Values Of Internal Energy Research Articles

Experimental Characterization and Phase-Field Damage Modeling of Ductile Fracture in AISI 316L

(1) Modeling and characterization of ductile fracture in metals is still a challenging task in the field of computational mechanics. Experimental testing offers specific responses in the form of crack-mouth (CMOD) and crack-tip (CTOD) opening displacement related to applied force or crack growth. The main aim of this paper is to develop a phase-field-based Finite Element Method (FEM) implementation for modeling of ductile fracture in stainless steel. (2) A Phase-Field Damage Model (PFDM) was coupled with von Mises plasticity and a work-densities-based criterion was employed, with a threshold to propose a new relationship between critical fracture energy and critical total strain value. In addition, the threshold value of potential internal energy—which controls damage evolution—is defined from the critical fracture energy. (3) The material properties of AISI 316L steel are determined by a uniaxial tensile test and the Compact Tension (CT) specimen crack growth test. The PFDM model is validated against the experimental results obtained in the fracture toughness characterization test, with the simulation results being within 8% of the experimental measurements. (4) The novel implementation offers the possibility for better control of the ductile behavior of metallic materials and damage initiation, evolution, and propagation.

Thermodynamic analysis of anaerobic digestion of Eichornia crassipes (Water Hyacinth) biomass from the Volta River basin of Ghana using fruit waste sludge as inoculum

In order to gain understanding on the utilization of biogas fuel derived from water hyacinth (WH) biomass and render it appealing as a sustainable gaseous fuel, the study reports on its various thermophysical, combustion and thermodynamic parameters. The parameters include, specific enthalpy, internal energy, low heating value, Wobbe number index, changes in Enthalpy, Entropy and Gibbs free energy. The experimental procedure was performed at temperature range of 29±3 °C for 61 days in a BlueSens laboratory-scale anaerobic digestion equipment. It comprised of three fermenter bottles designated as F1, F2 and F3. F1 served as the control and the rest served as the test fermenter bottles. The digestion of water hyacinth and fruit waste sludge (WH+FWS) recorded the highest biogas volumes of 19,798.79 ml in fermenter F2 and 19,168.55 ml in fermenter F3 with methane contents of 53.46 % and 51.85 %, respectively. In comparison, the biogas produced exclusively from the water hyacinth (WH) biomass yielded 12,014.49 ml in F2 and 11,384.25 ml in F3, with methane contents of 46.41 % and 43.31 %, respectively. The best biogas fuel was produced from the digestion of (WH+FWS) in fermenter F2 with an internal energy and enthalpy values of 258.6 KJ/kg. K and 344.9 KJ/kg. K, respectively. A low heating value and Wobbe number of 17.51 MJ/m³ and 17.78 MJ/m³ were determined respectively. The biogas production was simulated using the Gompertz modified kinetic equation in MATLAB and an average specific rate (Kexp) of 371.49 ml/gVS.day was obtained. The rate constant (Kexp) was applied in the linearized form of the Erying-Polanyi equation to determine the changes in Enthalpy Entropy, and Gibbs free energy as -2510.66 J, -304.78 J and 94,219 J, respectively which indicated that, the anaerobic digestion process in this study was only thermodynamically feasible at low temperatures.

From electrospray ionization to cold-spray ionization: How to evaluate the cooling effect on the gaseous ions?

Two methods of survival yields (SY) measurement treatment of thermometer ions whose fragmentation is activated by in-source collision induced dissociation have been investigated for evaluating the mean internal (<Eint >) and thermal (<Etherm >) energies of gaseous ions produced by electrospray ionization and cold-spray ionization (CSI). One of the methods is based on the use of the internal energy distributions (P (Eint )) as sigmoid derivatives connecting the experimental survival yields of different substituted benzylpyridinium cations. The <Eint > values are therefore converted in a thermal-like parameter called vibrational temperature (Tvib ) then obtained at each value of the voltage of the desolvation area. The second method is based on the modelling of ion behavior by the MassKinetics software where the value of the characteristic temperature parameter (Tchar ) is used for fitting theoretical survival yields (SYtheo ) with experimental data (SYexp ) calculated at several activation energy. A linear correlation is evidenced between the values of internal or thermal energy and the voltage of the orifice 1 at the origin of the ion activation in the desolvation area. The extrapolation at zero voltage of the thermal-like parameters (Tvib and Tchar ) indicates that, in agreement with the literature data, the ions are relatively hot in ESI (~650 K). But the use of a CSI source lowers this temperature down to ~300 K. In addition, with cold-spray ionization, this cooling effect is more important when methanol is used instead of acetonitrile although these two solvents have no influence on the gaseous ion temperature in electrospray ionization.

