Individual Fragments Research Articles

Velocity characteristics of fracture fragments of mica-crystal materials under high-speed impact

Determination of the velocity of individual fragments of a fragmented matter following an impact is necessary for studying the dynamic mechanical properties of materials. Various models descriptive of specific collision cases are used to predict the fragmentation parameters including the velocity of fragments. The models have been mostly designed to describe metallic materials. The research aims at experimental determination of the fragments destruction velocity following an impact against hard-melting non-metallic silicate material (potassium fluorphlogopite). Potassium fluorphlogopite targets have been shaped as flat plates sized 280x160x15 mm. The 23 mm steel ball (Steel 20) was used as a projectile. Four impact tests have been conducted with the following parameters: ball velocity 230 m/s and collision angle 90°; ball velocity 120 m/s and collision angle 90°; ball velocity 230 m/s and collision angle 30°; ball velocity 120 m/s and collision angle 30°. Velocity of burst fragments was determined on the basis of a video recording with Photron Fastcam SA5 high-speed camera. The video has been processed using frame-by-frame image analysis in ImageJ-FiJi software (TrackMate module). The experiment determined the velocities of individual burst fragments following an impact against hard-melting non-metallic silicate material, specifically potassium fluorphlogopite. It has been established that the change in the velocity of fragments in time corresponds to the hyperbolic function; a coefficient has been proposed to calculate the change in the velocity of potassium fluorphlogopite fragments break-off in time.

Spectral and proton acceptor properties of chloramphenicol

The absorption spectra of chloramphenicol aqueous solution were obtained experimentally. The absorption spectra of chloramphenicol isomers and the effect on the spectra of the formation of H-bonded complexes were calculated and interpreted using quantum chemistry methods. Calculation results showed that the absorption spectrum of chloramphenicol by position of bands and their nature is largely determined by the nitrobenzene fragment with little participation of propanol and dichloroacetamide fragments of chloramphenicol. The proton acceptor properties of individual chloramphenicol fragments and the effect of the formation of H-bonded complexes on them have been analyzed. Keywords: chloramphenicol, enantiomers, electronic absorption spectrum.

ЦИФРОВАЯ ТРАНСФОРМАЦИЯ ОБРАЗОВАНИЯ КАК ИННОВАЦИЯ

The third decade of the XXI century is characterized by the emergence of the phenomenon of digital transformation of various spheres of human life, including education. Digital transformation is an innovation at the stage of creation, when individual elements and structural fragments of qualitatively new systems appear. As a result, the qualitative characteristics of digital transformation that describe the expected results can be predominantly found in regulatory documents and programs. The aim of this article is to study the digital transformation of education (DTE) as innovation in the field of education using systematic and synergetic approaches. As a global problem of mankind, DTE has been studied in the unity of ontological, epistemological and axiological approaches. The paper describes the current state of the DTE. Generic signs of innovation are defined with respect to DTE. The features of the DTE as a complex system,the functioning of which is subordinate to the system-synergetic principles, have been revealed. Comparison of the concepts of “digitization”, “digitalization”, “digital transformation” in the field of education is carried out. The stages of development of the DTE are presented. The development of the DTE is described in the context of the enactiveness of a complex system and correlation with the sustainable development of the world. The systemic-synergetic properties of the DTE have been determined. Further research is needed to explore humanistic, axiological and ethical aspects of DTE.

Experimental determination of fragment dynamics of refractory non-metallic silicate material under high-velocity impact

The individual velocity of rupture fragments after impact is necessary to evaluate how dangerous they are after dispersion. The aim of the study is to experimentally determine the velocity of rupture fragments upon impact on a refractory non-metallic silicate material (potassium fluorophlogopite). The targets made from potassium fluorophlogopite were shaped in the form of flat plates with a size of 280x160x15 mm. A steel ball with a diameter of 23 mm was used as a projectile. Four impact experiments were performed with the following parameters: ball speed of 230 m/s and collision angle of 90°; ball speed of 120 m/s and collision angle of 90°; ball speed of 230 m/s and collision angle of 30°; ball speed of 120 m/s and collision angle of 30°. The velocity of the rupture fragments was determined through video recording obtained using a high-speed Photron Fastcam SA5 camera. The video was processed by analyzing frame-by-frame images using the ImageJ-FiJi. The velocities of individual rupture fragments upon impact on a refractory non-metallic silicate material are experimentally determined using the example of potassium fluorophlogopite. It is established that the nature of the change in the fragment velocity relative to time corresponds to a hyperbolic function and depends on the kinetic energy of the fragments. A coefficient for calculating the change in the velocity of rupture fragments of potassium fluorophlogopite relative to time is proposed.

