Low Fluidity Research Articles

Atomic force microscopy identifies the alteration of rheological properties of the cardiac fibroblasts in idiopathic restrictive cardiomyopathy.

Restrictive cardiomyopathy (RCM) is a rare disease characterized by increased ventricular stiffness and preserved ventricular contraction. Various sarcomere gene variants are known to cause RCM; however, more than a half of patients do not harbor such pathogenic variants. We recently demonstrated that cardiac fibroblasts (CFs) play important roles in inhibiting the diastolic function of cardiomyocytes via humoral factors and direct cell–cell contact regardless of sarcomere gene mutations. However, the mechanical properties of CFs that are crucial for intercellular communication and the cardiomyocyte microenvironment remain less understood. In this study, we evaluated the rheological properties of CFs derived from pediatric patients with RCM and healthy control CFs via atomic force microscopy. Then, we estimated the cellular modulus scale factor related to the cell stiffness, fluidity, and Newtonian viscosity of single cells based on the single power-law rheology model and analyzed the comprehensive gene expression profiles via RNA-sequencing. RCM-derived CFs showed significantly higher stiffness and viscosity and lower fluidity compared to healthy control CFs. Furthermore, RNA-sequencing revealed that the signaling pathways associated with cytoskeleton elements were affected in RCM CFs; specifically, cytoskeletal actin-associated genes (ACTN1, ACTA2, and PALLD) were highly expressed in RCM CFs, whereas several tubulin genes (TUBB3, TUBB, TUBA1C, and TUBA1B) were down-regulated. These results implies that the signaling pathways associated with cytoskeletal elements alter the rheological properties of RCM CFs, particularly those related to CF–cardiomyocyte interactions, thereby leading to diastolic cardiac dysfunction in RCM.

Study on the low temperature fluidity of biodiesel blended oil by maleic anhydride polymers with different molecular structures

ABSTRACT Adding pour point depressant (PPD) is one of the simple and high-efficiency methods to solve poor low-temperature flow performance of biodiesel-diesel blends, but the enhancing effect of polymeric PPDs is always influenced by the molecular structure. To explore the molecular structure-activity relationships, in this study, tetradecyl methacrylate-maleic anhydride (C14MC-MA), tetradecyl methacrylate-Itaconic anhydride (C14MC-IA) and tetradecyl methacrylate-citraconic anhydride (C14MC-CA) were synthesized and added into B20 (20 vol.% biodiesel +80 vol.% diesel). The enhancing effects of these different-structured copolymers on the low-temperature fluidity of B20 were compared. Results indicated that the enhancing effects of these copolymers were obviously affected by their molecular structure and polymerization ratios. The polar group imparted by acid anhydrides and the long side-chain alkyl group in methacrylic acid significantly enhanced the depressive effects, resulting in better fluidity at low temperatures for the synthesized polymers. Apart from the aldehyde group identical to that of MA, the methyl and methylene groups in CA and IA have considerable polarity and solubility, leading to an improvement of inhibition. Among that, C14MC-CA showed better enhancing effects on solid point (SP) and cold filter plugging point (CFPP) of B20 than that of C14MC-MA and C14MC-IA. When the dosage of C14MC-CA was 1000 ppm and the mole ratio was 9:1, the best depressive effect was achieved, and CFPP and SP were reduced by 12°C and 14°C, respectively. Also, the depressing mechanism of these copolymers on the eutectic reaction was studied by polarizing microscopy, differential scanning calorimetry and viscosity-temperature curves.

Mechanistic study of plastic layer permeability during coking of Australian metallurgical coals

