Influence Of Na Research Articles

Impact of Band‐gap Gradient in Semi‐Transparent and Bifacial Ultra‐Thin Cu(In,Ga)Se2 Solar Cells

AbstractUltra‐thin Cu(In,Ga)Se2 (CIGSe) solar cells on transparent conductive oxide back contact reduce the material consumption of rare indium and gallium and simultaneously exhibit great potential for semi‐transparent bifacial application. For highly efficient CIGSe solar cells, a steep back Ga grading and Na treatment are expected. However, Na will promote the formation of highly resistive GaOx at the rear interface owing to Ga accumulation. In this work, the three‐stage co‐evaporation process is renewed and the effect of the deposition sequence in the first stage on the Ga distribution as well as the cross‐correlated influence of Na is explored. In particular, the standard deposition sequence of Ga+In is altered to start with In. When a thin In layer is pre‐deposited on the back contact, the fill factor and efficiency increase. The deposition of In+Ga+In in the first stage of CIGSe growth leads to efficiencies 28% (on average) higher than for the standard deposition sequence of Ga+In. Additionally, 2.74% efficiency is reached under rear and 9.32% under simultaneous front and rear illumination. Therefore, adapting the deposition sequence in the first stage of CIGSe growth is identified as a key to improving the device performance on transparent back contact.

Influence of sodium hydroxide on phase transformation of gamma alumina to alpha alumina

AbstractCorundum and transition alumina powders are commonly produced through the Bayer process—that is, by digestion of bauxite in a sodium hydroxide solution, followed by gibbsite precipitation, which contains significant amounts of Na+ ions. During the de‐hydroxylation of gibbsite, Na+ is associated with retardation of the structural phase transformations between transition alumina and corundum (α‐Al2O3) phases, although the exact role of Na is unclear. The influence of Na+ ions on the phase transformation of γ‐Al2O3 to α‐alumina was investigated by varying the concentration of NaOH in aqueous γ‐Al2O3 suspensions. The phase transformation behavior of γ‐Al2O3 was monitored through thermal analysis, X‐ray diffraction, scanning electron microscope, X‐ray photoelectron spectrometer (XPS), and transmission electron microscope. As the Na concentration in γ‐alumina suspensions increased, the amount of α‐Al2O3 decreased in samples that were heat treated at 1200°C for 2 h. XPS analysis indicated that washing transition alumina powders with NH4OH solutions had decreased the surface concentration of Na+ and facilitated the phase transformation to α‐Al2O3.

EVALUATION OF THE POSSIBILITY OF USING SPENT TURBINE OIL AS A LUBRICATING ADDITIVE IN DRILLING MUD

Link for citation: Lambin A.I., Averkina E.V., Erygina A.N., Averkin N.A. Evaluation of the possibility of using spent turbine oil as a lubricating additive in drilling mud. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 10, рр. 169-178. In Rus. The relevance. The consumption of lubricants and, as a result, the volume of used oils increases annually. As a result, large volumes of them are accumulated, which require standard methods of handling them. It is known that oils, including waste ones, are used as lubricating additives to drilling mud. The practice of recent years has shown the expediency of replacing lubricating additives with used lubricating oils, which would ensure the preservation of the main and the achievement of new properties. This article presents the results of a study of micelle-forming solutions under the influence of Na and K salts on their filtration and crust-forming properties. The main aim: evaluation of the possibility of using spent turbine oil in the drilling mud as a component of a lubricating additive, as well as its effect on the main parameters of the drilling mud; study of the effect of oil, ether and salt interaction on the filtration and crust-forming properties of drilling mud. Objects: spent turbine engine oils selected at the drilling site during the construction of the well. Methods. Drilling mud indicators were measured. Water, technical oil and ether were used to form micelles. The studies were carried out using the methodology of a complete factor experiment, in which the studied effects of salt in solutions were approximated in the form of first-order polynomials. Results. By comparing the first coefficients of the polynomial models, a significant effect of sodium chloride on the rheological and filtration properties of solutions and the stickiness of their filtration films was revealed. The effect of chlorides on a group of eight solutions in different oil fractions was statistically confirmed, for which the Student and Mann–Whitney criteria were used. The paper introduces the graphical interpretation of some approximations of the equations of the effect the solution ingredients interaction on the response value.