Tunneling current between structural elements of thin graphene/nanotube films

Based on the constructed atomistic models of graphene/nanotube films with different numbers of nanotubes in supercells, we carried out in silico studies of the regularities of the nonuniform density distribution, which determine the presence of an island structure in such films. As a result of quantum molecular dynamics modeling, it is found that thin tubes of subnanometer diameter are enveloped in graphene sheets, which makes them energetically stable and stable. We also studied tunneling contacts between individual film fragments that are not covalently bound, in particular, between graphene sheets with different topologies of contacting zigzag and armchair edges, depending on the distance between them, and between tubes of different chiralities, including (6,3), (4,4), (6,5), (12,6) and (16,0). It is found that the tunnel contacts of tubes with a semiconductor type of conductivity are characterized by the presence of voltage intervals with a negative differential resistance in the I-V characteristic. Such voltage intervals are not observed at all for tubes with a metallic character of conductivity. The new knowledge obtained is important for assessing the electrical conductivity of such films, two-thirds of which are semiconductor tubes. Keywords: graphene, nanotubes, tunnel contacts.

Спектральные и протоноакцепторные свойства хлорамфеникола

The absorption spectra of chloramphenicol aqueous solution were obtained experimentally. The absorption spectra of chloramphenicol isomers and the effect on the spectra of the formation of H-bonded complexes were calculated and interpreted using quantum chemistry methods. Calculation results showed that the absorption spectrum of chloramphenicol by position of bands and their nature is largely determined by the nitrobenzene fragment with little participation of propanol and dichloroacetamide fragments of chloramphenicol. The proton acceptor properties of individual chloramphenicol fragments and the effect of the formation of H-bonded complexes on them have been analyzed.

Study of optical and cooperative parameters of fibrous quartz heat shielding on experimental data on its reflection spectra

The paper presents the results of a study of a number of key optical characteristics of some highly porous thermal protection materials based on amorphous SiO2 fibers in the near and mid IR ranges. In the optical part of the statistical simulation model of such materials, based on the rigorous Mie theory, its application requires the introduction of cooperative corrections to the results of interaction with electromagnetic radiation of individual fragments. These corrections are introduced into the model in the form of an additional multiplier (Cs) of the scattering and absorption Mie efficiencies, which was usually used as a model tuning parameter when interpreting the experimental results of thermophysical studies. In this work, using the example of TZM-23M materials (Russia), made of a relatively thick (~9 μm) silica fiber PS-23 (Belarus), for the first time, data were obtained that make it possible to study the Cs parameter as a spectral quantity. The study is based on the results of experimental determination of the spectral hemispherical reflectivity of layers of material of two or more optical thicknesses in the wavelength range 0.83-16.65 μm. These data and Zege's asymptotic formulas were used to estimate the values of the absorption and scattering coefficients. The spectral parameter Cs is determined from the value of the scattering coefficient in the process of solving the inverse optical problem. The data obtained are compared with the results calculated on the basis of classical approximations of the optical constants. The results of this work can be useful for specialists in the field of radiation heat transfer and the interaction of electromagnetic radiation with complex partially transparent media with high spectral albedo scattering values. Keywords: Silica fibrous thermal protection, reflectivity, experiment, absorption and scattering spectrum, optical model, Mie theory, cooperative corrections.

ИССЛЕДОВАНИЕ МНОГОСЛОЙНЫХ РАЗНОКУЛЬТУРНЫХ КОМПЛЕКСОВ ВЕРХНЕГО ПРИЧУМЫШЬЯ: КУЮК-I

The Kuyuk terrain covers both sides of the Chumysh river valley. On the western side, this is the Biysk-Chumysh Upland, on the eastern side - the Salair Ridge. Several archaeological complexes are known here, timed to specific orographic structures. The present work describes the first object discovered in 1959 and named Kuyuk-I. This segment of the Kuyuk terrain is related to the mouth area of the Kornachak river, which flows into the Chumysh from the left. This river formed a cape 1.37 meter long, dropping from 54 to 9 meters above the floodplain surface. A group of burial sites of the Andronovskaya culture of the Bronze Age and the Odintsovskaya culture of the early Middle Ages have been discovered on the cape. Therefore, cultural layers of the Neolithic Kornachak culture, individual fragments of ceramics of the late Bronze Age and materials of the Bystryanskaya culture of the early Iron Age were recorded.