A Molecular Dynamics Study of Nucleation and Grain Growth of Novel Al-15Mg&lt;sub&gt;2&lt;/sub&gt;Si-4.5Si Composite during Rapid Cooling Based Semi Solid Slurry Preparation

Owing to their several attractive features such as high hardness, high elastic modulus, light weight, high strength to weight ratio, high thermal conductivity, and high temperature strength, composites from Al-Mg2Si family offers promise towards deployment in several industries such as automobile, aerospace, marine, defence and electronic. The present molecular dynamics (employing LAMMPS) based simulation study is one of the first attempt to investigate the nucleation and grain growth mechanisms of Mg2Si phase at atomic level in case of novel Al-15Mg2Si-4.5Si composite, during semi-solid processing. Modified embedded atom method (MEAM) potential has been used to study the atomic interactions in the composite. Reaching the melt state at 1000 K, the temperature of the system is first decreased from 1000 K to 853 K and then the system is held at 853 K for 100 ps. The simulations are performed with three different cooling rates. With lowering of temperature, randomly distributed Mg and Si atoms form atomic clusters at arbitrary locations within the system, which is the nucleation stage for Mg2Si phase formation. Cluster size, radial distribution function has been used to investigate the structural evolution of Mg-Si clusters. Cooling rate significantly influences the grain size as well as the grain growth kinetics. The information about the thermodynamic state of the system has been revealed by extracting the values of internal energy, enthalpy, specific heat. during the slurry preparation and isothermal holding stages. The growth mechanism of Mg2Si nucleus has been characterized from the temporal variation of (Mg + Si) atoms taking part in the cluster formation. Power-law variation is observed in the cooling stage whereas a linear variation is observed in the isothermal stage.

AGATA: nuclear structure advancements with fusion-evaporation reactions

Nuclear-structure studies using fusion reactions are reviewed in terms of prospects for advancement using the next generation of gamma -ray tracking arrays such as AGATA. Properties discussed include those of light N=Z nuclei and rotational behaviour in heavy nuclei at high values of angular momentum and internal excitation energy.

ИССЛЕДОВАНИЕ УДАРНОГО ОТКЛИКА СОТОВОЙ КОНСТРУКЦИИ С ТОНКИМИ ОБШИВКАМИ ИЗ РАЗЛИЧНЫХ МАТЕРИАЛОВ

The use of honeycomb sandwich panels in the national economy has become widespread recently. Their advantages are the relative lightness with good strength capabilities. The article presents a calculation of the impact response between a honeycomb sandwich panel and an absolutely rigid spherical body. The value of internal and kinetic energy, as well as equivalent stress in a sandwich panel, is determined. The influence of materials of thin skins of sandwich panels on above values is analyzed. The problem is solved with computer simulation of the dynamic process in an explicit formulation. The work results are relevant in the design of structures that combine optimal strength and weight characteristics.

Thermodynamics of liquid and fluid mixtures from the kinetic Monte Carlo viewpoint.

In this study a binary mixture is modelled in a uniform simulation cell at various temperatures using an extended version of the grand canonical kinetic Monte Carlo (GC-kMC) method. The main goal of this study is to consider the thermodynamic properties of binary liquids, gases, and gas-liquid mixtures from a more general point of view than that applied to the particular case of vapour-liquid equilibrium when the pressure and partial chemical potentials in coexisting phases are the same. Particular attention is paid to thermodynamic functions such as chemical potentials, Gibbs free energy and entropy. For the pair potential of unlike molecules a more universal scheme is proposed in comparison with the Lorentz-Berthelot combining rule. The approach is tested on an Ar-Kr mixture in a wide range of temperatures. In all cases, the obtained values of chemical potentials, pressure and internal energy for the entire set of component densities and temperature fully satisfy the Gibbs-Duhem equation with a high degree of accuracy. For the case of vapour-liquid equilibrium, the developed approach made it possible to reproduce the experimental pressure-composition diagrams with the highest accuracy ever achieved in the literature. Despite the fact that the Ar-Kr mixture, according to Raoult's law, is close to an ideal system, it was found that the partial pressures in the liquid phase or in a dense supercritical gas mixture are non-linear functions of the composition, and the partial pressure of the heavier component (Kr) can even be negative.

