Capillary Surface Research Articles

Maternal GLP-1 receptor activation inhibits fetal growth.

Glucagon-like peptide 1 (GLP-1) regulates food intake, insulin production, and metabolism. Our recent study demonstrated that pancreatic α-cells-secreted (intraislet) GLP-1 effectively promotes maternal insulin secretion and metabolic adaptation during pregnancy. However, the role of circulating GLP-1 in maternal energy metabolism remains largely unknown. Our study aims to investigate systemic GLP-1 response to pregnancy and its regulatory effect on fetal growth. Using C57BL/6 mice, we observed a gradual decline in maternal blood GLP-1 concentrations. Subsequent administration of the GLP-1 receptor agonist semaglutide (Sem) to dams in late pregnancy revealed a modest decrease in maternal food intake during initial treatment. At the same time, no significant alterations were observed in maternal body weight or fat mass. Notably, Sem-treated dams exhibited a significant decrease in fetal body weight, which persisted even following the restoration of maternal blood glucose levels. Despite no observable change in placental weight, a marked reduction in the placenta labyrinth area from Sem-treated dams was evident. Our investigation further demonstrated a substantial decrease in the expression levels of various pivotal nutrient transporters within the placenta, including glucose transporter one and sodium-neutral amino acid transporter one, after Sem treatment. In addition, Sem injection led to a notable reduction in the capillary area, number, and surface densities within the labyrinth. These findings underscore the crucial role of modulating circulating GLP-1 levels in maternal adaptation, emphasizing the inhibitory effects of excessive GLP-1 receptor activation on both placental development and fetal growth.NEW & NOTEWORTHY Our study reveals a progressive decline in maternal blood glucagon-like peptide 1 (GLP-1) concentration. GLP-1 receptor agonist injection in late pregnancy significantly reduced fetal body weight, even after restoration of maternal blood glucose concentration. GLP-1 receptor activation significantly reduced the placental labyrinth area, expression of some nutrient transporters, and capillary development. Our study indicates that reducing maternal blood GLP-1 levels is a physiological adaptation process that benefits placental development and fetal growth.

Self-Powered Microfluidics for Point-of-Care Solutions: From Sampling to Detection of Proteins and Nucleic Acids.

Self-powered microfluidics presents a revolutionary approach to address the challenges of healthcare in decentralized and point-of-care settings where limited access to resources and infrastructure prevails or rapid clinical decision-making is critical. These microfluidic systems exploit physical and chemical phenomena, such as capillary forces and surface tension, to manipulate tiny volumes of fluids without the need for external power sources, making them cost-effective and highly portable. Recent technological advancements have demonstrated the ability to preprogram complex multistep liquid operations within the microfluidic circuit of these standalone systems, which enabled the integration of sensitive detection and readout principles. This chapter first addresses how the accessibility to in vitro diagnostics can be improved by shifting toward decentralized approaches like remote microsampling and point-of-care testing. Next, the crucial role of self-powered microfluidic technologies to enable this patient-centric healthcare transition is emphasized using various state-of-the-art examples, with a primary focus on applications related to biofluid collection and the detection of either proteins or nucleic acids. This chapter concludes with a summary of the main findings and our vision of the future perspectives in the field of self-powered microfluidic technologies and their use for in vitro diagnostics applications.

Capillary-lubrication force exerted on a two-dimensional particle moving towards a thin fluid film

A rigid object moving in a viscous fluid and in close proximity to an elastic wall experiences self-generated elastohydrodynamic interactions. This has been the subject of intense research activity, with recent and growing attention given to the particular case of elastomeric and gel-like substrates. Here, we address the situation where the elastic wall is replaced by a capillary surface. Specifically, we analyse the lubrication flow generated by the prescribed normal motion of a rigid infinite cylinder near the deformable interface separating two immiscible and incompressible viscous fluids. Using a combination of analytical and numerical treatments, we compute the emergent capillary-lubrication force at leading order in capillary compliance, and characterize its dependencies with the interfacial tension, viscosities of the fluids, and length scales of the problem. Interestingly, we identify two main contributions: (i) a velocity-dependent adhesive-like force; (ii) an acceleration-dependant inertia-like force. Our results may have implications for the mobility of colloids near complex interfaces and for the motility of confined microbiological entities.