The plastic layer permeability of five Australian coals was analyzed using two permeability measurement apparatuses operating under isothermal and thermal gradient induced coking conditions. In addition, the microstructure transitions across the plastic layers of the coals were analyzed using Synchrotron micro-CT. The permeability results and pore structure parameters derived from those analyses were correlated to better understand the mechanisms of plastic layer permeability. The high-rank coking coal with low fluidity showed a low plastic layer permeability over a wide temperature range and the generation of high internal gas pressure (IGP). Among all samples tested, the high-rank coal formed an intermediate plastic layer with the lowest number of isolated pores and the smallest size of open pores. This suggests that the lower deformability of the pore structures brought about by the low fluidity prevented additional pore growth and thus hindered pore interconnectivity. Additionally, it is possible that the low permeability in the resolidfied layer lends to pore expansion due to the difficulty of volatile release, evidenced by the larger volume of open pores within a larger size range of 50–100 µm. It appears that the intermediate plastic layer with less interconnectivity solidified into the expanded open pore structures in the resolidified layer through the driver of high IGP, thus contributing to the low permeability. In addition, the formation of the low permeable barrier seemed to redirect the volatiles evolved from the plastic layer toward the loose coal side, which dramatically reduced the temperature range of the plastic layer during its progression from the wall to the center. These results suggest that the plastic layer permeability is influenced by several factors which affect mass transfer in the plastic layer. As such, various approaches were used in this study to observe phenomena of plastic layer permeability.

Microstructure and macro properties of sustainable alkali-activated fly ash mortar with various construction waste fines as binder replacement up to 100%

Utilizing construction waste fines as eco-friendly binder for sustainable alkali-activated materials provides new approach to recycling construction waste. This work investigated the characterization of alkali-activated fly ash mortar (AAM) incorporating construction waste fines at varied types and replacement levels. The results showed that incorporating waste paste powder containing abundant hydrated products refined the pore size of AAM, but mixing waste mortar powder and waste concrete powder that contained massive inert quartz and calcite adversely affected the alkali-activated reaction and pore structure of AAM. The incorporation of construction waste fines was found to reduce the fluidity but increased the drying shrinkage of AAM. At identical replacement level of construction waste fines, the waste paste powder incorporated AMM has lower fluidity and greater drying shrinkage than the waste mortar powder or waste concrete powder incorporated AAM. Substituting waste paste powder for fly ash improved the mechanical strength of AAM, but the strength decreased as waste mortar powder or waste concrete powder was incorporated. Particularly, the AAM blended with 100% construction waste fines still owned good strength. Mixing construction waste powder reduced the chloride diffusion coefficient and chloride ingress depth of AAM, and the waste paste powder mixed AAM had better chloride resistance than the waste mortar powder or waste concrete powder mixed AAM. Therefore, the hydrated products in construction waste fines was revealed to benefit the micro-characteristics of alkali-activated materials, and optimizing the type and replacement level of construction waste fines can achieve sustainable AAM with good mechanical strength and chloride ingress resistance.

Experimental research on production law of multilayer heterogeneous reservoirs

In the development of multi-layer co-production heterogeneous reservoirs, problems such as serious inter-layer heterogeneity and interference always exist, resulting in an unclear understanding of inter-layer production. A clear understanding of the interference mechanism and influence of main controlling factors of multi-layer heterogeneous reservoirs on the production of small layers is the key to the effective development of the reservoirs. On the basis of clarifying the main controlling factors affecting the production of multi-layer heterogeneous reservoirs, this paper developed a multi-pipe parallel displacement experiment system to carry out indoor heterogeneous reservoir multi-layer water injection flooding experiments. Combined with dynamic and static parameters, the experiments simulated and evaluated the effects of factors such as permeability ratio, water cut, shutting down high permeability layers, production pressure difference, and change in crude oil viscosity in high permeability layers. The primary objective of this work is to reveal the mechanism of small-layer interference under different conditions, and clarify the influence of main control factors on the production of small-layer. The results show that the smaller the permeability ratio is, the weaker the difference in physical properties among layers along the vertical direction is. The reduction in the difference in seepage resistance decreases the dynamic interference among layers. The reduction in the water ratio among layers and shutting down high permeability layers can reduce the interlayer interference effectively. Increasing production pressure difference effectively improves the oil displacement efficiency of reservoirs with poor physical properties. A lower fluidity in the high permeability layers can effectively improve the oil displacement efficiency of other layers.

