Homogeneous Process Research Articles

Homogeneous Catalysts of RedOx Processes Based on Heteropolyacid Solutions. VI: Developing a Process for Low-Temperature Oxidation of CO with Oxygen

Research on the development of a homogeneous process for low-temperature oxidation of carbon monoxide in the presence of a “platinum group metal + vanadium-containing heteropolyacid (HPA)” catalytic system has been presented. The optimal reaction conditions, ensuring the maximum rate of CO oxidation to CO2, have been determined; for this reaction the kinetic features have been established, and its mechanism has been proposed. It has been shown that homogeneous systems based on PdII complex exhibit high activity and productivity, but have low stability and operate only at pH below 1,5. The stability of the catalyst can be increased by simultaneous introduction of σ- and π-donor ligands into the system; however, it is more effective to use the PtIV complex in the presence of catalytic amounts of palladium salt at a ratio of 100/1. The transition from HPA solutions with a low content of vanadium atoms (H7PMo8V4O40) to solutions of modified compositions (H10P3Mo18V7O84) ensures an increase in the activity and productivity of the system, with the kinetics of CO oxidation being maintained. The combined homogeneous catalyst PtIV + PdII + H10P3Mo18V7O84 remains stable during multi-cycle use without reducing activity, operates without an induction period and can be used at pH range of 1,7–2,0, which simplifies the process equipment.

Graphite Made from Coal by High-Temperature Treatment: An Insight into the Nanometric Carbon Structural Evolution

Graphite made from coal will not only widen the graphite mineral resource, but also significantly improve the value of coal utilization. In this study, anthracite coal was heated in the temperature range of 500 to 2900 °C to study the size increase of nanometric graphite crystallites from anthracite to real graphite. The carbon content rapidly increases to 99.2% when heated from room temperature to 1600 °C, and then gradually increases to 100% when the treated temperature increases to 2900 °C. The FTIR results show that methyl, methylene, and aromatic hydrocarbon, preexisting in the raw anthracite, were preserved in the JZS-500 sample, but that when the treated temperature ≥ 1000 °C, these C-H bonds almost disappear. The basic structural units (nano graphitic carbon) grow into distorted columns, and the basic structural units and micro-columns re-oriented and coalesced to form local molecular oriented domains with the temperature increase from anthracite to JZS-1500. When the temperature ≥ 1600 °C, amorphous carbon, onion-like carbon, turbostratic layers, and graphitic carbon co-occur within the graphitized coals. At the sub-micron scale, carbonization is a homogenous process, whereas graphitization is a heterogenous process. The average graphite crystalline size (La, lateral extension; Lc, stacking height) rapidly increases as the treatment temperature increases from 1600 to 2300 °C. Three coal structural transformation stages were classified according to the nanometric carbon structural evolution with temperature. This study will contribute to the efficient and value-added utilization of coal to make graphite materials.

Long-read genome assembly of the insect model organism Tribolium castaneum reveals spread of satellite DNA in gene-rich regions by recurrent burst events.

Eukaryotic genomes are replete with satellite DNAs (satDNAs), large stretches of tandemly repeated sequences that are mostly underrepresented in genome assemblies. Here we combined nanopore long-read sequencing with a reference-guided assembly approach to generate an improved, high-quality genome assembly, TcasONT, of the model beetle Tribolium castaneum Enriched by 45 Mb in repetitive regions, the new assembly comprises almost the entire genome sequence. We use the enhanced assembly to conduct global and in-depth analyses of abundant euchromatic satDNAs. Unexpectedly, we show the extensive spread of satDNAs in gene-rich regions, including long arrays. The sequence similarity relationships between satDNA monomers and arrays indicate a recent exchange of satDNA arrays between different chromosomes. We propose a scenario of their genome dynamics characterized by repeated bursts of satDNAs spreading through euchromatin, followed by a process of elongation and homogenization of arrays. We find that suppressed recombination on the X Chromosome has no significant effect on the spread of satDNAs but the X rather tolerates the amplification of satDNAs into longer arrays. Analyses of arrays' neighboring regions show a tendency of one satDNA to be associated with transposable-like elements. Using 2D electrophoresis followed by Southern blotting, we prove Cast satDNAs' presence in the fraction of extrachromosomal circular DNA (eccDNA). We point to two mechanisms that enable this satDNA spread to occur: transposition by transposable elements and insertion mediated by eccDNA. The presence of such a large proportion of satDNA in gene-rich regions inevitably gives rise to speculation about their possible influence on gene expression.