Guiding as a General Consequence of the Charged Particle Interaction with the Inner Surface of an Insulator Capillary—Guiding of 1 MeV Proton Microbeam through Polytetrafluoroethylene Macrocapillary

The transmission of energetic, 1 MeV proton microbeam through a single, cylindrical shaped, macrometer-sized polytetrafluoroethylene capillary was studied experimentally. The capillary axis was tilted with respect to the axis of the incident ion beam. The tilting, the aspect ratio of the capillary and the small beam divergence disabled the geometrical transmission of the beam through the target. The intensity, energy, deflection and charge state of the transmitted beam were investigated. We found that the pure guided transmission of a MeV/amu energy ion beam is observable. We clearly identified three completely different stages during the guiding process according to the measured energy distribution of transmitted particles. At the beginning the transmission intensity was low and only inelastic contributions with energy lower than 1 MeV were found in the spectrum. Later, in the second stage, the elastic peak appeared and became more and more significant. Finally, when the stable transmission evolved, only the elastic peak was present and the inelastic area was totally absent as a direct consequence of the ion guiding and as a result of the charged particle interaction with a charged inner surface of the insulator capillary.

Capillary constant and surface tension of isobutane–hydrogen solution in temperature range of 298–348 K

We presented the results of measuring of the capillary constant of isobutane–hydrogen solution in the temperature range of 298.15–348.15 K at pressures from the saturation pressure of pure isobutane up to 4 MPa. The surface tension of the solution was determined. The equations approximating the concentration and pressure dependences of the capillary constant and surface tension are constructed.

Capillary Constant and Surface Tension of Isobutane–Hydrogen Solution in the Temperature Range of 298–348 K

Capillary Constant and Surface Tension of Isobutane–Hydrogen Solution in the Temperature Range of 298–348 K

The Relationship between TNF-a, IL-35, VEGF and Cutaneous Microvascular Dysfunction in Young Patients with Uncomplicated Type 1 Diabetes.

The aim of this study was to analyze the relationship between immunological markers and the dysfunction of cutaneous microcirculation in young patients with type 1 diabetes. The study group consisted of 46 young patients with type 1 diabetes and no associated complications. Microvascular function was assessed with the use of nail fold capillaroscopy before and after implementing post-occlusive reactive hyperemia. This evaluation was then repeated after 12 months. Patients were divided into two subgroups according to their baseline median coverage (defined as the ratio of capillary surface area to surface area of the image area), which was established during the initial exam (coverageBASE). Additionally, the levels of several serum biomarkers, including VEGF, TNF-a and IL-35, were assessed at the time of the initial examination. HbA1c levels obtained at baseline and after a 12-month interval were also obtained. Mean HbA1c levels obtained during the first two years of the course of the disease were also analyzed. Patients with coverageBASE below 16.85% were found to have higher levels of VEGF and TNF-α, as well as higher levels of HbA1c during the first two years following diabetes diagnosis. Our results support the hypothesis that the development of diabetic complications is strongly influenced by metabolic memory and an imbalance of pro- and anti-inflammatory cytokines, regardless of achieving adequate glycemic control.

Embeddedness of liquid-vapour interfaces in stable equilibrium

We consider a classical (capillary) model for a one-phase liquid in equilibrium. The liquid (e.g., water) is subject to a volume constraint, it does not mix with the surrounding vapour (e.g., air), it may come into contact with solid supports (e.g., a container), and it is subject to the action of an analytic potential field (e.g., gravity). The region occupied by the liquid is described as a set of locally finite perimeter (Caccioppoli set) in \R^3 ; no a priori regularity assumption is made on its boundary. The (twofold) scope in this note is to propose a weakest possible set of mathematical assumptions that sensibly describe a condition of stable equilibrium for the liquid-vapour interface (the capillary surface), and to infer from those that this interface is a smoothly embedded analytic surface. (The liquid-solid-vapour junction, or free boundary, can be present but is not analysed here.) The result relies fundamentally on the recent varifold regularity theory developed by the author and Wickramasekera, and on the identification of a suitable formulation of the stability condition.

