Calcium Diffusion Research Articles

Simulation of chloride diffusion tests in cement paste and mortar made with CEM II and CEM VI cements

We developed a simplified coupled model to simulate the chloride ingress of cement paste and mortar fabricated with CEM II/C-M (S-LL) and CEM VI (S-V) cements. Diffusion of chloride, calcium, sodium, potassium, sulphate and hydroxyl ions is considered, resulting in a set of coupled mass balance equations. Source and sink terms are introduced to represent the dissolution/precipitation processes due to leaching, and interactions between free chloride and hydrated phases are considered through binding isotherm curves. Electrodiffusion phenomenon is introduced through a modified Poisson equation to enforce local electroneutrality. The model is applied to simulate bulk diffusion tests with exposure solutions containing NaCl, and NaCl + KOH to reduce leaching. The main features observed experimentally are correctly reproduced: a higher chloride content is predicted for the materials made with CEM II binder, and a much clearer peaking behavior near the exposed surface is predicted in the case of NaCl exposure.

A Comprehensive Fuzzy Model for Understanding Neuronal Calcium Distribution in Presence of VGCC, Na+/Ca2+ Exchanger, Buffer, and ER Fluxes.

Free Calcium ions in the cytosol are essential for many physiological and physical functions. The free calcium ions are commonly regarded as a second messenger, are an essential part of brain communication. Numerous physiological activities, such as calcium buffering and calcium ion channel flow, etc. influence the cytosolic calcium concentration. In light of the above, the primary goal of this study is to develop a model of calcium distribution in neuron cells when a Voltage-Gated Calcium Channel and Sodium Calcium Exchanger are present. As we know, decreased buffer levels and increased calcium activity in the Voltage-Gated Calcium Channel and Sodium Calcium Exchanger lead to Alzheimer's disease. Due to these changes, the calcium diffusion in that location becomes disrupted and impacted by Alzheimer's disease. The model has been constructed by considering key factors like buffers and ER fluxes when Voltage-Gated Calcium Channels and Sodium Calcium Exchangers are present. Based on the physiological conditions of the parameters, appropriate boundary conditions have been constructed in the fuzzy environment. This model is considered a fuzzy boundary value problem with the source term and initial boundary conditions are modeled by triangular fuzzy functions. In this, paper we observed the approximate solution of the mathematical model which was investigated by the fuzzy undetermined coefficient method. The solution has been performed through MATLAB and numerical results have been computed using simulation. The observation made that the proper operation of the Voltage-Gated Calcium Channel and Sodium Calcium Exchanger is critical for maintaining the delicate equilibrium of calcium ions, which regulates vital cellular activities. Dysregulation of Voltage-Gated Calcium Channel and Sodium Calcium Exchanger activity has been linked to neurodegenerative illnesses like Alzheimer's disease.

Spatial interactions impact on Ca-driven synaptic plasticity: An ionic cable theory perspective

We extend our previous paper on deriving an approximate analytical solution of a nonlinear cable equation by including other ion channels in neurons and calcium dynamics based on reaction-diffusion dynamics that lead to a system of nonlinear cable equations. Here, excitable dendrite possesses clusters of voltage-activated ion channels that are discretely distributed as point sources or hotspots of transmembrane current along a continuous cable structure of fixed length. Single and/or trains of action potentials and spatially distributed synaptic inputs drive the depolarisation and activate sparsely distributed voltage-dependent calcium channels. This leads to calcium influx and diffusion in the cable. Here, time-dependent analytical solutions were obtained by applying a perturbation expansion of the non-dimensional voltage (Φ) and non-dimensional calcium (ΦCa) and then solving the resulting set of integral equations. We use this framework to gain insights into calcium-driven synaptic plasticity in dendrites. Many previous studies have traditionally focused on the local impact of calcium on whether the synapse's strength is increased (potentiated) or decreased (depressed). Only recently have studies focusing on heterosynaptic plasticity been gaining popularity, and here we ask the question of how a local plasticity rule is influenced by the spatially and temporally distributed synaptic inputs. Specifically, we focus on how synaptic inputs and calcium influx impact a calcium-derived temporal learning window for spike-timing-dependent plasticity (STDP) at nearby sites to assess the nature of the resulting distance-dependent interaction on the associated learning window at the synapse of interest.

Theoretical study on the effect of torsional deformation on WTe2 as a cathode material for calcium ion batteries.

