of solution flow (bingamian, pseudo-laminar and turbulent) are established. Mathematical models of movement of the earthmoving machines working elements in clay solution are developed and investigated. Dynamics of the working element of an earthmoving machine movement in a clay solution is studied. Dependence of the feed force, torque and dynamic coefficient on the resistance forces, acting on the working body from the clay solution, is established. [ABSTRACT FROM AUTHOR]

Production of whipped confectionery (marshmallows, pressed fruit paste, sweets with light-textured centres) is a complex process difficult to control. To expand and modernise their production, it is necessary to find simpler technologies, both resource-and energy-saving, to increase the stability of the heterogeneous dispersed system, and to improve the quality of finished products. In this respect, applying food additives of the nanometer range in technology looks very promising due to their unique physicochemical parameters and their many functional and technological properties. In the paper, it is suggested to solve the problem of stabilising the polyphase structure of whipped confectionery products and to form their quality by using the food additive Magnetofood based on ferrous and ferric oxides (FeO.Fe2O3). Magnetofood is ultrafine powder with a particle size of ~80 nm. It has a high functional and technological potential: large specific surface and a set of useful properties (the additive is surface-active, with complex-forming, sorption, and stabilising properties). This allows us to recommend Magnetofood as an additive with a complex action to improve the quality and extend the shelf life of sugar confections like fruit paste and fruit jelly products, in particular, white and pink marshmallows. It has been found that addition of Magnetofood in the form of an aqueous suspension at the stage of swelling and dissolution of the gelling agent improves the shape and consistency, reduces the density of the foam structure by 1.12–1.15 times, reduces the amount of gelling agent by 10–12% for agar and by 7–9% for pectin, increases the mechanical strength of marshmallows by 11.5–12.6% for agar and by 8.2-9.1% for pectin. Besides, the foaming ability of egg white increases by 1.14-1.4 times (with constant foam stability (99±1)% due to the stabilising effect of Magnetofood nanoparticles), and the thixotropic property of the gel structure becomes 1.4–1.5 times as much. [ABSTRACT FROM AUTHOR]

The viscosity and the surface profile of a thixotropic gel were controlled via ultrasound vibrations. The ultrasound device consisted of two piezoelectric lead zirconate titanate transducers glued to each end of a 60-mm-long rectangular glass substrate. It generated a 71-kHz flexural standing wave along the length. A 0.9-mm-thick thixotropic gel film made from silicone oil and hydrophobic fumed silica was formed on the glass substrate. The ultrasound vibration decreased the film viscosity, and its surface profile could be changed by the acoustic radiation force acting from the gel to the surrounding air, generated by the flexural vibration of the substrate. The transient response of the surface profile was observed by switching the ultrasound excitation ON and OFF. When the excitation was switched OFF, the gel displacement gradually decreased, but the surface profile did not return to that of the initial steady state, indicating that the viscosity recovered in time to preserve the surface profile. When a pulsed megahertz (MHz) signal was used to control the gel deformation, the surface profile rapidly approached the initial steady-state profile after the excitation. [ABSTRACT FROM AUTHOR]

Therapeutic levels of lactulose were used with commercial starters (Yoflex 801, Yoflex 901 and Yomix 486) in yoghurt. In fact, Yoflex 801 was supplemented with 1.5% lactulose resulting in minor yoghurt quality alterations. This co-culture was retained to study the influence of lactulose levels (0, 4, 6, and 8 %) on yoghurt quality for 28 days at 4°C. Kinetic parameters, syneresis, proteolysis degree, and sensory characteristics were improved by increasing lactulose dose; thus, thixotropic and pseudoplastic gel was shown. Accordingly, functional yoghurt fermented with Yoflex 801, containing 4 to 6 % of lactulose, proved to be the most adequate choice. [ABSTRACT FROM AUTHOR]

The self-association equilibria of doxorubicin hydrochloride (DX), at high drug and NaCl concentrations, are studied by temperature scan fluorescence spectroscopy, with the support of molecular dynamics (MD) calculations. Even though all anthracyclines show dimerization equilibria, DX only can further associate into long polymeric chains according to DX mon ⇄ DX dim ⇄ DX pol. This is reflected not only in the mechanical properties of DX pol solutions (behaving as thixotropic gels) but also in their spectroscopic behaviour. Fluorescence, in particular, is the technique of election to study this complex set of equilibria. Upon increasing the temperature, DX pol melts into DX dim , which in turn is in equilibrium with DX mon. Since DX dim is non fluorescent, with a fluorescence temperature scan experiment the DX pol ⇄ DX mon equilibrium is probed. However, also information on the DX dimerization equilibrium can be derived together with the relevant thermodynamic parameters ruling the dimerization process (Δ H d i m ° = - 56 k J m o l - 1 ; Δ S d i m ° = - 97 J m o l - 1 K - 1). The residence time of DX molecules in the dimer (74.7 μs), as well as the monomers mutual orientation in the dimer, are characterized by means of theoretical and computational modelling. [ABSTRACT FROM AUTHOR]

