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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Modification of Inclusions in Molten Steel by Mg-Ca Transfer from Top Slag: Experimental Confirmation of the ‘Refractory-Slag-Metal-Inclusion (ReSMI)’ Multiphase Reaction Model

High-temperature experiments and Refractory-Slag-Metal-Inclusion (ReSMI) multiphase reaction simulations were carried out to determine the effect of the ladle slag composition on the formation behavior of non-metallic inclusions in molten steel. Immediately after the slag-metal reaction, magnesium migrated to the molten steel and a MgAl{sub 2}O{sub 4} spinel inclusion was formed due to a reaction between magnesium and alumina inclusions. However, the spinel inclusion changed entirely into a liquid oxide inclusion via the transfer of calcium from slag to metal in the final stage of the reaction. Calcium transfer from slag to metal was more enhanced for lower SiO{sub 2} content in the slag. Consequently, the spinel inclusion was modified to form a liquid CaO-Al{sub 2}O{sub 3}-MgO-SiO{sub 2} inclusion, which is harmless under steelmaking conditions. The modification reaction was more efficient as the SiO{sub 2} content in the slag decreases.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Surface Modification of 304 Stainless Steel by Electro-Spark Deposition

Electro-spark deposition (ESD) is a pulsed microwelding process that is used to apply surface coatings for the repair of damaged high value and precision products or modify their surfaces for specific properties. The low heat input, minimal heat-affected zone and the ability to form metallurgical bonding of coating to substrate are major advantages of the ESD process. Many applications require the components to have excellent surface performance, such as wear and corrosion resistance. ESD technique provides an approach to modify the component surface without compromising the bulk properties. In this study, surface modifications of 304 stainless steel by ESD were investigated. Titanium carbide (TiC), tungsten carbide (WC) and molybdenum (Mo) were employed as coating materials. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) analysis were conducted to characterize the microstructure and composition of the coatings. The coatings thicknesses were all around 40 µm. The results showed that TiC and WC coatings showed a dramatic increase in the microhardness, up to 5 times. WC coating improved the wear resistance by more than 5 times, while TiC and Mo coatings also improved it by approximately 2.5 times. Electro-chemical tests were conducted to investigate the corrosion resistance of the coatings. Mo coating exhibited a significant improvement in the corrosion resistance in 5% NaCl solutions, corroding 350 times slower than stainless steel. Synchrotron x-ray diffraction was performed to investigate the microstructure changes of the Mo-coated sample. Heat treatment was also carried out to investigate the corrosion behavior of Mo-coated 304 stainless steel at elevated service temperature in air or argon.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Surface Modification of High-Carbon Steel Using Fiber Laser and Its Thermal, Microstructural and Tribological Analysis

In this study, surface modification of high-carbon steel was carried out using 2 kW fiber laser and thermal, microstructural and tribological characterizations were performed. The process parameters selected for laser surface treatment were laser power (600-1500 W) and scan speed (3000-4500 mm/min). Infrared pyrometer was used to record the surface temperature during the process. The metallographic analysis was carried out using an optical microscope to find the depth and width of the laser-treated zone. Scanning electron microscopy and energy-dispersive spectroscopy were performed to reveal the microstructure and compositional changes taking place in the laser-treated zone. It was observed that the dendritic growth took place from the top surface toward the center of the laser-treated zone. The amount of dendritic growth can be related to the maximum surface temperature generated during the process. XRD analysis indicated the formation of some intermetallic compounds and phase shifts taking place in the laser-treated zone. Residual stress analysis was performed to analyze the amount of stress accumulation in the laser-treated zone. When the temperature cycle was analyzed, it was found that the melting of the steel resulted in the formation of a surface under compressive stress while the non-melt hardened zone developed a surface under tensile stress. The maximum Vickers microhardness value achieved was about 958.8 HV{sub 0.5} for 1500 W power and 3000 mm/min scan speed. Scratch test was performed on the laser-treated track, and it was found that the hardened zone showed better tribological properties with respect to the parent material. Finally, it was observed that the surface roughness value increased with higher heat input probably due to high rate of oxide formation as well as due to the presence of martensite in the laser-treated zone.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effect of Ti Modification on Microstructures and Properties of Carbidic Austempered Ductile Iron

