Search Results (357)

Background: Uterine torsion is rare in domestic cats and, when diagnosis is delayed, is associated with high maternal and fetal mortality. Conventional B-mode ultrasonography cannot reliably distinguish viable from devitalised uterine tissue, and Doppler ultrasonography, despite its capacity to assess uterine, ovarian, and fetal perfusion, has not been systematically applied to feline uterine torsion. Case Description: A 4-year-old queen in late gestation presented with acute abdominal pain, lethargy, abdominal distension, and tachypnoea. B-mode imaging showed an enlarged, fluid-distended uterine segment with thickened walls. Colour, spectral, and power Doppler revealed an absent to markedly reduced arterial flow distal to the torsion, elevated resistive and pulsatility indices in the uterine and ovarian arteries, and the loss of peripheral perfusion. The absence of fetal heartbeats and umbilical flow confirmed fetal nonviability. Laparotomy confirmed the torsion of a congested, devitalised uterine horn, with asymmetric fetal loading (two kittens in the torted horn, one fetal resorption in the contralateral horn) as the likely biomechanical cause. Ovariohysterectomy was performed without derotation. Histopathology confirmed haemorrhagic necrosis, and haematology showed severe regenerative anaemia and marked leucocytosis, which resolved progressively after surgery. Conclusions: Doppler ultrasonography supplied vascular and fetal viability information unavailable from B-mode imaging alone, supporting ovariohysterectomy over conservative detorsion. Based on the feline case reports identified during the preparation of this report, this appears to be among the first descriptions of a systematic, multi-vessel Doppler protocol combining colour, power, and spectral modalities with resistive and pulsatility index measurements in feline uterine torsion; as this observation derives from a single case, it should be regarded as preliminary. Full article

To address the challenges associated with severe lost-circulation formations, including large loss-channel dimensions, rapid fluid losses, and the tendency of conventional bridging or physical-filling materials to accumulate at fracture entrances rather than penetrate deeply into fractures and form stable pressure-bearing plugs, a slag–fly ash–gypsum–sodium ethylenediamine tetramethylene phosphonate (EDTMPS) controlled-setting lost-circulation system was developed in this study. A 4 wt% bentonite base slurry was used as the dispersion medium, while a slag–fly ash blend served as the principal cementitious component. Gypsum was used to regulate the setting reaction, and EDTMPS was employed to control the slurry-thickening process, thereby coordinating slurry pumping, fracture filling, and in situ setting. The operational feasibility, consolidation capability, and short-term pressure-bearing performance of the system were evaluated through formulation screening, tests of slurry placement and hardened-material properties, water-based drilling-fluid contamination evaluation, and pressure-bearing tests in regular fractures with apertures of 1–5 mm. The results showed that, at a slag-to-fly-ash mass ratio of 6:4, the hardened material exhibited a compressive strength of 12.91 MPa. Within the investigated dosage range, the highest observed 1 d and 3 d compressive strengths were both obtained at a gypsum dosage of 2.0%. Under conditions of 150 °C and 50 MPa, the addition of 1.5 g of EDTMPS extended the slurry thickening time from 2.6 h to 7.3 h, while the compressive strength of the hardened material after 24 h of curing reached 17.18 MPa. At a water-based drilling-fluid contamination ratio of 30%, the compressive strength of the hardened material was 13.86 MPa, corresponding to a strength-retention ratio of 80.7%. In straight, constant-aperture fractures with apertures of 1.0, 2.0, 3.0, 4.0, and 5.0 mm, the maximum pressures sustained by the plugs before breakthrough were 16, 15, 14, 13, and 12 MPa, respectively, and decreased with increasing fracture aperture. These results indicate that, within the formulation range, water-based drilling-fluid contamination conditions, and short-term pressure-bearing conditions in regular fractures investigated in this study, the system can coordinate slurry-thickening control, 24 h hardened strength, contamination tolerance, and pressure-bearing performance in regular fractures. The findings provide a verifiable formulation-design approach for reconciling the placement-time window of lost-circulation materials for severe lost circulation with their post-placement pressure-bearing capacity. Full article