Graphical abstract A thixotropic cysteine linked silver clusters hydrogel was prepared via photoreduction and was successfully applied as a drug delivery system. Highlights • A cysteine linked silver clusters (CLSC) hydrogel was prepared by photoreduction. • The CLSC hydrogel presented pH-stimuli behavior under acidic conditions. • The thixotropic property ensures direct injection and drug delivery to cancer cells. • The DOX@CLSC hydrogel shows remarkable inhibition efficacy on tumor growth. Abstract A biocompatible thixotropic hydrogel via photoreduction and self-assembly of silver clusters is described. This reaction avoids use of hydrogelators, crosslinkers or any exogenous toxic reducing agents, making it a facile and green method. Moreover, the formed 'smart' thixotropic hydrogel is pH-responsive and can encapsulate the hydrophobic anticancer drug doxorubicin hydrochloride (DOX). The thixotropic property allows it to be sol state, which can be injected directly into the site of breast tumors in mice; after removal of the shear stress, the sol reverts back to hydrogel, where it remains for delivery of DOX into cancerous cells. The DOX-loaded hydrogel presents remarkable inhibition efficacy towards tumor growth, in addition to reducing the organ toxicity. [ABSTRACT FROM AUTHOR]

Abstract Increased interest in aesthetic, natural nail coatings has encouraged more in-depth studies, and particularly of ultraviolet curable coatings, their formation, processing, characteristics, and removal. This study investigated the impact of various thixotropic agents (organically modified hectorite and bentonite clays) on water-based oligomer system rheology. Ingredients were evaluated to determine their influence on unreacted composite characteristics (viscosity and pigment suspension stability) and reacted film characteristics (modulus of elasticity, elongation at break, and film adhesion force). It is concluded that clay-based thixotropic agents are suitable for use as a suspension agent in nail polish formulations and, depending on the concentration, can decrease the risk of pigment sedimentation and syneresis. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Dynamic surface behavior and interfacial rheology of Xanthan Gum (XG) polymer and surfactant mixed aqueous solutions have been investigated in this work using Profile Analysis Tensiometry (PAT). The interactions of XG with anionic sodium dodecyl sulfate (SDS) and nonionic triton X100 surfactants were studied. The results demonstrate a significant influence of the XG thixotropic bulk rheology behavior on dynamic surface tension measurements. The time dependent thixotropic force (due to the movement and rearrangement of XG molecules under applied shear and relaxation time afterwards) was evaluated using a high precision buoyancy force measurement system. This extra thixotropic force can affect the expected balance of gravity and surface forces in the Gauss-Laplace equations and causes an abnormal increasing dynamic surface tension for aqueous XG solutions versus time in absence of surfactants. It is shown that the thixotropic property of this polymer can also induce an additional surface elasticity which can be measured by drop oscillation experiments via PAT. Therefore, surface elasticity measurements can be proposed as a novel method for determining the extent of fluid thixotropy. The results also showed strong interaction between XG and SDS molecules. At SDS concentrations below critical micelle concentration (CMC), the equilibrium surface tension of XG-SDS solution decreased considerably with increasing XG concentration. This interaction originates from the anionic nature of both XG and SDS molecules. The surface tension behavior of mixed solutions of XG and Triton X100 molecules did not show significant interactions. The obtained results allow improving the ability of the Gauss-Laplace Equation to calculate more accurately the dynamic surface tension of thixotropic fluids. [ABSTRACT FROM AUTHOR]

For a proper operational performance assessment of excess sewage sludge digesters in practice, a better understanding of waste activated sludge (WAS) rheological behaviour is important, especially regarding the low-shear and poor mixing zones in anaerobic digesters. The potential rheological instability of WAS with different total solids (TS) concentrations was studied in this research. The obtained yield-pseudoplastic behaviour showed varying patterns in a wide shear rate range, of which characterisation depended on hybrid model fitting of defined shear rate segments. Although a new mathematical expression improved the fitting quality, limited applicability of the empiric models reflected the samples’ transient rheological behaviour rather than intrinsic properties, challenging the included parameters definition. Characterised by the distinct flow status and transitions, the observed rheological instability gives more insight in viscoelastic and thixotropic effects on sludge flow and mixing behaviour in full-scale WAS treatment systems. Recommendations for developing a rheological measurement protocol were also formulated. [ABSTRACT FROM AUTHOR]