Improving the Quality of Friction Surface by Applying Antifriction Materials to Them

The article investigated the process of applying antifriction coatings to the surface of hardened cast iron gear wheels. The diffusion coating of cast iron wheels with vanadium greatly strengthened the surface and increased its wear resistance. Aluminium, tin bronze and copper were used as antifriction materials. The coating was applied with metal brushes. The brushes tore off individual fragments of anti-friction metal particles and smeared them over the surface of the coated product. Research results have confirmed the acceptability of this method instead of expensive finishing operations that cannot be applied to diffusion-hardened gears due to the shallow depth of the vanadium coating. The proposed method is universal for all types of metal products operating under sliding friction conditions. Results are presented as spatial histograms.

Исследование оптических и кооперативных параметров волокнистой кварцевой теплозащиты по экспериментальным данным о ее спектрах отражения

The paper presents the results of a study of a number of key optical characteristics of some highly porous thermal protection materials based on amorphous SiO2 fibers in the near and mid IR ranges. In the optical part of the statistical simulation model of such materials, based on the rigorous Mie theory, its application requires the introduction of cooperative corrections to the results of interaction with electromagnetic radiation of individual fragments. These corrections are introduced into the model in the form of an additional multiplier Cs of the scattering and absorption Mie efficiencies, which was usually used as a model tuning parameter when interpreting the experimental results of thermophysical studies. In this work, using the example of TZM-23M materials (Russia), made of a relatively thick (~ 9 μm) silica fiber PS-23 (Belarus), for the first time, data were obtained that make it possible to study the Cs parameter as a spectral quantity. The study is based on the results of experimental determination of the spectral hemispherical reflectivity of layers of material of two or more optical thicknesses in the wavelength range 0.83 - 16.65 μm. These data and Zege's asymptotic formulas were used to estimate the values of the absorption and scattering coefficients. The spectral parameter Cs is determined from the value of the scattering coefficient in the process of solving the inverse optical problem. The data obtained are compared with the results calculated on the basis of classical approximations of the optical constants. The results of this work can be useful for specialists in the field of radiation heat transfer and the interaction of electromagnetic radiation with complex partially transparent media with high spectral albedo scattering values.

Исследование языковой личности синхронного переводчика в ситуации перевода

The study of the phenomenon of linguistic personality (LP) is currently central in the modern field of linguistic science since the object of the research - a human being - is at the center of the linguistic paradigm. The study of LP of a conference interpreter is extremely challenging as it contributes to self-knowledge and self-improvement. Studying linguistic and communicative consciousness of a person in a moment of interpreting allows expanding the framework of the perception of the world, knowledge about the manifestations of linguistic and non-linguistic phenomena. The paper describes the concept of LP, sufficiently developed by Yu.N. Karaulov, which seems representative for the purposes of the above. The urgency of the research lies in the direct consideration of LP from the standpoint of anthropocentric linguistics, viewing the interpreter’s activities directly in the heat moment of the situation, taking into account nonliguistic «unnoticed background» of discursive representations and new meanings of the context. The result of the overview of the analysis was the creation of a LP map of interaction, as well as a linguistic description of linguistic units and structures in the form in which they are present in the consciousness of the LP subject. After analyzing two text-interviews of conference interpreters, we identified and described features of the representation of LP. The practical advantages of the presented research describe individual fragments of adequate and inadequate translation choice, specifics of interpreters’ speech behavior, and the translation techniques and approaches used. In general, the analysis showed consistently objective results reflecting the actual manifestations of the LP of a simultaneous interpreter.