Conventional partially hydrolyzed polyacrylamide (HPAM) suffers severe chain coiling, viscosity attenuation and precipitation under high-temperature and high-salinity reservoir brines, restricting its tertiary oil recovery efficiency. Herein, a novel carbon quantum dot hybrid terpolymer (QDHSTP) was synthesized via free-radical copolymerization, where silane-modified nitrogen-doped carbon quantum dots (FNCQDs) were covalently bonded to acrylamide (AM)/2-acrylamido-2-methylpropane sulfonic acid (AMPS)/diallyldimethylammonium chloride (DMDAAC) backbones. FTIR, ¹H NMR and thermogravimetric analysis (TGA) verified successful grafting of FNCQDs, while SEM revealed a continuous three-dimensional entangled network constructed by polymer chains. Steady and oscillatory rheology systematically characterized the solution viscoelasticity: QDHSTP solutions followed the power-law shear-thinning model, with flow behavior index n decreasing from 0.698 to 0.676 and consistency factor k rising from 80.91 to 131.13 mPa·sⁿ as concentration increased from 2000 to 3000 mg/L. All samples behaved as viscosity-dominated viscoelastic fluids, with elastic modulus exhibiting stronger frequency dependence. Benefiting from embedded FNCQDs, QDHSTP retained 79.74% and 76.06% of initial viscosity in 1.0 × 10⁴ mg/L NaCl and CaCl₂ brine, respectively, markedly better than that of the polymer without incorporated FNCQDs respectively, and maintained thickening capacity at 90 °C. Artificial sandstone core flooding demonstrated an incremental oil recovery of 29.8% over baseline waterflooding, attributed to mobility control and elastic residual oil stripping. This covalent nanohybrid strategy provides a facile route to construct thermo-salt tolerant polyacrylamides, offering a promising candidate polymer for harsh oil reservoir chemical flooding. Full article

This study investigates the onset of thermal convection in a power-law fluid saturating a bidispersive porous medium using linear stability analysis. The eigenvalue problem is solved using the normal mode technique in conjunction with a numerical boundary value solver (bvp4c). The interaction parameter exhibits dual behavior depending on the rheology: it destabilizes the system in shear-thinning fluids while stabilizing it in Newtonian and shear-thickening regimes under certain conditions. The permeability ratio is found to have a consistently stabilizing effect, with higher values significantly delaying the onset of convection. Thermal transport parameters also play a crucial role, with increasing Peclet numbers generally enhancing stability, although non-monotonic behavior is observed in the shear-thinning regime due to competing effects of convective enhancement and thermal diffusion. For low values of the Peclet numbers, shear-thickening fluids exhibit the lowest critical Rayleigh number (least stable) and shear-thinning fluids the highest one (most stable). In contrast, for high Peclet numbers, shear-thickening fluids remain the least stable, while Newtonian fluids exhibit maximum stability. Full article

Conventional full-span movable weirs may require complete lowering for sediment or debris release, reducing upstream water-level control and limiting operational efficiency. This study evaluates a smart rubber and steel (SRS) movable weir that enables selective gate operation through a one-way coupled hydraulic–structural framework using the Environmental Fluid Dynamics Code (EFDC) and MIDAS Civil. Four gate-operation scenarios and gate heights of 0.5, 1.0, 1.5, and 2.0 m were analyzed to characterize flow redistribution, hydraulic loading, gate response, longitudinal-rib performance, and the safety of anchor bolts, clamping plates, and the airbag system. Selective lowering substantially altered flow distribution, with side-gate lowering producing the most critical condition and increasing maximum velocity by approximately 267% relative to the fully raised condition at a 2.0 m gate height. Hydraulic demand became strongly localized near the lowered and adjacent raised spans, although the governing static load remained dominated by hydrostatic loading. Rib comparisons showed that redistributing stiffness through additional longitudinal stiffeners reduced stress and deformation without relying solely on gate thickening, while all component-level static checks satisfied the adopted safety criteria. The results demonstrate that integrating span-specific hydraulic redistribution with structural response provides a practical basis for structurally safe and material-efficient river-infrastructure design. Full article