Polyethylene Glycol Confined in SiO2-Modified Expanded Graphite as Novel Form-Stable Phase Change Materials for Thermal Energy Storage.

Form-stable phase change materials (FSPCMs) composed of poly(ethylene glycol) (PEG) encapsulated in SiO2-modified expanded graphite (EG@SiO2) were prepared and investigated for thermal energy storage behaviors. The modification of SiO2 on EG was done using a simple sol-gel method, and then the resulting EG@SiO2 was introduced to confine PEG at varying content (60-90 wt %). Surface properties (including microstructure, morphology, and functional groups), PEG adsorptivity, leakage-proof ability, and thermal energy storage of the prepared materials were thoroughly characterized and discussed. The EG@SiO2 with 15 wt % SiO2 outstandingly adsorbed PEG as compared to the pristine EG, showing up >80 wt % of PEG. As a result, PEG was well stabilized in EG@SiO2 porous network without leakage, owing to capillary force, surface tension, and hydrogen bonding interactions. The optimal 80 wt % PEG/EG@SiO2 composite possessed high crystallinity (93.5%), high thermal energy storage capacity (132.5 J/g), and excellent thermal conductivity (4.086 W/m·K). In addition, it exhibited good cycling durability after 500 repeated melting/crystallization cycles. The high thermal efficacy and inexpensiveness would make the PEG/EG@SiO2 FSPCMs suitable for scale-up applications in thermal energy storage.

Chemical vapour deposition in narrow capillaries: Electro-osmotic flow control in capillary electrophoresis

BackgroundIn capillary electrophoresis (CE), the inner surface of fused-silica capillaries is commonly covalently modified with liquid silanes to control electroosmotic flow (EOF). This liquid phase deposition (LPD) approach is challenging for long and narrow-diameter capillaries (≥1 m, ≤25 μm ID) inhibiting commercial production. Here, we use chemical vapour deposition (CVD) to covalently modify capillaries with different silanes. Using a home-built CVD device, capillaries were modified with neutral (3-glycidyloxypropyl) trimethoxysilane (GPTMS), the weak base (3-aminopropyl) trimethoxysilane (APTMS), the weak acid 3-mercaptopropyltrimethoxysilane (MPTMS) and the neutral hydrophobic trichloro(1H,1H,2H,2H-perfluorooctyl) silane (PFOCTS). Gas-phase modification of GPTMS with acid and ammonia allowed further modification of the surface prior to molecular layer deposition (MLD) of poly(p-phenylene terephthalamide) (PPTA) using the self-limiting sequential reaction between terephthalaldehyde (TA) and p-phenylenediamine (PD) vapours. ResultsCapillaries coated with GPTMS by CVD showed a greater reduction in EOF at all pH values than the conventional LPD. APTMS showed a reduction of the EOF at pH 9, with EOF reversal observed below pH 6. MPTMS provided a slightly lower EOF than an unmodified capillary at high pH, and a slightly higher EOF at lower pH. PFOCTS provided the most consistent EOF as a function of pH. The deposition of successive layers of PPTA resulted in increased surface coverage of the polymer and a greater reduction in EOF at pH higher than 5. The stability of a 10 μm ID GPTMS coated capillary was tested at pH 8.8 in a 200 mM CHES/Tris BGE for the separation of inorganic anions. Over 1.5 months of continuous operation (≈4130 runs), the reproducibility of the apparent mobilities for chloride, nitrite, nitrate and sulfate were 2.43%, 2.56%, 2.63% and 3.05%, respectively. The intra-day and inter-day column-to-column reproducibility and batch-to-batch reproducibility for all the coated capillaries ranged between 0.34% and 3.95%. SignificanceThe study demonstrates the superior performance of CVD coating for suppressing the EOF compared to LPD allowing the easy modification of long lengths of narrow capillary. The variation in silane, and the ability of MLD to modify and control the surface chemistry, provides a simple and facile method for surface modification. The stability of these coatings will allow long-term capillary electrophoresis monitoring of water chemistry, such as for monitoring fertiliser run-off in natural waters.