In this paper, we investigated the effect of titanium modification on microstructures and properties of carbidic austempered ductile iron (CADI) containing 3.72 wt.% C, 2.77 wt.% Si, and 0.51 wt.% Mn. The results showed that with the addition of 0.1 wt.% Ti, TiC particles were formed, and distributed in carbides and matrix. Microstructural observation indicated that the maximum diameter of graphite nodules decreased from 58 to 40 μm, and the shape of carbides transformed from network to fragmentation, which was related to the nucleation of the eutectic structure (γ + (Fe, Cr){sub 3}C) where TiC particles act as the nucleus. After isothermal quenching at 300 °C, the hardness of Ti-bearing CADI was 3.5 HRC higher than ordinary CADI, and the impact toughness was increased by 14.3%. Additionally, due to the decrease in exfoliation, the wear loss of Ti-bearing CADI was 14.8% lower than ordinary CADI during the block-on-ring wear test at the surface load of 300 N.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Structure and Properties of Epoxy/Fly Ash System: Influence of Filler Content and Surface Modification

Epoxy resin composites filled with pristine and organomodified fly ash were prepared and examined. The fly ash used is CaO-rich due to the origin of lignite from the northern Greece area and the power plants in Kozani. As matrix, the epoxy system with curing agent triethylenetetramine was used. A combination of mechanical stirring and ultrasonication was used for highly dispersed fly ash composites. SEM, FTIR spectroscopy and XRD measurements were used to study dispersion homogeneity, structure, degree of aggregation/agglomeration and interface formation of the matrix with the fly ash particles. The properties E′, E″ and relaxations α-(T{sub g}) and β-(Τ{sub β}) of the composites were assessed by DMA. Also, DSC and TGA measurements were used to characterize the thermal properties. Interesting results concerning the effect of the surface organomodification of fly ash on the network formation and the thermomechanical properties of the composites were derived. XRD and FTIR measurements reveal that the functional groups present on the surface of fly ash particles play a dominated role to interface formation. DMA results show that the fly ash surface modification affects the thermodynamic properties of the composites. Additionally, there is evidence showing that the short-scale β-relaxation is also affected by the fly ash surface organomodification.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Nuclear lactate dehydrogenase modulates histone modification in human hepatocytes

Highlights: • Nuclear LDH is up-regulated under oxidative stress. • SIRT1 is co-immunoprecipitated bound to nuclear LDH. • Nuclear LDH is involved in histone deacetylation and epigenetics. - Abstract: It is becoming increasingly apparent that the nucleus harbors metabolic enzymes that affect genetic transforming events. Here, we describe a nuclear isoform of lactate dehydrogenase (nLDH) and its ability to orchestrate histone deacetylation by controlling the availability of nicotinamide adenine dinucleotide (NAD{sup +}), a key ingredient of the sirtuin-1 (SIRT1) deacetylase system. There was an increase in the expression of nLDH concomitant with the presence of hydrogen peroxide (H{sub 2}O{sub 2}) in the culture medium. Under oxidative stress, the NAD{sup +} generated by nLDH resulted in the enhanced deacetylation of histones compared to the control hepatocytes despite no discernable change in the levels of SIRT1. There appeared to be an intimate association between nLDH and SIRT1 as these two enzymes co-immunoprecipitated. The ability of nLDH to regulate epigenetic modifications by manipulating NAD{sup +} reveals an intricate link between metabolism and the processing of genetic information.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

Double in-situ lignin modification in surfactant-assisted glycerol organosolv pretreatment of sugarcane bagasse towards efficient enzymatic hydrolysis

