Aging Treatment Research Articles

Influence of post heat treatment on tribological and microstructural properties of plasma wire arc additive manufactured maraging steels

Abstract Metallic alloys are increasingly being produced using wired arc additive manufacturing (WAAM). In this study, 18Ni300 defect-free maraging steels were produced using the WAAM technique. A traditional solution treatment, direct aging, and cryogenic heat treatment processes were applied to the WAAM produced maraging steels. The influence of conventional and novel cryogenic heat treatments on microstructural, mechanical, and tribological properties were examined. The microstructure of the as-built materials obtained by WAAM thermal cycling has mainly been homogenized through the solution, direct-aging, and cryogenic heat treatments. As a result, homogeneously distributed precipitate phases were obtained and the hardness increased by 30 % with a combination different post heat treatments. The cryogenic heat treatment improved the martensitic transformation and facilitated the formation of various Fe–Ni–Mo–Ti-containing intermetallic precipitates. Similarly, because of the different heat treatments, the wear resistance improved by a factor of 2–5.5 relative to the as-built material. Adding the cryogenic heat treatment to the traditional heat treatment procedure improves wear resistance by a factor of 1.2–2.9.

The aging-hardening behavior of short-time in high pressure die casting AlSi9MgMnZn alloy

Short-time aging is an effective industrial technique for enhancing the mechanical properties of high pressure die cast (HPDC) aluminum alloy components. However, the evolution of precipitation behavior during short-time aging of HPDC alloys remains unclear. In this study, the short-time aging behavior of HPDC AlSi9MgMnZn alloy was investigated. The results show that the AlSi9MgMnZn alloy exhibits effective aging-hardening, with an increment in hardness of approximately 30 HV through the optimal short-time aging treatment (aged at 180 °C for 120 minutes). Higher aging temperatures led to reduced peak hardness and rapid over-aging above 220 °C. The microstructure observation indicates that the peak short-time aging promotes the simultaneous precipitation of β″ precipitates, GP zones and nano Si phases. The contribution of different strengthening mechanisms to hardness was estimated, implying that the coexistence of β″ precipitates and GP zones can provide a positive contribution to aging-hardening during short-time aging. Moreover, as the aging temperature increases, the appearance of β′ precipitates reduces the strengthening effect, leading to a decrease in hardness.

Microstructure evolution and property enhancement of CuCr50 alloys through the synergistic effects by hot-forging deformation and heat treatment

In this study, CuCr50 alloys were prepared by aluminum thermal reduction-high frequency refining process, and the properties were improved through hot forging and heat treatment. With increasing deformation, large Cr particles were spheroidized and refined, significantly improving the performance of the alloy. When the deformation exceeds 27%, the conductivity reaches 17.73 MS/m, the hardness reaches 116.5 HB, and the density reaches 7.91 g/cm3. After solution at 975 °C for 1h and aging at 550 °C for 4h, the conductivity of the CuCr50 alloy further increased to 19.63 MS/m, the hardness reaches 121.5 HB. Compared with the as-cast alloy, the conductivity, hardness and density are increased by 71.07%, 18.81% and 2.99%, respectively. In the 5% deformed CuCr50 alloy the precipitates of nanoscale Cr particles formed a co-lattice with the copper matrix. In the 14% deformed CuCr50 alloy, nanoscale Cr particles precipitated and dispersed in the Cu matrix, and the relationship between the precipitated Cr phase and the Cu matrix was incoherent. The amount of precipitated Cr phase in the 27% deformed CuCr50 alloy had a semi-coherent relationship with the Cu matrix, the orientations of Cu(2‾00)//Cr(110). The hardness enhancement is mainly attributed to grain refinement and density increase, and the conductivity enhancement is mainly attributed to Cr particle precipitation after aging treatment.

Preoperative breast MR imaging influences surgical management in patients with invasive lobular carcinoma.

