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Materials (Basel, Switzerland) Jun 2024A new hydrothermal hot isostatic pressing (HHIP) approach, involving hydrothermal water conditions and no usage of inert gas, was hypothesized and tested on 3D-printed...
A new hydrothermal hot isostatic pressing (HHIP) approach, involving hydrothermal water conditions and no usage of inert gas, was hypothesized and tested on 3D-printed Al-10%Si-0.3%Mg (%Wt) parts. The aluminum-based metal was practically inert at the applied HHIPing conditions of 300-350 MPa and 250-350 °C, which enabled the employment of a long (6-24 h) HHIP treatment with hardly any loss of material (the overall loss due to corrosion was mostly <0.5% /). Applying the new approach on the above-mentioned samples resulted in an 85.7% reduction in the AM micro-pores, along with a 90.8% reduction in the pores' surface area at a temperature of 350 °C, which is much lower than the 500-520 °C applied in common argon-based aluminum HIPing treatments, while practically maintaining the as-recieved microstructure. These results show that better mechanical properties can be expected when using the suggested treatment without affecting the material fatigue resistance due to grain growth. The proof of concept presented in this work can pave the way to applying the new HHIPing approach to other AM metal parts.
PubMed: 38893980
DOI: 10.3390/ma17112716 -
Materials (Basel, Switzerland) Jun 2024This article presents the research results of depositing anti-friction coatings (Babbitt) using three different casting methods: static casting, flame soldering, and...
This article presents the research results of depositing anti-friction coatings (Babbitt) using three different casting methods: static casting, flame soldering, and clad welding. Babbitt alloy coatings deposited with different casting methods are discussed and explained in terms of changes in the coating properties, such as the microstructure, hardness, strength, and chemical composition. The results showed significant differences in the aforementioned properties, depending on the chosen coating deposition method. The results of the tests confirmed the importance of using shielding gas during deposition to ensure the chemical composition of the coating. The analysis revealed that decreases in the amounts of antimony and copper in the Babbitt coating compared with the initial concentrations were influenced by selective evaporation, oxidation, and the coating process parameters associated with different coating methods. To maintain the desired balance of mechanical properties in Babbitt coatings, it is important to control the antimony and copper contents. Clad welding deposition using a non-consumable tungsten electrode and argon shielding gas achieved a chemically stable coating quite close to the initial chemical composition of the Babbitt alloy.
PubMed: 38893926
DOI: 10.3390/ma17112662 -
Molecules (Basel, Switzerland) Jun 2024The objective of this study was to investigate the modification of glass surfaces by the synergistic combination of cold plasma and chemical surface modification...
The objective of this study was to investigate the modification of glass surfaces by the synergistic combination of cold plasma and chemical surface modification techniques. Glass surface hydrophobicity was obtained as a result of various plasma and deposition operational conditions. The mechanisms governing the hydrophobization process were also studied. Glass plates were activated with plasma using different gases (oxygen and argon) at different treatment times, ranging from 30 to 1800 s. Then, the plasma-treated surfaces were exposed to hexamethyldisilazane vapors at different temperatures, i.e., 25, 60, and 100 °C. Complete characterization, including contact angle measurements, surface free energy calculations, 3D profilometry, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and scanning electron microscopy, was accomplished. It was found that the extent of the hydrophobicity effect depends on both the plasma pre-treatment and the specific conditions of the hexamethyldisilazane deposition process. Plasma activation led to the formation of active sites on the glass surface, which promoted the adsorption and reaction of hexamethyldisilazane species, thereby inducing surface chemical modification. Longer plasma pre-treatment resulted in stronger modification on the glass surface, resulting in changes in the surface roughness. The largest water contact angle of ≈100° was obtained for the surface activated by argon plasma for 1800 s and exposed to hexamethyldisilazane vapors at 25 °C. The changes in the surface properties were caused by the introduction of the hydrophobic trimethylsilyl groups onto the glass surface as well as roughness development.
PubMed: 38893520
DOI: 10.3390/molecules29112645 -
Molecules (Basel, Switzerland) May 2024A nanocomposite of multi-walled carbon nanotubes (MWCNTs) decorated with molybdenum dioxide (MoO) nanoparticles is fabricated through the reduction of phosphomolybdic...
A nanocomposite of multi-walled carbon nanotubes (MWCNTs) decorated with molybdenum dioxide (MoO) nanoparticles is fabricated through the reduction of phosphomolybdic acid hydrate on functionalized MWCNTs in a hydrogen-argon (10%) atmosphere in a tube furnace. The MoO/MWCNTs composite is proposed as an anodic modification material for microbial fuel cells (MFCs). MWCNTs have outstanding physical and chemical peculiarities, with functionalized MWCNTs having substantially large electroactive areas. In addition, combined with the exceptional properties of MoO nanoparticles, the synergistic advantages of functionalized MWCNTs and MoO nanoparticles give a MoO/MWCNTs anode a large electroactive area, excellent electronic conductivity, enhanced extracellular electron transfer capacity, and improved nutrient transfer capability. Finally, the power harvesting of an MFC with the MoO/MWCNTs anode is improved, with the MFC showing long-term repeatability of voltage and current density outputs. This exploratory research advances the fundamental application of anodic modification to MFCs, simultaneously providing valuable guidance for the use of carbon-based transition metal oxide nanomaterials in high-performance MFCs.
