Porosity in wire-arc directed energy deposition of aluminum Formation mechanisms, influencing factors and inhibition strategies

Wire-arc directed energy deposition (DED) offers advantages such as high forming efficiency and the ability to create parts without potential constraints on size. It possesses unique advantages in the high-efficiency production of large or ultra-large alloy metal components, for example aluminum. However, the issue of porosity in wire-arc DED aluminum alloys has been a subject of widespread discussion. Porosity defects can induce stress concentration and site for crack formation and propagation. This deterioration results in diminished tensile strength and fatigue resistance, limiting the potential applications of wire-arc DED in aluminum alloy builds. To this end, for the first time, this review offers a thorough examination of prevalent porosity imperfections in wire-arc DED aluminum alloys, including gas pores, shrinkage cavities and porosity arising from the volatilization of elements. Particular emphasis is placed on elucidating the formation mechanisms and spatial distribution of hydrogen pores, which constitute the primary pore defects in wire-arc DED aluminum alloys. Moreover, the research scrutinizes the influence of various wire-arc DED techniques, arc modes, process parameters, and shielding gas environments on porosity formation. The inhibition strategies of porosity defects in wire-arc DED aluminum alloys, including laser-arc hybrid additive manufacturing, ultrasonic vibration assistance, external magnetic field, inter-layer rolling, inter-layer friction stir processing, ultrasonic peening treatment, laser shock peening, and hot isostatic pressing, are further summarized. Ultimately, this work anticipates the future trajectory of wire-arc DED aluminum alloys, offering valuable guidance for the fabrication of high-quality wire-arc DED aluminum alloy intricate components

Consecutive Slides on Axial View Is More Effective Than Transversal Diameter to Differentiate Mechanisms of Single Subcortical Infarctions in the Lenticulostriate Artery Territory

Objective: Lipohyalinosis or atherosclerosis might be responsible for single subcortical infarctions (SSIs); however, ways of differentiating between the two clinically remain uncertain. We aimed to investigate whether consecutive slides on axial view or transversal diameter is more effective to differentiate mechanisms by comparing their relationships with white matter hyperintensities (WMHs).Methods: All the participants from the Standard Medical Management in Secondary Prevention of Ischemic stroke in China (SMART) cohort who had SSIs in the lenticulostriate artery territory were included and categorized according to consecutive slides on axial view (≥4 consecutive slices or not) and transversal diameter (≥15 mm or not). The associations between the severity of WMHs and the different categories were analyzed.Results: Among the 3,821 patients of the SMART study, 281 had diffusion-weighted image-proven SSIs in the lenticulostriate artery territory. When classified by consecutive slides on axial view, SSIs on ≥4 slices were significantly associated with the severity of the WMHs, both in deep WMH (DWMH) (odds ratio [OR], 0.32; 95% confidence interval [CI], 0.11–0.97; p = 0.04) and periventricular hyperintensity (PVH) (OR, 0.37; 95% CI, 0.17–0.78; p = 0.01). No such association was found on the basis of the transversal diameter (p > 0.1).Conclusion: Consecutive slides on axial view (≥4 consecutive slices) might be more effective than transversal diameter to identify the atherosclerotic mechanisms of SSIs in the lenticulostriate artery territory.Clinical Trial Registration:http://www.clinicaltrials.gov. Unique identifier: NCT0066484

Identification of diagnostic signatures associated with immune infiltration in Alzheimer’s disease by integrating bioinformatic analysis and machine-learning strategies

ObjectiveAs a chronic neurodegenerative disorder, Alzheimer’s disease (AD) is the most common form of progressive dementia. The purpose of this study was to identify diagnostic signatures of AD and the effect of immune cell infiltration in this pathology.MethodsThe expression profiles of GSE109887, GSE122063, GSE28146, and GSE1297 were downloaded from the Gene Expression Omnibus (GEO) database to obtain differentially expressed genes (DEGs) between AD and control brain samples. Functional enrichment analysis was performed to reveal AD-associated biological functions and key pathways. Besides, we applied the Least Absolute Shrinkage Selection Operator (LASSO) and support vector machine-recursive feature elimination (SVM-RFE) analysis to screen potential diagnostic feature genes in AD, which were further tested in AD brains of the validation cohort (GSE5281). The discriminatory ability was then assessed by the area under the receiver operating characteristic curves (AUC). Finally, the CIBERSORT algorithm and immune cell infiltration analysis were employed to assess the inflammatory state of AD.ResultsA total of 49 DEGs were identified. The functional enrichment analysis revealed that leukocyte transendothelial migration, cytokine receptor interaction, and JAK-STAT signaling pathway were enriched in the AD group. MAF basic leucine zipper transcription factor F (MAFF), ADCYAP1, and ZFP36L1 were identified as the diagnostic biomarkers of AD with high discriminatory ability (AUC = 0.850) and validated in AD brains (AUC = 0.935). As indicated from the immune cell infiltration analysis, naive B cells, plasma cells, activated/resting NK cells, M0 macrophages, M1 macrophages, resting CD4+ T memory cells, resting mast cells, memory B cells, and resting/activated dendritic cells may participate in the development of AD. Additionally, all diagnostic signatures presented different degrees of correlation with different infiltrating immune cells.ConclusionMAFF, ADCYAP1, and ZFP36L1 may become new candidate biomarkers of AD, which were closely related to the pathogenesis of AD. Moreover, the immune cells mentioned above may play crucial roles in disease occurrence and progression