Optimization of the Homogenization Process of Ginseng Superfine Powder to Improve Its Powder Characteristics and Bioavailability.

As consumer demands evolve for health supplements, traditional ginseng products are facing challenges in enhancing their powder characteristics and bioavailability. The objective of this study was to prepare a novel ginseng superfine powder using a high-pressure homogenization (HPH) process. Response surface methodology was employed to determine the effects of HPH parameters (pressure, number of passes, and concentration) on particle size and the dissolution of the saponin components of the superfine powders. The Box-Behnken design of experiments was applied to ascertain the optimal HPH parameters for the smallest particle size and the highest dissolution of the saponin components. For the powders obtained at different parameters, the characterization of tap density, bulk density, flowability, water-holding capacity, appearance, and taste were observed. The optimized experimental conditions for the HPH process were as follows: 15,000 psi (pressure), 3 (number of passes), and 1 kg/L (concentration). The optimized values were 55 μm (particle size) and 83 mg/g (dissolution of the saponin components), respectively. The method offered technical support for the application of the HPH process in the preparation of ginseng powders. The objects of this research could be broadened to include a diverse array of botanical materials, addressing contemporary demands for cost-effectiveness and sustainability within the industry.

Development of thermomorphic ionic liquids derived from organophosphorus acids for homogeneous extraction processes

Development of thermomorphic ionic liquids derived from organophosphorus acids for homogeneous extraction processes

Continental-scale sediment mixing and dispersal across northern Gondwana: detrital zircon U-Pb-O-Hf isotopic evidence from the Cambro-Ordovician sandstones overlying the Arabian Shield

ABSTRACT The juvenile Neoproterozoic basement of the Arabian Shield is overlain with angular unconformity by a voluminous Cambro-Ordovician cover sequence known as the Saq Formation and Wajid Group. Provenance studies of this vast siliciclastic cover over the Saudi Arabian part of the Arabian-Nubian Shield (ANS) have to date been based solely on U-Pb zircon data and heavy minerals. We present the first combined in-situ U-Pb, δ18O and Lu-Hf isotopic data for detrital zircon from the Saq and Wajid units exposed along the northeastern margin and southern part of the Arabian Shield. U-Pb age spectra reveal prominent age peaks at ca. 0.8–0.55 Ga and 1.1–0.9 Ga with subordinate peaks at ca. 2.2–1.7 Ga and 2.7–2.5 Ga. The δ18O secular variation mirrors global compilations with Archaean zircon defining a restricted δ18O range of ca. 4.0–8.0 ‰ and younger zircon showing wide variation in δ18O up to ca. 14 ‰. The ca. 0.8–0.55 Ga age peak has the largest variation in εHf(t) with about half of all these Neoproterozoic zircon grains being juvenile (εHf(t) > 5), which are interpreted to be sourced from the juvenile terranes of the ANS. Neoproterozoic zircon with evolved εHf(t) signatures require a more distal source beyond the ANS. As extensive ca. 1.1–0.9 Ga crust is lacking in the vicinity of the ANS, the ca. 1.1–0.9 Ga age peak is interpreted to be derived from either contemporaneous orogenic belts in Central Africa or recycled from older sedimentary rocks containing these age components. Extreme variations in δ18O of post – Archaean zircon, together with the evolved εHf(t), indicate crustal thickening and increased incorporation of supracrustal material associated with collisional orogenesis. The remarkable similarities in age spectra and isotopic compositions of the Saq Formation and Wajid Group sandstones with those from other regions in northern Gondwana indicate a continental–scale homogenization and dispersion process.

Ultra-high-pressure homogenization in chicory root juice production

The demand for freshly squeezed natural fruit juices has increased in recent years, however their shelf life is quite short. Thermal processes applied to extend the shelf life of such products and increase their storage stability cause significant losses in color and other sensory properties, depending on the temperature applied. Therefore, the preference for high-pressure homogenization as an alternative to thermal processes is on the rise. We aimed to determine effects of ultra-high-pressure homogenization and production stages on some quality properties of chicory root juice. Ultra-high-pressure homogenization was applied at the pressure levels of 0 (Control), 50, 100, 150, and 200 MPA. The samples also included juice after homogenization with an ULTRA-TURRAX disperser and after a water bath. Ultra-high-pressure homogenization affected such quality characteristics of chicory root juice as total soluble solids (p < 0.01), pH (p < 0.01), L* (p < 0.01), a* (p < 0.01), b* (p < 0.01), a*/b* (p < 0.01), chroma (p < 0.01), hue angle (p < 0.01), and total color difference ΔE (p < 0.01). Higher levels of ultra-high-pressure homogenization pressure increased pH (p < 0.05), a* values (p < 0.05), and the a/b* ratio (p < 0.05) but reduced L* (p < 0.05), b* (p < 0.05), chroma (p < 0.05), and hue angle (p < 0.05) values of the juice samples. Thus, the use of ultra-high-pressure homogenization (100 and 200 MPa) contributed to improving the total soluble solids and redness values of chicory root juice. Our study showed that the ultra-high-pressure homogenization process improved the quality of chicory root juice.