High-performance CO2 adsorption of jellyfish-based activated carbon with many micropores and various heteroatoms

In this study, microporous activated carbon was produced from jellyfish-based biomass to capture carbon dioxide (CO2), toward addressing one of the biggest modern problems. The surface functional groups and porosity of activated carbon derived from jellyfish were investigated according to the activation conditions. It was confirmed that the jellyfish-based porous carbon prepared by NaOH activation comprised many micropores that facilitated CO2 adsorption under the influence of Na and P present in the microstructure of the jellyfish. In addition, the JFBC-based activated carbon had surface functional groups such as nitrogen, calcium, and magnesium, which facilitated CO2. The jellyfish-based activated carbon shows very excellent CO2 adsorption capacity (9.52 mmol/g and 5.18 mmol/g at 273 K and 298 K, respectively) compared to activated carbon prepared from porous carbon-based adsorbents for CO2 capture. This performance is attributed to the microstructure and various heteroatoms of the jellyfish biochar. Therefore, this study may provide insight into new biomass with competitive adsorption power and without requiring complicated manufacturing steps.

Enhanced phytotoxicity of 4-chloro-3-methyphenol and lindane under sodium and potassium salt stresses

Investigating the uptake of organic pollutants by plants under salt stress is critical for evaluating crop contamination, understanding the mechanism of plant uptake, and implementing phytoremediation. The uptake of a highly phytotoxic contaminant, 4-Chloro-3-Methyphenol (CMP, 45 mg L−1), from solutions by wheat seedling with or without Na+ and K+ was studied to illustrate the synergistic effect of salt on phytotoxicity of CMP, using uptake kinetics, transpiration, Ca2+ leakage and fatty acid saturation as indicators. The influence of Na+ and K+ on the uptake of lindane, a relatively low toxic contaminant, from soil was also explored. Under CMP-Na+ and CMP-K+ exposure, the concentrations of CMP in both root and shoot were lower than those under CMP exposure, as a result of the inhibition of transpiration caused by Na+ and K+ stresses. Low concentration of CMP did not reveal serious toxicity on cell membrane. No apparent difference of MDA generation in root cells was observed, due to the lethal concentration of CMP. The relatively small variation of Ca2+ leakage and fatty acid saturation degree in the root cell under exposure of CMP, CMP-Na+ and CMP-K+, compared to intracellular CMP content, suggested the enhanced phytotoxicity of CMP induced by salt. Higher MDA concentration in shoot cell under CMP-Na+ and CMP-K+ exposure compared with that under CMP exposure again showed the synergetic toxicity of CMP. High Na+ and K+ concentration significantly facilitated the uptake of lindane by wheat seedlings in soils, indicating that it could boost the permeability of cell membrane, thereby increasing the toxicity of linande to wheat seedlings. The short-term effect of low salt concentration on the uptake of lindane was not obvious, but long-term exposure also led to increased uptake. In conclusion, the presence of salt could amplify the phtotoxicity of organic contaminant via several mechanisms.

A Regulation Method of the Wettability of Solid Surfaces: Oil–Water Wettability Alteration by Replacing Adsorbed Polar Molecules via Salt Ions

Wettability of solid surfaces is generally regulated by modifying the microstructures and other properties of surfaces themselves. Here, we present that the wettability of solid surfaces exhibiting polar interactions with fluids can be substantially regulated only by adding a small amount of substances in fluids, instead of modifying the physicochemical properties of solid surfaces. We show that the adsorbed polar molecules on rock surfaces can be replaced by salt ions in the water phase, and ultimately the oil-wet surfaces are altered to water-wet. The influence of Na+ and Ca2+ ions on the wettability of rock surfaces with initially adsorbing stearic amine and pyrrole is revealed via molecular dynamics simulations. The contact angles of oil droplets are altered from 68.1° to 132.0° at most, which is very consistent with previous experimental measurements. The contact angles’ increase with increasing ionic concentration and the effect of divalent Ca2+ ions on the wettability alteration is more obvious compared to the monovalent Na+ ions. It is proved from the aspects of spatial distribution, microscopic interaction, and system energy of polar molecules and ions that the replacement of polar molecules is due to the negative substrates preferentially contacting with the free cations in the water phase. This work opens a new route for the regulation of surface wettability, especially in the field of water-flooding oil recovery technology.

Influence of Na+ disorder on cytoplasmic conductivity and cellular electromagnetic (EM) energy absorption of human erythrocytes (PONE-D-21-36089).