In this study, the electronic structure and diffusion barrier of the Ca-adsorbed WTe2 system under different torsion angles were calculated based on the first-principles method. The results show that the structure and properties of the pure WTe2 system and Ca-adsorbed WTe2 system are affected by torsional deformation. When the torsion angle is 6°, the intrinsic WTe2 changes from a direct band gap to an indirect band gap. The torsional deformation does not change the metallicity of the Ca-adsorbed WTe2 system. The Ca-d state electrons contribute to the electron density of WTe2. The calculation of the diffusion barrier shows that the torsion deformation promotes the diffusion of calcium on the surface of WTe2. This study provides a theoretical basis for the regulation of electrode materials. In this study, Materials Studio 8.0 software was used to construct the WTe2 model and Ca-adsorbed WTe2 model, and CASTEP module was used for first-principles calculation.

An efficient process for preparing regenerated magnets by dynamic recovery of Nd-Fe-B sintered magnet sludge

As a new technology for the short-process recovery of Nd–Fe–B sintered magnet sludge, the calcium thermal reduction diffusion method has attracted significant attention due to its low energy consumption, environmental friendliness, and high recovery rate. However, traditional calcium thermal reduction diffusion technology still has issues such as an insufficient reaction between the sludge and reducing agent after increasing the amount of reactants, the use of a large amount of reducing agent, and low recovery efficiency. Therefore, a novel dynamic calcium thermal reduction diffusion technology was proposed, with the calcium reduction diffusion of sludge and calcium undergoing a continuous mixing and diffusion state throughout the entire process, greatly improving the efficiency of the reaction. Compared with the traditional process, the amount of reactants was increased from a few grams to hundreds of grams, and the amount of reducing agent calcium was reduced by 25%. Subsequently, regenerated magnetic powder with a uniform particle size, good dispersion, and excellent magnetic properties was obtained. The saturation magnetization under a 3 T magnetic field was increased by 27.9% compared with the initial sludge. The maximum magnetic energy product of the magnet prepared by doping 50 wt% regenerated magnetic powder was 45 MGOe, which reached the highest level of the regenerated magnets prepared by recycling sludge. What is encouraging that this new technology had the advantage of achieving large-scale production and reducing production costs, providing a potential industrialization solution for the green and efficient recovery of Nd–Fe–B sintered magnet sludge.

An in vitro comparison of calcium ions release and diffusion ability of calcium hydroxide-based intracanal medicament in combination with three different vehicles like propolis, chitosan, and propylene glycol.

Calcium hydroxide, which is an intracanal medicament, is widely used in endodontics. Improvements can be made to its effectiveness, as calcium hydroxide is dependent on the vehicle. The study aims to compare and evaluate the release and diffusion ability of calcium hydroxide when mixed with - propolis, chitosan, and propylene glycol. For this study, 33 single-rooted extracted premolar teeth have been decoronated. After the working length and enlargement of the canals had been established, different preparations of calcium hydroxide with vehicles such as propolis, chitosan, and propylene glycol were loaded into the canals. Atomic absorption spectrophotometry was used to analyze the release of calcium ions in three groups, while a digital pH meter was used to determine an acid change. Atomic absorption spectrophotometry showed sustained releases of calcium ions and the digital pH meter showed increased diffusion capacity in the propylene glycol paste group in comparison to the other two groups. Propylene glycol vehicle made it easier to enter calcium hydroxide into the dentinal tubules.

First-principles calculations of bulk XTe2 (X = Mo, W) as anode materials for Ca ion battery.

Transition metal chalcogenides are excellent anode materials for calcium ion batteries (CIBs). In this study, the structural stability, electronic structure, and diffusion barrier of bulk XTe2 (X = Mo, W) were studied by first-principles calculations within the framework of density functional theory. The density of states analysis shows the metal behavior of XTe2 (X = Mo, W) during calcification. The voltage ranges of CayMoTe2 and CayWTe2 are 1.53-0.45 V and 1.48-0.41 V (y = 0-5), respectively. The diffusion barrier of Ca+ through XTe2 indicates that the compressive strain promotes the diffusion of calcium through XTe2. XTe2 is considered to be a promising electrode material for CIBs. In this paper, the transition metal chalcogenides model is constructed by Material Studio 8.0, and the first-principles calculation is carried out by CASTEP module.