Assessment of homogeneous electro-Fenton process coupled with microbial fuel cell utilizing Serratia sp. AC-11 for glyphosate degradation in aqueous phase

Glyphosate (GLY), a globally-used organophosphate herbicide, is frequently detected in various environmental matrices, including water, prompting significant attention due to its persistence and potential ecological impacts. In light of this environmental concern, innovative remediation strategies are warranted. This study utilized Serratia sp. AC-11 isolated from a tropical peatland as a biocatalyst in a microbial fuel cell (MFC) coupled with a homogeneous electron-Fenton (EF) process to degrade glyphosate in aqueous medium. After coupling the processes with a resistance of 100 Ω, an output voltage value of 0.64 V was obtained and maintained stable throughout the experiment. A bacterial biofilm of Serratia sp. AC-11 was formed on the carbon felt electrode, confirmed by attenuated total reflectance-Fourier transformed infrared (ATR-FTIR) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). In the anodic chamber, the GLY biodegradation rate was 100% after 48 h of experimentation, with aminomethylphosphonic acid (AMPA) remaining in the solution. In the cathodic chamber, the GLY degradation rate for the EF process was 69.5% after 48 h experimentation, with almost all of the AMPA degraded by the in situ generated hydroxyl radicals. In conclusion, the results demonstrated that Serratia sp. AC-11 not only catalyzed the biodegradation of glyphosate but also facilitated the generation of electrons for subsequent transfer to initiate the EF reaction to degrade glyphosate. This dual functionality emphasizes the unique capabilities of Serratia sp. AC-11, it as an electrogenic microorganism with application in innovative bioelectrochemical processes, and highlighting its role in sustainable strategies for environmental remediation.

Scalable Synthesis of Organic Core/Shell Architectures toward Dual-Wavelength Optical Waveguides.

Organic core/shell heterostructures have undergone rapid progress in materials chemistry owing to the integration of a wide array of unique properties. Nonetheless, the intricate challenge of regulating homogeneous nucleation and phase separation processes in excessively analogous cocrystal structures presents a formidable barrier to expanding the synthesis strategy for organic core/shell heterostructures. Herein, we successfully achieved a phase separation growth process facilitated by the organic alloy interface layer through a dynamic visualization to capture the intricate morphological evolution. By finely regulating the nucleation process, homogeneous self-assembly induced by high chemical and structural compatibility is circumvented, enabling the formation of organic core/shell heterostructures. Notably, this core/shell architecture boasts dual-wavelength emission at 496 and 696 nm, accompanied by an optical loss coefficient of 0.092 dB per micrometer. This methodology shows potential for extending to the scalable design of other conformational cocrystal heterostructure systems, thereby offering valuable insights into the realm of organic photonics.

Influence of chemical forms and homogenization process on the stability of vitamin A in infant follow-on formulas

Vitamin A is an essential micronutrient for infant development, and its stability is crucial to ensure adequate intake. This study aimed to investigate the vitamin A stability in infant follow-on formulas (IFF) depending on its chemical forms and on the homogenization process. For this propose, model IFF representative of commercialized formulas were formulated with varying vitamin A forms (retinol, retinyl esters or carotenoids) and homogenization process applied. Losses of vitamin A were assessed either before or after the homogenization process, or after a storage of 20 days at 40 °C. The homogenization process led to a vitamin A loss up to 14.3% at high pressure (350/40 bars, 8 passes) explained by important shearing forces leading to local heating of molecules. The presence of carotenoids and especially β-carotene led to a stabilization effect with a loss of only 40.7% of vitamin A during storage compared to 84.9% without carotenoids. Carotenoids provide a better resistance to lipid oxidation due to their synergetic effect with vitamin E. This study highlights that a good knowledge of vitamin A reactivity during processing and selection of chemical form with potential synergy with other compounds can improve its stability in IFF.

