Efficient Fabrication of Quartz Glass Using Laser Coaxial Powder-Fed Additive Manufacturing Approach.

This article investigates a laser-directed energy deposition additive manufacturing (AM) method, based on coaxial powder feeding, for preparing quartz glass. Through synergistic optimization of line deposition and plane deposition experiments, key parameters of laser coaxial powder feeding AM were identified. The corresponding mechanical properties, thermal properties, and microstructure of the bulk parts were analyzed. The maximum mechanical strength of the obtained quartz glass element reached 72.36 ± 5.98 MPa, which is ca. 95% that of quartz glass prepared by traditional methods. The thermal properties of the obtained quartz glass element were also close to those prepared by traditional methods. The present research indicates that one can use laser AM technology that is based on coaxial powder feeding to form quartz glass with high density and good thermodynamic properties. Such quartz glass has substantial potential in, for example, optics and biomedicine.

Harvesting Environment Mechanical Energy by Direct Current Triboelectric Nanogenerators.

As hundreds of millions of distributed devices appear in every corner of our lives for information collection and transmission in big data era, the biggest challenge is the energy supply for these devices and the signal transmission of sensors. Triboelectric nanogenerator (TENG) as a new energy technology meets the increasing demand of today's distributed energy supply due to its ability to convert the ambient mechanical energy into electric energy. Meanwhile, TENG can also be used as a sensing system. Direct current triboelectric nanogenerator (DC-TENG) can directly supply power to electronic devices without additional rectification. It has been one of the most important developments of TENG in recent years. Herein, we review recent progress in the novel structure designs, working mechanism and corresponding method to improve the output performance for DC-TENGs from the aspect of mechanical rectifier, tribovoltaic effect, phase control, mechanical delay switch and air-discharge. The basic theory of each mode, key merits and potential development are discussed in detail. At last, we provide a guideline for future challenges of DC-TENGs, and a strategy for improving the output performance for commercial applications.

Material removal characteristics and particle motions in abrasive water jet quantitative machining.

Abrasive water jet quantitative machining (AWJQM) is a method that enables the production of lightweight mirrors. Investigating material removal characteristics and particle motions in AWJQM is necessary to understand its erosion mechanism and improve its processability. A material removal model based on computational fluid dynamics was established in this study by integrating the transition condition of the brittle-ductile mechanism and the single-particle erosion model. Quantitative machining experiments were carried out to verify the material removal model, and experimental data were consistent with the simulation results. Further simulation experiments were carried out to explore the particle distribution under different working pressures or slurry viscosities. Results showed that operating parameters affect the workpiece surface profile by changing the flow field distribution and particle behavior.

A five-year review of prevalence and treatment outcomes of pre-extensively drug-resistant plus additional drug-resistant tuberculosis in the Henan Provincial Tuberculosis Clinical Medicine Research Centre.

OBJECTIVES: This study investigated the prevalence and significant clinical outcomes of pre-extensively drug-resistant plus additional drug-resistant tuberculosis (pre-XDR-plus) in Henan Provincial Chest Hospital between 2017 and 2021. METHODS: We analysed and summarized the drug sensitivity test (DST) results of clinical Mycobacterium tuberculosis (MTB) strains in TB patients seeking care in the Tuberculosis Clinical Medical Research Centre of Henan Province between 2017 and 2021. Medical records of pre-extensively drug-resistant plus additional drug-resistant TB patients were statistically analysed, including demographic characteristics, regimens, and outcomes. RESULTS: Of the 3689 Mycobacterium tuberculosis strains, 639 (17.32%), 353 (9.56%), and 109 (2.95%), multidrug-resistant tuberculosis (MDR-TB), pre-extensively drug-resistant tuberculosis (pre-XDR), and pre-XDR-plus, respectively. The proportion of MDR decreased from 19.1% in 2017 to 17.5% in 2021 (χ2 = 0.686, P = 0.407), the proportion of pre-XDR from 11.4% in 2017 to 9.0% in 2021 (χ2 = 2.39, P = 0.122), and pre-XDR-plus from 4.7% in 2017 to 1.8% in 2020, with the declining trend was significant (χ2 = 9.348, P = 0.002). The most commonly used anti-TB drugs were pyrazinamide (PZA, 37/46, 80.43%) and cycloserine (CS, 32/46, 69.57%), followed by linezolid (LZD, 25/46, 54.35%), protionamide (TH, 25/46, 54.35%), and para-aminosalicylic acid (PAS, 23/46, 50.00%). Patients receiving the LZD regimen were 5 times more likely to have a favourable outcome than those not receiving LZD (OR = 6.421, 95% CI 2.101-19.625, P = 0.001). Patients receiving a regimen containing CS were 4 times more likely to have a favourable outcome compared to those not taking CS (OR = 5.444, 95% CI 1.650-17.926, P = 0.005). CONCLUSIONS: Our data suggest that the population of pre-XDR-plus had significantly decreased over the past five years in the Henan Provincial Chest Hospital. The COVID-19 and flood disaster affect TB patients' selection of medical services. In addition, the pre-XDR-plus patients whose regimens contain LZD or CS were more likely to have favourable outcomes.