The purpose of the study is to assess the role of preoperative magnetic resonance (MR) imaging on the surgical management of invasive lobular carcinoma (ILC) and to evaluate whether breast density and background parenchymal enhancement (BPE) influence surgical treatment. This retrospective study was conducted on 56 patients who were diagnosed with ILC between 2014 and 2020. All patients had mammogram and ultrasound. Preoperative MRI was available in 34 patients. Age, menopausal status, breast density, BPE, multifocality/multicentricity and surgical treatment were collected. Mean pathological tumour size was 36.4 mm (range 5-140 mm). Dense breasts had larger tumours compared to non-dense breasts (P = 0.072). Of the 34 patients with MRI, 6 opted for mastectomy. Of the remaining 28 cases, MRI findings upgraded surgery to mastectomy in 54% (15/28) because mammogram/ultrasound underestimated tumour extent in 25% (7/28), or multifocal/multicentric disease was identified in 29% (8/28). Tumour size was underestimated by MRI in 7% (2/28). In the non-MRI subgroup, 64% (14/22) of patients underwent breast-conserving surgery, but 29% of them (4/14) required a second-stage mastectomy due to extensive margin involvement. There was no difference in mastectomy rate between patients with MRI (62%) and without MRI (55%) (P = 0.061). Tumour size correlation between MRI and histopathology demonstrated an excellent intraclass correlation coefficient (P < 0.001). Surgical treatment recommendation was not significantly impacted by breast density or BPE. Breast MRI improves surgical management of patients with ILC in providing additional diagnostic information often missed with standard imaging modalities, and without increasing mastectomy rate. Surgical treatment is not impacted by breast density or BPE.

220. SHORT-AND LONG-TERM OUTCOMES OF ROBOT ASSISTED MINIMALLY INVASIVE ESOPHAGECTOMY FOR ESOPHAGEAL CANCER: A PROPENSITY SCORE-MATCHED STUDY

Abstract Background Conventional minimally invasive esophagectomy (C-MIE) for esophageal cancer has become widespread and standardized. In Japan, robot-assisted MIE (RAMIE) has been covered by national health insurance since 2018. However, the superiority of RAMIE over conventional MIE remains controversial. In this study, we will clarify the short-and long-term outcomes of RAMIE compared to C-MIE. Methods Short-term outcomes were compared using propensity score-matching (PSM) for C-MIE group (324 cases) and RAMIE group (101 cases) performed from 2010 to 2023. Long-term outcomes were compared using PSM for C-MIE group (313 cases) and RAMIE group (69 cases) up to 2021, when a minimum three-year observation period was available. Covariates for PSM were age, sex, tumor location, histological type, cT, cN, preoperative treatment, abdominal approach, and range of lymph node dissection. Results For short-term outcomes, 96 cases were included in each group after PSM. There were no significant differences in age, sex, tumor location, histological type, cT, cN, and preoperative treatment. Operative time was significantly longer in RAMIE group than in C-MIE group (overall procedure: 657 vs. 764 min, P&amp;lt;0.001; thoracic prpcedure: 306 vs. 411 min, P&amp;lt;0.001). Blood loss was significantly lower in RAMIE group than in C-MIE group (145 vs. 64 ml, P&amp;lt;0.001). The rate of recurrent laryngeal nerve palsy (Clavien-Dindo classification, Grade II or higher) was significantly lower in RAMIE group than in C-MIE group (10% vs. 0%, P&amp;lt;0.001). There were no significant differences in the rates of anastomotic leakage and postoperative pneumonia between both groups (P=0.159, 0.709). For long-term outcomes, 69 cases were included in each group after PSM. The 3-year overall survival rate was 70.8% in C-MIE group and 77.1% in RAMIE group, and the 3-year disease-free survival rate was 63.5% in C-MIE group and 58.8% in RAMIE group, both showing no significant difference (P=0.406, P=0.651). Conclusions RAMIE has the potential to reduce recurrent laryngeal nerve palsy compared to C-MIE and long-term outcomes for both procedures were comparable.