Influence of Internal Energies on Optical Properties of Methyl Ammonium Lead Triiodide Thin Layers

In this study, various forms of energies affecting optoelectronic properties of CH3NH3PbI3 thin films are presented and explained experimentally and using theoretical models. Different concentrations of CH3NH3PbI3 solution were prepared, and thin films were deposited using spin-coating at a speed of 1000 rpm for 90 seconds and annealed at 100o C for about 60 minutes. Optical measurements were obtained, and the films were analyzed. The results showed that some properties, like absorption coefficients, ranged between 4.68073 - 22.19402×102 cm-1, dielectric constant between 4.10497 - 4.96329, and band gap between 1.6121 – 2.1642 eV. Various energies were determined, including transition energies, obtained as 1.742 eV, VE losses as 1.732 eV, average band gap at 1.723 eV, and SE losses at 1.714 eV. These values of internal energy had a significant direct influence on the optoelectronic properties of CH3NH3PbI3 and thus concluded that they could be used to provide initial helpful information in designing and modeling hybrid perovskite optical devices.

Thermodynamic analysis of cooling cycles based on statistical physics modeling of ethanol adsorption isotherms

Thermodynamic analysis of two different adsorption cooling cycles was presented; the first cycle is based on an isobaric adsorption process and the second one projects an isothermal adsorption instead of an isobaric adsorption. These cooling cycles are carried out by employing the grand canonical ensemble of the statistical physics formalism. This investigation is done for two different adsorbate/adsorbent pairs i.e. Ethanol/Waste Palm Trunk (WPT-AC) and Ethanol/Mangrove wood (M-AC). The corresponding adsorption isotherms have been fitted by statistical physics models to give a description of the adsorption process through interpretations of the evolution of the involved physico-chemical parameters, specific for this process. The results showed that the ethanol molecules have been mainly adsorbed with a multimolecular process and non-parallel to the adsorbent surface involving an aggregation process before molecules adsorption. Their adsorption energies are varying from 1.40 to 3.64 kJ/mol for WPT-AC and from 3.2 to 3.81 kJ/mol for the M-AC. These values reflected a physisorption process. The calculated internal energy values suggested the exothermicity and the spontaneity of the ethanol adsorption process. The investigation aims providing a methodology of calculation of the COP for an adsorption cooling cycle by using the statistical physics treatment. The entropy and the enthalpy functions are calculated and used to perform the thermodynamic evaluation and to calculate the coefficient of performance (COP). This parameter was found to be in the interval [0.12–0.69] for ethanol/WPT-AC and [0.11-0.6] for ethanol/M-AC for the first cycle and for the second cycle [0.15-0.81] and [0.15-0.74] respectively.

Amplifying the photovoltaic properties of azaBODIPY core based small molecules by terminal acceptors modification for high performance organic solar cells: A DFT approach

Molecular engineering of azaBODIPY based molecule was done to construct four novel small photoactive materials (SM1-SM4) by varying terminal thiophene spaced acceptors for theoretical investigation of photovoltaic properties. In the present study, DFT and TD-DFT methods using B3LYP functionalwith a basis set of 6-31G were employed to systematically evaluate wavelength, determine parameters (absorption values, first excitonic energy, LHE), charge transfer elements (fill factor FF, open circuit voltage Voc), reactivity descriptors (IP and EA) and electronic processes (FMO, DOS, TDM) of modelled molecules (SM1-SM4). All studied molecules showed intense optical absorption in the visible region (710–751 nm), strong light harvesting capability, clearly assigned HOMO-LUMO placement, and lessened exciton binding energies due to highly electron withdrawing acceptor moieties. Greater dipole moment in solution phase than in the gas phase as compared to gaseous medium indicated that these small molecules possessed good solubility in Benzonitrile solvent.The internal reorganization energy values of novel molecules suggested their reliability as efficient hole transport materials. Additionally, results interpreted through analysis of values of Voc (with PTB7-Th), and FF, anticipated an escalation of power conversion efficiency. Among all considered molecules, SM2 and SM3 emerged as promising photovoltaic materials owing to their significant optical properties, reduced band gaps, rapid exciton dissociation, and high estimated PCE. Conclusively, these supportive outcomes favor the structural amendment of small molecules through effective terminal acceptor entities which could enhance the efficiency of photovoltaic materials.