Post-operative blood pressure and 3-year major adverse cardiac events in Chinese patients undergoing PCI.

BACKGROUND: There is no clear evidence for the target value of blood pressure control after Percutaneous coronary intervention (PCI). Therefore, our study was designed to explore the relationship between blood pressure after PCI and major adverse cardiac events (MACE) during 3-year follow-up. METHODS: This study is a prospective study. We included the patients who were diagnosed with acute coronary syndrome and underwent PCI stent implantation operation. The study initially collected information of 552 patients. The start and end times of the study are from January 1, 2017 to December 31, 2020. The independent variables of this study are the average systolic blood pressure and the average diastolic blood pressure after PCI. The dependent variable is the occurrence of MACE events in patients within 3 years after PCI. MACE is defined as acute myocardial infarction, recurring chest pain, heart failure, stroke, revascularization and cardiac death. RESULTS: A total of 514 subjects met the inclusion criteria. The average age of the study subjects is 61.92 ± 9.49 years old, of which 67.12% are male. 94 subjects had a MACE event within 3 years, and the occurrence rate was 18.29%. There is no significant non-linear or linear relationship between diastolic blood pressure and MACE events. There is a curvilinear relationship between the average systolic blood pressure of patients after PCI and MACE events within 3 years and the inflection point is 121. On the left side of the inflection point, the effect size and 95% CI are 1.09 and 1.01-1.18, respectively (P = 0.029). The impact size and 95% CI at the right inflection point were 1.00 and 0.98-1.02(P = 0.604), respectively. CONCLUSION: There is a curvilinear relationship between systolic blood pressure and prognosis of patients after PCI. Under the premise of ensuring the safety of patients, maintaining lower blood pressure after surgery is beneficial to improve the prognosis of patients.

Mir-23a inhibition attenuates ischemic/reperfusion-induced myocardial apoptosis by targeting XIAP.

MicroRNAs are a group of single-strand, non-coding RNAs that inhibit the translation of protein-coding genes. Recent studies indicated that miRNAs are broadly involved in the development of cardiovascular diseases, including arrhythmia, hypertrophy, heart failure and cardiac injury. In this study, we report that miR-23a, a tumor suppressor, acts as an apoptotic promoter in rats undergoing ischemic/reperfusion. In rats subjected to ischemic/reperfusion injury, the expression of miR-23a in heart tissue was upregulated significantly. The infarct area and the apoptosis rate also increased. In contrast, knockdown of miR-23a by tail injection of antagomir-23a attenuated the ischemic/reperfusion injury. Moreover, we used Western blots to determine that miR-23a targeted XIAP to influence the expression of caspase and the NFkB pathway. In summary, miR-23a was shown to be part of a novel regulatory pathway that contributed to ischemic/reperfusion injury.

Short- and long-term efficacy and safety of triple vs. dual antithrombotic therapy in patients with drug-eluting stent implantation and an indication for oral anticoagulation: a meta-analysis.