SWEET-Cat: A view on the planetary mass-radius relation

SWEET-Cat (Stars With ExoplanETs Catalog) was originally introduced in 2013, and since then, the number of confirmed exoplanets has increased significantly. A crucial step for a comprehensive understanding of these new worlds is the precise and homogeneous characterization of their host stars. We used a large number of high-resolution spectra to continue the addition of new stellar parameters for planet-hosting stars in SWEET-Cat following the new detection of exoplanets listed both in the Extrasolar Planets Encyclopedia and in the NASA exoplanet archive. We obtained high-resolution spectra for a significant number of these planet-hosting stars, either observed by our team or collected through public archives. For FGK stars, the spectroscopic stellar parameters were derived for the spectra following the same homogeneous process using ARES+MOOG as for the previous SWEET-Cat releases. The stellar properties were combined with the planet properties to study possible correlations that could shed more light on the star-planet connection studies. We have increased the number of stars with homogeneous parameters by 232 (sim 25<!PCT!> -- from 959 to 1191). We focus on the exoplanets that have had both mass and radius determined to review the mass-radius relation, and we find results consistent with the ones previously reported in the literature. For the massive planets, we also revisit the radius anomaly, confirming a metallicity correlation for the radius anomaly already hinted at in previous results.

Stochastic stability of random stacking of blocks

The paper explores the stability of a tower obtained by stacking identical rectangular blocks on top of each other with an inherent randomness due to slight positional offsets between successive blocks. With probabilistic modeling techniques, the diffusive behavior of the stacking process is studied and the collapse is seen as a first passage time problem. In the considered model, alignment errors are idealized as independent Gaussian random variables with zero mean and given standard deviation. We derive expressions for the joint probability density functions of block positions, and analyze their correlation. The study extends to the stochastic stability of a stack of given height, by exploring the statistical characteristics of the center of gravity of the part of tower above each block. Eventually, the probabilistic analysis of collapse is developed to quantify the statistics of the number of blocks that can be heaped up before the tower topples. Although this problem may initially appear playful, it offers an illustrated introduction to first passage problems on a non homogenous process. From a practical standpoint, this analysis offers a simple understanding of the influence of alignment errors on the overall stability of a stack, which may find several fields of application.

Interactions, structures, and functions of pomegranate peel reinforced starch film

This work aimed to exploit the effects of pomegranate peel (PP) addition (10 %) and homogenization process (0–12,000 rpm) on the film-forming behavior and interactions of starch film to improve its microstructures and properties. Microrheology results showed that the viscosity of the film suspension was reduced by homogenization, and the amylopectin aggregation was restricted by PP particles under film formation. This helped improve the accessibility of starch and PP, increasing the hydrogen bond energy in the composites from 18.12 to 19.35 kJ/mol and promoting the ester bonds as confirmed by the FTIR results. As a result, the starch film reinforced by PP and homogenization showed a uniform and compact microstructure with reduced water activity, increased UV-blocking capacity (from 67.46 % to 90.11 %), enhanced mechanical resistance, and reduced water vapor permeability (from 4.70 to 2.21 × 10−10·g·m−1·s−1·Pa−1). Additionally, the starch film with 10 % PP also presented superior antimicrobial properties and antioxidant activity with rates of over 86 %, providing an effective strawberry preservation function.

Mechanism of homogenization temperature and time on Fe-containing phase transition in AA8014 aluminum alloy

The presence of coarse Fe-containing phases detrimentally affects the fracture toughness of 8xxx aluminum alloys, and their complete dissolution during homogenization is unattainable. Therefore, it is essential to determine the optimal homogenization temperature and time to facilitate particle breakup during hot rolling, necessitating the development of effective homogenization processes. This study systematically examines the effect of homogenization temperature and time on the transition of Fe-containing phases in AA8014 aluminum alloy using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The transition mechanisms of Fe-containing phases during homogenization were elucidated through first-principles calculations, thermodynamics, and kinetics calculations. Under homogenization conditions of 610–650 ℃/12 h and 630 ℃/1–20 h, the Al6(Fe,Mn) phase initially transforms into the α-Al12(Fe,Mn)3Si phase with a “micropore structure” via the reaction. Subsequently, the α-Al12(Fe,Mn)3Si phase transforms into the Al3(Fe,Mn) phase. First-principles calculations confirm the sequential stability enhancement of the Al6(Fe,Mn), α-Al12(Fe,Mn)3Si+6Al, and Al3(Fe,Mn) phases. Homogenization kinetics indicate an optimal homogenization time of 11.5 h at 630 ℃, rationalizing the observed phase transitions and homogenization treatment. This study provides a foundation for the manufacture of 8xxx series aluminum alloys.