Can silver diamine fluoride reduce invasive treatments with general anesthesia?

This study aims to retrospectively evaluate the differences in dental treatments rendered in general anesthesia (GA) for patients who did or did not receive application of silver diamine fluoride (SDF) prior to GA. 1559 patients (≤6 years) who completed treatment with GA for caries at University of California San Francisco (UCSF) between 2015 and 2019 were included in the study. At baseline patients' electronic health record was reviewed to collect planned treatment, complete dental treatment and demographics. Patients were identified as SDF group (N = 335, 21.49%) or comparison (N = 1224, 78.51%). Dental treatments rendered were compared between the SDF and comparison group with multi-variable regression, including variables for demographics and clinical findings at baseline. The initial analysis identified variations in gender, age, dental pain, pulp involvement, and initial treatment plans between the SDF and comparison groups at baseline. In an unadjusted analysis, the SDF group displayed a statistically significant increase in the number of crown procedures but a notable decrease in the number of pulp therapy and extraction treatments completed (p < 0.05). An adjusted multivariable model affirmed the inverse relationship between SDF application and completion of pulp therapy and extractions at the time of GA (p < 0.05). No significant association was identified with the total number of crowns needed and SDF. The model further indicated a positive correlation between the total count of pulp therapy and extractions completed with patient age and the wait-time for GA. In conclusion, pre-GA application of SDF to carious primary teeth is negatively correlated with completed pulp therapy and extraction. SDF application prior to dental treatment with GA may be a valuable tool to reduce invasive dental procedures in GA.

Sleep Disturbances and Dry Eye Symptoms and Signs, Systemic Conditions, and Inflammatory Markers in the Dry Eye Assessment and Management Study

Purpose: To investigate the association between sleep disturbances, dry eye disease (DED) severity, and DED risk factors. Methods: We conducted a secondary analysis of the Dry Eye Assessment and Management (DREAM) study, a randomized trial of 535 patients with moderate-to-severe DED. Participants self-reported sleep disturbances at baseline. DED symptoms were assessed using the Ocular Surface Disease Index and Brief Ocular Discomfort Index. DED signs were assessed using tear film break-up time, Schirmer test, corneal and conjunctival staining, tear osmolarity, and meibomian gland dysfunction assessment. Immune cells were assessed using conjunctival impression cytology. Outcomes were compared between participants with ongoing and no history of sleep disturbances, adjusting for confounders. Results: The mean age was 58 years, and 81% were women. Ongoing sleep disturbances (n = 113) were significantly associated with older age (mean 60.5 vs. 57.4; P = 0.03), smoking (39.8% vs. 28.7%; P = 0.02), and DED treatment. Systemic conditions associated with sleep disturbances included thyroid dysfunction (26.5% vs. 15.7% P = 0.007), irritable bowel (18.6% vs. 5.4%; P &lt; 0.0001), osteoarthritis (38.9% vs. 21.6%; P = 0.0007), and depression (30.1% vs. 11.5%; P &lt; 0.0001). Sleep disturbances were associated with lower conjunctival staining scores (2.46 vs. 2.77; P = 0.03) and higher concentrations of dendritic cells in ocular surface white blood cells (12.0% vs. 8.1%; P = 0.01). Conclusions: Sleep disturbances were associated with older age, smoking history, systemic diseases, and higher dendritic cell concentration among patients with moderate-to-severe DED. These findings support further investigation of sleep disturbances as a comorbidity of patients with DED. Additional research is needed to understand the mechanisms behind this relationship.

Noncovalent Interactions-Driven Self-Assembly of Polyanionic Additive for Long Anti-Calendar Aging and High-Rate Zinc Metal Batteries.