THE TRADITION OF SPOILING VESSELS: ORIGINS ACCORDING TO THE ARCHEOLOGICAL DATA OF CISCAUCASIA

The article reviews the deformed metallic and ceramic vessels of the Maikop-Novosvobodnenskaya community. The study is mainly based on the author’s photographs and sketches, stored in the State Hermitage Museum. The artifacts themselves were published numerous times, but the deformation of vessels, in particular, has not yet been covered. The revealed defects allow us to conclude that some of the vessels of the Maikop Kurgan were damaged intentionally; prior to placing the vessels into the grave, some of them could have been repaired. Of particular interest is a bronze bucket found in the Maikop Kurgan: its hinges for mounting the arched handles were purposely broken, i.e. the bucket was placed in the grave in the “murdered” state. The article analyzes all known shapes of bronze vessels from the whole assemblage of the Maikop-Novosvobodnenskaya community and its periphery. It has been revealed that all of them have some forms of defects or traces of repair. In most cases they are not suitable for household use, which is the very feature of the tradition of placing them in graves. Damage or repair of metallic vessels or spoilage of pottery could have been considered as a possibility for using the damaged vessels by the kinsman in the “land of ancestors”, and an individual fragment of a vessel acquired magical properties. The origins of spoiling vessels and the use of individual shreds in funerary rites has its roots in funerary rites of the Proto-Yamnaya culture of the Pre-Maikop period of Ciscaucasia. Thus, we believe that this tradition was borrowed by the bearers of the Maikop culture from their predecessors. Subsequently, it was passed to the tribes of the Middle Bronze Age.

Miniaturized peptidomimetics and nano-vesiculation in endothelin types through probable nano-disk formation and structure property relationships of endothelins’ fragments

Abstract Endothelins (ETs), which are multi-functional-peptides with potential for antagonist-based-therapy in various physiological-malfunctionings, including cardiovascular, nephrological, oncologic, and diabetic conditions, may produce newer chemical entities and drug leads. The present study deals with molecular-modeling of the ETs’ sub-types, ET-I, II, and III to find the structure property-relationship (SPR) of the ETs, and individual fragments derived from the ET sub-type ET-I. The ETs peptidic tails’ amino acid (AA) sequence’s structural differences and similarities, various dissected fragments of the ET-I, and SPR comparison with the sarafotoxin-6b (SRT-6b), a structurally-related snake-venom, showed points of dissimilarities for their structural specifications, geometric disposition, and physico-chemical properties. The generation of miniaturized (shortened sequence) peptides towards offering peptidomimetic compounds of near- and far-values compared SPR with estimations for log P, hydration energy, and other molecular and quantitative structure activity relationship (QSAR) were based on random and ordered-fragments derived from the original ET-I AA’s sequence, and sequential distance changes in the original ET-I sequence’s chain of 1–21 AA. The feasibility of alternate and bond length parameters-based possible cysteine–cysteine cyclizations, sequence homology, AA’s positional demarcation, and presence/absence of cysteines, homology-based basic non-cysteine and cysteines-AA based cyclization, total structure and fragments end-to-end cyclizations, and geometrical analogy-based miniaturized sequence of the shorter AAs from the original ET-I sequence, together with mutated replacements with naturally constituent AAs of the ETs, and SRT-6 sequences were utilized. The major findings of the fragmented sequences, and sequences at par with the original ETs to provide structures similar to the size, volume and with molecular and electronic properties of electrostatic potential and total charge density distribution, crucial factors in receptor bindings were investigated. The SPRs, molecular properties, and QSAR values were estimated to compare and validate the findings with the known homologous compounds, ET-I, and its known and potent antagonists. The study resulted in leads of smaller and larger sizes of peptide-based compounds which may have prospects as potent antagonist and in future needs their bioactivity evaluations after the synthesis. Moreover, approach to plausible vesiculation of the ETs, and the involved processes and structural requirements, together with the molecular interactions in settling a nano-vesicle of the peptidic structure with a possible mechanism is also suggested.

Examining relational social ontologies of disaster resilience: lived experiences from India, Indonesia, Nepal, Chile and Andean territories

PurposeThe neoliberal resilience discourse and its critiques both contribute to its hegemony, obscuring alternative discourses in the context of risk and uncertainties. Drawing from the “ontology of potentiality”, the authors suggest reclaiming “resilience” through situated accounts of the connected and relational every day from the global south. To explore alternate possibilities, the authors draw attention to the social ontology of disaster resilience that foregrounds relationality, intersectionality and situated knowledge.Design/methodology/approachQuilting together the field work experiences in India, Indonesia, Nepal, Chile and Andean territories, the authors interrogate the social ontologies and politics of resilience in disaster studies in these contexts through six vignettes. Quilting, as a research methodology, weaves together various individual fragments involving their specific materialities, situated knowledge, layered temporalities, affects and memories. The authors’ six vignettes discuss the use, politicisation and resistance to resilience in the aftermath of disasters.FindingsWhile the pieces do not try to bring out a single “truth”, the authors argue that firstly, the vignettes provide non-Western conceptualisations of resilience, and attempts to provincialise externally imposed notions of resilience. Secondly, they draw attention to social ontology of resilience as the examples underscores the intersubjectivity of disaster experiences, the relational reaching out to communities and significant others.Originality/valueDrawing from in-depth research conducted in six disaster contexts by seven scholars from South Asia, South America and Northern Europe, the authors embrace pluralist situated knowledge, and cross-cultural/language co-authoring. Thus, the co-authored piece contributes to diversifying disaster studies scholarship methodologically.