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Analysis and research on power distribution law of power generation based on HHT transform

In recent years, tidal current power generation technology has achieved rapid development. On the basis of summarizing the characteristics of tidal current power generation, this paper comprehensively analyzes the distribution law of electric energy in tidal current power generation. Hilbert huang transform was applied to the trend of energy in power quality detection and analysis, the key can power on the trend of the measured data grouping processing, and carried out in accordance with the time period, such as day, month and year of HHT analysis, can get tide power distribution, can verify the HHT analysis in the trend of the power law research in the application feasibility and accuracy

Study on the Key Problems of UHVAC/DC Power Grids with New Generation Large Synchronous Condenser

In order to cope with the great pressure caused by the gradually exhaustion of fossil energy and environmental protection and climate warming, the development and application of the renewable energy has become an important foundation and development direction in the field of energy. However, due to the impact of energy and resource endowment, China’s load center and renewable energy base into the characteristics of long-range reverse distribution, the use of long-distance large-capacity transmission potential is necessary. With the “strong DC system and weak AC system” problem of the company power grid is increasingly prominent, the higher demand of dynamic reactive power support is put forward in the UHV DC power transmission project. Then, the large-capacity dynamic reactive power of new generation synchronous condenser is large-scale built up in the UHV DC/AC power system. Due to the high requirement of response speed and capacity in the UHV DC power transmission, the structure, dynamic characteristics, excitation control and relay protection and other aspects of the large synchronous condenser are different from generators and traditional synchronous condenser. Based on this, the dynamic reactive power demand of UHV DC power system is analyzed in this paper. Then, the main situation of large synchronous condenser is considered. In addition, the key points of the excitation control system and protection system are also discussed in this paper. There are important theoretical and practical significance for the safe and reliable operation of the UHV DC/AC power system

Study on the Key Problems of UHVAC/DC Power Grids with New Generation Large Synchronous Condenser

In order to cope with the great pressure caused by the gradually exhaustion of fossil energy and environmental protection and climate warming, the development and application of the renewable energy has become an important foundation and development direction in the field of energy. However, due to the impact of energy and resource endowment, China’s load center and renewable energy base into the characteristics of long-range reverse distribution, the use of long-distance large-capacity transmission potential is necessary. With the “strong DC system and weak AC system” problem of the company power grid is increasingly prominent, the higher demand of dynamic reactive power support is put forward in the UHV DC power transmission project. Then, the large-capacity dynamic reactive power of new generation synchronous condenser is large-scale built up in the UHV DC/AC power system. Due to the high requirement of response speed and capacity in the UHV DC power transmission, the structure, dynamic characteristics, excitation control and relay protection and other aspects of the large synchronous condenser are different from generators and traditional synchronous condenser. Based on this, the dynamic reactive power demand of UHV DC power system is analyzed in this paper. Then, the main situation of large synchronous condenser is considered. In addition, the key points of the excitation control system and protection system are also discussed in this paper. There are important theoretical and practical significance for the safe and reliable operation of the UHV DC/AC power system

Structural Characteristics and the Antioxidant and Hypoglycemic Activities of a Polysaccharide from Lonicera caerulea L. Pomace

In this study, a novel polysaccharide, LPP, was obtained from Lonicera caerulea L. pomace by ultrasonic-assisted heating and was purified by Sephadex G-100. The structural characteristics of LPP showed that the molecular weight (Mw) was 8.53 × 104 Da; that it was mainly composed of galacturonic acid, followed by galactose; that it possessed the characteristic functional groups of polysaccharides; and that it had an absence of O-glycosidic bonds and crystalline and triple helix structures. Furthermore, LPP exhibited a favorable thermodynamic stability and antioxidant, hypoglycemic, and hypolipidemic activities in a dose-dependent manner in vitro, demonstrating that LPP can be used as an agent to regulate glycolipid metabolism. Additionally, the relationship between its bio-activities is discussed in this paper. The results revealed that the RP, •OH, and NO2− radicals had synergistic promoting effects, and polysaccharides with a strong antioxidant ability may have excellent hypoglycemic and hypolipidemic effects. Collectively, these results suggest that LPP has a strong bio-activity, and that Lonicera caerulea L. pomace can be used as a potential polysaccharide source