Molecular in Silico Test of the Interaction Between Keloid Cell Protein TGF – β1 (PDB ID: 3TZM) and Lycopene Compounds

Keloids are pathological scars, characterized histologically by excessive aggregation of type I collagen and fibroblasts in the reticular dermis inflammation. Scar tissue (keloid) is one problem the most frustrating in wound healing. Clinically, keloids are defined as a scar that invades adjacent healthy tissue and seldom experience regression along time. Keloids can be said to be a disorder of the healing wound, which form growth excessive from network scar, exceed limit wound, and beyond the normal time (can be years) wound healing process. In this research conducted development drug anti - keloids in silicon from compound secondary metabolites Lycopene with target protein TGF-β1 with code PDB ID: 3TZM. Testing conducted with series process covers analysis of compounds and proteins, physicochemical properties, ADME, RMSD value ≤ 2 Å, geometry optimization, 3D and 2D interactions between compounds and target proteins using DOCK 6. Based on results test in silicon, will be obtained compound docking score quercetin with the 3TZM ligand that t has the potential to be developed into one candidate drug anti keloids with score bond energy free (affinity) – 71,453, van derwals bond energy value (vdw) -71,990, ES energy value 0,536 and internal repulsive energy value 72,413.

Simulations of internal energy and pρT properties of monatomic fluids from accurate ab initio potentials and their uncertainty analysis

Ab initio potentials available in the literature are used to investigate the internal energy and pρT properties of helium, neon, argon, krypton, and xenon by molecular dynamics simulations. The total uncertainty of the simulation data is evaluated by reasonably quantifying the contributions from both the simulation method and the potential models. The theoretical predictions of this work are compared with recent experimental pρT data as well as the NIST data for the gas and supercritical phases to check the quality of this work. In most cases, agreement is found between the internal energy and pρT property values of this work and the literature data and the differences are smaller than the corresponding simulation uncertainty. It is concluded that the simulation data of this work are accurate enough to be used with confidence in different technical and practical applications over a wide temperature and density range.

Energy absorption characteristic of bionic lightweight protective structure with curved tubes under impact loading

Reinforcing and toughening materials with light quality in engineered structures remains a challenge. In the biological tissues of numerous animal and plant species, efficient strategies have evolved to construct structures that have excellent mechanical properties. As a kind of biological structure with high-strength fiber, beetle elytron not only provides protection function for beetles, but also makes beetles light enough to obtain good flight ability. Because of these advantages of inner fibrous structure of elytron, the bionic investigation of beetle elytron has gradually become one of the research focuses in civil engineering and automobile anti-collision fields. In the present work, the honeycomb and tubes composed of fiber in the beetle elytra was analyzed, and a variety of bionic thin-walled honeycomb structures with curved hollow tubes were designed and modeled. The energy absorption ability of the bionic honeycomb structures with different types of tubes under impact loading were calculated by finite element software. The internal energy values and collapse processes of bionic structures were compared and analyzed at different crushing displacements. The parameter study, including wall thickness and impact angle, was carried out in the collapse time range from 0 ms to 8 ms. These results could be applied in developing crush-resistant materials in the field of automotive passive safety.

МОДЕЛЮВАННЯ ПРОЦЕСУ ДЕЗІНТЕГРАЦІЇ РУДНОЇ ПОРОДИ В БАРАБАННОМУ МЛИНІ З ВИКОРИСТАННЯМ МЕТОДУ СКІНЧЕНИХ ЕЛЕМЕНТІВ

Розглянуто особливості руху рудних матеріалів в барабанному млині. Розроблено математичну модель процесу подрібнення рудних матеріалів з позиції балансу енергетичних величин процесу руйнування За використанням методу скінчених елементів показано, що виділений в будь-якому місці елемент завантаження піддається деформації з боку сусідніх елементів завантаження (шматків руди) в умовах всебічного нерівнокомпонентного стиснення контактними силами. Проаналізовано вплив напрямку сил контактного тертя при стисненні на ефективність руйнування рудної маси Данні сили суттєво впливають на появу максимальних зсувних (дотичних) напружень, які залежать від максимальних нормальних напружень, що виникають в шматках рудної породи Показана можливість керування режимами навантаження для підвищення ефективності процесу подрібнення.