Bayesian Processing of Data on Bursts of Pressure Vessels

Two alternative Bayesian approaches are proposed for the prediction of fragmentation of pressure vessels triggered off by accidental explosions (bursts) of these containment structures. It is shown how to carry out this prediction with post-mortem data on fragment numbers counted after past explosion accidents. Results of the prediction are estimates of probabilities of individual fragment numbers. These estimates are expressed by means of Bayesian prior or posterior distributions. It is demonstrated how to elicit the prior distributions from relatively scarce post-mortem data on vessel fragmentations. Specifically, it is suggested to develop priors with two Bayesian models known as compound Poisson-gamma and multinomial-Dirichlet probability distributions. The available data is used to specify non-informative prior for Poisson parameter that is subsequently transformed into priors of individual fragment number probabilities. Alternatively, the data is applied to a specification of Dirichlet concentration parameters. The latter priors directly express epistemic uncertainty in the fragment number probabilities. Example calculations presented in the study demonstrate that the suggested non-informative prior distributions are responsive to updates with scarce data on vessel explosions. It is shown that priors specified with Poisson-gamma and multinomial-Dirichlet models differ tangibly; however, this difference decreases with increasing amount of new data. For the sake of brevity and concreteness, the study was limited to fire induced vessel bursts known as boiling liquid expanding vapour explosions (BLEVEs).

Philosophical Value of the Confucian Treatise "Kong-Zi Jia Yu"

This article reveals the philosophical value of the Confucian treatise "Kong-zi jia yu," it examines issues of the theoretical importance for the history of world sinology. In the historicо-philosophical tradition, this text has long been attributed to the Confucian scientist Van Su (3rd century), however, not so long ago the situation changed significantly. In the modern scientific community, disputes around the authorship and time of writing this treatise continue. The content of "Kong-zi jia yu" is composed of stories from the life of Confucius, his conversations with his closest students, as well as prominent political figures of that time. These conversations are philosophical dialogues, they concern the most important ontological, ethical, aesthetic and epistemological issues, such as: harmonization of the Tianxia on the basis of virtuous management, the philosophical need for ritual practice, cosmological device of the Tianxia, issues traditional for early Confucianism of a pedagogical and educational nature, moral self-improvement. The diverse theme of "Kong-zi jia yu" is a valuable source that reveals the essence of the philosophy of early Confucianism. Individual fragments of "Kong-zi jia yu" coincide with the classic Confucian monuments "Shang shu," "Lun yu," "Xiao jing," etc. Although "Kong-zi jia yu" for a number of reasons, is not considered a classic text of Confucianism, but it carries an enduring philosophical value. The study of "Kong-zi jia yu" seems to the author of this work to be an urgent scientific task, the solution of which can expand the arsenal of world philosophical knowledge, as well as contribute to the dialogue of the philosophical cultures of the East and West.