Polythiophene enveloped tungsten-oxide hybrid nanofillers dispersed oleo (Pithecellobium Dulce seed oil) polyurethane bi-functional nanocomposite coatings

Sustainable resource-based oleo-polyurethanes with low viscosity, superior fluidity, and good ability to spread on the surface of the substrate without involving any organic solvents, led to the formulation of volatile organic compounds (VOCs) free polymer coatings. Here, work reports the use of Pithecellobium Dulce seed oil (PDO), an eco-friendly, abundantly available, and sustainable resource for the synthesis of oleo-polyurethane (PDPU) and formulation of its nanocomposites coatings. To enhance their physicomechanical, anticorrosive, and antimicrobial properties, the tungsten oxide (WO), polythiophene (PTH), and polythiophene enveloped tungsten oxide (PTH/WO) hybrid nanofillers were dispersed in the proposed oleo-PDPU matrix. The physicochemical properties of PDPU and their nanocomposites along with the physicomechanical characterization of their coatings were conducted using standard laboratory/American Standard Testing Methods (ASTMs), spectroscopic methods (FTIR, XRD, NMR), microscopic techniques (SEM and TEM), and thermo-gravimetric analysis (TGA) techniques were used for structural, morphological, and thermal characterization. Their corrosion protective performances were analyzed using salt mist chamber, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). Their microbial resistance performance against the S. aureus, E. coli, and P. aeruginosa bacteria was also investigated using the well diffusion method. These studies revealed that the hybrid nanofillers (PTH/WO) dispersed PDPU coatings possess highest antibacterial and anticorrosive activity as compared to plain PDO-based polyurethanes (PDPU) and other such systems reported in the literature.

Insights into aggregation dynamics of NACore peptides from coarse-grained simulations.

Alpha(α)-synuclein is closely related to the pathogenesis of Parkinson's disease (PD). The NACore, a fragment of α-synuclein, is considered to be the key region of α-synuclein that causes PD. The aggregation dynamics of NACores are studied via coarse-grained molecular dynamics simulations. We find that NACores can self-assemble into a large cluster at high concentrations. The aggregation dynamics can be divided into three stages. The growth kinetics for the first and second stages follows the power law, Smax ~ tγ , with the second stage faster than the first one. The characteristic lifetime for the high concentration is 40 times larger than that for the low concentration, implying the low fluidity. Understanding the aggregation dynamics of NACores is helpful to develop drugs for therapeutic prevention and intervention.

Product market competition and stock return dependence

We model the spillover effect between competing firms’ daily idiosyncratic stock returns, using spatial econometric techniques. Contagion effect from rival firms dominates competitive effect, and the net effect is larger from negative return shocks of rival firms than from positive ones. The net effect is strong for firms in product markets with low concentration and high product market fluidity.

Preparation and performance evaluation of graphene/hydroxypropyl methylcellulose composite aerogel for high viscosity oil adsorption

With the society development, offshore oil leakage has become a global concern. The high viscosity and low fluidity of crude oil tend to prevent its diffusion to porous adsorbents, resulting in inefficient oil spill handling. To deal with the problem of intractable oil spills at sea, a two-step hydrothermal reduction method combined with ice templates was used to prepare graphene/hydroxypropyl methylcellulose composite aerogels (RGA/HPMCs). Thanks to the rough surface and efficient photo-thermal conversion efficiency, the average light absorbance of RGA/HPMC can reach 90.4% in the entire solar spectral range, and the temperature of the upper surface of the aerogel can be rapidly heated to 88.3 °C within 40 s under 1 sun illumination, resulting in a significant reduction in the viscosity of the crude oil and an enhancement of the adsorption capacity for it, up to 124.43 g·g−1 within 22 min. In addition, the good mechanical properties of RGA/HPMC led to no obvious damage when subjected to 300 cyclic compression experiments under 70% strain. And after five times of adsorption-extrusion desorption, the adsorption capacity remained above 90% of the initial adsorption capacity, indicating that the aerogel has good reusability and broad application prospect in the field of offshore oil spill treatment.

