Fragmentation Threshold Research Articles

Removal of micro-nano particles based on water-assisted enhanced plasma shock wave

Foreign micro/nanoparticles can compromise the production and performance of semiconductors, high-energy laser systems, and other technologies. Owing to the strong adhesion (in GPa) of these particles to the surfaces of these devices, removing them using traditional methods such as ultrasound is difficult. Laser plasmas at high temperatures and pressures can effectively clean the micro/nanoparticles. Compared with traditional air media, laser plasma generates stronger shock waves and water flow erosion underwater, which can effectively clean these particles. In this study, we analysed the particle removal process under the action of laser plasma in water dielectrics, primarily the distribution characteristics of particles under spatial phase transition, final removal efficiency, removal thresholds, and optimal removal regions of particles with different sizes, as well as the corresponding academic analysis based on thermodynamic effects. We used a silicon wafer that was subjected to a high-energy laser beam to generate plasma shock waves underwater, which were used to remove micro- and nano-sized impurities. We found that the shock wave pressure of the plasma and water flow gradually decreased from the centre to the outside, and the corresponding action region could be divided into three areas, namely, 0–30°, 30–45°, and 45–50°, with particle removal rates of 96.93 %, 75.52 %, and 36.60 %, respectively. For particles in the 0–30° and 30–45° regions, the maximum removal rate corresponded to particle sizes ranging from 50–200 nm and greater than 200 nm, respectively. However, in the 45–60° region, the pressure of the shock wave was lower than the fragmentation threshold and, hence, had the worst particle removal effect owing to the lowest pressure. We believe that these findings will provide guidance for the subsequent development of particle removal technologies using underwater laser plasma shock waves.

An inflationary disk phase to explain extended protoplanetary dust disks

Context. Understanding planetesimal formation is an essential first step towards understanding planet formation. The distribution of these first solid bodies drives the locations where planetary embryos, which eventually form fully-fledged planets, grow. Aims. We seek to understand the parameter space of possible protoplanetary disk formation and evolution models of our Solar System. A good protoplanetary disk scenario for the Solar System must meet at least the following three criteria: (1) It must produce an extended gas and dust disk (e.g. 45 au for the dust); (2) within the disk, the local dust-to-gas ratio in at least two distinct locations must sufficiently increase to explain the early formation of the parent bodies of non-carbonaceous and carbonaceous iron meteorites; and (3) dust particles, which have condensed at high temperatures (i.e. calcium–aluminium-rich inclusions), must be transported to the outer disk. Though current protoplanetary disk models are able to satisfy one or two of these criteria, none have been successful in recreating all three. We aim to find scenarios that satisfy all three. Methods. In this study we used a 1D disk model that tracks the evolution of the gas and dust disks. Planetesimals are formed within the disk at locations where the streaming instability can be triggered. We explored a large parameter space to study the effect of the disk viscosity, the timescale of infall of material into the disk, the distance within which material is deposited into the disk, and the fragmentation threshold of dust particles. Results. We find that scenarios with a large initial disk viscosity (α > 0.05), a relatively short infall timescale (Tinfall < 100–200kyr), and a small centrifugal radius (RC ~ 0.4 au; i.e. the distance within which material falls into the disk) result in disks that satisfy all three criteria needed to represent the protoplanetary disk of the Solar System. The large initial viscosity and short infall timescale result in a rapid initial expansion of the disk, which we dub the ‘inflationary phase’ of the disk. Furthermore, a temperature-dependent fragmentation threshold, which accounts for cold icy particles breaking more easily, results in larger and more massive disks. This, in turn, results in more ‘icy’ than ‘rocky’ planetesimals. Such scenarios are also better in line with our Solar System, which has small terrestrial planets and massive giant planet cores. Finally, we find that scenarios with large RC cannot transport calcium–aluminium-rich inclusions to the outer disk and do not produce planetesimals at two locations within the disk.