Modeling calcium diffusion and crosslinking dynamics in a thermogelling Alginate-Gelatin-Hyaluronic acid ink: 3D bioprinting applications

Alginate-based inks are widely used in 3D bioprinting. Its crosslinking by Ca2+ ions is extremely important to achieve scaffolds with optimal mechanical properties. Notably, despite previous studies on calcium diffusion in alginate systems, there have been no reported data regarding the effect of temperature on the diffusion and crosslinking dynamics of thermogelling alginate-based hydrogels. This study focuses on investigating the kinetics of the crosslinking front and Ca2+ diffusion within a matrix of Alginate-Gelatin-Hyaluronic acid ink, exploring the impact of temperature and Ca2+ concentration. The Ca2+ diffusion rate or ink crosslinking rate increase as the crosslinker concentration and ink temperature increase. Additionally, the mechanical properties of the scaffolds, assessed through compression, tension, and dynamic tests, were correlated with the crosslinking time.The innovative aspect of this study lies in the development of a code that simulates the diffusion of Ca2+ ions from the exterior to the interior of a hydrogel structure. Specifically, the code facilitates the calculation of the crosslinking time for a cylindrical structure up to a specified thickness, providing valuable insights for the production of airways or blood vessels. Furthermore, the Python script, incorporating the numerical model, manages to simulate the crosslinking dynamics of scaffolds of any shape, and properly fits the rheological measurements of dynamic moduli during the crosslinking process. This represents a significant advance for the precise and controlled scaffold fabrication process using 3D bioprinting.

Biaxial compressive strain enhances calcium binding and mobility on two-dimensional Sc2C: a density functional theory investigation.

In this work, we investigated calcium binding and diffusion on pristine and biaxially strained 2D Sc2C via density functional theory calculations, for potential applications in calcium-ion batteries (CIBs). We found that 2D Sc2C is metallic under PBE, HSE06, and DFT+U approximation conditions, and thus can be potentially used as an electrode material for CIBs. Results showed that pristine 2D Sc2C adsorbs calcium modestly, with relatively low binding energy on the most stable site (0.38 eV). Interestingly, this value shoots up to -1.94 eV and -3.23 eV at 5% and 10% biaxial compressive strains, respectively. Furthermore, calcium's diffusion energy barrier, which is already low (80 meV) on pristine 2D Sc2C, goes down further (to 35 meV) upon application of median biaxial compressive strain (5%). As a result of the enhanced binding of calcium on strained 2D Sc2C, the maximum stable calcium concentration was also boosted. Consequently, the calculated theoretical specific energy capacity of 2D Sc2C with biaxial compressive strain is higher compared to that of the pristine case (878.29 mA h g-1vs. 1051.84 mA h g-1). The average open circuit voltages of the two cases are high and quite close at 9.3 V (pristine) and 9.0 V (with 5% biaxial compressive strain). Our results demonstrated that biaxial compressive strain could be tapped to improve the properties of 2D MXenes, such as Sc2C, thereby enhancing the battery performance indicators of these materials, such as theoretical specific energy capacity and open circuit voltage. Such findings are of great importance in the emerging new technology of CIBs.

New promising class of anode materials for Ca-ion battery: polyaromatic hydrocarbons

Using first-principles calculations we propose new anode materials for calcium-ion batteries, namely anthracene (AN), tetracene (TN) and pentacene (PN) crystals. We show that adsorption of calcium atoms on isolated AN, TN and PN molecules is energetically favorable, as well as intercalation into bulk crystals in a wide range of calcium concentrations. For all crystals, volume expansion during intercalation is less than 20% and for pentacene, it is less than 8%. We assess the diffusion and electronic properties of AN, TN and PN. We show that calcium diffusion barriers along the polyacene molecules are less than 0.45 eV, but calcium diffusion is limited by “jumps” between the molecules. Sequential band filling upon increasing levels of intercalation leads to the reentrant semiconducting-metallic-semiconducting behavior. Our results point to the promise of anthracene, tetracene, and pentacene as anodes for calcium-ion batteries.

Abstract 14960: Coronary Artery Calcium Distribution Patterns Are Independently Predictive of Adverse Cardiovascular Events: Observations From the Dallas Heart Study