Capillary surfaces: Stability, index and curvature estimates

Abstract In this paper, we investigate the connection between the index and the geometry and topology of capillary surfaces. We prove an index estimate for compact capillary surfaces immersed in general 3-manifolds with boundary. We also study noncompact capillary surfaces with finite index and show that, under suitable curvature assumptions, such surface is conformally equivalent to a compact Riemann surface with boundary, punctured at finitely many points. We then prove that a weakly stable capillary surface immersed in a half-space of R 3 \mathbb{R}^{3} which is minimal or has a contact angle less than or equal to π / 2 \pi/2 must be a half-plane. Using this uniqueness result, we obtain curvature estimates for strongly stable capillary surfaces immersed in a 3-manifold with bounded geometry.

Dietary rumen-protected L-arginine or N-carbamylglutamate enhances placental amino acid transport and suppresses angiogenesis and steroid anabolism in underfed pregnant ewes

This study aimed to investigate the effects of dietary supplementation of underfed Hu ewes from d 35 to 110 of gestation with either rumen-protected L-arginine (RP-Arg) or N-carbamylglutamate (NCG) on placental amino acid (AA) transport, angiogenic gene expression, and steroid anabolism. On d 35 of gestation, 32 Hu ewes carrying twin fetuses were randomly divided into four treatment groups, each consisting of eight ewes, and were fed the following diets: A diet providing 100% of NRC's nutrient requirements for pregnant ewes (CON); A diet providing 50% of NRC's nutrient requirements for pregnant ewes (RES); RES diet plus 5 g/d NCG (RES + NCG); or RES diet plus 20 g/d RP-Arg (RES + ARG). On the d 110 of pregnancy, blood samples were taken from the mother, and samples were collected from type A cotyledons (COT; the fetal portions of the placenta). The levels of 17β-estradiol and progesterone in the maternal serum and both the capillary area density (CAD) and capillary surface density (CSD) in type A COT were decreased in response to Arg or NCG supplementation when compared to the RES group. The concentrations of arginine, leucine, putrescine and spermidine in type A COT were higher (P < 0.05) in the RES + ARG or RES + NCG group than in the RES group. The mRNA expression levels of inducible nitric oxide synthase (iNOS) and solute carrier family 15, member 1 (SLC15A1) were increased (P < 0.05) while those of progesterone receptor (PGR) and fibroblast growth factor 2 (FGF2) were decreased in type A COT by supplementation with either NCG or RP-Arg compared to the RES group. The results suggest that providing underfed pregnant ewes from d 35 to 110 of gestation with a diet supplemented with NCG or RP-Arg improves placental AA transport, and reduces the expression of angiogenic growth factor genes and steroid anabolism, leading to better fetal development.

Comprehensive Perturbation Approach to Nonlinear Viscous Gravity–Capillary Surface Waves at Arbitrary Wavelengths in Finite Depth

This study presents a comprehensive analysis of the second-order perturbation theory applied to the Navier–Stokes equations governing free surface flows. We focus on gravity–capillary surface waves in incompressible viscous fluids of finite depth over a flat bottom. The amplitude of these waves is regarded as the perturbation parameter. A systematic derivation of a nonlinear-surface-wave equation is presented that fully takes into account dispersion, while nonlinearity is included in the leading order. However, the presence of infinitely many over-damped modes has been neglected and only the two least-damped modes are considered. The new surface-wave equation is formulated in wave-number space rather than real space and nonlinear terms contain convolutions making the equation an integro-differential equation. Some preliminary numerical results are compared with computational-modelling data obtained via open source CFD software OpenFOAM.

Directed alignment of graphene-oxide liquid crystals in confined spaces: Effects of flow, pickering stabilization, and phase transition