Massive Protostellar Disks as a Hot Laboratory of Silicate Grain Evolution

Typical accretion disks around massive protostars are hot enough for water ice to sublimate. We here propose to utilize the massive protostellar disks for investigating the collisional evolution of silicate grains with no ice mantle, which is an essential process for the formation of rocky planetesimals in protoplanetary disks around lower-mass stars. We, for the first time, develop a model of massive protostellar disks that includes the coagulation, fragmentation, and radial drift of dust. We show that the maximum grain size in the disks is limited by collisional fragmentation rather than by radial drift. We derive analytic formulae that produce the radial distribution of the maximum grain size and dust surface density in the steady state. Applying the analytic formulae to the massive protostellar disk of GGD27-MM1, where the grain size is constrained from a millimeter polarimetric observation, we infer that the silicate grains in this disk fragment at collision velocities above ≈10 m s−1. The inferred fragmentation threshold velocity is lower than the maximum grain collision velocity in typical protoplanetary disks around low-mass stars, implying that coagulation alone may not lead to the formation of rocky planetesimals in those disks. With future measurements of grain sizes in massive protostellar disks, our model will provide more robust constraints on the sticking property of silicate grains.

Fragmentation thresholds simulated for antibubbles with various infinitesimal elastic shells

Abstract Antibubbles are small gas bubbles comprising one or multiple liquid or solid cores, typically surrounded by stabilising shells. Acoustically active microscopic antibubbles have been proposed for use as theranostic agents. For clinical applications such as ultrasound-guided drug delivery and flash-echo, it is relevant to know the fragmentation threshold of antibubbles and the influence of the stabilising shells thereon. For antibubbles with an infinitesimal frictionless elastic shell of constant surface tension, we simulated ultrasoundassisted fragmentation by computing radial pulsation as a function of time using an adapted Rayleigh-Plesset equation, and converting the solutions to time-variant kinetic energy of the shell and time-variant surface energy deficit. By repetition over a range of pressure amplitudes, fragmentation thresholds were found for antibubbles of varying size, core volume, shell stiffness, and driving frequency. As backscattering increases with scatterer size, and as drug delivery would require vehicles just small enough to pass through capillaries with a relatively large payload, we chose to present typical results for antibubbles of resting diameter 6 μm with a 90% incompressible core. At a driving frequency of 13 MHz, the fragmentation threshold was found to correspond to a mechanical indices less than 0.4, irrespective of shell stiffness. This mechanical index is not considered unsafe in diagnosis. That means that antibubbles acting as drug-carrying vehicles could release their payload under diagnostic conditions.

Viscoelastic effects probed by drop-jet collisions

We experimentally probe the stability of a continuous liquid jet deformed by successive impacts of immiscible drops. For Newtonian jets, two fragmentation thresholds are observed, which can be associated to two critical jet extensions. For viscoelastic jets, however, these fragmentations are partially or totally suppressed and cannot be correlated to any critical jet extension. We explain this dramatic change by the different drainage dynamics of the produced filaments, which we successfully model for both the Newtonian and viscoelastic jets. For the latter, long-lived filaments made of the jet liquid appear, which connect the encapsulated immiscible drops, giving rise to a new structure called Capsules On A String (COAS).

Insight into a stepped fragmentation of coal-related model compounds using a tandem Orbitrap mass spectrometer

To provide basic knowledge for coal conversion, twenty one coal-related model compounds (MCs) were analyzed using a tandem Orbitrap mass spectrometer (MS). Higher-energy collisional dissociation (HCD), a method of Orbitrap MS, unraveled the detailed fragmentation pathways and de-alkylation behaviors of the ionized MCs under collision energies from 10 to 80 eV. Chemical bond breaking, hydrogen loss, rearrangement reaction, and elimination of neutral fragments were discussed to elucidate clear fragmentation pathways. For arenes without alkyl chains, a higher energy threshold of fragmentation was observed with the increasing of aromatic ring due to a higher conjugate effect of condensed aromatic structure. The existence of alkyl chains decreased the threshold of fragmentation because of the electron-donating effect of alkyl chains. Heteroatom-containing aromatic compounds, a series of important species in coal, showed a diversified fragmentation patterns due to a low bond dissociation energy and a weak conjugate effect compared with arenes. Fragmentation pathways and de-alkylation behaviors of coal-related MCs will contribute to building monitoring methods for coal and its derivatives conversions in chemical industry.

On the Hydrogen Oxalate Binding Motifs onto Dinuclear Cu and Ag Metal Phosphine Complexes.