Cytoplasmic conductivity of human erythrocytes may be significantly disturbed by the composition of the external suspending media. Effects of external NaCl on cytoplasmic conductivity of human erythrocyte (Human Red Blood Cells, HRBC) were investigated in a simple NaCl system. Using thermodynamic theory cytoplasmic conductivities could be calculated from internal [K+], [Na+], [Cl-] and [HCO3-]. Effect of cell volume and cell water changes were introduced and allowed for using the Debye-Hückel-Onsager relation and Walden's rule of viscosity. Cell volume and cell water change of HRBCs were measured in suspending isotonic solutions with conductivities from 0.50 S m-1 up to hypertonic solutions of conductivity of 2.02 S m-1 at selected temperatures of 25°C (standard benchmark temperature) and 37°C (physiological temperature). In isotonic solutions, cytoplasmic conductivity of human erythrocyte decreases with rise in the external media ionic concentration and vice versa for hypertonic solutions. The HRBC is capable of rapidly regulating its volume (and shape) over quite a wide range of osmolality. Specific Absorption Rate (SAR, 900 MHz) values (W kg-1) of electromagnetic radiation are below safe limits at non-physiological 25°C but above legal limits at 37°C [National Council on Radiation Protection and Measurements, NCRP]. However, at 37°C under both hypertonic [Na+] and isotonic but low [Na+], SAR increases further beyond legal limits.

The influences of Na+, Ca2+ on the water-in-oil Pickering emulsion stabilized by stearic acid modified hydrophobic calcium carbonate particles

The properties of Pickering emulsions is affected by many factors, one of the most typical of which is the ionic environment. Existing studies have mainly focused on the effect of ions in the continuous phase on oil-in-water Pickering emulsions, and usually only single species of ions are studied. The water-in-oil Pickering emulsions are commonly used to encapsulate a variety of water-soluble functional substances, which often contain various of ions. Therefore, it is necessary to study the effect of ions in the internal phase on the properties of inverse Pickering emulsions. The inverse Pickering emulsions with an average droplet size of 100 μm were prepared using hydrophobized calcium carbonate particles. Subsequently, Na+ and Ca2+ were introduced into the internal phase to investigate their effects on the emulsion. The results show that the presence of Na+ can aggravate droplet coalescence, and Ca2+ can cause severe damage to the emulsions and even lead to phase inversion. It was speculated that Na+ can weaken the surface charge of particles by compressing the electric double layer, resulting in lower electrostatic repulsion between particles, thus changing the dispersion state of the particles and ultimately affecting the properties of the emulsion. And Ca2+ can combine with and release stearate from the particle surface through chemical reactions, thus changing the wettability of the particles and resulting in breaking and phase inversion of the emulsions. The present work is informative for the setting of the phase composition and the prediction of stability during the application of inverse Pickering emulsions.

Improved colonic inflammation by nervonic acid via inhibition of NF-κB signaling pathway of DSS-induced colitis mice

BackgroundNervonic acid (C24:1∆15, 24:1 ω-9, cis-tetracos-15-enoic acid; NA), a long-chain monounsaturated fatty acid, plays an essential role in prevention of metabolic diseases, and immune regulation, and has anti-inflammatory properties. As a chronic, immune-mediated inflammatory disease, ulcerative colitis (UC) can affect the large intestine. The influences of NA on UC are largely unknown. PurposeThe present study aimed to decipher the anti-UC effect of NA in the mouse colitis model. Specifically, we wanted to explore whether NA can regulate the levels of inflammatory factors in RAW264.7 cells and mouse colitis model. MethodsTo address the above issues, the RAW264.7 cell inflammation model was established by lipopolysaccharide (LPS), then the inflammatory factors tumor necrosis factor-α (TNF-α), Interleukin-6 (IL-6), Interleukin-1β (IL-1β), and Interleukin-10 (IL-10) were detected by Enzyme-linked immunosorbent assay (ELISA). The therapeutic effects of NA for UC were evaluated using C57BL/6 mice gavaged dextran sodium sulfate (DSS). Hematoxylin and eosin (H&E) staining, Myeloperoxidase (MPO) kit assay, ELISA, immunofluorescence assay, and LC-MS/MS were used to assess histological changes, MPO levels, inflammatory factors release, expression and distribution of intestinal tight junction (TJ) protein ZO-1, and metabolic pathways, respectively. The levels of proteins involved in the nuclear factor kappa-B (NF-κB) pathway in the UC were investigated by western blotting and RT-qPCR. ResultsIn vitro experiments verified that NA could reduce inflammatory response and inhibit the activation of key signal pathways associated with inflammation in LPS-induced RAW264.7 cells. Further, results from the mouse colitis model suggested that NA could restore intestinal barrier function and suppress NF-κB signal pathways to ameliorate DSS-induced colitis. In addition, untargeted metabolomics analysis of NA protection against UC found that NA protected mice from colitis by regulating citrate cycle, amino acid metabolism, pyrimidine and purine metabolism. ConclusionThese results suggested that NA could ameliorate the secretion of inflammatory factors, suppress the NF-κB signaling pathway, and protect the integrity of colon tissue, thereby having a novel role in prevention or treatment therapy for UC. This work for the first time indicated that NA might be a potential functional food ingredient for preventing and treating inflammatory bowel disease (IBD).