Synovitis is an inflammatory disorder in horses that contributes to cartilage degradation and osteoarthritis. This study evaluated the effects of intra-articular administration of high-molecular-weight (HMW), linear (non-cross-linked) hyaluronic acid (HA) in an equine model of lipopolysaccharide (LPS)-induced acute synovitis. In this randomized blinded study, acute synovitis was induced in radiocarpal joints of 16 adult horses using LPS (0.25 ng). After 12 h, joints were treated intra-articularly with either 2 mL of phosphate-buffered saline (PBS; control group) or 2 mL of HMW-HA (20 mg/mL; 2280 kDa; treatment group). Horses underwent orthopedic, ultrasonographic, and synovial fluid evaluations. Horses treated with HMW-HA exhibited lower synovial membrane thickening and reduced lameness scores compared with controls. Synovial fluid analysis demonstrated increased concentrations of HMW-HA during the acute inflammatory phase in treated joints. Reduced chondroitin sulfate release was also detected following HMW-HA administration. Lower lipid peroxidation levels (TBARS) were observed in the treated group at 24 h and 14 days. Intra-articular administration of high-molecular-weight linear hyaluronic acid was associated with increased synovial availability of HMW-HA during the acute inflammatory phase, attenuation of pain-related clinical signs and synovial membrane thickening, and modulation of the redox environment. These findings support a modulatory role of linear HMW-HA in the intra-articular environment. Full article

Viscous fingering is a canonical nonlinear interfacial instability that arises when a less viscous fluid displaces a more viscous one under an adverse viscosity contrast. Despite extensive investigations into the effects of fluid properties, operating conditions, and rheology, systems involving a shear-thickening displaced phase remain largely unexplored. Here, three-dimensional numerical simulations of immiscible air–fluid displacement in a Hele–Shaw cell are performed to elucidate how interfacial tension, air-inlet velocity, and gap-depth gradient regulate instability evolution. Increasing interfacial tension strengthens the Laplace-pressure barrier, suppresses shear-induced necking and pinch-off, and preserves finger topology; however, it intensifies flow diversion and delays the advancement of the central finger. Increasing the inlet velocity markedly amplifies the local interfacial shear rate and triggers pronounced shear thickening. The resulting viscous-resistance barrier redistributes momentum toward paths of least hydraulic resistance, directly promoting tip splitting and severe topological breakup. Even a small gap-depth gradient reorganizes the local hydraulic resistance and pressure field. Positive and negative gradients induce resistance-reduction and throttling effects, respectively, generating pronounced pressure shielding that governs asymmetric momentum transfer and preferential flow-path selection. These findings identify the capillary, rheological, and geometric mechanisms controlling viscous fingering during the air-driven displacement of shear-thickening fluids. Because such instabilities compromise the integrity of geological-fracture seals and the operating efficiency of semi-solid flow batteries, this study provides a mechanistic basis for stabilizing immiscible displacement and optimizing industrial fluid-transport systems. Full article

