Plug-and-play positioning error compensation model for ripple suppressing in industrial robot polishing.

The industrial robot-based polisher has wide applications in the field of optical manufacturing due to the advantages of low cost, high degrees of freedom, and high dynamic performance. However, the large positioning error of the industrial robot can lead to surface ripple and seriously restrict the system performance, but this error can only be inefficiently compensated for by measurement before each processing at present. To address this problem, we discovered the period-phase evolution law of the positioning error and established a double sine function compensation model. In the self-developed robotic polishing platform, the results show that the Z-axis error in the whole workspace after compensation can be reduced to ±0.06m m, which reaches the robot repetitive positioning error level; the Spearman correlation coefficients between the measurement and modeling errors are all above 0.88. In the practical polishing experiments, for both figuring and uniform polishing, the ripple error introduced by the positioning error is significantly suppressed by the proposed model under different conditions. Besides, the power spectral density (PSD) analysis has shown a significant suppression in the corresponding frequency error. This model gives an efficient plug-and-play compensation model for the robotic polisher, which provides possibilities for further improving robotic processing accuracy and efficiency.

Theoretical and experimental investigations in thermo-mechanical properties of fused silica with pulsed CO2 laser ablation.

Laser ablation is widely used as a flexible and non-contact processing technology for the fabrication of fused silica. However, the introduction of thermal stress inevitably leads to crack growth and reduces the lifetime of fused silica. Due to the complicated coupling interaction and properties of fused silica, the unclear thermal stress formation is the bottleneck restricting further development of laser ablation. In this article, a three-dimensional multi-physics thermo-mechanical model was developed to reveal the evolution mechanism, and experiments were performed to validate the simulated results. The surface morphology evolution was elaborated during process cycles, with recoil pressure identified as the key factor in determining surface morphology. Moreover, thermal stress was quantified utilizing optical retardance and stress birefringence, effectively distinguishing between non-thermal and thermal stress induced by laser ablation. The theoretical simulations fit well with experimental measurements. Meanwhile, stress distribution and evolution behaviors were revealed under different processing parameters by this model. This work not only contributes to a profound understanding of the laser ablation process but also establishes a theoretical foundation for achieving high surface quality and non-thermal stress laser ablation.

Cardiopulmonary prognosis of prophylactic endotracheal intubation in patients with upper gastrointestinal bleeding undergoing endoscopy.

BACKGROUND: It is controversial whether prophylactic endotracheal intubation (PEI) protects the airway before endoscopy in critically ill patients with upper gastrointestinal bleeding (UGIB). The study aimed to explore the predictive value of PEI for cardiopulmonary outcomes and identify high-risk patients with UGIB undergoing endoscopy. METHODS: Patients undergoing endoscopy for UGIB were retrospectively enrolled in the eICU Collaborative Research Database (eICU-CRD). The composite cardiopulmonary outcomes included aspiration, pneumonia, pulmonary edema, shock or hypotension, cardiac arrest, myocardial infarction, and arrhythmia. The incidence of cardiopulmonary outcomes within 48 h after endoscopy was compared between the PEI and non-PEI groups. Logistic regression analyses and propensity score matching analyses were performed to estimate effects of PEI on cardiopulmonary outcomes. Moreover, restricted cubic spline plots were used to assess for any threshold effects in the association between baseline variables and risk of cardiopulmonary outcomes (yes/no) in the PEI group. RESULTS: A total of 946 patients were divided into the PEI group (108/946, 11.4%) and the non-PEI group (838/946, 88.6%). After propensity score matching, the PEI group (n=50) had a higher incidence of cardiopulmonary outcomes (58.0% vs. 30.3%, P=0.001). PEI was a risk factor for cardiopulmonary outcomes after adjusting for confounders (odds ratio [OR] 3.176, 95% confidence interval [95% CI] 1.567-6.438, P=0.001). The subgroup analysis indicated the similar results. A shock index >0.77 was a predictor for cardiopulmonary outcomes in patients undergoing PEI (P=0.015). The probability of cardiopulmonary outcomes in the PEI group depended on the Charlson Comorbidity Index (OR 1.465, 95% CI 1.079-1.989, P=0.014) and shock index >0.77 (compared with shock index ≤0.77 [OR 2.981, 95% CI 1.186-7.492, P=0.020, AUC=0.764]). CONCLUSION: PEI may be associated with cardiopulmonary outcomes in elderly and critically ill patients with UGIB undergoing endoscopy. Furthermore, a shock index greater than 0.77 could be used as a predictor of a worse prognosis in patients undergoing PEI.