Linear stability of a thixotropic fluid obeying the Moore model is investigated in pipe flow using a temporal stability analysis in which infinitesimally small perturbations, represented by normal modes, are superimposed on the base flow and their evolution in time is monitored in order to detect the onset of instability. An eigenvalue problem is obtained, which is solved numerically using the pseudo-spectral Chebyshev-based collocation method. The neutral instability curve is plotted as a function of the thixotropy number of the Moore model. Based on the results obtained in this work, it is concluded that the thixotropic behavior of the Moore fluid has a destabilizing effect on pipe flow. [ABSTRACT FROM AUTHOR]

Semi-solid processing of aluminum alloys is a well-known manufacturing technique able to combine high production rates with parts quality, resulting in high performance and reasonable component costs. The advantages offered by semi-solid processing are due to the shear thinning behavior of the thixotropic slurries during the mold filling. This is related to the microstructure of these slurries consisting of solid, nondendritic, near-globular primary particles surrounded by a liquid matrix. This paper presents a review on the formation of this nondendritic microstructure, reports on the different proposed mechanisms that might be responsible, and illustrates the relationship between microstructure and properties, in particular, tensility, fatigue, wear, and corrosion resistance. [ABSTRACT FROM AUTHOR]

Background. Yield shear stress (YSS) well characterizes the thixotropic status of blood, that exemplifi es a reversible loss of blood fluidity due to a low shear rate. At the stable haematocrit ratio YSS depends mainly on the fi brinogen level. Aim. Since the role of other biochemical factors in the YSS phenomenon in cerebral ischaemia has not been well known, we have undertaken this problem in a group of stroke patients. Material and Methods. The study was carried out in 36 patients with acute ischaemic stroke and in 12 controls. YSS was estimated by means of microviscometric method. In all subjects the concentration of the following biochemical factors were assayed: albumin, IgG, IgA, IgM, apolipoprotein A, and B, cholesterol, triglycerides, LDL, HDL and fi brinogen. Then the thixotroipic effect of all biochemical factors and their correlations to fi brinogen were estimated by means of mathematical formulas. Results. We found a positive correlation in relation to the following thixotropic effects: for all subjects and separately for patients' group: Alb(YSS) (p < 0.001), ApoA(YSS) (p < 0.001), ApoB(YSS) (p < 0.05), chol(YSS) (p < 0.01), HDL(YSS) (p < 0.05); for patients group without additional diseases: Alb(YSS) (p < 0.05), ApoA(YSS) (p < 0.005), chol(YSS) (p < 0.05), HDL(YSS) (p < 0.02), LDL(YSS) (p < 0.05). There were not any signifi cant correlations in controls. Conclusion. Results of the study indicated that in the interaction between the red cells and fi brinogen some additional factors appearing or activating during ischaemic process may play a role. [ABSTRACT FROM AUTHOR]

In this paper, cationic organic montmorillonites (OMts) were prepared by dry, semi-dry, and wet methods. The structures and properties of these OMts according to the modification methods were studied. By the characterization of XRD, TG-DTA, lipophilicity, and thixotropy, the results showed that cationic OMt prepared by wet method with sufficient surfactants had better properties, including contact angle, swelling capacity, thixotropic loop area, and thermal stability compared with cationic OMt prepared by dry and semi-dry methods. Attention should be paid that with low ratio amount of surfactants used, cationic OMt prepared by the semi-dry method had favorable properties compared with cationic OMt prepared by wet method, and it had the potential to be applied in industrial field due to its environment-friendly and modification efficiency characteristics. [ABSTRACT FROM AUTHOR]

This study was undertaken to investigate the influence of predeformation in rotary swaging strain induced melt activation (SIMA) process on the microstructural characteristics and mechanical properties of C5191 copper alloy. In this paper, plastic energy was utilized as an indicator to assess the value of stored energy in materials. The plastic energy of rotary swaging (RS) under different conditions was calculated by numerical simulation using FORGE 3D software and integral equations. The results showed that the plastic energy of RS was only related to the billet radial strain, and the plastic energy of each pass reduced with the increasing of the RS passes number. The twinning and dislocation distributions in the rotary swaged materials and semi-solid materials were analyzed by the electron backscatter diffraction technique. These results illustrated the migration of high-angle boundaries were migrated and defects were removed during recrystallization. Semi-solid C5191 alloy were prepared under different radial strains. It was found that the increase of plastic energy, decrease the spherical grains formation duration. Meanwhile, the high plastic energy promoted the refinement of spherical grains, the reduction of neck-grains number, and the enhancement of hardness. [ABSTRACT FROM AUTHOR]