BACKGROUND: The optimal antithrombotic regimen after coronary stenting in patients taking oral anticoagulants (OACs) is still unclear. Therefore, this meta-analysis focused on the short- and long-term efficacy and safety of triple therapy (TT: OAC, aspirin, and thienopyridine) and dual therapy (DT: OAC plus single antiplatelet drug or aspirin plus thienopyridine). METHODS: We searched PubMed, Embase, the Cochrane Library, Wangfang database, and Google Scholar up to December 1, 2015 (January 1, 2000 - December 2015), from randomized and nonrandomized studies comparing TT and DT in patients with OACs undergoing drug-eluting stent (DES) implantation. Major adverse cardiac and cerebrovascular events (MACCE) were the main outcome. Safety outcome was major bleeding (MB). RESULTS: Of 964 publications identified, 1 randomized study and 27 nonrandomized studies of 31,346 patients were included. Overall, TT and OAC plus clopidogrel were associated with a lower risk of MACCE, stroke, MI, and allcause mortality compared with dual antiplatelet therapy or OAC plus aspirin. Additionally, short-term use of triple antithrombotic regimen with OAC, aspirin, and clopidogrel is associated with equivalent risk of major bleeding and decreased rate of MACCE. Long-term use of OAC plus clopidogrel after TT was associated with equal or better benefit and safety outcomes. CONCLUSION: For patients on OAC after coronary stenting, triple therapy (OAC, aspirin, clopidogrel) should be considered in the short term, followed by more long-term therapy with OAC plus clopidogrel. More randomized studies are needed to confirm these findings.

[Synthesis of PANI/TiO3 nanorods composites by reverse micelle template and their properties].

PANI/TiO2 nano-composites with different amount of nanometer TiOz were synthesized by using reverse micelle formed from cationic surfactant cetyltrimethyl ammonium bromide (CTAB) as the template. The structure and properties of PANI/TiO2 nano-composites were investigated by FTIR, UV-Vis, TG, TEM and photoluminescence spectroscopy. The self-assembly mechanism of PANI/TiO2 nanorods composites in reversed micelle was discussed briefly. The results indicate that the synthesized nano-composites are PANI/TiO2 nanorods with an average diameter and length around 30-40 nm and 400 nm respectively. The infrared spectrum shows that a strong interaction exists between PANI and TiO2 nano-particles. The thermal stability of PANI/TiO2 nanorods improves with the contents of TiO2 increasing. The absorption of PANI/TiO2 nano-composites was found to be very intense in the range of violet and visible light by UV-Vis spectrum. The fluorescence of PANI/TiO2 nanorods was excited at 416 nm, and the intensity of fluorescence was strengthened greatly with increasing TiO2 concentration. The mechanism of the strengthened fluorescence quantum efficiency and fluorescence intensity of PANI/TiO2 was investigated through the charge transfer and exciton dissociation in PANI/TiO2 nanorods composites.

Effect of heart rate and coronary calcification on the diagnostic accuracy of the dual-source CT coronary angiography in patients with suspected coronary artery disease.

OBJECTIVE: To evaluate the diagnostic accuracy of a dual-source computed tomography (DSCT) coronary angiography, with a particular focus on the effect of heart rate and calcifications. MATERIALS AND METHODS: One hundred and nine patients with suspected coronary disease were divided into 2 groups according to a mean heart rate (< 70 bpm and >or= 70 bpm) and into 3 groups according to the mean Agatston calcium scores ( 400). Next, the effect of heart rate and calcification on the accuracy of coronary artery stenosis detection was analyzed by using an invasive coronary angiography as a reference standard. Coronary segments of less than 1.5 mm in diameter in an American Heart Association (AHA) 15-segment model were independently assessed. RESULTS: The mean heart rate during the scan was 71.8 bpm, whereas the mean Agatston score was 226.5. Of the 1,588 segments examined, 1,533 (97%) were assessable. A total of 17 patients had calcium scores above 400 Agatston U, whereas 50 had heart rates >or= 70 bpm. Overall the sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) for significant stenoses were: 95%, 91%, 65%, and 99% (by segment), respectively and 97%, 90%, 81%, and 91% (by artery), respectively (n = 475). Heart rate showed no significant impact on lesion detection; however, vessel calcification did show a significant impact on accuracy of assessment for coronary segments. The specificity, PPV and accuracy were 96%, 80%, and 96% (by segment), respectively for an Agatston score less than 100% and 99%, 96% and 98% (by artery). For an Agatston score of greater to or equal to 400 the specificity, PPV and accuracy were reduced to 79%, 55%, and 83% (by segment), respectively and to 79%, 69%, and 85% (by artery), respectively. CONCLUSION: The DSCT provides a high rate of accuracy for the detection of significant coronary artery disease, even in patients with high heart rates and evidence of coronary calcification. However, patients with severe coronary calcification (> 400 U) remain a challenge to diagnose.