Introduction: The coronary artery calcium (CAC) diffusivity index (DI) may improve risk stratification for those with Agatston CAC > 0 in older individuals. We aimed to assess whether the distribution of CAC would improve risk prediction of cardiovascular (CV) events beyond the traditional Agatston CAC score in a younger population. Methods: Among Dallas Heart Study 2 (DHS2) participants with Agatston CAC > 0 and no history of CVD (35% of entire cohort), we studied 1013 participants with CAC DI at DHS2. The raw CAC DI was calculated as 1 - (CAC in most affected vessel/total CAC) and categorized into concentrated (<25th%), standard (25-75th%), and diffuse (>75th%) patterns. Multivariable Cox proportional hazards regression and C statistics were calculated for coronary events (CHD) and all CVD, and all-cause mortality. Models were adjusted for total Agatston score, race, gender, BSA, smoking history, diabetes, and statin use. Results: Mean age of the DHS2 study cohort was 55 ± 9.4 years (48% women, 45% Black). The median follow up was 9 ± 2.5 years (55 CHD, 97 CVD, and 120 all-cause mortality events) (Figure, A) . CAC DI was modestly correlated with Agatston CAC (Spearman rho = 0.60, p<0.01). In models adjusted for total Agatston score, risk factors, and demographics, compared with a concentrated pattern, a diffuse CAC pattern was associated with incident CHD (HR [95%CI]: 5.32 [1.68-16.86]); CVD (HR [95%CI]: 3.21 [1.66-6.21]), and all-cause mortality (HR [95%CI]: 2.02 [1.18-3.47] (Figure, B) . Findings were similar for continuous CAC DI. Addition of continuous CAC DI to adjusted models including Agatston CAC improved the C-statistic for CHD (0.79 to 0.81, p<0.01) and CVD (0.71 to 0.73, p<0.01). Conclusions: Beyond the validated Agatston score, higher CAC DI at baseline improves risk prediction of incident CHD and CVD events in a younger population-based cohort. Further studies are warranted to evaluate the clinical utility of assessing distribution patterns of CAC.

On the role of calcium diffusion and its rapid buffering in intraflagellar signaling.

We have considered the realistic mechanism of rapid Ca2+ (calcium ion) buffering within the wave of calcium ions progressing along the flagellar axoneme. This buffering is an essential part of the Ca2+ signaling pathway aimed at controlling the bending dynamics of flagella. It is primarily achieved by the mobile region of calmodulin molecules and by stationary calaxin, as well as by the part of calmodulin bound to calcium/calmodulin-dependent kinase II and kinase C. We derived and elaborated a model of Ca2+ diffusion within a signaling wave in the presence of these molecules which rapidly buffer Ca2+. This approach has led to a single nonlinear transport equation for the Ca2+ wave that contains the effects brought about by both as necessary buffers for signaling. The presence of mobile buffer calmodulin gives rise to a transport equation that is not strictly diffusive but also exhibits a sink-like effect. We solved straightforwardly the final transport equation in an analytical framework and obtained the implied function of calcium concentration. The effective diffusion coefficient depends on local Ca2+ concentration. It is plausible that these buffers' presence can impact Ca2+ wave speed and shape, which are essential for decoding Ca2+ signaling in flagella. We present the solution of the transport equation for a few specified cases with physiologically reasonable sets of parameters involved.

Microstructural modification of papaya tissue during calcium diffusion: Effects on macrostructure level

The microstructural changes in papaya tissue during calcium diffusion, the effect on drying kinetics and texture parameters were investigated. Calcium pretreatment was applied to papaya samples for 3 h, at a solution concentration of 1.5 g Ca(OH)2/100 mL H2O, and a solution temperature of 25 °C; subsequently, the samples were convectively dried at 70 °C, air flow of 1.5 m/s, and a relative humidity of 5 ± 2%. Calcium content was determined using the Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) technique, the microstructure of the samples was analyzed by High-Resolution Scanning Electron Microscopy (HR-SEM), and the elementary analysis was performed by Energy-Dispersive X-ray Spectroscopy (EDS). Effective diffusivity of calcium (DefCa) and moisture (Defw) were calculated during pretreatment and drying, respectively and texture parameters were determined by double compression using a texturometer. The transport mechanism determined during calcium pretreatment was diffusion with a DefCa = 3.10 × 10−10 m2/s. Also, branched calcium microstructures in the cell walls of tissue were observed due to the calcium effect, it was supported by elemental analysis, which showed an increase of calcium in section restructured compared to non-restructured. During drying, Defw = 1.86 × 10−9 m2/s was higher in pretreated compared to non-pretreated samples with Defw = 1.17 × 10−9 m2/s, indicating a higher drying rate and moisture loss. The texture values changed significantly (α ≤ 0.05) due to calcium pretreatment and drying; the calcium microstructures caused higher cohesiveness, springiness, gumminess, and chewiness. Calcium modifies the microstructure and composition of papaya tissue; therefore, drying kinetics and texture parameters depend on this modification.