The partial substitution of wheat flour (WF) by apricot kernel flour (AKF) in the range of 4-24 % was made. Physicochemical, hydration and pasting properties of WF-AKF blends were studied. The effect of AKF addition on the rheological and textural behaviours, respectively, of composite pastes and gels was also investigated. Flours blend exhibits higher protein, fat and ash contents than WF. AKF addition increased the capacities of binding and holding water and decreased the swelling capacity. Pasting properties of WF-AKF decreased with increasing AKF levels. The rheological measurements of pastes showed that the incorporation of AKF decreased the elastic/viscous moduli and the consistency index of pastes but increased the flow behaviour index, which indicates their thixotropic behaviour. Once the gel was set, WF partially substituted by high level of AKF, gave rise to weak gels revealed by a decrease in their hardness. [ABSTRACT FROM AUTHOR]

This work applies a fractional flow model to describe a time-variant behavior of non-Newtonian substances. Specifically, we model the physical mechanism underlying the thixotropic and anti-thixotropic phenomena of non-Newtonian flow. This study investigates the behaviors of cellulose suspensions and starch-milk-sugar pastes under constant shear rate. The results imply that the presented model with only two parameters is adequate to fit experimental data. Moreover, the parameter of fractional order is an appropriate index to characterize the state of given substances. Its value indicates the extent of thixotropy and anti-thixotropy with positive and negative order, respectively. [ABSTRACT FROM AUTHOR]

Pectin is an anionic, water-soluble polymer predominantly consisting of covalently 1,4-linked α-D-galacturonic acid units. This naturally occurring, renewable and biodegradable polymer is underutilized in polymer science due to its insolubility in organic solvents, which renders conventional polymerization methods impractical. To circumvent this problem, cerium-initiated radical polymerization was utilized to graft methoxy-poly(ethylene glycol) methacrylate (mPEGMA) onto pectin in water. The copolymers were characterized by 1H nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA), and used in the formation of supramolecular hydrogels through the addition of -cyclodextrin ( -CD) to induce crosslinking. These hydrogels possessed thixotropic properties; shear-thinning to liquid upon agitation but settling into gels at rest. In contrast to most of the other hydrogels produced through the use of poly(ethylene glycol) (PEG)-grafted polymers, the pectin-PEGMA/α -CD hydrogels were unaffected by temperature changes. [ABSTRACT FROM AUTHOR]

The present study examined the physical properties of soybean oleogels and commercial confectionery filling fats and evaluated the oil migration properties in model praline systems. Soybean oleogels were prepared using different oleogelators namely monoglyceride (MAG oleogels) and a mixture of sorbitan tri-stearate (STS) with lecithin (50:50) (Lec-STS oleogels). Both MAG oleogels and Lec-STS oleogels demonstrated a flat solid fat content (SFC) profile with zero SFC at 40 °C. At low temperature, MAG oleogels and Lec-STS oleogels demonstrated a non-flowing gel-like property due to the ability of the oleogelator to entrap liquid oil. In addition, oleogels also showed thixotropic behavior indicating the possible capability to prevent migration of filling fats to coatings and also good flow ability during pumping though manufacturing equipment. The textural property of oleogels also did not change significantly upon storage indicating good structural stability. When used as in a model praline system, oleogels demonstrated a migration delaying property. [ABSTRACT FROM AUTHOR]

Rheological measurements on a model thixotropic suspension by Dullaert and Mewis [J. Non-Newtonian Fluid Mech. 139(1-2), 21-30 (2006); Rheol. Acta 45, 23-32 (2005)] are extended to include large amplitude oscillatory shear (LAOS) flow, shear flow reversal, and a novel unidirectional LAOS flow to provide an extended rheological data set for testing constitutive models. We use this extended data set to test a new structure-based model developed by improving the Delaware thixotropic model [A. Mujumdar et al., J. Non-Newtonian Fluid Mech. 102, 157-178 (2002); A. J. Apostolidis et al., J. Rheol. 59, 275-298 (2015)]. Model parameters are determined from steady, small amplitude oscillatory, and step shear rate tests. Holding those parameters fixed, model predictions are compared to LAOS experiments. Similar comparisons are made for three contemporary models from the literature. Two of these models use a scalar internal structural parameter and include the modified Jeffreys model proposed by de Souza Mendes and Thompson [Rheol. Acta 52, 673-694 (2013)]. The third model is based on fluidity additivity [F. Bautista et al., J. Non-Newtonian Fluid Mech. 80, 93-113 (1999)]. A common weakness in all models is shown to be the use of scalar order parameters that cannot account for the reversal of flow directionality inherent in LAOS flow. This is further illustrated by comparison with flow reversal and unidirectional LAOS experiments. [ABSTRACT FROM AUTHOR]