FEATURES OF SPATIAL ORGANIZATION OF THE SYSTEM OF PEDESTRIAN ZONES IN THE HISTORICAL CENTER OF KYIV

Abstract. The article substantiates the need to complete the formation of an integrated network of pedestrian spaces in the historic center of Kiev. Now the historic center covers three hills - the Upper Town, Pechersk and Kiev-Pechersk Lavra. However, the problem of creating an integrated network of pedestrian connections in the historic center of Kyiv has not yet been solved, and its formation is one of the urgent tasks today. After all, the creation of a holistic system of pedestrian ways in the historic city makes it possible to increase its tourist potential and ensure the preservation and development of historical and cultural heritage. The author proposes a method of spatial analysis to assess the state of public spaces in the city. The author's comparative analysis of two cities in the UK confirmed the importance and cost-effectiveness of pedestrian public spaces.
 It is noted that the existing transport infrastructure of the city of Kyiv does not provide for the formation of new pedestrian zones. The author analyzes the central squares of Kyiv: Independence Square, Troitska, Tolstoy, European, Sofiyska, Mykhailivska, Lvivska and Peremohy Squares in terms of comfortable pedestrian movement and the availability of public places. It turned out that in terms of transport accessibility, they are convenient, but not suitable for pedestrians; by use - have mainly administrative, political functions; sometimes - cultural; by category of comfort - are inconvenient, there are no sanitary conditions, places for sitting, rest, greens; these are mainly transport interchanges; by category of social function - meeting places, commercial spaces; there are no signs of identity. Means of forming a network of pedestrian public spaces and proposals for the design of individual fragments of the city are proposed. The author determines how transit space and stationary spaces are used, whether it is possible to use them as a citywide public space and connect it to the main axis along Volodymyrska and Khreschatyk.

Across Edges: Art to Cartography; One Landscape to the Next

Abstract. Maps have the empowering effect of placing the “world at your fingertips,” compressing portions of it into a more “knowable” form. I find that some places have this map-like character even in real life—natural environments that are sliced by sharp, unexpected edges and contrasts into more accessible and digestible fragments. Over the years I have explored creating maps that heighten these places’ compressed quality but also preserve their immersive aspect.This search led me first to the field of landscape architecture, and then into two dimensions after I realized that creating these idealized places out in real world was mostly a fantasy. I began piecing together travel photographs into abstract photomontages, later reinterpreted in oil paints, that sharpen natural edges and contrasts to depict imaginary places. I then transitioned to watercolors, and toward depicting places not quite as imaginary, using the same fractured style to combine travel-inspired landscapes with bird’s-eye views.Finding the task of painting the individual fragments less engaging than the process of shaping them into compositions, I came to think of these works as maps in terms of both theory and process—in emphasizing the spatial relationships between scenes rather than the individual scenes themselves. My motivation for creating these maps has expanded beyond personal fulfilment to include conveying the fragility of the natural remnants and contrasts that captivate me.

Data pre-processing to increase the quality of optical text recognition systems

The subject of study in the article is the formulation of a modern concept of improving the quality of work of optical recognition systems by using a set of various algorithms for preprocessing document images at the user's discretion. The research synthesizes algorithms that compensate for external negative influences (unfavorable geometric factor, poor lighting conditions when photographing, the effect of noise, etc.). The methods used imply a certain sequence of data preprocessing stages: geometric transformation of the original images, their processing with a set of various filters, image equalization without increasing the noise level to increase the contrast of images, the binarization of images with adaptive conversion thresholds to eliminate the influence of uneven photo illumination. The following results were obtained. A package of algorithms for preliminary processing of photographs of documentation has been created, in which, to increase the functionality of data identification, a face detection algorithm is also built in, intended for their further recognition (face recognition). A number of service procedures are provided to ensure the convenience of data processing and their information protection. In particular, interactive procedures for text segmentation with the possibility of anonymizing its individual fragments are proposed. It helps provide the confidentiality of the processed documents. The structure of the listed algorithms is described and the stability of their operation under various conditions is investigated. Based on the results of the research, a text recognition software was developed using the Tesseract version 4.0 optical character recognition (OCR) program. The program "HQ Scanner" is written in Python using the OpenCV library. An original technique for evaluating the effectiveness of the algorithms using the criterion of the maximum probability of correct text recognition has been implemented in software. A large number of examples of system operation and software testing results are provided. Conclusions. The results of the research conducted are a basis for developing software for creating cost-effective and easy-to-use OCR systems for commercial use.

The role of protein acetylation in regulating mitochondrial fusion and fission.

The dynamic processes of mitochondrial fusion and fission determine the shape of mitochondria, which can range from individual fragments to a hyperfused network, and influence mitochondrial function. Changes in mitochondrial shape can occur rapidly, allowing mitochondria to adapt to specific cues and changing cellular demands. Here, we will review what is known about how key proteins required for mitochondrial fusion and fission are regulated by their acetylation status, with acetylation promoting fission and deacetylation enhancing fusion. In particular, we will examine the roles of NAD+ dependant sirtuin deacetylases, which mediate mitochondrial acetylation, and how this post-translational modification provides an exquisite regulatory mechanism to co-ordinate mitochondrial function with metabolic demands of the cell.