Organosolv pretreatment effectively fractionates lignocellulosic biomass for efficient enzymatic hydrolysis, yielding fermentable sugars. However, substantial lignin redeposition on the substrate surface and residual lignin content exacerbate lignin’s inhibitory effects on subsequent enzymatic hydrolysis. Here, an in-situ lignin modification is proposed to address this challenge by incorporating polyethylene glycol (PEG) series into glycerol organosolv (GO) pretreatment. According to the results obtained, PEG-assisted GO pretreated substrate exhibited significantly increased sugar yield during enzymatic hydrolysis, particularly with PEG 4000, showing 35.4% higher glucose yield over 72 h. The improved glucose yield with PEG could be attributed to changes in the physicochemical structure and properties of residual lignin, mitigating its non-productive interaction with cellulase enzymes. PEG's presence in GO pretreatment also increased β-O-4 linkages preservation by 55% and reduced phenolic hydroxyl groups by 28% in lignin fragments versus no surfactants. This outcome resulted from introducing glycerol and PEG hydroxyl tails into the lignin structure, forming α-etherified lignin and rendering it more hydrophilic. Simulations confirmed strong Van Der Waals and hydrogen bonding interactions between lignin units and PEG, hindering lignin fragments repolymerization. Incorporating PEG in the organosolv pretreatment proves highly beneficial for cellulase-mediated lignocellulosic biorefinery, resembling a lignin-first strategy. The optimized process enables efficient biomass utilization for sustainable fuels and chemicals production.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Reduction of water content in calcium aluminate cement with/out phosphate modification for alternative cementation technique

Cementation of the secondary aqueous wastes from TEPCO Fukushima Daiichi Nuclear Power Plant is challenging due to the significant strontium content and radioactivity, leading to a potential risk of hydrogen gas generation via radiolysis of water content. The present study investigates the reduction of water content in calcium aluminate cement (CAC) with/out phosphate modification by a heat-treatment during the solidification. The reduction of water in the CAC was found restricted by the rapid formation of crystalline hydration phases, whereas the phosphate-modified system allowed the gradual reduction of water, achieving the reduction of 60% water content at 95 °C. Curing at 60–95 °C also eliminated the significant cracks found at 35 °C in the phosphate system. The possible difference in the amorphous products, NaCaPO{sub 4}·nH{sub 2}O type at 35°C and Ca(HPO{sub 4})·xH{sub 2}O type at 60–95 °C, may have contributed to the improvement in the microstructure together with the change in the pore size distribution.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Enhancement of low-temperature solid oxide fuel cell performance and durability via surface chemistry modification

The development of active cathodes is one of the most critical challenges to lowering the operating temperature for solid oxide fuel cells (SOFCs). Here, in this work, we demonstrated that by modifying the cathode surface chemistry at a relatively low temperature, the cathode activity and durability can be simultaneously enhanced on high-performing, low-temperature cathodes such as (La 0.6 Sr 0.4 ) 0.95 Co 0.2 Fe 0.8 O 3-δ (LSCF) and Sr 0.5 Sm 0.5 CoO 3-δ (SSC). This low-temperature modification using multi-valent cations activates the highly defected surface and maintains the nanoscale electrocatalysts by bypassing the high-temperature sintering procedure for SOFC fabrication. The modified cathode at 600°C shows an order of magnitude reduction in impedance to only 0.05 Ωcm 2 with a peak power density of 1.1 W/cm 2 and increases stability over 2000 h. The combination of in situ characterization, distribution of relaxation time analysis on impedance spectroscopy, and surface chemistry analysis reveals the importance of surface chemistry control on the gas-solid reaction activity and durability and provides the design principle for numerous future solid oxide cells.

25 ENERGY STORAGE↗
DOE OSTI2023

Processing aluminum alloy with hybrid wire arc additive manufacturing and ultrasonic nanocrystalline surface modification to improve porosity, surface finish, and hardness

Here, in this paper, a novel hybrid wire arc additive manufacturing (WAAM) and ultrasonic nanocrystal surface modification (UNSM) on porosity manipulation and surface properties of aluminum 5356 alloys was studied. The goal is to improve the quality of the WAAM-built part by eliminating bigger pores and reducing its size, reducing surface roughness, and increasing surface hardness. The as-built WAAM and WAAM-UNSM-treated samples were quantitatively studied for porosity using an X-ray micro-computed tomography (μ-CT). The surface roughness was measured on the surface profile of the same samples before and after UNSM treatment. Followed by the Vickers micro-hardness tests to evaluate the hardness modified by the influence of the UNSM treatment. It was found that the bigger pores in the as-built WAAM samples were eliminated and the medium-sized pores were shrunk to almost half the size after the UNSM treatment. Further, the UNSM treatment showed a significant improvement in both surface roughness and hardness on the WAAM Al5356 samples. This experimental work demonstrates the critical advantages of hybrid WAAM-UNSM in improving the qualities of the WAAM processed parts.