Zinc anodes of zinc metal batteries suffer from unsatisfactory plating/striping reversibility due to interfacial parasitic reactions and poor Zn2+ mass transfer kinetics. Herein, methoxy polyethylene glycol-phosphate (mPEG-P) is introduced as an electrolyte additive to achieve long anti-calendar aging and high-rate capabilities. The polyanionic of mPEG-P self-assembles via noncovalent-interactions on electrode surface to form polyether-based cation channels and in situ organic-inorganic hybrid solid electrolyte interface layer, which ensure rapid Zn2+ mass transfer and suppresses interfacial parasitic reactions, realizing outstanding cycling/calendar aging stability. As a result, the Zn//Zn symmetric cells with mPEG-P present long lifespans over 9000 and 2500 cycles at ultrahigh current densities of 120 and 200mA cm-2, respectively. Besides, the coulombic efficiency (CE) of the Zn//Cu cell with mPEG-P additive (88.21%) is much higher than that of the cell (36.4%) at the initial cycle after the 15-day calendar aging treatment, presenting excellent anti-static corrosion performance. Furthermore, after 20-day aging, the Zn//MnO2 cell exhibits a superior capacity retention of 89% compared with that of the cell without mPEG-P (28%) after 150 cycles. This study provides a promising avenue for boosting the development of high efficiency and durable metallic zinc based stationary energy storage system.

In-situ formed stable Pt nanoclusters on ceria-zirconia solid solutions induced by hydrothermal aging for efficient low-temperature CO oxidation

Pt nanoclusters (PtC) on the surface of ceria-zirconia solid solutions exhibit superior low-temperature CO oxidation activity compared to Pt single atoms (Pt1). However, the redispersion behavior of the PtC to Pt1 lowers the efficiency of CO Oxidation. In this work, the stable surface hydroxyl groups were constructed by high-temperature hydrothermal aging treatment. Specifically, the Pt1 catalyst (Pt/CZOe-SA) prepared by atom trapping was subjected to high-temperature hydrothermal treatment to obtain the stable PtC catalyst (Pt/CZOe-HT) with in-situ formed PtC. The experimental results showed that PtC with 2–3 nm size could achieve excellent low-temperature activity and thermal stability. In addition, the ab initio molecular dynamics and density functional theory calculations revealed the specific evolution process of dynamic dispersion for PtC with or without hydroxyl groups from the femtosecond scale, suggesting that the hydroxyl groups limited the dispersion of PtC in the form of “energy fence”. The hydrothermal treatment not only introduced high-temperature stable hydroxyl groups to improve the stability of the in-situ formed PtC, but also optimized the ratio of Pt1 and PtC, and then enhanced the low-temperature activity by the synergistic effect between Pt1 and PtC. The present work can provide theoretical guidance for developing high-performance and high-stability Pt-based catalysts.

Achieving superior high-temperature strength in an additively manufactured high-entropy alloy by controlled heat treatment

High-entropy alloys (HEAs) usually exhibit high strengths at ambient and low temperatures but rapidly degraded tensile properties with increased temperature. In this study, a high-strength HEA, (CoCrNi)94(TiAl)6, is selected and subjected to laser powder bed fusion (L-PBF) and ageing treatment. The microstructural evolution and mechanical property development of the material over a wide range of temperatures are thoroughly investigated. It is found that the as-printed microstructure is dominated by numerous ultrafine cellular structures (∼1 μm) with cell boundaries decorated by Al2O3 nanoparticles, leading to high 0.2% yield strength (YS = 725∼750 MPa) and excellent elongation (>28%) at room temperature. The cellular structures remain up to 700 °C but disappear at or above 800 °C. Ageing at or above 600 °C leads to significant γ′ precipitation with the particle size increasing constantly with increased temperature. The samples containing both cellular structures and coarsened γ′ precipitates (aged at 700 °C) exhibit the highest YS (∼1227 MPa) and ultimate tensile strength (UTS∼1539 MPa) at room temperature and display unprecedented YS at high temperatures, i.e., 949 MPa at 600 °C and 728 MPa at 700 °C, respectively. The exceptional tensile strengths are mainly due to the γ′ precipitates and cell boundaries decorated by Al2O3 nanoparticles which may have acted as strong barriers for dislocation motion. At room temperature, the sample deforms mainly by dislocation slip and formation of stacking faults while at elevated temperatures, deformation becomes increasingly planar as characterized by the formation of increased number of stacking faults and the activation of twinning.