Influence of Na+ on vaterite formation, content and yield using steamed ammonia liquid waste as a calcium source

The effect of Na+ concentration on the crystalline phase, morphology, and content of vaterite in a system with different Ca2+ and CO32− ratios using steamed ammonia liquid waste as the calcium source and the effect of Na+ on the yield of vaterite was studied systematically for the first time.

Slight compositional variation-induced structural disorder-to-order transition enables fast Na+ storage in layered transition metal oxides

The omnipresent Na+/vacancy orderings change substantially with the composition that inevitably actuate the ionic diffusion in rechargeable batteries. Therefore, it may hold the key to the electrode design with high rate capability. Herein, the influence of Na+/vacancy ordering on Na+ mobility is demonstrated firstly through a comparative investigation in P2-Na2/3Ni1/3Mn2/3O2 and P2-Na2/3Ni0.3Mn0.7O2. The large zigzag Na+/vacancy intralayer ordering is found to accelerate Na+ migration in P2-type Na2/3Ni1/3Mn2/3O2. By theoretical simulations, it is revealed that the Na+ ordering enables the P2-type Na2/3Ni1/3Mn2/3O2 with higher diffusivities and lower activation energies of 200 meV with respect to the P3 one. The quantifying diffusional analysis further prove that the higher probability of the concerted Na+ ionic diffusion occurs in P2-type Na2/3Ni1/3Mn2/3O2 due to the appropriate ratio of high energy ordered Na ions (Naf) occupation. As a result, the interplay between the Na+/vacancy ordering and Na+ kinetic is well understood in P2-type layered cathodes.

Effects of sodium aluminate on the performance of seawater sea-sand engineered cementitious composites

In this study, a quick setting seawater sea-sand engineered cementitious composite (SS-ECC) was prepared using sodium aluminate (NaAlO2, NA). The effects of the amount of NA and different types of water (seawater and freshwater) on the setting time, compressive strength, flexural strength, and tensile properties of the SS-ECC were studied. The influence of NA on the hydration reaction and microstructure of the SS-ECC was examined through X-ray diffraction (XRD), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FE-SEM). Experimental results revealed that NA and seawater reduced the setting time of the SS-ECC, particularly at 4% NA, and slightly improved the early strength of the SS-ECC. However, too much NA would decrease the late strength of the SS-ECC. The incorporation of NA enhanced the ultimate tensile strain of the SS-ECC. And the SS-ECC with 4% NA exhibited evident strain-hardening characteristics under tension, with the ultimate tensile strain reaching a maximum of 4.61%. The calculated toughness and residual strength indexes indicated that the SS-ECC could be defined as an ideal elastoplastic material. Based on this, a bilinear uniaxial tensile stress–strain constitutive model of the SS-ECC was established. In addition, the XRD and TGA results demonstrated that NA promoted the hydration of cement, generation of AFt and AFm, and polycondensation reaction to generate C-A-S-N and N-A-S-H gels. This decreased the setting time of the SS-ECC and improved the early strength. However, the product obtained by the early rapid reaction might have encapsulated the cement raw materials, thereby preventing further hydration in the later stage. This was not conducive to the long-term strength development of the SS-ECC.

Influence of Na+, Ca2+ and R3+ (R = Y, Lu, Gd) co-doping on the spectroscopic properties of Pr3+:BaF2 single crystal

A series of high quality x%Pr3+:BaF2 (x = 0.6, 1, 2); (1%Pr3+, 2%Na+):BaF2; (1%Pr3+, y%Ca2+):BaF2 (y = 3, 5) and (0.6%Pr3+, 10%R3+):BaF2 (R = Y, Lu, Gd) crystals were grown via a temperature gradient technique (TGT).