Hardness↗
DOE OSTI2015

Improved electrochemical and thermal performances of layered Li[Li 0.2 Ni 0.17 Co 0.07 Mn 0.56 ]O 2 via Li 2 ZrO 3 surface modification

We successfully coated a conductive Li 2 ZrO 3 layer on the surface of Li-rich layered cathode Li[Li 0.2 Ni 0.17 Co 0.07 Mn 0.56 ]O 2 in order to enhance its electrochemical performances. For the crystal structures, electrochemical properties and thermal stabilities of the bare and coated materials are studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), electron diffraction spectroscopy (EDS), inductively coupled plasma (ICP), galvanostatic cycling, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). We found that the electrochemical performances of Li-rich cathode material are obviously improved by Li 2 ZrO 3 surface modification. Especially, the 1 wt.% Li 2 ZrO 3 -coated material demonstrates the best cycling performance, with capacity retention of 89% after 50 cycles, much better than that of the pristine one, 64%. Intensive explorations indicate that the improved electrochemical properties can be attributed to the Li 2 ZrO 3 surface layer, which not only stabilizes the cathode structure by decreasing the loss of oxygen, but also protects the Li-rich cathode material from side reaction(s) with the electrolyte and thus suppressing the fast growth of solid electrolyte interface (SEI) film on the surface of oxide particles.

25 ENERGY STORAGE↗
DOE OSTI2015

Surface modification induced phase transformation and structure variation on the rapidly solidified recast layer of titanium

In this study, neodymium-doped yttrium orthovanadate (Nd:YVO{sub 4}) as a laser source with different scanning speeds was used on biomedical Ti surface. The microstructural and biological properties of laser-modified samples were investigated by means of optical microscope, electron microscope, X-ray diffraction, surface roughness instrument, contact angle and cell cytotoxicity assay. After laser modification, the rough volcano-like recast layer with micro-/nanoporous structure and wave-like recast layer with nanoporous structure were generated on the surfaces of laser-modified samples, respectively. It was also found out that, an α → (α + rutile-TiO{sub 2}) phase transition occurred on the recast layers of laser-modified samples. The Ti surface becomes hydrophilic at a high speed laser scanning. Moreover, the cell cytotoxicity assay demonstrated that laser-modified samples did not influence the cell adhesion and proliferation behaviors of osteoblast (MG-63) cell. The laser with 50 mm/s scanning speed induced formation of rough volcano-like recast layer accompanied with micro-/nanoporous structure, which can promote cell adhesion and proliferation of MG-63 cell on Ti surface. The results indicated that the laser treatment was a potential technology to enhance the biocompatibility for titanium. - Highlights: • Laser induced the formation of recast layer with micro-/nanoporous structure on Ti. • An α → (α + rutile-TiO{sub 2}) phase transition was observed within the recast layer. • The Ti surface becomes hydrophilic at a high speed laser scanning. • Laser-modified samples exhibit good biocompatibility to osteoblast (MG-63) cell.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Nanostructures evolution assessment and spectroscopic properties modification induced by electronic energy loss in KTaO 3 crystal

Modifications of micro/nanostructure and photoelectric properties under swift ion irradiation (645 MeV Xe 35+ ) of KTaO 3 crystal with varying electronic energy losses (7.2–31.4 keV/nm) and ion velocities (0.18–5.00 MeV/u) have been studied by combining experimental and calculated approaches. The i-TS calculations combined with molecular dynamics simulations are compared with the experimental observations, revealing the inner track fine structures from individual spherical defects to continuous ion tracks with core–shell morphologies, and a quantitative relationship, including the melting (0.42 eV/atom), damage (0.75 eV/atom), and amorphous (1.71 eV/atom) thresholds, is established to successfully predict the inner disorder/amorphous proportions and track damage morphologies. The surface nanostructures of nanohillocks (isolated or partial overlaps) and nanopits (serious overlaps) directly depend on the combined action of the deposited potential and kinetic energies of incident ions, which induce local melting and sublimation in the near-surface region. Owing to the decreased recombination and the increased separation efficiency between electrons and holes, the higher photogenerated charge carrier mobility enhanced the photocurrent effect, further optimizing the photoconductivity performance in Xe 35+ -irradiated KTaO 3 . Therefore, controlled defect engineering using the ion irradiation technique, as an effective strategy, could design tailored nanostructure systems and regulate photoelectric properties, further promoting the development of novel technological applications.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Structural modification and photoluminescence studies of Eu in lamellar fluorphlogopite by the adjustment of layer charge