PubMed: 38893417
DOI: 10.3390/molecules29112541 -
The American Journal of Case Reports Jun 2024BACKGROUND A 52-year-old male patient presented with symptoms of chronic cough and persistent tracheal irritation 26 years after surgical closure of a tracheostoma,...
BACKGROUND A 52-year-old male patient presented with symptoms of chronic cough and persistent tracheal irritation 26 years after surgical closure of a tracheostoma, supported by an autologous auricular cartilage graft and cutaneous transplant. At the initial clinical presentation, the patient was an active smoker, with a cumulative dose of 31 pack years. CASE REPORT Bronchoscopy revealed endotracheal hair growth and local inflammation at the graft site. Initial anti-inflammatory, antimycotic, and antibacterial therapy was administered, followed by endoscopic structure remodeling. There were multiple recurrences with similar symptoms, showing isolated hair growth, without inflammation. Annual endoscopic restructuring sessions were indicated, and the patient experienced them as highly relieving. Recurrent hair growth was finally terminated by argon plasma laser-coagulation and after smoking cessation. We hypothesize that the onset of hair growth was triggered by the patient's cigarette smoking. CONCLUSIONS Endotracheal hair growth is a potential complication of autograft-supported tracheal restructuring. The initial administration of antimicrobial and anti-inflammatory medication, combined with endoscopic restructuring, could have contained the active inflammation; the application of argon plasma laser-coagulation finally stopped the hair growth. Smoking is associated with the upregulation of molecular signaling pathways in the respiratory epithelium, which can stimulate hair follicles, such as sonic hedgehog protein, WNT-1/ß-catenin, and epidermal growth factor receptor.
Topics: Humans; Male; Middle Aged; Hair; Bronchoscopy; Tracheostomy; Trachea; Smoking; Ear Cartilage; Argon Plasma Coagulation; Tracheal Diseases
PubMed: 38889103
DOI: 10.12659/AJCR.943909 -
Chemistry of Materials : a Publication... Jun 2024Recent advances in anion-redox topochemistry have enabled the synthesis of metastable mixed-anion solids. Synthesis of the new transition metal oxychalcogenide SrMnONaSe...
Recent advances in anion-redox topochemistry have enabled the synthesis of metastable mixed-anion solids. Synthesis of the new transition metal oxychalcogenide SrMnONaSe by topochemical Na intercalation into SrMnOSe is reported here. Na intercalation is enabled by the redox activity of [Se] perselenide dimers, where the Se-Se bonds are cleaved and a [Na Se] antifluorite layer is formed. Freshly prepared samples have 16(1) % Na-site vacancies corresponding to a formal oxidation state of Mn of +2.32, a mixed-valence between Mn (d) and Mn (d). Samples are highly prone to deintercalation of Na, and over two years, even in an argon glovebox environment, the Na content decreased by 4(1) %, leading to slight oxidation of Mn and a significantly increased long-range ordered moment on the Mn site as measured using neutron powder diffraction. The magnetic structure derived from neutron powder diffraction at 5 K reveals that the compound orders magnetically with ferromagnetic MnO sheets coupled antiferromagnetically. The aged sample shows a metamagnetic transition from bulk antiferromagnetic to ferromagnetic behavior in an applied magnetic field of 2 T, in contrast to the Cu analogue, SrMnOCuSe, where there is only a hint that such a transition may occur at fields exceeding 7 T. This is presumably due to the higher ionic character of [Na Se] layers compared to [Cu Se] layers, reducing the strength of the antiferromagnetic interactions between MnO sheets. Electrochemical Na intercalation into SrMnOSe leads to the formation of multiphase sodiated products. The work shows the potential of anion redox to yield novel compounds with intriguing physical properties.
PubMed: 38883431
DOI: 10.1021/acs.chemmater.4c00801 -
Medicine Jun 2024Argon gas poisoning is an often overlooked yet critical public health concern with the potential for severe and persistent neurological consequences. Current treatment...
RATIONALE
Argon gas poisoning is an often overlooked yet critical public health concern with the potential for severe and persistent neurological consequences. Current treatment protocols primarily focus on acute-phase management, but a comprehensive understanding of the long-term neurological effects remains incomplete.
PATIENT CONCERNS
A 22-year-old male worker was found unconscious in the furnace room of an argon production facility. After regaining consciousness, he presented with symptoms of dizziness, headache, fatigue, and irritability. Neurological examination revealed impairments in both recent and remote memory, notably pronounced short-term memory deficits and reduced arithmetic skills.