Effect of aging temperature on microstructure and mechanical properties of (Ti1400+TiC)/Ti6Al4V composites

Titanium matrix composites, due to their high strength, high modulus, and high temperature resistance, have become ideal materials that meet the lightweight and high-performance requirements in the aerospace industry. However, their poor ductility remains a key issue that restricts their widespread application. In this study, (Ti1400+TiC)/TC4 composites were prepared by low-energy ball milling and spark plasma sintering and subjected to solution treatment and aging treatment. The effects of aging temperature on the composition, microstructure, and mechanical properties of the composites were analyzed, and the strengthening mechanism of (Ti1400+TiC)/TC4 composites was discussed. The aging temperature between 350 ℃ and 700 ℃ had little effect on the microstructure of TC4 matrix and the discontinuous three-dimensional network structure of TiC particles. As the aging temperature increased, the elongated α-phase within the Ti1400 region became shorter and thicker, and Cr’s rapid diffusion resulted in β-phase being more widely distributed. After aging at 600 ℃, the tensile strength of the composite was 1202 MPa, and its total elongation reached 11.3 %, showing excellent strength-plasticity matching. The mechanical properties of composites are mainly affected by the microstructure in the Ti1400 region. The elongated α-phase in the Ti1400 region provides high strength for the composite. The thicker α-phase and the widely distributed β-phase led to more uniform strain within the composite, avoiding premature fracture caused by stress concentration near TiC particles and promoting ductility in the composite.

High-strength aluminum alloy processed by micro laser powder bed fusion (μ-LPBF): Coordination of laser formability, microstructure evolution, and mechanical properties

As the scale of additive manufacturing process (e.g., laser spot size, powder particle size, powder layer thickness) decreases, the application of micro laser powder bed fusion (μ-LPBF) involves novel mechanisms for process, microstructure and performance coordination. This study provides a systematic view of the processing window and performance enhancement of high-strength Al-Mg-Sc-Zr alloy fabricated by μ-LPBF. The effects of μ-LPBF parameters on defect control and densification activity of the printed parts were analyzed, so as to obtain the suitable processing window. The influence of building orientation and heat treatment on microstructural characteristics and mechanical properties of μ-LPBF processed parts was studied. The μ-LPBF Al-Mg-Sc-Zr exhibited sound surface quality (Ra of 6.088 μm) and considerably refined grains with an average size of 1.102 μm, which was related to the high cooling rate (8.6 × 107 K/s) induced by a small-sized laser beam (25 μm) and a tiny powder particle size distribution (2–20 μm) applied in μ-LPBF. After aging treatment (325 °C/4 h), the superior ultimate tensile strength of 590.24 ± 4.75 MPa combined with the sufficiently high elongation of 11.99 ± 1.17 % was achieved. Due to the significantly decreased scale of μ-LPBF production, the anisotropy caused by the variation of building directions was negligible. These enhanced mechanical properties were attributed to the combined effect of the grain size refinement, the higher number density (1.2 × 1024/mm3) of interior precipitates within grains, and the small-sized molten pool size of μ-LPBF. Computational fluid dynamics (CFD) simulation was applied to reveal the molten pool thermodynamics, indicating that a higher thermal temperature gradient (up to 9.8×107 K/m), a smaller molten pool size (with the width of 38.7–69.8 μm and depth of 8.7–30.0 μm) were generated in μ-LPBF. This work presents great potential in processing high-precision metallic components with fine structural feature size and satisfactory manufacturing quality.