Influence of Na and Ca contents on swelling behavior of Indian expansive soils

Influence of Na and Ca contents on swelling behavior of Indian expansive soils

Albumin-Hyaluronan Interactions: Influence of Ionic Composition Probed by Molecular Dynamics.

The lubrication mechanism in synovial fluid and joints is not yet fully understood. Nevertheless, intermolecular interactions between various neutral and ionic species including large macromolecular systems and simple inorganic ions are the key to understanding the excellent lubrication performance. An important tool for characterizing the intermolecular forces and their structural consequences is molecular dynamics. Albumin is one of the major components in synovial fluid. Its electrostatic properties, including the ability to form molecular complexes, are closely related to pH, solvation, and the presence of ions. In the context of synovial fluid, it is relevant to describe the possible interactions between albumin and hyaluronate, taking into account solution composition effects. In this study, the influence of Na+, Mg2+, and Ca2+ ions on human serum albumin–hyaluronan interactions were examined using molecular dynamics tools. It was established that the presence of divalent cations, and especially Ca2+, contributes mostly to the increase of the affinity between hyaluronan and albumin, which is associated with charge compensation in negatively charged hyaluronan and albumin. Furthermore, the most probable binding sites were structurally and energetically characterized. The indicated moieties exhibit a locally positive charge which enables hyaluronate binding (direct and water mediated).

Effects of High Salinity on Alginate Fouling during Ultrafiltration of High-Salinity Organic Synthetic Wastewater.

Ultrafiltration is widely employed in treating high-salinity organic wastewater for the purpose of retaining particulates, microbes and macromolecules etc. In general, high-salinity wastewater contains diverse types of saline ions at fairly high concentration, which may significantly change foulant properties and subsequent fouling propensity during ultrafiltration. This study filled a knowledge gap by investigating polysaccharide fouling formation affected by various high saline environments, where 2 mol/L Na+ and 0.5–1.0 mol/L Ca2+/Al3+ were employed and the synergistic influences of Na+-Ca2+ and Na+-Al3+ were further unveiled. The results demonstrated that the synergistic influence of Na+-Ca2+ strikingly enlarged the alginate size due to the bridging effects of Ca2+ via binding with carboxyl groups in alginate chains. As compared with pure alginate, the involvement of Na+ aggravated alginate fouling formation, while the subsequent addition of Ca2+ or Al3+ on the basis of Na+ mitigated fouling development. The coexistence of Na+-Ca2+ led to alginate fouling formed mostly in a loose and reversible pattern, accompanied by significant cracks appearing on the cake layer. In contrast, the fouling layer formed by alginate-Na+-Al3+ seemed to be much denser, leading to severer irreversible fouling formation. Notably, the membrane rejection under various high salinity conditions was seriously weakened. Consequently, the current study offered in-depth insights into the development of polysaccharide-associated fouling during ultrafiltration of high-salinity organic wastewater.

Influences of alkali incorporation and electrodeposited metal layer on formation of MoS2 in CZTS thin films

In this work, the CZTS absorbers were prepared by sol-gel method and the combination of electrodeposition and sol-gel method. The influence of Na and/or K incorporation on the thickness of MoS2 during sulfurization process was investigated. XRD, Raman, and SEM characterizes presented that K incorporation could help to suppress the formation of MoS2, which induced to reduce the thickness of MoS2. Additionally, Na and/or K doping could eliminate the existence of the voids and improve the quality of CZTS thin film. Besides, the CZTS absorbers fabricated by the combination process of electrodeposition and sol-gel shown a better adhesion than that fabricated by sol-gel method.

Identification of copper-sulfide species on the cuprite surface and its role in sulfidization flotation

Cuprite is an important copper-oxide mineral that is difficult to recover in flotation. Therefore, it is necessary to study the flotation behavior of cuprite to recover copper resources. In this work, Na 2 S was used to modify the cuprite surface to enhance its floatability. The effect of Na 2 S on the flotation behavior of cuprite was determined by microflotation tests. The influence of Na 2 S on xanthate adsorption on the cuprite surface was determined by surface adsorption measurements, zeta potential tests, and infrared spectroscopy analysis. The surface sulfidization products on the cuprite surface were determined by X-ray photoelectron spectroscopy analysis. The microflotation tests showed that Na 2 S could enhance the cuprite floatability. The surface adsorption measurements, zeta potential tests, and infrared spectroscopy analysis indicated that sulfidization could strengthen the adsorption of xanthate on the cuprite surface and reduce the collector consumption. The X-ray photoelectron spectroscopy analysis indicated that a hydrophobic and stable copper-sulfide film formed on the cuprite surface. These results confirmed that sulfidization could enhance the cuprite surface hydrophobicity, which improved the cuprite flotation. • Cuprite floatability was enhanced after sulfidization. • Surface sulfidization of cuprite could reduce collector consumption. • Copper-sulfide film formed on the cuprite surface. • High-activity Cu–S n species existed on the cuprite surface after sulfidization.