Background/Objectives: Lymphedema is a chronic condition caused by impaired lymphatic function that is characterized by fluid accumulation with progression to tissue thickening and fibrosis. Although various noninvasive assessment methods have been proposed, studies that have integrated fluid, structural, and stiffness-related changes are limited. To address this gap, we conducted an integrated multimodal assessment combining multiple-frequency bioelectrical impedance analysis (MFBIA), ultrasound tissue thickness measurements, and shear wave elastography (SWE) to characterize stage-specific changes in breast cancer-related lymphedema. Methods: This prospective cross-sectional study included patients who had undergone breast cancer surgery. Participants were classified into the clinical and subclinical lymphedema groups based on MFBIA criteria. Dermal thickness, subcutaneous thickness, and tissue stiffness measurements in both upper limbs were obtained using SWE on the same day. MFBIA parameters including extracellular water ratio, 5 kHz impedance ratio, and phase angle were assessed. Ipsilateral and contralateral limbs were compared, and correlation analyses of variables were performed. Results: Dermal thickness and subcutaneous thickness in the ipsilateral limb were greater than those in the contralateral limb in the overall cohort and subclinical group. Increased tissue stiffness measured using SWE was observed only in the clinical lymphedema group. MFBIA parameters in the clinical group were higher than those in the subclinical group. According to the correlation analysis, MFBIA parameters were associated with tissue thickness and SWE parameters were not correlated with other variables. Conclusions: These findings support the clinical utility of a multimodal approach for the stage-specific evaluation of breast cancer-related lymphedema, thereby facilitating stage-based and individualized management. Full article

Accurate wellbore-pressure prediction is essential for safe drilling and pressure management in ultra-deep wells, where high temperature and pressure strongly alter drilling-fluid rheology. Existing rheological-parameter models are often calibrated for specific fluids and narrow temperature–pressure ranges, limiting their use in ultra-deep-well hydraulics. We measured three water-based drilling fluids at temperatures and pressures up to 210 °C and 206.5 MPa, compared seven rheological models, and developed a multidimensional evaluation method considering global fitting accuracy, extreme-condition performance, low-shear-rate representation, absolute shear-stress deviation, and model complexity. Using ambient-condition Herschel–Bulkley (H-B) parameters as baselines, we proposed a temperature–pressure (T-P)-coupled correction model requiring fluid-specific calibration to predict H-B parameters over the tested range. The fluids exhibited temperature-induced thinning, pressure-induced thickening, and shear-thinning behavior. The H-B model showed the best overall performance, with mean R² values above 0.997 and mean absolute percentage errors below 2.5% for all fluids. Substituting the corrected parameters into the H-B equation yielded mean shear-stress errors no greater than 4.04%. Field validation showed that the T-P-coupled model reduced the mean circulating-pressure-loss error from 2.72% to 0.78%. This approach provides practical inputs for rheology estimation and circulating-pressure calculation in ultra-deep wells under wide temperature and pressure conditions. Full article

For casing damage phenomena including casing corrosion, rupture, and seal failure that frequently occur in carbon capture, utilization, and storage (CCUS) injection-production wells under long-term gas injection and pressure fluctuations, combined with the characteristics of ultra-fine cement slurry such as concentrated hydration heat release and vulnerability to acidic environment corrosion, this study synthesized tartaric acid-intercalated Mg-Al layered double hydroxides (TA-LDHs) through ion-exchange reaction as a functional retarder, and focused on screening the water–cement ratio as well as the dosages of fluid loss additive and dispersant suitable for CCUS working conditions. The results demonstrate that at a water–cement ratio of 0.7 with 1.5% fluid loss additive TSJ-1, 0.4% dispersant FSJ-1, and 0.2% TA-LDHs retarder, the cement slurry presents excellent rheological properties, a short thickening transition time, and remarkable resistance to acidic environment erosion. Plugging performance evaluations reveal that under simulated formation water conditions, the system maintains a breakthrough pressure gradient above 90.5 MPa·m⁻¹ and a plugging efficiency of more than 99%, and after 30 days of curing, its compressive strength reaches 29 MPa while the plugging efficiency is improved to 99.37%. Furthermore, after exposure to CO₂-saturated simulated formation brine at 80 °C and 20 MPa for 30 days, the TA-LDHs-modified cement exhibited a compressive strength of 27.0 MPa and a strength retention of 93.1%, while its permeability increased by only 23.1%. In comparison, the compressive strength retention of the control cement was 80.8%, and its permeability increased by 138.5%. These results indicate that the TA-LDHs-modified ultra-fine cement possesses favorable plugging performance and improved resistance to CO₂-induced degradation, showing potential for casing damage remediation in CCUS wells. Full article