Adsorption of Ca on borophene for potential anode for Ca-ion batteries.

Two-dimensional borophene can be used in rechargeable batteries due to its high specific surface area. In this paper, the performance of borophene as an anode material for calcium ion batteries is predicted based on density functional theory calculations. The calculation results show that P doping enhances the calcium storage properties of borophene. The maximum adsorption number of calcium atoms in the P-doped system is 7, with a theoretical capacity of 964 mAh/g. DOS analysis showed that borophene exhibited metallic properties after adsorbing calcium atoms, which improved the electrical conductivity of the electrode material. Calculation of the diffusion energy barrier shows that strain has an effect on calcium diffusion in monolayer borophene, and compressive strain promotes calcium diffusion through borophene. The findings suggest that borophene may be a promising electrode material for calcium-ion batteries. In this paper, the intrinsic model and doping model of borophene are constructed by Material Studio 8.0, and the first-principles calculation is carried out by CASTEP module.

Atomically Resolved Interfacial Analysis of Bone‐Like Hydroxyapatite Nanoparticles on Titanium

Titanium is commonly used for medical devices, including osseointegrating implants, owing to its biocompatibility and mechanical properties. Nanostructuring titanium implants is known to enhance the healing process by promoting bone growth on the implant surface. Hydroxyapatite nanoparticles, resembling natural bone mineral, have been used to further improve osseointegration. While previous studies have investigated the osseointegration of titanium implants using atom probe tomography, limited research has focused on the attachment of synthetic hydroxyapatite to titanium. Herein, electron microscopy and atom probe tomography are used to reveal the assembly of synthetic hydroxyapatite nanoparticles in the titanium oxide surface. By sputter coating with chromium, a suitable matrix is formed for detailed interfacial analysis. The results demonstrate the diffusion of calcium, phosphorus, and carbon from hydroxyapatite nanoparticles into the titanium oxide surface.

Determinants of the maximal functional reserve during repeated supramaximal exercise by humans: The roles of Nrf2/Keap1, antioxidant proteins, muscle phenotype and oxygenation

When high-intensity exercise is performed until exhaustion a “functional reserve” (FR) or capacity to produce power at the same level or higher than reached at exhaustion exists at task failure, which could be related to reactive oxygen and nitrogen species (RONS)-sensing and counteracting mechanisms. Nonetheless, the magnitude of this FR remains unknown. Repeated bouts of supramaximal exercise at 120% of VO2max interspaced with 20s recovery periods with full ischaemia were used to determine the maximal FR. Then, we determined which muscle phenotypic features could account for the variability in functional reserve in humans. Exercise performance, cardiorespiratory variables, oxygen deficit, and brain and muscle oxygenation (near-infrared spectroscopy) were measured, and resting muscle biopsies were obtained from 43 young healthy adults (30 males). Males and females had similar aerobic (VO2max per kg of lower extremities lean mass (LLM): 166.7 ± 17.1 and 166.1 ± 15.6 ml kg LLM−1.min−1, P = 0.84) and anaerobic fitness (similar performance in the Wingate test and maximal accumulated oxygen deficit when normalized to LLM). The maximal FR was similar in males and females when normalized to LLM (1.84 ± 0.50 and 2.05 ± 0.59 kJ kg LLM−1, in males and females, respectively, P = 0.218). This FR depends on an obligatory component relying on a reserve in glycolytic capacity and a putative component generated by oxidative phosphorylation. The aerobic component depends on brain oxygenation and phenotypic features of the skeletal muscles implicated in calcium handling (SERCA1 and 2 protein expression), oxygen transport and diffusion (myoglobin) and redox regulation (Keap1). The glycolytic component can be predicted by the protein expression levels of pSer40-Nrf2, the maximal accumulated oxygen deficit and the protein expression levels of SOD1. Thus, an increased capacity to modulate the expression of antioxidant proteins involved in RONS handling and calcium homeostasis may be critical for performance during high-intensity exercise in humans.

Fractional order reaction diffusion of calcium regulating NFAT production in T Lymphocyte

[Formula: see text] signals have a crucial role in the immune system for cell functions such as proliferation, differentiation, apoptosis and gene transcription as well as the activation of Nuclear factor of activated T Cell (NFAT) which modulates the immune response of the cells. In this study, a fractional order spatiotemporal calcium dynamics model is formulated using the reaction-diffusion equation incorporating parameters like buffers, source influx, [Formula: see text] and [Formula: see text]. Grünwald estimation is employed to obtain the solution and stability analysis has been performed. The analysis of numerical results provides novel insights about the role of Brownian motion, super diffusion, source influx, buffers, etc., in the regulation of calcium and NFAT concentration levels in T cell and the conditions which might lead to disordered immune responses causing diseases such as HINI, HIV and HBV.