We have developed a "self-healing" polyglycerol sebacate-polyethylene glycol methyl ether methacrylate (PGS-PEGMEMA)/ -Cyclodextrin ( CD) hydrogel which could be sheared into a liquid during injection and has the potential to quickly "heal" itself back into gel post-injection. This hydrogel was shown to be biocompatible and biodegradable and therefore appropriate for use in vivo. Furthermore, the storage and loss moduli of the hydrogels could be tuned (by varying the concentration of αCD) between a fraction of a kPa to a few 100 kPa, a range that coincides with the moduli of cells and human soft tissues. This property would allow for this hydrogel to be used in vivo with maximal mechanical compatibility with human soft tissues. In vitro experiments showed that the hydrogel demonstrated a linear mass erosion profile and a biphasic drug (doxorubicin) release profile: Phase I was primarily driven by diffusion and Phase II was driven by hydrogel erosion. The diffusion mechanism was modeled with the First Order equation and the erosion mechanism with the Hopfenberg equation. This established fitting model could be used to predict releases with other drugs and estimate the composition of the hydrogel required to achieve a desired release rate. [ABSTRACT FROM AUTHOR]

This work investigated the effect of the addition of different antioxidants (ascorbic acid, glucose oxidase, cysteine, and jabuticaba extract) on the rheological and sensorial properties of the probiotic petit suisse cheese. Absence of influence of the antioxidants at the physicochemical characteristics of the petit suisse cheese was observed. Overall, the petit suisse cheeses presented weak gel characteristics and behaved as pseudoplastic material, except for control. All treatments exhibited a thixotropic non-Newtonian behavior; however, higher hysteresis area was obtained for control sample, which indicates that antioxidants incorporated to petit suisse had a protective effect on the typical thixotropic behavior of the Quark gel. The commercial sample presented higher scores for all aspects by consumers, whereas the probiotic petit suisse samples presented opposite behavior. Projective mapping was able to generate a vocabulary where the sample containing jabuticaba skin extract obtained by supercritical extraction was characterized by the panelists as presenting grape flavor and purple color. [ABSTRACT FROM AUTHOR]

The microstructure and mechanical properties of AZ91D alloy thin-wall parts produced by the rheomolding (RM) process were investigated and compared with the same alloy formed by conventional high-pressure die casting (HPDC). The results indicate that the RM process is able to get such AZ91D parts in which α-Mg with average size of 27.36 μm are spherical and uniformly distributed in the matrix, and the matrix is a mixture of numerous fine α-Mg and intermetallic β-MgAl. High mechanical properties including ultimate tensile strength (UTS) of 270 MPa, yield strength (YS) of 169 MPa, elongation of 7.1%, and Vickers hardness of 102 are obtained in parts formed by RM due to the fine and uniform microstructure and less porosities. Compared with HPDC, the UTS, YS, elongation, and hardness of RM AZ91D are increased by 14.4, 9.7, 86.8, and 21.4%, respectively. The solidified grains in RM AZ91D alloy show a smaller aluminum gradient than that in HPDC. This indicates that the solidification of the RM AZ91D is closer to equilibrium. [ABSTRACT FROM AUTHOR]

Cinnamon leaf oil contains a high percentage of eugenol and has antimicrobial, antioxidant and antiinflammatory properties. However, the undiluted oil can cause irritation to the skin. Therefore, the aims of this study were to develop and evaluate cinnamon leaf oil nanocream using palm oil. Nanocream base was prepared using different ratios of oil, surfactants and water. The surfactant used were mixture of Tween 80:Carbitol or Tween 80:Span 65 at different hydrophile-lipophile balance values. The pseudoternary phase diagrams were constructed to identify the nanocream base areas and the results showed that the nanocream bases using Span 65 as co-surfactant produced bigger cream area. Fifteen formulations using mixtures of Tween 80:Span 65 were further evaluated for accelerated stability test, droplet size, zeta potential, rheological properties and apparent viscosity. The nanocream base which had an average droplet size of 219 nm and had plastic low with thixotropic behavior was selected for incorporation of 2% cinnamon leaf oil. The nanocream containing cinnamon leaf oil had the average size of 286 nm and good rheological characteristics. The in vitro release study demonstrated that eugenol as the main constituent of cinnamon leaf oil was released for about 81% in 10 h. The short-term stability study conducted for 6 months showed that the cinnamon leaf oil nanocream was stable at a temperature of 25° and thus, cinnamon leaf oil nanocream is a promising natural based preparation to be used for topical application. [ABSTRACT FROM AUTHOR]