Influence of Na and K contents on the antibacterial response of piezoelectric biocompatible NaxK1-xNbO3 (x = 0.2–0.8)

Owing to the potential risk of bacterial infection during- or post-surgical operations, the development of antibacterial prosthetic orthopedic implants is in continuous thrust. In this perspective, the present work investigates the synergistic effect of surface polarization and compositional variation of Na and K contents in biocompatible NaxK1-xNbO3 (x = 0.2 to 0.8) in improving their antibacterial performance. The processing parameters were optimized to obtain dense and phase pure piezoelectric NaxK1-xNbO3 (x = 0.2−0.8). The sintered samples were polarized at the temperature and voltage of 500 °C and 20 kV, respectively, for 30 min. The effect of surface polarization on viability and adhesion of S. aureus and E. coli bacteria on piezoelectric NaxK1-xNbO3 (x = 0.2−0.8) as well as hydroxyapatite or HA (control) samples have been analyzed, quantitatively as well as qualitatively. The viability of S. aureus bacteria was reduced by (41, 29, 50 %) and (28, 20, 30 %) on the positively and negatively polarized surfaces of NaxK1-xNbO3 (x = 0.2, 0.5, 0.8) samples, respectively, as compared to non-polarized HA. For E. coli bacteria, the negatively and positively polarized surfaces of NaxK1-xNbO3 (x = 0.2, 0.5, 0.8) samples show reduced viability of bacteria by (49, 37, 52 %) and (31, 24, 45 %), respectively, as compared to non-polarized HA. In addition to surface charge polarization, sodium (x = 0.8) and potassium (x = 0.2) rich compositions further improve the antibacterial performance of NaxK1-xNbO3. Various assays associated with enzymatic activities were also performed to examine the effect of polarization and compositional variation on the reactive oxygen species (ROS) generation. The ROS generation and ROS induced bacterial damage was observed to be maximum on the positively polarized surfaces of sodium (x = 0.8) and potassium (x = 0.2) rich compositions of NaxK1-xNbO3. These enzymatic activities results were further corroborated with qualitative antibacterial analyses (live/ dead assay). Although, non-polarized NaxK1-xNbO3 (x = 0.2, 0.5, 0.8) samples illustrated significantly higher antibacterial response as compared to HA, quantitative and qualitative results reveal that polarized surfaces of sodium (Na0.8K0.2NbO3) and potassium (Na0.2K0.8NbO3) rich NaxK1-xNbO3 samples show the maximum reduction in viability and adhesion of S. aureus and E. coli bacteria.

Structural Effects of Cation Binding to DPPC Monolayers.

Ions at the two sides of the plasma membrane maintain the transmembrane potential, participate in signaling, and affect the properties of the membrane itself. The extracellular leaflet is particularly enriched in phosphatidylcholine lipids and under the influence of Na+, Ca2+, and Cl- ions. In this work, we combined molecular dynamics simulations performed using state-of-the-art models with vibrational sum frequency generation (VSFG) spectroscopy to study the effects of these key ions on the structure of dipalmitoylphosphatidylcholine. We used lipid monolayers as a proxy for membranes, as this approach enabled a direct comparison between simulation and experiment. We find that the effects of Na+ are minor. Ca2+, on the other hand, strongly affects the lipid headgroup conformations and induces a tighter packing of lipids, thus promoting the liquid condensed phase. It does so by binding to both the phosphate and carbonyl oxygens via direct and water-mediated binding modes, the ratios of which depend on the monolayer packing. Clustering analysis performed on simulation data revealed that changes in area per lipid or CaCl2 concentration both affect the headgroup conformations, yet their effects are anticorrelated. Cations at the monolayer surface also attract Cl-, which at large CaCl2 concentrations penetrates deep to the monolayer. This phenomenon coincides with a radical change in the VSFG spectra of the phosphate group, thus indicating the emergence of a new binding mode.