[Mechanism of Notch3 signaling pathway regulating the differentiation of aortic dissection vascular stem cells into smooth muscle cells].

OBJECTIVE: To explore whether the differentiation of vascular stem cells (VSC) into smooth muscle cells (SMC) in aortic dissection (AD) is dysregulated, and to verify the role of Notch3 pathway in this process. METHODS: Aortic tissues were obtained from AD patients undergoing aortic vascular replacement and heart transplant donors at Department of Cardiovascular Surgery, Guangdong Provincial People's Hospital Affiliated to Southern Medical University. VSC were isolated by enzymatic digestion and c-kit immunomagnetic beads. The cells were divided into normal donor-derived VSC group (Ctrl-VSC group) and AD-derived VSC group (AD-VSC group). The presence of VSC in the aortic adventitia was detected by immunohistochemical staining, and VSC was identified by stem cell function identification kit. The differentiation model of VSC into SMC established in vitro was induced by transforming growth factor-ß1 (10 µg/L) for 7 days. They were divided into normal donor VSC-SMC group (Ctrl-VSC-SMC group), AD VSC-SMC group (AD-VSC-SMC group) and AD VSC-SMC+Notch3 inhibitor DAPT group (AD-VSC-SMC+DAPT group,DAPT 20 µmol/L was added during differentiation induction). The expression of contractile marker Calponin 1 (CNN1) in SMC derived from aortic media and VSC were detected by immunofluorescence staining. The protein expressions of contractile markers α-smooth muscle actin (α-SMA), CNN1 as well as Notch3 intracellular domain (NICD3) in SMC derived from aortic media and VSC were detected by Western blotting. RESULTS: Immunohistochemical staining showed there was a population of c-kit-positive VSC in the adventitia of aortic vessels, and VSC from both normal donors and AD patients had the ability to differentiate into adipocytes and chondrocytes. Compared with normal donor vascular tissue, the expressions of SMC markers α-SMA and CNN1 of tunica media contraction in AD were down-regulated (α-SMA/ß-actin: 0.40±0.12 vs. 1.00±0.11, CNN1/ß-actin: 0.78±0.07 vs. 1.00±0.14, both P < 0.05), while the protein expression of NICD3 was up-regulated (NICD3/GAPDH: 2.22±0.57 vs. 1.00±0.15, P < 0.05). Compared with Ctrl-VSC-SMC group, the expressions of contractile SMC markers α-SMA and CNN1 were down-regulated in AD-VSC-SMC group (α-SMA/ß-actin: 0.35±0.13 vs. 1.00±0.20, CNN1/ß-actin: 0.78±0.06 vs. 1.00±0.07, both P < 0.05), the protein expression of NICD3 was up-regulated (NICD3/GAPDH: 22.32±1.22 vs. 1.00±0.06, P < 0.01). Compared with AD-VSC-SMC group, the expressions of contractile SMC markers α-SMA, CNN1 were up-regulated in AD-VSC-SMC+DAPT group (α-SMA/ß-actin: 1.70±0.07 vs. 1.00±0.15, CNN1/ß-actin: 1.62±0.03 vs. 1.00±0.02, both P < 0.05). CONCLUSIONS: Dysregulation of VSC differentiation into SMC occurs in AD, while inhibition of Notch3 pathway activation can restore the expression of contractile proteins in VSC-derived SMC in AD.

Densi-melting effect for ultra-precision laser beam figuring with clustered overlapping technology at full-spatial-frequency.

Laser beam figuring (LBF), as a processing technology for ultra-precision figuring, is expected to be a key technology for further improving optics performance. To the best of our knowledge, we firstly demonstrated CO2 LBF for full-spatial-frequency error convergence at negligible stress. We found that controlling the subsidence and surface smoothing caused by material densification and melt under specific parameters range is an effective way to ensure both form error and roughness. Besides, an innovative "densi-melting" effect is further proposed to reveal the physical mechanism and guide the nano-precision figuring control, and the simulated results at different pulse durations fit well with the experiment results. Plus, to suppress the laser scanning ripples (mid-spatial-frequency (MSF) error) and reduce the control data volume, a clustered overlapping processing technology is proposed, where the laser processing in each sub-region is regarded as tool influence function (TIF). Through the overlapping control of TIF figuring depth, we achieved LBF experiments for the form error root mean square (RMS) reduced from 0.009λ to 0.003λ (λ=632.8 nm) without destroying microscale roughness (0.447 nm to 0.453 nm) and nanoscale roughness (0.290 nm to 0.269 nm). The establishment of the densi-melting effect and the clustered overlapping processing technology prove that LBF provides a new high-precision, low-cost manufacturing method for optics.