Effects of Inhibitors Generated by Dilute Phosphoric Acid Plus Steam-Exploded Poplar on Saccharomyces cerevisiae Growth

The pretreatment of lignocellulosic biomass is important for efficient bioethanol conversion, but causes undesirable by-products that inhibit microbial growth, conversely affecting the bioconversion efficiency. In this study, the main inhibitors derived from dilute phosphoric acid plus steam-exploded poplar wood were identified as 0.22 g/L furfural, 3.63 g/L acetic acid, 0.08 g/L syringaldehyde, etc., indicating the green nature and low toxicity of the pretreatment process. The effects of the three typical inhibitors (furfural, acetic acid, and syringaldehyde) on Saccharomyces cerevisiae 1517RM growth were analyzed and shown to prolong the lag phase of microbial growth to different degrees. In all the inhibitor groups, the ergosterol secretion was boosted, indicating low cell membrane fluidity and robustness of the strain to an adverse environment. The cell electronegativity and morphology of S. cerevisiae 1517RM also changed under different growth conditions, which was helpful for monitoring the physicochemical properties of cells. Furfural, acetic acid, and syringaldehyde had a synergistic effect on each other, providing an important reference to improving the subsequent ethanol fermentation process.

Totally Bio-based Kenaf Fiber-Feather Resin Green Composite

Milled waste feathers and chopped kenaf short fibers were used as the matrix resin and reinforcements, respectively, and the production of totally bio-based composites was attempted via hot-press compression molding, changing the fiber content and/or fiber length of the kenaf fibers to optimize the properties. The tensile strength of the composites increased with increasing the fiber content at first. However, the increase of the tensile strength of the composites leveled off and then decreased over the fiber content of 30 wt% due to the occurrence of insufficient filling of the matrix feather resin around the fibers which, we suggest, was due to the low fluidity of the feathers during the molding. However, the thermal stability could be enhanced when the fiber content was set at over 50 wt%. The increase of the loss modulus, E″, of the composites in the temperature range above the softening temperature of the feather resin was greatly suppressed, and E″ became almost unchanged, even at 200 °C, when the fiber content was set at 60 wt%.

Improvement of Storage Stability of Zein-Based Pickering Emulsions by the Combination of Konjac Glucomannan and L-Lysine.

In this work, L-lysine (Lys) was employed together with konjac glucomannan (KGM) to fabricate zein colloidal particles (ZCPs) aimed at enhancing the storage stability of Pickering emulsions. With the addition of Lys, zein-Lys colloidal particles (ZLCPs) and zein-Lys-KGM (ZLKCPs) exhibited smaller particle size (133.64 ± 1.43, 162.54 ± 3.51 nm), polydispersity index (PDI) (0.10 ± 0.029, 0.13 ± 0.022), π value, and more adsorbed protein. Meanwhile, KGM underwent deamidation in an alkaline solution, so the emulsions stabilized by ZLKCPs exhibited a solid gel-like structure with higher storage modulus (G′) and loss modulus (G′′), leading to lower fluidity and better stability. The synergistic effects of Lys and KGM improved the stability of the emulsion. Hydrophobic interactions and hydrogen bonds were the main driving forces forming colloidal particles, which were determined by driving force analysis.

Eco-friendly magneto-photothermal sponge for the fast recovery of highly viscous crude oil spill

The green remediation of crude oil spills is a global concern due to the high viscosity and low fluidity of such oil. Sorbents with heating functions are promising candidates for reducing the viscosity of crude oil and accelerating its cleanup. Herein, we introduce an eco-friendly sponge with the dual functionality of magnetic and photothermal heating for the rapid recovery of heavy oil spills with very high viscosity. The magneto-photothermal sponge was fabricated by the facile dip-coating of magnetoferritin (MPfFn) nanoparticles, polydopamine (PDA), and polydimethylsiloxane (PDMS) on a melamine sponge (MS). The resulting PDMS-MPfFn-MS exhibited excellent hydrophobicity and adequate flame-retardancy. Owing to the electromagnetic–thermal and photothermal conversion properties of the MPfFn/PDA coating, the surface of the functionalized sponge could be rapidly heated to 112.5 °C under alternating magnetic field (f = 502.05 kHz, H = 10.5 kA m−1) or 81.9 °C under light illumination (1 kW m−2). The fast and continuous recovery of extremely highly viscous oil was realized by a combination of solar and magnetic heating with a vacuum pump, and the recovery rate reached 50.6 g h−1 cm−2. The proposed approach integrates the safety and temperature controllability of magnetic heating and the energy-saving feature of solar heating, thereby serving as a new solution for addressing viscous crude oil spills.