Because of its versatility for processing, graphene oxide (GO) serves as a superior substance for two-dimensional carbon-based materials. Controlling GO alignment is crucial to augment its inherent anisotropic nature. Here, we report the controlled alignment of GO confined in the rectangular and circular capillary tubes. GO aligns in contrasting orientations according to the phase of GO dispersion during loading into a capillary. Upon GO liquid crystal (LC) loading, GO-layers are oriented tangential to the inner surface of capillary, resulting in a concentric organization of the GO-layers. In the LC phase, the GO orientation is mainly influenced by the flow so that the GOs are aligned tangential to the hydraulic shear plane. However, GO self-assembles parallel to the capillary cross-section when loaded in the isotropic phase and then concentrated into the LC phase. Surprisingly, by excluding flow-induced effects, the GO layer is aligned perpendicular to the inner surface throughout the capillary. This unexpected alignment of the GO-layers is initiated in the meniscus region by the “Pickering effect” (i.e., tangential adsorption of GO along the Air-Liquid interface). Upon solvent evaporation, GO dispersions experience a sequential isotropic to nematic phase transition from the meniscus to the central region. During the phase transition, the orientation of the GO layer is determined by the long-range ordering of the LC phase. As a result, the alignment effect caused by the Air-Liquid interface determines the GO alignment throughout the capillary. Our results provide useful insight into the delicate control of GO alignment in a confined space. Precise control of GO alignment in a confined space can be achieved based on the appropriate directional design of the Air-Liquid interface and the corresponding sequential phase transition.

#3685 PERICYTE AND CXCL12 PLAY CRUCIAL ROLE IN THE RECOVERY OF ACUTE KIDNEY INJURY

Abstract Background and Aims Pericytes are mesenchyme-derived perivascular cells attached to the abluminal surface of capillaries as well as the major origin of myofibroblasts in the animal model of unilateral ureteral obstruction (UUO) and ischemia-reperfusion injury (IRI). Although previous studies reported that myofibroblasts may be beneficial during acute kidney injury (AKI) via growth factor secretion, reconstitution and stabilization of the collagen framework for tubular cell regeneration, lack of solid evidence and definite mechanism make the role of pericyte/myofibroblast in AKI remain controversial. Method To clarify this, we used platelet-derived growth factor receptor β (PDGFRβ)-specific antibody following AKI in C57BL/6 mice to inhibit pericytes. In the meantime, We used Gli1-CreERT2;Cxcl12fl/fl genetically modified mice to conditionally knockout CXCL12 specifically in pericytes before IRI. Results The expression of PDGFRβ on pericytes increased after IRI. In group of administration of PDGFRβ antibody, proliferation and transition to myofibroblasts of pericytes were inhibited. Inflammation became worse and renal recovery was impeded after AKI. The chemokine stromal cell-derived factor-1 (SDF-1) which is also known as the C-X-C-type chemokine CXCL12 decreased as well. Furthermore, we demonstrated that CXCL12 was secreted mainly by pericytes and its receptor CXCR4 was expressed on tubular cell during IRI by in situ hybridization. When knockout of CXCL12 was performed before IRI, the renal microvascular rarefaction was noted after AKI and the recovery of renal function was impaired. Renal tubular cell proliferation decreased and apoptosis increased as well. Conclusion In summary, these findings demonstrated that pericytes contribute to renal repair after IRI through CXCL12 secretion.

Capillary surface modification using millimolar levels of aminosilane reagent for highly efficient separation of phenolic acids and flavonols by capillary electrophoresis with UV detection.

Phytochemical analysis of phenolic acids and flavonols poses a challenge, necessitating the development of an efficient separation method. This facilitates the quantification of these compounds, yielding valuable insights into their benefits. To develop a highly effective separation of phenolic acids and flavonols by capillary electrophoresis and ultraviolet (UV) detection through the modification of the capillary surface using 3-aminopropyltriethoxysilane (APTES) at millimolar concentrations. The capillary surface is modified with 0.36 mM-APTES solution. The electrolyte is 20.0 mM borate buffer (pH9.0). Separation performance (plate number N, resolution Rs ), stability, and reproducibility of the coating procedure are evaluated using the analysis of phenolic acids, rutin and quercetin. The modified capillary provided efficient separation with plate numbers N ≥ 1.0 × 104 m-1 and resolution Rs ≥ 0.8 for all pairs of adjacent peaks of the separation of five selected phenolic acids, rutin, quercetin, caffeine and methylparaben (as internal standard). The precisions of the relative migration times for 17 consecutive analyses of samples over 3h were 1% relative standard deviation (RSD) for rutin and 7% RSD for quercetin. The analysis of rutin and quercetin in 12 dietary supplement product samples only required a simple dilution step for sample preparation. A straightforward modification technique utilising millimolar concentrations of APTES resulted in highly efficient separation of phenolic acids, rutin and quercetin, accompanied by high precision and surface stability. The modified capillary proved successful in analysing rutin and quercetin content in dietary supplements.