The benefit of Ca in improving pinning of BaZrO3-Y2O3 doubly-doped YBa2Cu3O7-x/Ca0.3Y0.7Ba2Cu3O7-x multilayer nanocomposite films

This work examines the pinning enhancement in BaZrO 3 (BZO) +Y2O3 doubly-doped (DD) YBa2Cu3O7 (YBCO) nanocomposite multilayer (DD-ML) films. The film consists of two 10 nm thin Ca0.3Y0.7Ba2Cu3O7-x (CaY-123) spacers stacking alternatively with three BZO + Y2O3/YBCO layers of 50 nm each in thickness that contain 3 vol% of Y2O3 and BZO doping in the range of 2–6 vol%. Enhanced magnetic vortex pinning and improved pinning isotropy with respect to the orientation of magnetic field (B) have been achieved in the DD-ML samples at lower BZO doping as compared to that in the single-layer counterparts (DD-SL) without the CaY-123 spacers. For example, the pinning force density (F p ) of ∼58 GNm−3 in 2 vol.% of DD-ML film is ∼110% higher than in 2 vol% of DD-SL at 65 K and B//c-axis, which is attributed to the improved pinning efficiency by c-axis aligned BZO nanorods through diffusion of Calcium (Ca) along the tensile-strained channels at BZO nanorods/YBCO interface for improvement of the interface microstructure and hence pinning efficiency of BZO nanorods. An additional benefit is in the considerably improved J c (θ) and reduced J c anisotropy in the former over the entire range of the B orientations. However, at higher BZO doping, the BZO nanorods become segmented and misoriented, which may change the Ca diffusion pathways and reduce the benefit of Ca in improving the pinning efficiency of BZO nanorods.

Evaluation of transport properties of deteriorated concrete due to calcium leaching with coupled CT image analysis and random walk simulation

Concrete may deteriorate when chronically in contact with water due to the leaching of calcium ions. This study conducted a natural diffusion test for calcium ions with a minute cylindrical specimen of 3 mm in diameter and 6 mm in height to determine leaching at 20 and 80 °C in 33 days. One piece of limestone as aggregate was inserted inside each specimen to investigate the effect of the interfacial transition zone (ITZ). Changes in mass transfer in the leaching and non-leaching regions in bulk cement paste were evaluated using synchrotron X-ray computed tomography (CT) in a micrometer order. A deeper dissolution front of Ca(OH)2 inside the specimen was observed for a higher temperature leaching test. Random walk simulation was performed to obtain diffusion parameters. Results showed that the calcium diffusion coefficient of non-deteriorated ITZ is about ten times as high as that of the non-leaching region. For the leaching region, the diffusion coefficient is about 50 times and 100 times as high as that of the non-leaching region at 20 °C and 80 °C, respectively. In addition, the Ca(OH)2 dissolution front appeared deeper inside the specimen in the direction where aggregate is close or exposed to the dissolution front because of ITZ.

Probing the mechanism of annexin mediated plasma membrane repair.

The integrity of the plasma membrane is essential for maintaining cell homeostasis and eucaryotic cells have developed robust mechanisms for rapidly sealing plasma membrane ruptures. The repair process involves recruitment of multiple proteins to the damage site as triggered by the influx of calcium ions from the cytosol. Several members of the Annexin family are involved in membrane repair although their functional role in membrane remodeling is not fully understood. Biophysical experiments and modeling in synergy with cell experiments offer tools which can provide additional insight into Annexin mediated repair mechanisms. We review our recent studies into membrane remodeling and protein structures induced by Annexin binding. Using a unique platform of planar, free-edged membrane patches, the edge region of a membrane hole can be experimentally mimicked under controlled conditions. Using this platform, Annexins induce spontaneous membrane curvature leading to distinct, curved morphologies. We discuss the theoretical modeling of curvature effects and the formation of membrane necks around holes. We also describe AFM results resolving the organization of Annexins on membranes with molecular detail. Finally, we describe quantification of the calcium influx in cells during subjected to laser rupture. Detailed analysis and modeling of calcium diffusion and pumping allows extraction of key parameters for repair such as the timescale of hole closure.