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As a new type of surface engineering technology， ultrahigh-speed laser cladding technology has the advantages of rapid processing，precision control， and low thermal influence， which is applicable to the preparation of coatings on a variety of materials.In order to study the effect of cladding speed on the microstructure and properties of M2 coatings， M2 coatings were prepared on the surface of Q235 steel using ultrahigh-speed laser cladding technology.The influence of cladding speed on the microstructure and properties of the coatings was studied.The microstructure， phase composition， hardness， wear resistance， and corrosion resistance of the coatings were tested using scanning electron microscopy (SEM)， X-ray diffraction (XRD)， a hardness tester， a tribometer， and an electrochemical workstation， respectively.Results showed that at a cladding speed of 1.2 m/min， the coating was seamlessly bonded to the substrate， with a microhardness of 757.1 HV， a friction coefficient of 0.448， and a corrosion current density Jcorr of 1.98 × 10-6 A/cm2.As the cladding speed increased， gaps appeared at the coating-substrate interface， grain size decreased， dilution rate decreased， hardness increased， and friction coefficient decreased.At a cladding speed of 40.0 m/min， larger cracks formed at the coating-substrate interface， with an equivalent average grain diameter of 1.76 μm， a dilution rate of 6.8%， an average microhardness of 828.1 HV， an average friction coefficient of 0.345， and a corrosion current density Jcorr of 1.26 ×10-7 A/cm2.The cladding speed had a significant impact on the macroscopic morphology and performance of the ultra-high-speed laser cladding coatings.With increasing cladding speed，cracks appeared in the coating region，while the equivalent diameter of the grains decreased and the hardness， wear resistance， and corrosion resistance improved.The phase composition of all coatings consisted of martensite， retained austenite， and carbides.This work provides a theoretical basis for the preparation and parameter optimization of M2 high-speed steel materials.

Laser spraying technology is a new type of thermal spraying technology， which is based on the principle of using laser as a heat source to heat the powder so that the particles reach a molten or semi-molten state and form a coating on the surface of the substrate.In this work， the nickel coatings were fabricated on the surface of nickel mesh through laser spraying.The surface morphology of the coatings was characterized by scanning electron microscopy (SEM).The catalytic activity of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) of electrodes was characterized by electrochemical methods， and the effect of nickel particle size on the electrolytic catalytic performance of coatings was studied.The results showed that the particle size affected the degree of melting of the particles when passing through the laser.The number of particles deposited on the surface of the prepared electrodes increased as the particle size decreased， and pore structure particles were found on the electrode surface， while the HER and OER overpotentials of the electrodes decreased， the double-layer capacitance value increased， and the impedance decreased， indicating that the HER and OER activities of the prepared electrodes were enhanced.The electrode prepared with an average particle size of 45 μm powder showed the best catalytic activity in HER and OER， with overpotentials of 416 mV and 371 mV， respectively， at a current density of 10 mA/cm2.This study provided a new method for the efficient and low-cost green preparation of catalytic electrodes for hydrogen production by alkaline water electrolysis.