The two-dimensional thermal liquid jet of a non-Newtonian power-law fluid is investigated under shear-rate-dependent thermal diffusivity, resulting in a one-way coupled nonlinear system governing momentum and thermal transport. Two physically distinct free-surface thermal boundary conditions are examined: adiabatic insulation and convective heat loss. Conservation laws and conserved quantities for the governing system are derived systematically using the multiplier method. By coupling an appropriate conserved vector with an admitted Lie point symmetry, the governing partial differential equations are reduced to a coupled system of ordinary differential equations. Closed-form parametric families of solutions are then obtained for the thermal field. The analysis reveals fundamentally different thermal transport mechanisms across rheological regimes: shear-thinning fluids enhance thermal redistribution and become increasingly sensitive to convective cooling as the Biot number increases, whereas shear-thickening fluids suppress internal thermal transport, promoting greater thermal retention within the jet core and reducing the influence of free-surface cooling. These findings clarify the interplay between rheology, nonlinear thermal diffusion and free-surface cooling and provide new analytical insight into downstream thermal transport in non-Newtonian liquid jets. Full article

Reducing water-insoluble residues while maintaining sufficient rheological performance remains a key challenge for guar gum-based fracturing fluid thickeners. Natural guar gum (GG) is widely used in fracturing fluids, but its relatively high content of water-insoluble residues can impair permeability and reduce fracture conductivity. In this study, GG was modified by low-substitution etherification using a glycerol ether-based modifier (GMH-1) under mild alkaline reaction conditions to develop a reduced-residue thickener for fracturing fluid applications. The modification conditions were optimized through an L9 orthogonal design combined with single-factor analysis. Under the optimal conditions of 35 °C, 2.0 h, 2.0 wt % NaOH, and 0.2 wt % GMH-1, the modified product (GMGG) exhibited an apparent viscosity of 125.3 mPa·s and a water-insoluble residue content of 5.1% in a 0.6 wt % aqueous solution; in comparison, GG showed a viscosity of 89.3 mPa·s and a residue content of 12.4%. FTIR, UV-Vis spectroscopy, and elemental analysis provided indirect but consistent evidence for low-substitution chemical modification and the introduction of oxygen-containing hydrophilic groups while largely preserving the polysaccharide backbone. GMGG also showed improved rheological and thermal response behavior, suggesting that low-substitution glycerol etherification may provide a feasible route to balance residue reduction and viscosity enhancement. These results indicate the potential of this strategy for designing reduced-residue guar-based thickeners for fracturing fluids, while further molecular-level characterization is still required to determine the exact substitution pattern and mechanism. Full article

Accurate characterization and prediction of drilling fluid rheological properties under high-temperature and high-pressure (HTHP) conditions are core prerequisites for safe and efficient deep well drilling operations. To systematically clarify the thermobaric rheological laws and intrinsic coupling mechanism of high-density drilling fluids, this study takes 2.0 g/cm³ oil-based drilling fluid (OBDF) and water-based drilling fluid (WBDF) as research objects, and carries out full-scale rheological tests via a Fann iX77 HTHP rheometer under temperatures ranging from room temperature to 200 °C and pressures from atmospheric pressure to 200 MPa. The results show that the shear stress of both fluids is positively correlated with pressure and shear rate and negatively correlated with temperature. 150 °C is identified as the critical thermal thickening temperature for WBDF: above this temperature, polymer degradation and solid precipitation cause abnormal viscosity growth, and high shear rates can effectively alleviate this thickening effect by promoting the dispersion of precipitates. There are significant differences in rheological sensitivity between the two systems: WBDF rheology is dominated by temperature dependence, while OBDF exhibits high sensitivity to both temperature and pressure due to the compressibility of the oil continuous phase; temperature and pressure exert a mutual inhibitory effect on fluid rheology. The proposed Arrhenius–Powell one-step global coupled prediction model achieves favorable prediction accuracy for both OBDF and non-thickened WBDF, with the coefficient of determination (R²) no less than 0.96. The model can provide reliable basic parameters for HTHP wellbore hydraulic calculation and pressure loss prediction, fully meeting the accuracy requirements of field engineering applications. Full article