DIAGNOSIS
Argon gas poisoning, hypoxic encephalopathy, and mild hepatic and renal dysfunction.
INTERVENTIONS
Upon admission, symptomatic supportive measures included oxygen therapy via nasal cannula (3 L/min), daily hyperbaric oxygen therapy (1.5 ATA, 60 minutes), oral neurotrophic methylcobalamin (0.5 mg, 3 times daily), and intravenous vitamin C infusion (2 g daily) to scavenge oxygen free radicals.
OUTCOME
A 2-year telephone follow-up indicated persistent short-term memory impairment, particularly with memorizing numbers. In a memory test, he achieved a digit span forward of 5 but a digit span backward of 2, indicating impairment. Despite these challenges, his daily life and work performance remained largely unaffected.
LESSON
This case offers valuable insights into the biological mechanisms underlying prolonged neurological sequelae following asphyxiating gas exposure, specifically the persistent impairment of hippocampal function.
Topics: Humans; Male; Memory Disorders; Argon; Young Adult; Hyperbaric Oxygenation; Hypoxia, Brain
PubMed: 38875417
DOI: 10.1097/MD.0000000000038545 -
Heliyon Jun 2024The corrosion behavior of alloy Ni 201 in molten sodium hydroxide (NaOH) at 600 °C was investigated at varying basicity levels of the molten NaOH. The ability for Ni...
The corrosion behavior of alloy Ni 201 in molten sodium hydroxide (NaOH) at 600 °C was investigated at varying basicity levels of the molten NaOH. The ability for Ni 201 to form passivating oxides was investigated after immersion tests varying from 70 to 340 h under atmospheres of argon and argon with different partial pressure of water. Morphology and thicknesses of the corrosion products were characterized by Scanning Electron Microscopy (SEM) and crystallography of the corrosion products by X-ray Diffraction (XRD). Dynamic polarizations were made to investigate the effects of basicity and electrochemical potential. The results showed that Ni 201 corroded at a reduced rate in molten acidic NaOH compared to neutral NaOH due to the formation of NiO. The oxide scales formed on Ni 201 in acidic NaOH were shown to grow non-parabolically and did not result in full corrosion protection as the oxide scales showed crack development over time.
PubMed: 38868009
DOI: 10.1016/j.heliyon.2024.e31995 -
Optics Express May 2024Using the three-dimensional classical ensemble approach, we theoretically investigate the nonsequential double ionization of argon atoms in an intense laser field...
Using the three-dimensional classical ensemble approach, we theoretically investigate the nonsequential double ionization of argon atoms in an intense laser field enhanced by bowtie-nanotip. We observe an anomalous decrease in the double ionization yield as the laser intensity increases, along with a significant gap in the low momentum of photoelectrons. According to our theoretical analysis, the finite range of the induced field by the nanostructure is the fundamental cause of the decline in double ionization yield. Driven by the enhanced inhomogeneous field, energetic electrons can escape from the finite range of nanotips without returning. This reduces the possibility of re-scattering on the nucleus and imprints the finite size effect into the double ionization yield and momentum distribution of photoelectrons in the form of yield decline and a gap in the photoelectron-momentum distribution.
PubMed: 38859108
DOI: 10.1364/OE.523593 -
Heliyon Jun 2024In drug delivery, it is common to use porous particles as carrier media, instead of dense particles, due to their high specific surface area and available entrapment...
In drug delivery, it is common to use porous particles as carrier media, instead of dense particles, due to their high specific surface area and available entrapment volume, which allows a higher amount of drug to be encapsulated and then released. Chitosan microparticles are extensively used in drug delivery, but porous chitosan microparticles are scarcely reported. In this work, the preparation of porous chitosan microparticles using membrane emulsification is addressed, a technology that involves mild operating conditions and less energy consumption than traditional methods (such as ultrasound), and with higher control of the particle size. The dense structure is obtained by a water-in-oil emulsion. The porous structure is obtained by a gas-in-water-in-oil G/W/O double emulsion, where argon bubbles get entrapped in an aqueous chitosan solution that is further emulsified in a paraffin/petroleum ether mixture. Porous chitosan particles were obtained with sizes of 7.7 ± 1.6 μm, which was comparable with dense chitosan particles (6.2 ± 2.3 μm). The pore structure was optimized by varying the argon flow rate, being optimized at 0.24 L h. The impact of drug loading by adsorption or encapsulation, and of the drug release behaviour when using porous and dense particles were assessed, using the protein bovine serum albumin (BSA) as a model drug. The results showed that by encapsulating BSA the loading efficiency was above 95 % for both types of particles, with the release being slightly slower for the dense particles. As for the adsorbed BSA, the loading efficiency was significantly higher for porous particles - 70 % - against the 40 % for dense particles. Porous chitosan particles were successfully obtained using the membrane emulsification technology and showed that these carriers are advantageous regarding drug loading and release.
PubMed: 38845862
DOI: 10.1016/j.heliyon.2024.e31823