Stimulation of skeletal muscle angiogenesis in aged rats by (+)-epicatechin: Identification of underlying mechanisms

Studies have linked the development of sarcopenia to reductions in capillary vessel network density and suggest that such changes may partly account for the loss of skeletal muscle (SkM) mass and function. Thus, the interest in identifying and evaluating safe and effective candidate compounds that can stimulate angiogenesis. We previously reported on the capacity of (+)-epicatechin (+Epi) to reverse SkM atrophy and loss of function in aged rats. We also reported on the apparent angiogenic effect of +Epi in mouse brain cortex. However, no studies have evaluated the angiogenic potential of +Epi in SkM. Using 23 month old male rats, we evaluated the angiogenic effect of 8 weeks of 1 mg/kg/day oral treatment of +Epi on SkM (gastrocnemius). To identify underlying mechanisms, we evaluated the PI3K/eNOS pathway, as well as the expression of the angiogenic factors HIF1-α, VEGF and VEGFR2. Results demonstrate that + Epi stimulates increases in protein levels for HIF1-α (∼35%), VEGF (∼40%), VEGFR2 (∼25%), as well as CD31 (capillaries, ∼25%). Such effects were linked with the activation (phosphorylation) of PI3K (∼30%), eNOS (∼90%), VEGFR2 at T951 (∼90%) and T996 amino acid sites (∼110%). +Epi also stimulated increased synthesis of phosphatidylinositol trisphosphate (∼30%) and tetrahydrobiopterine (∼90%), as well as of nitric oxide (∼140% in gastrocnemius and ∼70% in plasma) and cyclic guanosine monophosphate (∼90%) in gastrocnemius and in plasma (∼40%). In summary, in aged rats oral treatment with +Epi stimulates SkM angiogenesis and such actions may partly account for the reversal of the deleterious effects of sarcopenia.

The Influence of Post-Treatment on Micropore Evolution and Mechanical Performance in AlSi10Mg Alloy Manufactured by Laser Powder Bed Fusion.

Gas-induced porosity is almost inevitable in additively manufactured aluminum alloys due to the evaporation of low-melting point elements (e.g., Al, Mg, and Zn) and the encapsulation of gases (e.g., hydrogen) during the multiple-phase reaction in the melt pool. These micropores are highly unstable during post-heat treatment at elevated temperatures and greatly affect mechanical properties and service reliability. In this study, the AlSi10Mg samples prepared by LPBF were subjected to solution heat treatment at 560 °C for 0.5 and 2 h, followed by artificial aging at 160 °C, 180 °C and 200 °C, respectively. The defect tolerance of gas porosity and associated damage mechanisms in the as-built and heat treated AlSi10Mg alloy were elucidated using optical, scanning electron microscopic analysis, X-ray micro computed tomography (XCT) and room temperature tensile testing. The results showed the defect tolerance of AlSi10Mg alloy prepared by LPBF was significantly reduced by the artificial aging treatment due to the precipitation of Mg-Si phases. Fracture analysis showed that the cooperation of fine precipitates and coarsened micropores assists nucleation and propagation of microcracks sites due to stress concentration upon tensile deformation and reduces the tensile elongation at break.

Quench sensitivity and transformation kinetics of high vacuum die casting AlSi10MgMn alloy

AlSi10MgMn alloy high vacuum die castings are being widely used in automotives. T6 heat treatment can increase the casting mechanical properties. In this study, the time-temperature-transformation (TTT) and time-temperature-property (TTP) curves of high vacuum die casting (HVDC) AlSi10MgMn alloy were measured by interrupted quenching method, and the quench sensitivity range of the alloy was obtained. Based on the results, the quench factor analysis (QFA) method was used to predict the mechanical properties of alloy at different cooling rates. The microstructure transformation of the alloy during isothermal process was analyzed by phase transformation kinetics. The results show that the quench sensitivity range is 295–445°C with the nose temperature of 370°C. The phase transformation rate of the alloy at 460°C is higher than that at 280°C based on the results of phase transformation kinetics. The rod-shaped β-Mg2Si phases precipitate during the isothermal process and grow up with the extension of holding time, which Reduce the density of the fine age-induced precipitates β '' and increase the size of precipitate free zones (PFZ) after the followed aging treatment. The critical cooling rate of the alloy should be higher than 7.7°C /s to obtain good comprehensive mechanical properties.