We report the binding geometries of the isomers that are formed when the hydrogen oxalate ((CO2)2H=HOx) anion attaches to dinuclear coinage metal phosphine complexes of the form [M1M2dcpm2(HOx)]+ with M=Cu, Ag and dcpm=bis(dicyclohexylphosphino)methane, abbreviated [MM]+ . These structures are established by comparison of isomer‐selective experimental vibrational band patterns displayed by the cryogenically cooled and N2‐tagged cations with DFT calculations of the predicted spectra for various local minima. Two isomeric classes are identified that feature either attachment of the carboxylate oxygen atoms to the two metal centers (end‐on docking) or attachment of oxygen atoms on different carbon atoms asymmetrically to the metal ions (side‐on docking). Within each class, there are additional isomeric variations according to the orientation of the OH group. This behavior indicates that HOx undergoes strong and directional coordination to [CuCu]+ but adopts a more flexible coordination to [AgAg]+ . Infrared spectra of the bare ions, fragmentation thresholds and ion mobility measurements are reported to explore the behaviors of the complexes at ambient temperature.

Optimizing ultrasound frequency in burst wave lithotripsy

Unlike shock wave lithotripsy, burst wave lithotripsy (BWL) uses tone bursts, consisting of many periods of sine wave. The fragmentation threshold of a stone depends on the burst frequency or, for a given frequency, on the stone size. In this work, an analytical theoretical approach to modeling mechanical stresses in a spherical stone has been developed. The theory is based on the method previously used to study the acoustic radiation force acting on an elastic stone [Sapozhnikov and Bailey, J. Acoust. Soc. Am. (2013)]. It has been shown that at low frequencies, when the wavelength is much greater than the diameter of the stone, the maximum principal stress is approximately equal to the pressure amplitude of the incident wave. With increasing frequency, when the diameter of the stone begins to exceed about half the wavelength in a surrounding liquid (the exact condition depends on the material of the stone), the maximum stress increases and can reach five times the pressure amplitude or even more. This observation suggests adjusting the BWL frequency depending on the stone diameter in order to comminute it into passable fragments. [Work supported by NIH, Nos. P01-DK043881 and RBBR 20-02-00139.]

Reemergence of Yellow Fever in Brazil: The Role of Distinct Landscape Fragmentation Thresholds.

Yellow Fever Virus (YFV) reemergence in Brazil was followed by human suffering and the loss of biodiversity of neotropical simians on the Atlantic coast. The underlying mechanisms were investigated with special focus on distinct landscape fragmentation thresholds in the affected municipalities. An ecological study in epidemiology is employed to assess the statistical relationship between events of YFV and forest fragmentation in municipal landscapes. Negative binomial regression model showed that highly fragmented forest cover was associated with an 85% increase of events of YFV in humans and simians (RR = 1.85, CI 95% = 1.24–2.75, p=0.003) adjusted by vaccine coverage, population size, and municipality area. Intermediate levels of forest cover combined with higher levels of forest edge densities contribute to the YFV dispersion and the exponential growth of YF cases. Strategies for forest conservation are necessary for the control and prevention of YF and other zoonotic diseases that can spillover from the fragmented forest remains to populated cities of the Brazilian Atlantic coast.

The water-ice line as a birthplace of planets: implications of a species-dependent dust fragmentation threshold

The thermodynamic structure of protoplanetary discs is determined by dust opacities, which depend on the size of the dust grains and their chemical composition. In the inner regions, the grain sizes are regulated by the level of turbulence (e.g. α viscosity) and by the dust fragmentation velocity that represents the maximal velocity that grains can have at a collision before they fragment. Here, we perform self-consistently calculated 2D hydrodynamical simulations that consider a full grain size distribution of dust grains with a transition in the dust fragmentation velocity at the water-ice line. This approach accounts for the results of previous particle collision laboratory experiments, in which silicate particles typically have a lower dust fragmentation velocity than water-ice particles. Furthermore, we probe the effects of variations in the water abundance, the dust-to-gas ratio, and the turbulence parameter on the disc structure. For the discs with a transition in the dust fragmentation velocity at the water-ice line, we find a narrow but striking zone of planetary outward migration, including for low viscosities. In addition, we find a bump in the radial pressure gradient profile that tends to be located slightly inside the ice line. Both of these features are present for all tested disc parameters. Thus, we conclude that the ice line can function both as a migration trap, which can extend the growth times of planets before they migrate to the inner edge of the protoplanetary disc, and as a pressure trap, where planetesimal formation can be initiated or enhanced.