The stagnation point flow of thixotropic fluid towards a linear stretching surface is investigated. Mass transfer with first order chemical reaction is considered. The resulting partial differential equations are reduced into the ordinary differential equations. Dimensionless velocity and concentration fields have been computed. Graphical plots are presented to illustrate the details of flow and mass transfer characteristics and their dependence upon the physical parameters. Numerical values of surface mass transfer are first computed and then analyzed. [ABSTRACT FROM AUTHOR]

Low-molecular-mass gelators and relevant molecular gels have been employed for water purification owing to their convenience and efficiency, but the process is time consuming due to low extraction efficiency originated from limited contact of the two phases. In this work, two novel di-cholesterol-based gelators, 1 and 2 , with a ferrocenyl unit were synthesized and the gels based on 2 possess a smart thixotropic property. In particular, 2 /heptane gel, the shear force induced phase transition is fast (within seconds) and fully reversible without the need of heating–cooling cycle. Based upon the thixotropic molecular gel, a novel separation strategy, which combines the great efficiency of liquid–liquid extraction and the convenience of liquid–solid separation, has been successfully conducted for removing iodine from wastewater. It was demonstrated that iodine was removed within several minutes and the extraction efficiency (72%) was the same with the one using corresponding liquid. Furthermore, 2 /heptane gel is also responsive to chemical oxidation and variation in temperature. FTIR, NMR, CD and XRD studies revealed that helical fibers were formed via intermolecular hydrogen bonding and van der Waals interaction. It is believed that the results presented in this work are of importance for extending real-life applications of molecular gels. [ABSTRACT FROM AUTHOR]

To distinguish it clearly from nonlinear viscoelasticity, we define "ideal thixotropy" as "a timedependent viscous response to the history of the strain rate, with fading memory of that history," endowing such fluids with memory but no elasticity. An "ideal thixotropic fluid" has instantaneous stress relaxation upon cessation of flow and no elastic recoil on removal of stress. We describe "nonideal thixotropic" fluids as those whose viscoelastic time scales governing stress relaxation are much shorter than those governing the thixotropic response. This ensures that a clear distinction can be maintained between "thixotropy" and "nonlinear viscoelasticity." The stress tensor for an ideal thixotropic fluid can in general be expressed as a contraction product of a fourth rank viscosity tensor with the velocity gradient tensor, in which the viscosity tensor depends on the history of the flow. We show examples of constitutive equations that meet the definitions of ideal thixotropy or nonideal thixotropy. We also show examples of constitutive equations that have been designated as "thixotropic" by virtue of containing an equation for evolution of a "structure parameter," but whose behavior is indistinguishable from that of ordinary nonlinear viscoelasticity, and so should not be considered thixotropic. [ABSTRACT FROM AUTHOR]

The present study proposed a thixotropic model to examine the variations in the thixotropic behaviour of waste activated sludge after the application of different thermal specific energies ( E S ). The model is based on the definition of the time dependence of a structural parameter, S , which quantifies the structural level of the internal structure at any time and shear rate, and the instantaneous variations in the alignment and deformation of flocs. The thixotropic behaviour was quantified based on the kinetic coefficients for the breakdown and build-up processes, which appeared to depend on the shear rate. The application of thermal E S significantly reduced the steady state viscosity and the kinetic coefficient for the breakdown process, suggesting that the thixotropy slightly increased. Complementarily, the sludge was further characterised to understand the variations in sludge rheology. The extracellular polymeric substances (EPSs) present in sludge were fractionated and subsequently analysed by gel permeation chromatography, which revealed that thermal treatment solubilised most of the peptides and proteins of low molecular weight but denatured the high molecular weight proteins. On the other hand, the capillary suction time increased at low thermal E S and decreased at high thermal E S . However, the water removed by centrifugation was increased even at low temperatures, despite the increase in the capillary suction time value. [ABSTRACT FROM AUTHOR]