Acute Kidney Injury in Rhabdomyolysis: A 5-Year Children's Hospital Network Study.

Rhabdomyolysis is a skeletal muscle injury that can cause myoglobinuria and acute kidney injury (AKI). Risk factors for AKI in children are not clearly understood with no standardized treatment guidelines for rhabdomyolysis. Our study explores factors associated with AKI and management of pediatric patients with rhabdomyolysis. Medical records from a children's hospital network over a 5-year period were retrospectively reviewed. The results are described with respect to the presence or absence of AKI. Of the 112 patients who met the inclusion criteria, AKI incidence was 7.1% (n = 8), with all affected patients having exertional etiology. The overall mean age was 13.5 years; patients without AKI were younger than patients with AKI (13.3 versus 17; p < 0.001). Using regression models for hypothesis generation, we found that patients with AKI were more likely to be older (OR = 1.44, 95%CI [1.11-2.19]; p = 0.03), have myoglobinuria (OR = 22.98, 95%CI [2.05-432.48]; p = 0.02), and have received intravenous bicarbonate (OR = 16.02, 95%CI [1.44-228.69]; p = 0.03). In our study, AKI was uncommon and associated with older age, myoglobinuria and bicarbonate treatment. Larger, prospective studies are needed to further understand AKI risk factors and optimal management of pediatric rhabdomyolysis.

Unveiling the Stability of Encapsulated Pt Catalysts Using Nanocrystals and Atomic Layer Deposition.

Platinum exhibits desirable catalytic properties, but it is scarce and expensive. Optimizing its use in key applications such as emission control catalysis is important to reduce our reliance on such a rare element. Supported Pt nanoparticles (NPs) used in emission control systems deactivate over time because of particle growth in sintering processes. In this work, we shed light on the stability against sintering of Pt NPs supported on and encapsulated in Al2O3 using a combination of nanocrystal catalysts and atomic layer deposition (ALD) techniques. We find that small amounts of alumina overlayers created by ALD on preformed Pt NPs can stabilize supported Pt catalysts, significantly reducing deactivation caused by sintering, as previously observed by others. Combining theoretical and experimental insights, we correlate this behavior to the decreased propensity of oxidized Pt species to undergo Ostwald ripening phenomena because of the physical barrier imposed by the alumina overlayers. Furthermore, we find that highly stable catalysts can present an abundance of under-coordinated Pt sites after restructuring of both Pt particles and alumina overlayers at a high temperature (800 °C) in C3H6 oxidation conditions. The enhanced stability significantly improves the Pt utilization efficiency after accelerated aging treatments, with encapsulated Pt catalysts reaching reaction rates more than two times greater than those of a control supported Pt catalyst.

Phase transformation during solid-solution and aging treatment of a Mg-Gd-Y-Zn-Zr alloy containing LPSO and W phases

In this study, solid-solution and aging treatments were conducted on a hot-drawn Mg-9.5Gd-4Y–2Zn-0.3Zr alloy wire, which included long period stacking order (LPSO) phases and a Mg3Zn3RE2 (W phase) with a diameter of 4 mm. Subsequently, the phase transformations within the alloy were meticulously analyzed. Following solid solution treatment, the W-Mg3Zn3RE2 phase in the edge region almost completely dissolved, leaving behind blocky RE-rich phases. Conversely, the core region retained more of the original LPSO phase, resulting in significant microstructural differences between the core and the edge. The aging treatment induced a more pronounced hardening response in the core region, achieving a peak hardness of 136.33 HV at 96 h. By contrast, the edge regions exhibited a weaker aging response. Specifically, edge region 1 showed minimal fluctuations in hardness without significant hardening, while edge region 2 reached its peak hardness of 103.13 HV at 96 h. The differential hardening effects induced by aging treatment primarily stemmed from the formation and distribution of precipitate phases. Both the core region and edge regions initially precipitated β-Mg5Gd at the grain boundaries, with stacking faults (SFs) forming within the grains. However, dense and uniform precipitation of the β′-Mg7Gd phase also occurred within the core region. Therefore, controlling the precipitation of the W phase was crucial for tuning the mechanical properties of the Mg-9.5Gd-4Y–2Zn-0.3Zr alloy.