Hole-initiated melting process of thin films.

We perform numerical and experimental studies on the melting process of thin films initiated by a small hole in the continuum regime. The presence of a nontrivial capillary surface, namely the liquid/air interface, leads to a few counterintuitive results: (1) The melting point is elevated if the film surface is partially wettable, even with a small contact angle. (2) For a film that is finite in size, melting may prefer to start from the outer boundary rather than a hole inside. (3) More complex melting scenarios may arise, including morphology transitions and the "de facto" melting point being a range instead of a single value. These are verified by experiments on melting alkane films between silica and air. This work continues a series of investigations on the capillary aspects of melting. Both our model and analysis approach can be easily generalized to other systems.

Histo-morphometric vicissitudes in diet-controlled diabetic placenta: A quantitative stereological model

BackgroundAn affordable approach accepted worldwide to successfully treat mild maternal hyperglycemia in gestational diabetes (GDM), is diet-controlled therapy. As no elaborate research was available, this study was crafted to investigate morphometric stereological details and to determine the mean placental oxygen diffusion capacity for patients who were kept on diet therapy for mild gestational hyperglycemia. MethodsA clinical trial (NCT04907708) was conducted from January 2018 to February 2019. A total of 70 women completed the study, out of which 35 served as healthy controls as Group A and 35 were diagnosed as mild gestational diabetics according to WHO criteria (Group B). These patients were kept on a restricted calorie diet with light exercise during gestation and were followed regularly during gestation. Soon after delivery, conserved placentas underwent complete gross, microscopic, and stereological investigations with the point and intersection -counting methods. ResultsSignificant differences were observed for placental width and syncytial knots (p＜ ​0.010 and 0.025 respectively) between the groups on gross and light microscopy. Most of the parameters were non-significant, though numerically more in the GDM group. On stereological details, mean placental volume, mean placental components volumes (villi, inter-villous space, fetal capillary, and fetal connective tissue), mean villi and mean fetal capillary diameter, mean villi and capillary surface density and mean morphometric diffusing capacity of placenta showed non-significant results between the groups. ConclusionMinimal changes were observed in gross, microscopy, and morphometric stereological details in the placentae of GDM patients managed with nutritional therapy during gestation compared with the healthy controls.

Non-line-of-sight multiple reflection underwater wireless optical communications channel model based on a capillary waves rough sea surface.

In a non-line-of sight reflective underwater wireless optical communications (UWOC) link, the transmitted beam relies on reflections from the sea surface to propagate to the underwater receiver. Most previous research on reflective channels has sufficiently considered single reflections from a smooth or rough surface, while ignoring the effect of multiple reflections. In fact, a rough sea surface may cause the reflected photons to hit the sea surface again, which is referred as a multiple reflection process. To make up for deficiencies in the existing literature, we first construct a capillary waves rough sea surface model, and then present a multiple reflection channel model with the help of the Monte Carlo ray tracing approach. The path loss and channel impulse response (CIR) were further evaluated based on the model for different communications scenarios. Numerical results suggest that multiple reflections increase the path loss by more than about 5dB, and reduce the CIR amplitude to less than one-third compared to a single reflection. The work done in this paper aims to provide theoretical support for UWOC system design.

Surface Modified Optical Fiber Fabry–Perot Cavity Pressure Sensor With Carbon Film

By the method of pulsed laser deposition of a Ni/C bilayer precursor films and annealing in air, amorphous carbon films were prepared on the surface of the capillary used for fabrication of optical fiber Fabry-Perot (FP) cavity pressure sensors. The surface morphologies of the coated and annealed carbon films were investigated through scanning electron microscopy. The images reveal that surface modification smoothes the irregular particles on the capillary surface and releases the stress induced by carbon and nickel deposition and oxy-hydrogen flame welding. Performance tests showed that the surface modified pressure sensors have good linearity for pressure response and the cavity length variations during the full cycle of pressure change is within 31 nm. Furthermore, thanks to the introduction of carbon films, the long-term stability of the cavity length can be kept within 10 nm during the tested 150 days.