Effect of SiC Deposition Behavior on Microstructure and Mechanical Properties of Cold-Sprayed Al5056/SiC Composite Coatings

To study the effect of deposition behavior of the reinforcement on microstructure and property of cold-sprayed metal matrix composite coating, four Al5056 composite powders containing 15 wt.%, 30 wt.%, 45 wt.% and 60 wt.% SiC were mixed to prepare the composite coatings by cold spraying. Effect of the SiC deposition behavior on microstructure, SiC distribution, micro-/nanohardness, surface residual stress and shear strength of the coatings were studied. Experimental results show that the increase in SiC content in the powder increased the SiC collision with the deposited SiC particles, which caused the difference in SiC content and distribution in the composite coatings. The SiC deposition behavior caused the SiC morphology to evolve from integrity to small cracks and complete fragmentation. The SiC deposition behavior effectively influenced its peening effect on the deformed Al5056 particles, that is, as the SiC fragmentation threshold arrived, the nanohardness, surface residual stress and shear strength of the coating showed the corresponding transition point. The surface residual stress state of the deformed Al5056 matrix could in turn affect the SiC deposition by increasing the SiC deposition efficiency at the minimum compressive stress.

Understanding Hypervelocity Sampling of Biosignatures in Space Missions.

The atomic-scale fragmentation processes involved in molecules undergoing hypervelocity impacts (HVIs; defined as >3 km/s) are challenging to investigate via experiments and still not well understood. This is particularly relevant for the consistency of biosignals from small-molecular-weight neutral organic molecules obtained during solar system robotic missions sampling atmospheres and plumes at hypervelocities. Experimental measurements to replicate HVI effects on neutral molecules are challenging, both in terms of accelerating uncharged species and isolating the multiple transition states over very rapid timescales (<1 ps). Nonequilibrium first-principles-based simulations extend the range of what is possible with experiments. We report on high-fidelity simulations of the fragmentation of small organic biosignature molecules over the range v = 1−12 km/s, and demonstrate that the fragmentation fraction is a sensitive function of velocity, impact angle, molecular structure, impact surface material, and the presence of surrounding ice shells. Furthermore, we generate interpretable fragmentation pathways and spectra for velocity values above the fragmentation thresholds and reveal how organic molecules encased in ice grains, as would likely be the case for those in “ocean worlds,” are preserved at even higher velocities than bare molecules. Our results place ideal spacecraft encounter velocities between 3 and 5 km/s for bare amino and fatty acids and within 4–6 km/s for the same species encased in ice grains and predict the onset of organic fragmentation in ice grains at >5 km/s, both consistent with recent experiments exploring HVI effects using impact-induced ionization and analysis via mass spectrometry and from the analysis of Enceladus organics in Cassini Data. From nanometer-sized ice Ih clusters, we establish that HVI energy is dissipated by ice casings through thermal resistance to the impact shock wave and that an upper fragmentation velocity limit exists at which ultimately any organic contents will be cleaved by the surrounding ice—this provides a fundamental path to characterize micrometer-sized ice grains. Altogether, these results provide quantifiable insights to bracket future instrument design and mission parameters.

Tree recruitment failure in old‐growth forest patches across human‐modified rainforests

Abstract Land‐use change threatens biodiversity in tropical landscapes, but its impact on rainforest regeneration remains poorly known. In fact, the landscape‐scale patterns driving the diversity of regenerating plants within forest fragments have been rarely explored, and we are uncertain whether such drivers vary across regions with different land‐use change patterns. We assessed the effect of landscape composition (forest cover and matrix openness) and configuration (forest patch density) on species diversity of sapling assemblages (trees ≥30 cm height and &lt;1 cm diameter) in old‐growth forest fragments from three Mexican rainforest regions with different disturbance levels (n = 20 landscapes per region). We separately assessed old‐growth forest specialists (OGS) and forest generalist (FG) species to test the hypotheses that: (a) OGS species show recruitment limitation (‘loser’ species), and can therefore be negatively impacted by landscape changes, especially by forest loss and matrix openness in more deforested regions; and (b) FG species can regenerate and even proliferate in more disturbed landscapes (‘winner’ species). We recorded ~24,000 plants from 415 species. Landscape composition showed stronger effects than landscape configuration. The diversity of OGS species generally decreased in more deforested landscapes dominated by open matrices, and FG species followed the opposite response, especially in the regions with high‐to‐intermediate degree of disturbance. Overall, forest fragmentation (patch density) showed weak or no effects on species diversity, especially after controlling for forest cover effects (i.e. fragmentation per se). In contrast to the fragmentation threshold hypothesis, the effect of fragmentation was independent of the regional context. Moreover, FG species were affected by landscape attributes operating at larger scales than OGS species. Synthesis. Our findings support our hypotheses, and suggest that forest loss and matrix openness, not fragmentation per se, can cause the recruitment failure of tree assemblages in highly deforested rainforests. This can be related to source and dispersal limitation in more deforested landscapes with treeless matrices. Therefore, to promote the regenerative potential (resilience) of forest patches in human‐modified tropical landscapes, conservation programs should focus on preventing forest loss (even the smallest forest patches) and improving matrix quality with treed elements, particularly in highly deforested tropical regions.