Rosemary extract activates oligodendrogenesis genes in mouse brain and improves learning and memory ability

Rosemary (Rosmarinus officinalis L.) is a rich source of dietary bioactive compounds such as rosmarinic acid and carnosol with a large repertoire of pharmacological properties, including anti-inflammatory and neuroprotective activities. In the present study, we investigated rosemary as a potential new therapeutic agent for cognitive function and other symptoms of aging. In this present study, we have aimed to investigate the effects of oral administration of rosemary extract (RME) on learning and memory in the context of other biomarkers-related cognitive function and neurotransmitter levels in senescent accelerated prone 8 (SAMP8) mouse, a model of accelerating aging and Alzheimer’s disease. The Morris water maze (MWM) test showed improved spatial learning and memory behavior in RME treated SAMP8 mouse. Moreover, RME decreased Aβ42 and inflammatory cytokine levels and increased BDNF, Sirt1, and neurotransmitter levels in SAMP8 mouse. Whole-genome microarray analysis revealed that RME significantly increased gene expression related to oligodendrocyte differentiation, myelination, and ATP production in the hippocampus and decreased gene expression related to stress, neuroinflammation, and apoptosis. Also, in the SAMP8 hippocampus, RME significantly increased Olig1 and Olig2 expression. Altogether, our study is the first to report improvement of spatial learning and memory of RME, modulation of genes important for oligodendrogenesis, and Anti-neuroinflammatory effect by suppressing Aβ42 levels in mouse brain and thus highlights the prospects of RME in the treatment of cognitive dysfunction and aging.

Lumican is Both a Novel Risk Factor and Potential Plasma Biomarker for Vascular Aging, Capable of Promoting VSMCs Senescence through Interacting with Integrin α2β1.

Vascular aging, a common pathogenesis of senile chronic diseases, significantly increases morbidity and mortality in older adults; its intricate cellular and molecular mechanisms necessitate further investigation. Lumican (LUM) and integrin α2β1(ITGα2β1) are profibrotic extracellular matrix proteins and vital cell regulatory receptors, respectively. However, their roles in vascular aging remain unclear. This study sought to elucidate the connection between LUM and vascular aging as well as the biological mechanism of LUM/ITGα2β1 in this process. Using an enzyme-linked immunosorbent assay, we discovered that plasma LUM was elevated in vascular aging individuals and was positively correlated with brachial-ankle pulse wave velocity. Additionally, immunohistochemical and western blot analyses confirmed LUM upregulation in arteries of older adults and aged mice, as well as in senescent vascular smooth cells (VSMCs). Wild-type and LUM semiknockout (Lum-/+) mice, along with primary VSMCs extracted from these mice, were exposed to angiotensin II (Ang II) to induce stress-induced senescence model. LUM semiknockout mitigated Ang Ⅱ-induced arteriosclerosis, hypertension, vascular aging and remodeling in mice. Both in vitro and in vivo studies revealed that LUM deficiency suppressed p53, p21, collagen 1 and collagen 3 upregulation and synthetic phenotype formation in VSMCs stimulated by Ang Ⅱ. Treating VSMCs with a ITGα2β1 antagonist reversed the aforementioned changes triggered by LUM proteins. Briefly, LUM functions as a potential marker and risk factor for vascular aging and promotes pathological changes by affecting ITGα2β1 in VSMCs. This study introduces a novel molecular target for the early diagnosis and treatment of vascular aging and age-related vascular diseases.