Optimization of lung tissue pre-treatment by bead homogenization for subsequent culturomics

The discovery that the lung harbors a diverse microbiome, as revealed by next-generation sequencing, has significantly altered our understanding of respiratory health and disease. Despite the association between the lung microbiota and disease, the nature of their relationship remains poorly understood, and culture isolation of these microorganisms could help to determine their role in lung physiology. Current procedures for processing samples from the lower respiratory tract have been shown to affect the viability of microorganisms, so it is crucial to develop new methods to improve their survival. This study aimed to improve the isolation and characterization of lung microorganisms using a bead-beating homogenization method in a mouse model. Microsphere diameter and bead-beating time affected the survival of the microorganisms (E. coli, S. aureus and C. albicans). Using 2.3 mm diameter microspheres for 60 s of bead-beating promoted the survival of both bacteria and yeast strains. After intratracheal instillation of these microorganisms in mice, approximately 70% of the cells were recovered after the tissue homogenization. To assess the efficiency of the proposed method, the diversity of bacteria was compared between the homogenate and lung tissue samples. Ninety-one genera were detected in the lung tissue, and 63 in the homogenate. Bacterial genera detected in the homogenate represented 84% of the total abundance of the microbiota identified in the lung tissue. Taken together, these results demonstrate that the tissue homogenization process developed in this study recovered the majority of the microorganisms present in the lung. This study presents a bead-beating homogenization method for effective cultivation of lung tissue microorganisms, which may help to improve the understanding of host–microbe interactions in the lung.

Crystalline phase control of ferroelectric HfO2 thin film via heterogeneous co-doping

Our study investigates heterogeneous co-doped HfO2 thin films integrated into metal-ferroelectric-metal stacks, achieved by incorporating multiple layers doped with various species during the atomic layer deposition process. This approach creates an artificial crystallization temperature gradient across the HfO2 film, influencing the preferred nucleation sites of HfO2 during rapid thermal processing. Our findings demonstrate that the phase composition of the annealed HfO2 film is primarily determined by heterogeneous or homogeneous crystallization processes. In cases of heterogeneous crystallization, where crystallization initiates from nuclei formed at electrode/HfO2 interfaces, grains predominantly crystallize in the orthorhombic phase. Conversely, grains are more likely to crystallize in the monoclinic phase if they originate from nuclei formed at the center of the HfO2 film. Additionally, we observe correlations between the texture of the HfO2 film and the texture of the electrodes.

Timescale dependent homogeneous assembly of lipid-polymer hybrid nanoparticles in laminar mixing for enhanced lung cancer treatment

The homogeneity of core–shell structure lipid-polymer hybrid nanoparticles (HNPs) is crucial for efficient intracellular cargo delivery. While microfluidic techniques have been recognized for their capabilities in precisely controlling the size and drug encapsulation efficiency, there is little research exploring the impact of mass transfer behavior within microchannels on the homogeneous assembly process of HNPs. Here, we manipulated the laminar flow state within TrM device to achieve controlled assembly of HNPs and explored a timescale dependent assembly technique to ensure the homogeneity of folate modified HNPs (FHNPs). Our founding indicate that this method enabled the control over the growth kinetics of PLGA cores within a timescale (τgrow) of 1–15 ms. The homogeneous ligand assembly on the surface of FHNPs can only be achieved when τgrow exceeds the timescale of functional lipid coating (τcoating). Compared to conventional bulk mixing methods, this strategy significantly reduces the risk of heterogeneous assembly in FHNPs fabrication and ensures consistent reproducibility across batches. The homogeneous FHNPs (HFHNPs) fabricated through this method exhibit precise control over particle size (ranging from 75 nm to 150 nm), low polydispersity index, and consistent core–shell structure. Furthermore, this strategy enhances the density of available folate ligands on the surface of FHNPs. In subsequent in vitro and in vivo anti-tumor assays, the icariside Ⅱ (IS) loaded HFHNPs (IS@HFHNPs) exhibited enhanced cellular uptake and tumor accumulation behavior. the timescale dependent homogeneous assembly method for HNPs developed in this research presents a promising avenue for maintaining quality in the synthesis of self-assembly composite nanomecidine.