Lost circulation of wellbore fluids within fissured zones constitutes a primary factor contributing to increased non-productive time (NPT) and restricted rate of penetration (ROP). Conventional gel-based lost circulation materials (LCMs) inherently suffer from a tradeoff between pumpability and in situ fracture retention, and they lack a design methodology quantitatively correlated with drilling engineering parameters. In this study, a shear-responsive gel with a dual physically crosslinked network—combining hydrophobic association and Fe³⁺-mediated ionic coordination—was prepared through a single-step water-based radical polymerization process, utilizing commercially available monomers. By systematically tuning the hydrophobic monomer and Fe³⁺ contents, the gel’s fracture-sealing efficacy, autogenous healing ability, and shear rheological characteristics were evaluated, establishing a quantitative correlation between the critical shear rate and drilling parameters. The empirical data demonstrate that with an increase in the hydrophobic monomer dosage from 0.4 wt% to 1.2 wt%, the critical shear rate decreases from 22.5 s⁻¹ to 8.6 s⁻¹, exhibiting an exponential decay relationship. The optimized formulation, G0.8F0.5, demonstrates a low initial viscosity of 245 mPa·s under high shear conditions, which surges to 6180 mPa·s at a shear rate of 14.2 s⁻¹, achieving a thickening factor of 29.4. Upon incubation at 80 °C for a duration of 12 h, the formulated gel restores 94.9% of its mechanical tensile strength and 96.3% of its fracture strain, whereas the Fe³⁺-free control sample fails to heal. In dynamic plugging tests using a 3 mm fracture plate, G0.8F0.5 achieves a breakthrough pressure of 12.8 MPa with a minimal fluid loss of 98 mL. The LCM forms a monolithic gel block positioned at the middle-to-rear section of the fracture, outperforming conventional gel counterparts. Drilling hydraulics simulations reveal that deploying this gel reduces the annular equivalent circulating density (ECD) by 0.06 g/cm³. Furthermore, under idealized conditions, this approach is calculated to enhance the ROP by approximately 26%. The proposed molecular design of a shear-responsive, dual physically crosslinked network provides a viable technical pathway for quantitatively tailoring the shear-responsive properties of while-drilling LCMs. Full article

High-mobility group box 1 (HMGB1) has been implicated in matrix remodeling and fibrotic disorders; however, its role in tuberculosis (TB)-associated pleural fibrosis remains unknown. Pleural fluid levels of HMGB1 and matrix metalloproteinase-1 (MMP-1) in patients with TB pleural effusion (TBPE, n = 36) or transudative pleural effusion (TPE, n = 14) were measured. The effects of Mycobacterium tuberculosis H37Ra (MTBRa) on HMGB1 and MMP-1 expression and their effects on mesothelial–mesenchymal transition (MMT) in human pleural mesothelial cells (PMCs) were assessed. The levels of HMGB1 and MMP-1 were significantly higher in TBPE than in TPE. Elevated HMGB1 and MMP-1 levels in TBPE were positively correlated and both factors were significantly associated with post-TB residual pleural thickening (RPT), particularly in patients with RPT ≥ 10 mm. Colocalized expression of HMGB1 and MMP-1 was also observed in the pleural mesothelium of TBPE patients. MTBRa significantly induced HMGB1 expression in PMCs through activation of the JNK/AP-1 signaling pathway, leading to MMT, enhanced collagen synthesis, and upregulation of MMP-1. Furthermore, silencing of MMP-1 markedly attenuated HMGB1-triggered MMT response. Collectively, HMGB1 promotes pleural fibrogenesis through JNK/AP-1-dependent and MMP-1-mediated MMT, suggesting that targeting the HMGB1/MMP-1 axis may represent a potential therapeutic strategy for TB-related pleural fibrosis. Full article