The microstructure-rheology relationship for a model, thermoreversible nanoparticle gel is investigated using a new technique of time-resolved neutron scattering under steady and timeresolved large amplitude oscillatory shear (LAOS) flows. A 21 vol. % gel is tested with varying strength of interparticle attraction. Shear-induced structural anisotropy is observed as butterfly scattering patterns and quantified through an alignment factor. Measurements in the plane of flow show significant, local anisotropy develops with alignment along the compressional axis of flow, providing new insights into how gels flow. The microstructure-rheology relationship is analyzed through a new type of structure-Lissajous plot that shows how the anisotropic microstructure is responsible for the observed LAOS response, which is beyond a response expected for a purely viscous gel with constant structure. The LAOS shear viscosities are observed to follow the "Delaware-Rutgers" rule. Rheological and microstructural data are successfully compared across a broad range of conditions by scaling the shear rate by the strength of attraction, providing a method to compare behavior between steady shear and LAOS experiments. However, important differences remain between the microstructures measured at comparatively high frequency in LAOS experiments and comparable steady shear experiments that illustrate the importance of measuring the microstructure to properly interpret the nonlinear, dynamic rheological response. [ABSTRACT FROM AUTHOR]

In this work we review the literature for possible confirmation of a phenomenon that was proposed to develop when water is left to stand for some time undisturbed in closed vessels. The phenomenon has been termed thixotropy of water due to the weak gel-like behaviour which may develop spontaneously over time where ions and contact with hydrophilic surfaces seem to play important roles. Thixotropy is a property of certain gels and liquids that under normal conditions are highly viscous, whereas during mechanical processing their viscosity diminishes. We found experiments indicating water's self-organizing properties, long-lived inhomogeneities and time-dependent changes in the spectral parameters of aqueous systems. The large-scale inhomogeneities in aqueous solutions seem to occur in a vast number of systems. Long-term spectral changes of aqueous systems were observed even though the source of radiation was switched off or removed. And water was considered to be an active excitable medium in which appropriate conditions for self-organization can be established. In short, the thixotropic phenomenon of water is further indicated by different experimental techniques and may be triggered by large-scale ordering of water in the vicinity of nucleating solutes and hydrophilic surfaces. [ABSTRACT FROM AUTHOR]

Abstract: The flow characteristics and rheological properties of natural gas hydrate slurry, with initial water cuts ranging from 5 to 30vol%, were investigated in a flow loop. The experimental results indicate that the hydrate slurry can be considered a pseudoplastic fluid and presents more obvious shear-thinning behaviour with the increase in the hydrate volume fraction. The study on the fluid morphology demonstrated that the original structure of the water-in-oil emulsion is destroyed by the formation of gas hydrate, and the hydrate slurry is ultimately transported as a solid dispersion system. An empirical Herschel–Bulkley-type equation that considers the hydrate volume fraction was developed to improve the description of the rheological properties of the hydrate slurry. The apparent viscosities of the hydrate slurry calculated by the new equation were in accordance with the experimental data. Shutting-down/restarting tests using three shutting-down times (2h, 4h, and 8h) were performed. The experimental results indicate that the hydrate slurry can be easily and safely restarted from the static state after a long shutting-down period and exhibits obvious thixotropic behaviour with increasing shutting-down time. [Copyright &y& Elsevier]

We present a novel approach for using large-amplitude oscillatory shear flow experiments (LAOS) to determine--in a simple, direct, and robust manner--the mechanical behavior of materials that possess a microstructure and may exhibit solidlike, liquidlike, viscoelastic, viscoplastic, and/or thixotropic behavior. As the stress amplitude and frequency are independently varied, two classes of motion are observed: (i) structure-changing motions, characterized by a nonsinusoidal response, when the stress amplitude is large enough to cause microstructural changes and the frequency is of the order of the reciprocal of the time scale of microstructural changes; and (ii) constant-structure motions, characterized by a sinusoidal response, when either the stress amplitude is not large enough to cause microstructural changes or the stress amplitude is large enough to cause microstructural changes but the frequency is much larger than the reciprocal of the time scale of microstructural changes. For a commercial hair gel, we confirm experimentally the existence of these two classes of motions, which was theoretically predicted by de Souza Mendes and Thompson [Rheol. Acta 52(7), 673-694 (2013)]. In contrast to the presently available LAOS analyses, which focus on the structure-changing motions, our methodology--quasilinear LAOS or QL-LAOS--relies for the most part on data obtained from constant-structure motions. This fact simplifies dramatically the experiments and the analysis and provides material functions the physical meanings of which are quite evident. [ABSTRACT FROM AUTHOR]