Congenital heart disease (CHD) and patent ductus arteriosus (PDA) are risk factors of necrotizing enterocolitis (NEC) in infants. However, it is unclear whether the prognosis of NEC is different between very preterm infants (VPIs) with and without heart diseases. This was an observational cohort study that enrolled VPIs (born between 24+0 and 31+6 weeks) admitted to 79 tertiary neonatal intensive care units (NICU) in the Chinese Neonatal Network (CHNN) between 2019 and 2021. The exposure was CHD or isolated PDA, and VPIs with NEC were divided into three groups: complicated with CHD, with isolated PDA, and without heart diseases. The primary outcomes were NEC-related adverse outcomes (death or extrauterine growth restriction (EUGR)). Logistic regression models were used to adjust potential confounders and calculate the odds ratios (ORs) and 95% confidential intervals (CIs) for each outcome. A total of 1335 VPIs with NEC were enrolled in this study, including 65 VPIs with CHD and 406 VPIs with isolated PDA. The VPIs with heart diseases had smaller gestational ages and lower body weights at birth, more antenatal steroids use, and requiring inotrope prior to the onset of NEC. While suffering from NEC, there was no significant increased risks in NEC-related death in VPIs with either CHD (adjusted OR [aOR]: 1.10; 95% CI: 0.41–2.50) or isolated PDA (aOR: 1.25; 95% CI 0.82–1.87), and increased risks in EUGR were identified in either survival VPIs with CHD (aOR: 2.35; 95% CI: 1.31–4.20) or isolated PDA (aOR: 1.53; 95% CI: 1.16–2.01) in survivors. The composite outcome (death or EUGR) was also more often observed in VPIs with either CHD (aOR: 2.07; 95% confidence interval [CI]: 1.20–3.60) or isolated PDA (aOR: 1.51; 95% CI: 1.17–1.94) than that without heart diseases. VPIs with either CHD or isolated PDA were associated with significantly prolonged duration of fasting, extended time to achieve full enteral feeding, and longer ventilation duration and hospitalization duration. Similar characteristics were also seen in VPIs with isolated PDA, with the exception that VPIs with CHD are more likely to undergo surgical intervention and maintain a prolonged fast after NEC. Conclusion: In VPIs with NEC, CHD and isolated PDA are associated with an increased risk in worse outcomes. We recommend that VPIs with cardiac NEC be managed with aggressive treatment and nutrition strategies to prevent EUGR. What is Known: • CHD and PDA are risk factors for NEC in infants, which can lead to adverse outcomes such as death and EUGR. • NEC in infants with heart disease differs clinically from that in infants without heart disease and should be recognized as a separate disease process. What is New: • CHD and isolated PDA are associated with increased risks of EUGR in VPIs with NEC. • Risk factors associated with VPIs with cardiac NEC suggested these patients should be managed with aggressive treatment and nutrition strategies to adverse outcomes. [ABSTRACT FROM AUTHOR]

This multicenter retrospective study was conducted to explore the effects of different courses and durations of invasive mechanical ventilation (MV) on the respiratory outcomes of very low birth weight infants (VLBWI) in China. The population for this study consisted of infants with birth weight less than 1500 g needing at least 1 course of invasive MV and admitted to the neonatal intensive care units affiliated with the Chinese Neonatal Network within 6 h of life from January 1st, 2019 to December 31st, 2020. Univariate and multivariate logistic regression analyses were performed to evaluate associations between invasive MV and respiratory outcomes. Adjusted odds ratios (ORs) were computed with the effects of potential confounders. (1) Among the 3183 VLBWs with a history of at least one course of invasive MV, 3155 (99.1%) met inclusion criteria and were assessed for the primary outcome. Most infants received one course (76.8%) and a shorter duration of invasive MV (62.16% with ventilation for 7 days or less). (2) In terms of the incidence of all bronchopulmonary dysplasia (BPD) (mild, moderate, and severe BPD), there were no significant differences between different invasive MV courses [For 2 courses, adjusted OR = 1.11 (0.88, 1.39); For 3 courses or more, adjusted OR = 1.07 (0.72, 1.60)]. But, with the duration of invasive MV prolonging, the OR of BPD increased [8–21 days, adjusted OR = 1.98 (1.59, 2.45); 22–35 days, adjusted OR = 4.37 (3.17, 6.03); ≥ 36 days, adjusted OR = 18.44 (10.98, 30.99)]. Concerning severe BPD, the OR increased not only with the course of invasive MV but also with the duration of invasive MV [For 2 courses, adjusted OR = 2.17 (1.07, 4.40); For 3 courses or more, adjusted OR = 2.59 (1.02, 6.61). 8–21 days, adjusted OR = 8.42 (3.22, 22.01); 22–35 days, adjusted OR = 27.82 (9.08, 85.22); ≥ 36 days, adjusted OR = 616.45 (195.79, > 999.999)]. (3) When the interaction effect between invasive MV duration and invasive MV course was considered, it was found that there were no interactive effects in BPD and severe BPD. Greater than or equal to three courses would increase the chance of severe BPD, death, and the requirement of home oxygen therapy. Compared with distinct courses of invasive MV, a longer duration of invasive MV (> 7 days) has a greater effect on the risk of BPD, severe BPD, death, and the requirement of home oxygen therapy. [ABSTRACT FROM AUTHOR]