CO2 adsorption investigation by statistical physics: Thermodynamic analysis for cooling cycle application

In this paper, the adsorption isotherms of the carbon dioxide onto highly porous activated carbon have been fitted by advanced statistical physics models to give reasonable interpretations of this process. Fitted physico-chemical parameters values have been deducted by means of the best fitting model. To describe the adsorption process, the fitting results showed that the CO2 molecules formed only one layer on the modified activated carbon. These molecules have been mainly docked with a parallel position on adsorbent receptor sites with adsorption energies varying from 7.16 kJ/mol to 8.24 kJ/mol. These values reflected a physisorption process. The calculated internal energy values suggested the spontaneity and the exothermicity of the CO2 adsorption process onto the modified activated carbon (MAC). As application, the enthalpy function is utilized and calculated to perform the thermodynamic evaluation of an adsorption cycle for a CO2 adsorption cooling system and to calculate the coefficient of performance (COP) as a function of regeneration temperature. This parameter was found to be in the interval [0.09–0.19] corresponding to regeneration temperature varying from 303 K to 343 K.

Optimal area variation for maximum stiffness isostatic beams under parametric linear distributed loads

The stiffness maximization of elastic straight Euler-Bernoulli beams under the action of linearly distributed loads is addressed. The goal is achieved by minimizing the average compliance, which is given by the value of internal elastic energy distributed over the length of the beam. Studies in the literature suggest considering this approach since it provides, unlike the minimization of the maximum deflection, a constant bending stress behavior along the beam axis. An isoperimetric constraint on the material volume is also considered and optimal solutions are derived by means of calculus of variations. Three types of boundary conditions are discussed, namely cantilever, simply supported and guided-simply supported beams. Introducing a well known relation between the cross sectional area and moment of inertia, closed-form solutions for several cross sections commonly used in engineering are derived. Finally, a sensitivity analysis with respect to the load parameters is addressed within a numerical example.

Dynamic characteristics of bubbles in spherical bubble group considering evaporation and condensation of water vapor

&lt;sec&gt;In order to explore the dynamic characteristics of bubbles in the cavitation bubble cluster in detail, the dynamic equation of a bubble with arbitrary location inside the bubble cluster is established in this paper, based on the interactions between bubbles inside the bubble cluster driven by ultrasound. The effects of evaporation and condensation of the water vapor are also taken into account in the derivation process. Based on the proposed equation, the influences of the bubble position, number of bubbles, and initial radius of bubbles on the dynamic characteristics of cavitation bubbles are studied, and the corresponding change laws of the bubble radius, energy, temperature, pressure, as well as the number of water vapor molecules in a bubble are investigated under ultrasound.&lt;/sec&gt;&lt;sec&gt; The calculation results are shown below. 1) Comparing with an isolated bubble, the oscillation of a bubble inside the bubble cluster is suppressed by its surrounding bubbles, which leads to the fact that the vibration amplitude of a bubble inside the bubble cluster is smaller, and that the internal energy, maximum temperature, maximum pressure and the number of water molecules in the bubble all become smaller. As the distance between the bubble and the center of the bubble cluster increases, the vibration amplitude of the bubble become larger. 2) The initial radii of the bubbles in the bubble cluster can significantly affect the normalized vibration amplitude, collapse time, internal energy, temperature, and pressure of bubbles, as well as the number of water vapor molecules in bubbles of the bubble cluster. 3) As the number of bubbles in the bubble cluster increases, the vibration amplitudes of the bubbles decrease. 4) The higher the ultrasonic frequency, the smaller the oscillation amplitude of the bubble; the smaller the maximum pressure and energy of the bubble, the larger the minimum value of the internal pressure and temperature of the bubble and the less the number of water molecules in the bubble. When the ultrasonic frequency increases, the cavitation effects of bubbles in the bubble cluster are suppressed. 5) As the ultrasonic sound pressure increases, the oscillation amplitudes of the bubbles in the bubble cluster increase, the maximum values of the bubbles' radii increase, the collapse times of the cavitation bubbles increase, and the number of oscillations of bubbles decreases after the cavitation bubbles have collapsed. Additionally, the maximum value of internal energy, temperature, pressure, and the number of water molecules in the bubble also increase as the ultrasonic sound pressure increases, while the minimum value of the pressure and temperature of the bubble decrease. Besides, when the ultrasonic sound pressure increases, the cavitation effects of the bubbles in the bubble cluster turn stronger.&lt;/sec&gt;&lt;sec&gt; This paper focuses on the dynamic characteristics of ultrasonic cavitation bubble cluster from the theoretical aspect and the results can be further applied to experimental analysis.&lt;/sec&gt;