Effects of granulocyte-colony stimulating factor on the repair of balloon-injured arteries.

BACKGROUND: The dysfunction of vascular endothelial cells plays a key role in starting arterial restenosis. The circulating endothelial progenitor cells (EPCs) can be mobilised by cytokines and are recruited to sites of injury, where they may participate in intima repair and the recovery of endothelial function. In the present study, we examined the hypothesis that mobilisation of EPCs by exogenous recombinant human granulocyte-colony stimulating factor (rhG-CSF) can promote vascular proliferation, reduce vascular inflammation and decrease the rate of restenosis. METHODS: Male rats were randomly divided into the rhG-CSF and control groups. The animals were injected daily with 30 microg/kg rhG-CSF or 0.9% NaCl subcutaneously for 7 days, then the animals underwent balloon angioplasty of the common carotid artery. The animals were euthanased at 2 or 4 weeks after injury, and the carotid arteries were harvested and processed for immunohistochemistry, scanning electron microscopy (SEM), morphometric analysis of endothelialisation and neointimal formation at 1 hour, and 3, 7, 14 and 28 days after injury. Immunohistochemistry for proliferation cell nuclear antigen (PCNA) and reverse transcriptase polymerase chain reaction (RT-PCR) for endothelial nitric oxide synthase (eNOS) mRNA were also conducted for evaluating the proliferation of cells of the vessel wall and the possible mechanism of the repairing. RESULTS: Four weeks after balloon damage, SEM showed increased re-endothelialisation of the denuded vessels in the G-CSF treated animals compared with the control animals [(60.6 +/- 7.3)% versus (41.6 +/- 3.3)%, p < 0.01]. Re-endothelialisation was paralleled by a decrease in inflammation in the vessel wall. Histological examination showed that neointimal formation, vascular smooth muscle cells and fibrous tissue of the G-CSF group were less than those of the control group. Morphometry showed the lumen area of the G-CSF group was larger than that of the control group, and the neointimal area and percent of intimal hyperplasia were significantly smaller than those of the control group. Immunohistochemical staining for PCNA positive cells was less in the G-CSF treated animals compared with the control animals (42.9% versus 72.8%, p < 0.01). CONCLUSION: rhG-CSF-induced mobilisation of EPCs regenerated endothelium and inhibited neointimal hyperplasia after vascular injury. This cytokine therapy may be a feasible strategy for the promotion of re-endothelialisation after angioplasty.

[Photophysical properties of poly (2-methoxy-5-octyloxy)-p-phenylene vinylene/TiO2 nano-composites].

The photoelectric composites of poly (2-methoxy-5-octyloxy)-p-phenylene vinylene/nanometer TiO2 (PMOCOPV/ TiO2) with different nanometer TiOz amount were synthesized through dehydrochlorination in-situ polymerization. The results of Fourier transform infrared spectroscopy and Raman spectroscopy indicated that the surface of nanometer TiO2 was coated with PMOCOPV. UV-Vis spectrum showed that the absorption of PMOCOPV/TiO2 nano-composites was strengthened in the range of violet and visible light with the contents of TiO2 increasing. The composite dimensions were observed by highly resolution transmission electron microscope, PMOCOPV/TiO2 nano-composites dispersed uniformly and possessed core-shell structure, the diameter of PMOCOPV/TiO2 was measured to be about 30 nm, and the thickness of the PMOCOPV coating was about 8-10 nm. Photoluminescence spectroscopy indicated that the maximum emission wavelength of the PMOCOPV/TiO2 was red-shifted with increasing TiO2 concentration. The fluorescence lifetime of PMOCOPV/TiO2 was about 1 ns. The intensity and lifetime of fluorescence was increased remarkably with the contents of TiO2 increasing. The mechanism of the strengthened fluorescence quantum efficiency and fluorescence intensity of PMOCOPV/TiO2 was investigated through the charge transfer, exciton dissociation and potential energy in PMOCOPV/TiO2 nano-composites.