How dust fragmentation may be beneficial to planetary growth by pebble accretion

Context. Pebble accretion is an emerging paradigm for the fast growth of planetary cores. Pebble flux and pebble sizes are the key parameters used in the pebble accretion models. Aims. We aim to derive the pebble sizes and fluxes from state-of-the-art dust coagulation models and to understand their dependence on disk parameters and the fragmentation threshold velocity, and the impact of those on planetary growth by pebble accretion. Methods. We used a 1D dust evolution model including dust growth and fragmentation to calculate realistic pebble sizes and mass flux. We used this information to integrate the growth of planetary embryos placed at various locations in the protoplanetary disk. Results. Pebble flux strongly depends on disk properties including size and turbulence level, as well as the dust aggregates’ fragmentation threshold. We find that dust fragmentation may be beneficial to planetary growth in multiple ways. First of all, it prevents the solids from growing to very large sizes, at which point the efficiency of pebble accretion drops. What is more, small pebbles are depleted at a lower rate, providing a long-lasting pebble flux. As the full coagulation models are computationally expensive, we provide a simple method of estimating pebble sizes and flux in any protoplanetary disk model without substructure and with any fragmentation threshold velocity.

The radial structure of planetary bodies formed by the streaming instability

Comets and small planetesimals are believed to contain primordial building blocks in the form of millimeter to centimeter sized pebbles. One of the viable growing mechanisms to form these small bodies is through the streaming instability (SI) in which pebbles cluster and gravitationally collapse toward a planetesimal or comet in the presence of gas drag. However, most SI simulations are global and lack the resolution to follow the final collapse stage of a pebble cloud within its Hill radius. We aim to track the collapse of a gravitationally bound pebble cloud subject to mutual collisions and gas drag with the representative particle approach. We determine the radial pebble size distribution of the collapsed core and the impact of mutual pebble collisions on the pebble size distribution. We find that virial equilibrium is never reached during the cloud evolution and that, in general, pebbles with a given Stokes number (St) collapse toward an optically thick core in a sequence from aerodynamically largest (St ~ 0.1) to aerodynamically smallest (St ~ 2 × 10−3). We show that at the location where the core becomes optically thick, the terminal velocity vt,* ~ 60 m s−1St2 is well below the fragmentation threshold velocity. While collisional processing is negligible during cloud evolution, the collisions that do occur are sticking. These results support the observations that comets and small planetary bodies are composed of primordial pebbles in the millimeter to centimeter size range.

Performance analysis and evaluation of IEEE 802.11 distributed coordination function using OPNET

This paper discusses the distributed coordination function (DCF) access mechanism which is a carrier sense multiple access with collision avoidance (CSMA/CA) scheme. Simulation projects for different DCF performance parameters have been built using the OPNET network simulator. The projects are mainly basic service set (BSS) topology simulated under different parameter values (data rate, fragmentation, RTS/CTS, number of nodes, and load condition). Simulation results show when the DCF access mechanism is better under what load condition, and how to choose the best fragmentation threshold and other access-mechanism specific parameters according to the network conditions. Simulation results were validated against a theoretically calculated maximum throughput (the simulation maximum throughput was about 70% of the theoretically calculated maximum throughput).