Highlights: • The structure of fluorphlogopite was modified by the decrease of layer charge. • Characteristic emission of Eu{sup 3+} was greatly enhanced as doped to the modified clay. • The emitting color changed from orange-red to red in respect to the original host. • This is a new strategy to enhance the luminescence of inorganic layered materials. - Abstract: In this paper, the lamellar fluorphlogopite was structurally modified by the adjustment of layer charge and the rare earth Eu{sup 3+} was doped to fluorphlogopite with a subsequent high temperature solid state reaction process. The structural modification involved a preliminary treatment of fluorphlogopite with HNO{sub 3} and oxalic acid to reduce the layer charge density, and part of the charge-reduced fluorphlogopite was converted to a homoionic Na form by ion exchange with NaCl or NaB(C{sub 6}H{sub 5}){sub 4}. It has been noticed that the interlayer spacing of modified fluorphlogopite is decreased as compared with the original fluorphlogopite due to the ionic radius difference between K{sup +} and Na{sup +}. The photoluminescence study suggests that adjustment of layer charge of fluorphlogopite is beneficial to enhance the luminescence intensity excited with near UV light, and the layered system may be a potential red light component for the use of solid-state lighting and other optoelectronic fields.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Atmospheric pressure plasma - $\mathrm{ARGET}$ $\mathrm{ATRP}$ modification of poly(ether sulfone) membranes: A combination attack

We report a novel surface modification technique for grafting alkyl methacrylate monomers from commercial poly(ether sulfone) (PES) nanofiltration membranes is developed through a combination of helium and oxygen atmospheric pressure plasma treatment followed by Activators Regenerated by Electron Transfer (ARGET) Atom Transfer Radical Polymerization (ATRP). The resulting membrane surfaces show degree of grafting increases of 28%, 94%, and 270% for methyl methacrylate (C1), hexyl methacrylate (C6), and stearyl methacrylate (C18), respectively, when characterized with Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy. Scanning Electron Microscopy and Atomic Force Microscopy (AFM) show a rippled, fibrous morphology for the PES membranes grafted with C18 and reinforced through molecular dynamics simulations. AFM of the PES membranes grafted with C18 show an increase of ~ 23% in root-mean square (RMS) roughness as well as 4x higher adhesion force when probed with a hydrophobic gold cantilever tip when compared with the unmodified PES membranes, confirming a successful surface grafting reaction and increase in surface hydrophobicity, respectively. This technique allows enhanced synthesis of polymer grafted membranes using relatively green reaction solvent and enables “structure-by-design” surface morphology control with future applications in membrane separation processes such as organic solvent nanofiltration, gas separations, and desalination.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Advancements in the modification of TiFe alloys for enhanced hydrogen Storage: Strategies and future Directions

Hydrogen is considered a promising clean energy source, and a potential alternative to conventional fossil fuels. TiFe alloy has been particularly interesting due to its ability to reversibly absorb and desorb hydrogen at room temperature and low pressure. The initial hydrogen absorption stage of TiFe alloy requires activation under high-temperature and high-pressure conditions, which hinders its practical application. Here, this paper primarily examines the impact of elemental substitution methods on the hydrogen storage capabilities of TiFe alloys, with a particular emphasis on elucidating the mechanisms associated with various substituent elements. Commonly utilized elements, such as Mn, V, and Zr, significantly improve the activation performance of TiFe alloys. Additionally, the incorporation of elements such as Ni, Cr, Ce, and Y contributes to the modulation of phase composition, as well as the enhancement of activation and kinetic properties. However, there exists a notable deficiency in systematic investigations concerning alternative elements, coupled with a frequent oversight of the preparation process's influence on the hydrogen storage characteristics of these alloys. Consequently, the mechanisms by which different elements affect the hydrogen storage process in TiFe alloys remain inadequately understood among current research, thereby complicating the establishment of experiment-based design guidelines for TiFe alloys. Furthermore, the plasma treatment and high-entropy alloying present new approaches for optimizing the hydrogen storage properties of TiFe alloys. This paper aims to present novel research perspectives and insights to scholars in the field by introducing methods for the modification of TiFe alloys.