The viscoelastic characteristics of in-vitro carotid plaque by Kelvin-Voigt fractional derivative modeling

Atherosclerotic plaque with a thin fibrous cap can be ruptured by shear force. Exploiting the mechanical properties of plaques within different histological regions can help to better understand the physical mechanisms of the plaque. The association between the plaque components and viscoelasticity was studied when mapping the viscoelasticity to histological features. Eleven in-vitro carotid plaques were tested with ramp-hold relaxation nanoindentation tests. Viscoelasticity (elastic modulus E0, fluidity α, and viscosity τ) was characterized by Kelvin-Voigt fractional derivative (KVFD) modeling. There is a significant difference (p < 0.001) on E0, α, and τ between the collagen-rich (CR) group and the non-collagen-rich (NCR) group. In the CR group, the elastic modulus E0 was higher but the fluidity α and viscosity τ were lower than those of the NCR group. Receiver operating characteristic (ROC) analysis revealed that combinations of E0 and α can be used as a CR indicator with an area under the curve (AUC) of 0.770. There was a negative correlation between E0 and the percentages of myxoid degeneration (r = −0.160, p < 0.001), necrosis (r = −0.229, p < 0.001) and inflammatory cells (r = −0.130, p < 0.001), and a positive correlation between elasticity E0 and the percentage of foam cells (r = 0.121, p < 0.001). There was a positive correlation between fluidity α and the percentage of necrosis (r = 0.308, p < 0.001). The results confirmed the clinical evidence that the CR group with higher elasticity and lower fluidity has higher resisting ability, whereas the NCR group with lower elasticity and higher fluidity has accompanied with more myxoid degeneration, extracellular lipids and necrosis.

Structure regulation and influence of comb copolymers as pour point depressants on low temperature fluidity of diesel fuel

Adding pour point depressants (PPDs) is a simple and efficient method to remediate the low temperature fluidity of diesel, however, the depressive effects of these polymeric PPDs are always affected by their molecular structure and polarity. In this work, to obtain high-efficiency PPDs for diesel, a series of comb copolymers of tetradecyl methacrylate-benzalacetone (C14MC-BAE), tetradecyl methacrylate-methyl cinnamate (C14MC-MCA) and tetradecyl methacrylate-ethyl 3-benzoylacrylate (C14MC-EBLA) were synthesized by the regulation of molecular structure. The depressive effects of these copolymers on the cold filter plugging point (CFPP) and solid point (SP) of diesel were studied and compared with that in previous reports. Results showed monomers with carbonyl group closer to benzene ring in side chain have better inhibition. As the mole ratio of monomer up to 9:1, these PPDs had the best depressive effect on CFPP and SP of diesel. Thereinto, C14MC-EBLA (9:1) at 2000 ppm decreased the CFPP and SP of diesel by 12 °C and 15 °C, respectively. Furthermore, the morphology and crystallization behavior of wax crystals in diesel before and after adding PPDs were analyzed by polarizing optical microscope, differential scanning calorimeter and viscosity-temperature curves.

ДОСЛІДЖЕННЯ ВПЛИВУ УМОВ ОДЕРЖАННЯ НАНОКОМПОЗИТІВ ПА6/ММТ НА ЇХ ТЕРМІЧНІ ВЛАСТИВОСТІ

The influence of additional thermal and thermomechanical treatment of PA6/MMT nanocomposites obtained from the formic acid solution on their heat resistance and technological properties was investigated. Thermal analysis established that heating the nanocomposite to a temperature of 250 ºС and treating it on a capillary plastometer IIRT at a temperature of 230 ºС increases the degree of crystallinity and heat resistance of the samples. It is shown that additionally treated nanocomposites also have lower fluidity and significantly higher values of softening temperature.

Migration and Distribution of PAH4 in Oil to French Fries Traced Using a Stable Isotope during Frying.