Abrupt fragmentation thresholds of eight zonal forest types in mainland Spain

This study quantifies patchiness of eight types of zonal forests in three biogeographic regions of mainland Spain (Atlantic, Alpine and Mediterranean) which together occupy 1,726,578 ha. Their dominant species and European Habitat Type codes (EU Directive 92/43 EEC) are: Fagus sylvatica (9120, 9130 and 9150), Quercus robur and Q. pyrenaica (9230), Q. suber (9330), Pinus uncinata (9430), P. nigra ssp. salzmannii (9530) and P. pinea (subset of 9540). We applied the Korcak’s exponent B, which describes a hyperbolic relationship between the cumulative frequency of the number of patches and their sizes. The objectives were: 1) detect possible patch size intervals in which B varies significantly, explicitly identifying area thresholds, and 2) contribute to development of a robust forest mass fragmentation indicator. Exponent B was found by segmented regression analysis. The vector data were extracted from a filtered version of the Spanish Forest Map 1:50,000 (1997–2006). After validating the procedure by applying it to a previously published dataset, we found that in all cases the patch size range could be split into two significant intervals around relatively small threshold areas of 27–101 ha. In the one on the left, the rate at which relatively large patches become less abundant was always very slow (B = 0.017–0.094). After this threshold had been passed, the rate increased abruptly (B = 1.100–2.590). Both this high fragmentation and its lack of parsimony were unexpected in zonal forest types. General interpretations converge to the coexistence of forest patches of different ages due to human pressure events.

The observational impact of dust trapping in self-gravitating discs

ABSTRACT We present a 3D semi-analytical model of self-gravitating discs, and include a prescription for dust trapping in the disc spiral arms. Using Monte Carlo radiative transfer, we produce synthetic ALMA (Atacama Large Millimeter/submillimeter Array) observations of these discs. In doing so, we demonstrate that our model is capable of producing observational predictions, and able to model real image data of potentially self-gravitating discs. For a disc to generate spiral structure that would be observable with ALMA requires that the disc’s dust mass budget is dominated by millimetre- and centimetre-sized grains. Discs in which grains have grown to the grain fragmentation threshold may satisfy this criterion; thus, we predict that signatures of gravitational instability may be detectable in discs of lower mass than has previously been suggested. For example, we find that discs with disc-to-star mass ratios as low as 0.10 are capable of driving observable spiral arms. Substructure becomes challenging to detect in discs where no grain growth has occurred or in which grain growth has proceeded well beyond the grain fragmentation threshold. We demonstrate how we can use our model to retrieve information about dust trapping and grain growth through multiwavelength observations of discs, and using estimates of the opacity spectral index. Applying our disc model to the Elias 27, WaOph 6, and IM Lup systems, we find gravitational instability to be a plausible explanation for the observed substructure in all three discs, if sufficient grain growth has indeed occurred.

Are Habitat Fragmentation Effects Stronger in Marine Systems? A Review and Meta-analysis

The importance of habitat fragmentation in driving biodiversity loss has been recently debated. While the negative effects of habitat loss are well-documented, the effects of habitat fragmentation independent of habitat loss (e.g., habitat configuration) are more equivocal. Marine ecosystems have been underrepresented in past reviews, yet may differ fundamentally from terrestrial systems in their responses to habitat fragmentation because of the nature of energy/material flow, open population structure of most marine species, and narrow habitat extents. We conducted a systematic literature review and meta-analysis on the effects of habitat fragmentation in marine ecosystems. In our review of 180 studies from 28 articles, we found that habitat fragmentation effects were more often negative than positive, although the overall mean effect did not differ from zero. Interestingly, the mean effect was positive when the response was a measure of abundance, biodiversity, or population/ecosystem stability. Habitat fragmentation had overwhelmingly negative effects when it involved hydrological fragmentation. We found some support for the fragmentation threshold hypothesis via a weak negative relationship between habitat percent cover in the landscape and the habitat fragmentation effect. Results of this review on the effects of habitat fragmentation in marine ecosystems are largely consistent with another recent review finding that habitat fragmentation (independent of habitat loss) does not have consistent, negative impacts on biodiversity, and in many cases may increase biodiversity. Future work should focus on factors driving this variability and employ multi-scale frameworks to test for congruence between patch- and landscape-scale studies.

Electron impact ionization and fragmentation of biofuels

We present in this article, a review of our recent experimental and theoretical studies published in the literature on electron impact ionization and fragmentation of the primary alcohols methanol, ethanol, 1-propanol and 1-butanol (C1–C4). We discuss the mass spectra (MS) of these alcohols, measured for the electron impact energy of 70 eV and also, total (TICS) and partial (PICS) ionization cross sections in the energy range from 10 to 100 eV, which revealed the probability of forming different cations, by either direct or dissociative ionization. These experimental TICS are summarized together with theoretical values, calculated using the Binary-encounter Bethe (BEB) and the independent atom model with the screening corrected additivity rule (IAM-SCAR) methods. Additionally, we compared data of appearance energies – AE and discussed the application of the extended Wannier theory to PICS in order to produce the ionization and ionic fragmentation thresholds for the electron impact of these alcohols.