Hydrogen storage↗
DOE OSTI2017

Impact of common clandestine structural modifications on synthetic cathinone “bath salt” pharmacokinetics

Since 2009, the synthetic cathinones (“bath salts”) have risen in popularity as drugs of abuse. However, there are a paucity of studies that have determined the impact of functional group modifications in the synthetic cathinone chemical structures on plasma and central nervous system (CNS) pharmacokinetics. In the present study, we investigated the in vivo plasma and CNS pharmacokinetics of three synthetic cathinones whose structures differ by lengthening of the α-alkyl chain: methylone (-CH{sub 3}), butylone (-CH{sub 2}CH{sub 3}), and pentylone (-CH{sub 2}CH{sub 2}CH{sub 3}). Male Sprague-Dawley rats were treated with a 20 mg/kg subcutaneous dose of the individual synthetic cathinone. Blood samples were obtained at specific times from a jugular vein cannula over an 8 hour period. Over a separate three-hour period, CNS samples were obtained using a microdialysis cannula surgically implanted into the lateral ventricle. In the plasma, pentylone, with the longest α-alkyl chain, displayed the highest C{sub max} and AUC{sub 0–∞}, and the longest t{sub 1/2.} Decreasing the α-alkyl chain length as in butylone and methylone significantly decreased the C{sub max}, AUC{sub 0–∞}, and t{sub 1/2}. The plasma pharmacokinetic values are consistent with the greater lipophilicity associated with α-alkyl side chain lengthening. Conversely, in the CNS, methylone and butylone displayed higher C{sub max} and AUC{sub 0–∞} values than pentylone. These contrary findings in the CNS and plasma demonstrate that lengthening of the α-alkyl chain of methylone, butylone, and pentylone yields differential pharmacokinetic properties in the CNS as compared to the plasma. - Highlights: • Adding α-methyl groups increase synthetic cathinone plasma C{sub max}, AUC{sub 0–∞,} t{sub 1/2.} • Adding α-methyl groups decrease synthetic cathinone CNS C{sub max}, AUC{sub 0–∞,} t{sub 1/2.} • The CNS has greater exposure to the synthetic cathinones as compared to the plasma.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Cocaine promotes both initiation and elongation phase of HIV-1 transcription by activating NF-κB and MSK1 and inducing selective epigenetic modifications at HIV-1 LTR

Cocaine accelerates human immunodeficiency virus (HIV-1) replication by altering specific cell-signaling and epigenetic pathways. We have elucidated the underlying molecular mechanisms through which cocaine exerts its effect in myeloid cells, a major target of HIV-1 in central nervous system (CNS). We demonstrate that cocaine treatment promotes HIV-1 gene expression by activating both nuclear factor-kappa B (NF-ĸB) and mitogen- and stress-activated kinase 1 (MSK1). MSK1 subsequently catalyzes the phosphorylation of histone H3 at serine 10, and p65 subunit of NF-ĸB at 276th serine residue. These modifications enhance the interaction of NF-ĸB with P300 and promote the recruitment of the positive transcription elongation factor b (P-TEFb) to the HIV-1 LTR, supporting the development of an open/relaxed chromatin configuration, and facilitating the initiation and elongation phases of HIV-1 transcription. Results are also confirmed in primary monocyte derived macrophages (MDM). Overall, our study provides detailed insights into cocaine-driven HIV-1 transcription and replication. - Highlights: • Cocaine induces the initiation phase of HIV transcription by activating NF-ĸB. • Cocaine induced NF-ĸB phosphorylation promotes its interaction with P300. • Cocaine enhances the elongation phase of HIV transcription by stimulating MSK1. • Cocaine activated MSK1 catalyzes the phosphorylation of histone H3 at its Ser10. • Cocaine induced H3S10 phosphorylation facilitates the recruitment of P-TEFb at LTR.

60 APPLIED LIFE SCIENCES↗