Isotope-labeled four polycyclic aromatic hydrocarbons (PAH4-d12) were applied to study the migration and distribution of PAH4 in oil to French fries during frying. The results showed that the mobilities of PAH4-d12 showed a downtrend within 0-6 h and then an uptrend, and PAH4-d12 were mainly distributed in the crust of the French fries, especially five-ring PAHs-d12. The correlation analysis showed that PAH4-d12 migration was mainly caused by oil absorption of French fries. The low fluidity of the oil slowed down the PAH4-d12 migration, which was accelerated as the total polar component increased (higher than 15-20%). Additionally, higher frying temperature enhanced the crust ratio and porous structure of French fries, which explained the abundant five-ring PAHs-d12 distributed in the crust. This study provided references for optimizing the frying parameters: the exposure of PAH4 in French fries to humans can be reduced by controlling the oil quality and weakening the crust of the French fries.

A solar-heated antibacterial sodium alginate aerogel for highly efficient cleanup of viscous oil spills

Hypothesis. Major oil spills highlight the need for environmentally responsible and cost-effective recovery technologies. However, challenges remain for heavy oil spill recovery because of its high viscosity and low fluidity. To achieve this goal, an ecofriendly bio-based aerogel with efficient photothermal conversion ability was developed as a novel absorbent to achieve the fast removal of heavy oil spill by reducing the oil viscosity.Experiments. From the renewable and abundant raw material sodium alginate (SA), hydrophobic and antibacterial SA/graphene oxide/ZIF-8 aerogel (SAGZM) was successfully fabricated via freezing-drying and chemical vapor deposition (CVD) technique. A series of characterization and tests, including aerogel structure, selective wettability, photothermal conversion ability, crude oil removal capability, and antibacterial ability, have been investigated in detail. SAGZM aerogels have rich pore structure, high porosity, excellent mechanical properties, and better photothermal conversion efficiency.Findings. Under sunlight illumination, the recovery ability of SAGZM for heavy crude oil was investigated through infrared thermal imaging, oil permeability behavior analysis, and the continuous absorption for crude oil. In addition, these results are well supported by the theoretical liquid absorption coefficient. This study indicates that SAGZM is highly efficient in in situ regulating oil viscosity through its remarkably photothermal conversion capability. Importantly, SAGZM possesses an excellent antibacterial ability that is often neglected in the design of environmentally friendly materials in extending its service life. The findings of this work not only provide an eco-friendly bio-based aerogel material but also demonstrate that the photo-responsive SAGZM is efficient in heavy crude oil absorption. The proposed solar-heated SA-based aerogel provides a sustainable approach and material to solve the recovery problem of viscous crude oil spills.

Effects of coal characteristics on the structure and performance of coal-based carbon foam prepared by self-foaming technique under atmospheric pressure

Carbon foams with open cell structure and high compressive strength were produced using three strongly caking bituminous coals without any pretreatment, by a proposed self-foaming technique under atmospheric pressure with the characteristics of simple operation, safety, and efficiency. The chemical composition, thermoplastic behavior, and pyrolysis characteristics of the raw coals were characterized by FT-IR, Raman, solid-state 13C NMR, Gieseler fluidity, Audibert-Arnu dilatation, and TG/DTG techniques. The results showed that the structure and mechanical properties of the carbon foams could be mainly controlled by fluidity and the chemical composition of the raw coals under the same initial foaming pressure. The carbon foams produced from DS coal with high fluidity and aliphatic carbon contents originated from the cyclic aliphatic structures presented open-cell structures, large cell size, andhigh porosity (78.43%) and showed a low compressive strength of 2.71 MPa. Carbon foam obtained from the TL coal with low fluidity, and large aromatic cluster structure presented thick ligaments, relatively uniform cell distribution and better crystalline structure, which showed the highest compressive strength of 18.13 MPa.

Fluidity is the way to life: lipid phase separation in bacterial membranes.

A hallmark of biological membranes is the dynamic localization of lipids and proteins. Lipids respond to temperature reduction below a critical point with phase separation, and poikilothermic animals and also bacteria adapt their lipid content to prevent gel phase formation in membranes. In a new study, Gohrbandt etal (2022) show that reduced membrane fluidity in bacterial cells causes reversible phase separation without membrane rupture invivo, highlighting the physical robustness of biological membranes.