Computational and Experimental Studies of Biolubricant Stability Derived from Oleic Acid

In the present work, the stability of six biolubricant compounds, i.e. Acetal, Ketal, D[4.4], D[4.5], Cyclic-6, and Cyclic-7, was evaluated both theoretically and experimentally. These compounds were prepared from oleic acid through hydroxylation and esterification reactions. The computational study of the compounds was conducted by using the Density Functional Theory (DFT) method at B3LYP level of theory and 6-31 G (d,p) basis set. The theoretical stability was reflected from the internal energy value of the hydrolysis reaction of the biolubricant compounds to form the 9,10-dihydroxystearic acid. The order of stability is given as follows: Cyclic-6 (-3.458 kJ/mol) &gt; Acetal (-3.446 kJ/mol) &gt; Cyclic-7 (-3.364 kJ/mol) &gt; D[4.5] (-3.343 kJ/mol) &gt; D[4.4] (-3.261 kJ/mol) &gt; Ketal (-3.058 kJ/mol). On the other hand, the experimental stability of the biolubricant compounds was measured using the American Society for Testing and Material (ASTM) standard method for total acid number (TAN) and total base number (TBN). It was found that the Cyclic-6 derivative yielded the lowest TAN (1.37 mg KOH/g) and TBN (3.53 mg KOH/g) values compared to the other biolubricant compounds. Meanwhile, the Cyclic-6 also showed the lowest internal energy value (-3.458 kJ/mol) from the computational study due to the high stability of six-membered ring. These results reveal that the experimental TAN and TBN values could be predicted from the theoretical internal energy value, i.e. TAN (mg KOH/g) = 35.183 (DE) – 123.02 (R2 = 0.9226) and TBN (mg KOH/g) = 105.71 (DE) – 369.72 (R2 = 0.8946), which is remarkable.

Production of PAH cations with narrow internal energy distribution using single nanosecond pulsed laser

The internal energy dynamics of three examples of PAHs are probed using a high resolution energy time of flight spectrometer. The measured H-loss rates are converted to internal energy values for a range of UV photon wavelengths. Multi step multi photon absorption scheme is proposed to estimate the possible internal energy values with reasonable accuracies. This was possible because of the ultrafast radiationless internal conversion process in PAHs and their structural rigidity. Thus, a method is proposed to produce PAH cations with narrow and known internal energy distribution using a single nanosecond pulsed laser, paving a way to study statistical unimolecular decay in PAHs very efficiently.

Internal Energy Deposition in Infrared Matrix-Assisted Laser Desorption Electrospray Ionization With and Without the Use of Ice as a Matrix.

The internal energy deposited into analytes during the ionization process largely influences the extent of fragmentation, thus the appearance of the resulting mass spectrum. The internal energy distributions of a series of para-substituted benzyl pyridinium cations in liquid and solid-state generated by infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) were measured using the survival yield method, of which results were subsequently compared with conventional electrospray ionization (ESI). The comparable mean internal energy values (e.g., 1.8-1.9eV at a collision energy of 15eV) and peak widths obtained with IR-MALDESI and ESI support that IR-MALDESI are essentially a soft ionization technique where analytes do not gain considerable internal energy during the laser-induced desorption process and/or lose energy during uptake into charged electrospray droplets. An unusual fragment ion, protonated pyridine, was only found for solid IR-MALDESI at relatively high collision energies, which is presumably resulted from direct ionization of the pre-charged analytes in form of salts. Analysis of tissue with an ice layer consistently yielded ion populations with higher internal energy than its counterpart without an ice layer, likely due to a substantially enhanced number of IR absorbers with ice. Further measurements with holo-myoglobin show that IR-MALDESI-MS retains the noncovalently bound heme-protein complexes under both native-like and denaturing conditions, while complete loss of the heme group occurred in denaturing ESI-MS, showing that the softness of IR-MALDESI is equivalent or superior to ESI for biomolecules.