Time dependent and steady state flow properties of two different branded (Cremica and Funfoods) commercial mayonnaise samples of different formulation (egg and eggless) were tested using concentric cylinder rheometer. Mayonnaise samples were characterized as a shear thining (Pseudoplastic) liquid with yield stress and demonstrated thixotropic properties also. All the samples irrespective of testing conditions (temperature and shear rates) confirmed time dependent shear thinning behaviour. Steady state rheological data of all the samples was well described by Hurshel Bulkley model (R² > 0.967, SE = 0.106). Hahn model was found to be the most appropriate model to describe time dependent rheology of mayonnaise. Adequacy of fitting of Hahn model was explained in terms of standards error (SE) and coefficient of determination (R²) root mean square error values. [ABSTRACT FROM AUTHOR]

Abstract: Rheological property data (practically and theoretically significant) of typical desalination-membrane fouling layers are reported for the first time in this study, involving two stages. First, desalination of brackish water (with 30mg/L sodium alginate) was carried out under constant flux; Ca2+-ion concentration 1mM–8mM was used. Linear temporal trans-membrane pressure increase, associated with constant specific fouling resistance α, indicated uniformity of growing alginate layers. Fouling resistance α increased with calcium concentration. Subsequently, fouled membrane segments were tested in a parallel-plate rheometer, operating in oscillatory and steady shearing modes. Key rheological parameters of fouling layers, including storage (G′) and loss (G″) moduli, complex and shear viscosities, were assessed in relation to their permeability and other characteristics. Alginate fouling layers possess viscoelastic properties characteristic of rather stiff gels; moreover, they belong in the class of thixotropic materials with yield stress. Layers from feed-water of small Ca+2-ion concentration exhibit strong elastic character, high viscosities and yield stresses; the elastic character and rheological parameter values are reduced with increasing Ca2+-ion concentration. The high Na-ion concentration in the fouling layers appears to significantly influence their structure; however, considering the complicated dynamics of developing layers, the relative significance of the abundant Na-ions compared to Ca2+-ions is unclear. [Copyright &y& Elsevier]

Low-molecular-weight gels have great potential for use in a variety of fields, including petrochemicals, healthcare, and tissue engineering. These supramolecular gels are frequently metastable, implying that their properties are kinetically controlled to some extent. Here, we report on the in situ supramolecular gel formation by mixing 1,3-cyclohexane diamine (1) and isocyanate derivative (2) without any catalysis at room temperature in various organic solvents. A mixture of building blocks 1 and 2 in various organic solvents, dichloromethane, tetrahydrofuran, chloroform, toluene, and 1,4-dioxane, resulted in the stable formation of supramolecular gel at room temperature within 60–100 s. This gel formation was caused by the generation of urea moieties, which allows for the formation of intermolecular hydrogen-bonding interactions via reactions 1 and 2. In situ supramolecular gels demonstrated a typical entangled fiber structure with a width of 600 nm and a length of several hundred μm. In addition, the supramolecular gels were thermally reversible by heating and cooling. The viscoelastic properties of supramolecular gels in strain and frequency sweets were enhanced by increasing the concentration of a mixed 1 and 2. Furthermore, the supramolecular gels displayed a thixotropic effect, indicating a thermally reversible gel. [ABSTRACT FROM AUTHOR]

The durability of reinforced concrete structures is dependent on the ability of the concrete cover to combat the ingress of chlorides and carbon dioxide in marine and urban environments. In recent years, interest in additive manufacturing, specifically referring to extrusion based three-dimensional concrete printing (3DCP), has been growing in the construction industry. Despite this being a promising technology that can save construction time, costs and resources, certain issues regarding the lack of fusion between subsequent printed layers have been brought to light. Research has shown that the lack of fusion at the interlayer regions can act as ingress pathways for corrosion contaminants, such as carbon dioxide and chloride aqueous solution, that can cause deterioration. This study investigates the interlayer bond strength (flexural strength) and durability performance of 3D printed concrete subjected to pass times between 0 and 30 min and compares the results to reference cast concrete of the same concrete mixture. The durability study includes Durability Index testing (oxygen permeability, water sorptivity and chloride conductivity index), accelerated concrete carbonation and chloride-induced corrosion. The results show that the cast samples outperform printed samples, yielding greater flexural strength and durability properties, and emphasize the importance of improving the 3DCP interfacial bond. Cast samples are shown to have randomly distributed, compact voids compared to the interconnected and elongated pores located at the interlayer regions of printed samples. In addition, printed samples yield lower interlayer bond strength and durability properties with an increase in pass time, which is attributed to surface moisture evaporation as well as the thixotropic behaviour of the concrete mixture. Good relationships between the mechanical strength and durability performance are also presented. [ABSTRACT FROM AUTHOR]