Long-lasting organics removal via •OH adsorbed transition metal flocs: Electron transfer-mediated H-bond and van der Waals force

Homogenous advanced oxidation processes (AOPs) based on transition metal catalysts toward the activation of H2O2 to hydroxyl radical (•OH) have been widely applied to organic pollutants removal, such as Fenton and Fenton-like processes. These transition metal catalysts mostly flocculate as the pH increases. It's worth noting that the formed transition metal flocs are complex heterogeneous aggregations with active substances, providing diverse reaction spaces and interfaces. However, it is a challenge to distinguish the roles of transition metal flocs in the organic pollutants removal from homogeneous catalytic reactions. Herein, we unveiled a pathway for the long-lasting removal of organic pollutants via Cr flocs adsorbed with •OH (HO•-Cr flocs) using a stepwise method. First, adsorbed •OH (•OHads) within the HO•-Cr flocs was proved to be the active site forming hydrogen bond (H-bond) and van der Waals force with organic pollutants. Then, the presence of switchable electron transfer between Cr and OH groups within the HO•-Cr flocs was revealed, contributing to the persistent existence of •OHads and consequently ensuring the long-lasting organics removal. Further, this removal pathway of organic pollutants was confirmed during the leather wastewater treatment. These findings will complement a different pathway for organic pollutants removal via transition metal flocs and extend the lifetime of homogeneous AOPs based on transition metal catalysts, providing significant implications for their design and optimization.

Molecular insight into the dual effect of salts: Promoting or inhibiting the nucleation and growth of carbon dioxide clathrate hydrates

Facing the huge gap between the growing CO2 emissions and net-zero emissions target to mitigate global warming, the long-term storage of excess CO2 becomes an intractable issue. Sequestering CO2 in the oceans as clathrate hydrates is a promising solution. Many unanswered questions still exist at the molecular level regarding how ions in seawater kinetically affect the formation of CO2 hydrates, particularly the dual effect: as the concentration rises, salt ions shift from being a promoter of hydrate formation to becoming an inhibitor. Herein, we report the homogeneous nucleation process of CO2 hydrates in saline solutions via molecular dynamics simulations. Consistent with experimental findings, our results show that nucleation is promoted within certain salt concentration ranges; however, the evidence suggests that ions do not act as nucleation sites. Multiple ion-induced variations in the aqueous phase are analyzed, including changes in the mobility, structure, and CO2 solubility. We find that the presence of ions strengthens the hydrophobic interactions among the dissolved CO2 molecules, which are associated with the salting-out phenomenon, accounting for the promoting effect of salts at low concentrations. However, as the salt concentration increases, this advantage is offset, leading to the inhibiting effect at high salt concentrations. We demonstrate that anions are inevitably involved in the construction of the solid hydrate phase. Their presence disrupts the native tetrahedral connectivity of water molecules and imparts negative charges to the solid phase, thereby attracting cations. In addition to advancing our understanding of the intricate interactions among water, guest, and additive molecules to germinate ordered solid structures, these findings can accelerate the development and utilization of sustainable hydrate-based applications.

Influence of inhomogeneities in chemical composition and porosity of sintered steel on development of martensitic transformation

The article is devoted to the study of martensitic transformation in porous sintered steels. When analyzing the process of development of marten­sitic transformation in porous sintered steel, the influence of two factors was assessed: depletion of carbon in the near-surface layers of pores and a change in the energy balance due to relaxation of transformation stresses on free surfaces of the pores. The martensitic transformation was studied in porous steel with a carbon content of 1.56 wt. % obtained after pressing and sintering of a mixture of PZhRV iron powders and GK-3 graphite in hydrogen atmosphere at 1200 °C. Gas carburizing at 1100 °C and homogenization helped to achieve the specified carbon content. The samples were quenched in a sodium chloride solution at a temperature of 27 °C. Pre-cooling was used from temperatures Ast to 800 °C at a rate of 62 °C/s. X-ray microanaly­sis of carbon distribution was carried out using the installation CAMECA Microsonde M.S. 46 with a probe diameter of two microns. The martensite plates predominantly formed on the pores’ surfaces and their cross section had shape close to rhomboidal. The data obtained on the morphology of α′-phase crystals growing from pores and the study by X-ray spectral microanalysis of carbon distribution along the largest martensite plates convince us of the absence of any significant changes in carbon content and, as a consequence, their influence on development of martensitic transformation in the area of pores is not the leader. For sintered porous steels, an irremovable factor in the increase in temperature is the presence of porosity, in contrast to a removable factor – inhomogeneity of the chemical composition, which is caused by incompleteness of the alloy homogenization processes, both during sintering and during the austenitization process that precedes quenching.