Laser cleaning of RTV coating on the insulator surface by using millisecond pulse lasers.

High-efficiency and high-quality removal of sulfurized silicone rubber from insulator surfaces is paramount for high-voltage power systems. To address this issue, and aiming to achieve precise and nondestructive cleaning of room temperature vulcanized (RTV) coatings, we selected millisecond laser cleaning technology in this study. Successful and efficient cleaning of the RTV coating was performed by adjusting laser parameters. Characterization techniques, including scanning electron microscopy, energy-dispersive x-ray spectroscopy, and confocal microscopy, were employed to comprehensively assess the cleaning effects and ensure the integrity of the substrate surface. The results indicate that by adjusting the scanning power combination of the high power of the millisecond pulse laser to 200 W and the low power of 150 W, the glass substrate surface maintains excellent roughness and micro-morphological features after laser cleaning, providing optimal conditions for subsequent processing and utilization. This research contributes an efficient and cost-effective solution to the insulation treatment process in high-voltage power systems.

Facile Synthesis of Aminated Graphene Quantum Dots for Promising and Selective Detection of Cobalt and Copper Ions in Aqueous Media.

Due to the rapid development of industrialization, various environmental problems such as water resource pollution are gradually emerging, among which heavy metal pollution is harmful to both human beings and the environment. As a result, there are many metal ion detection methods, among which fluorescence detection stands out because of its rapid, sensitive, low cost and non-toxic characteristics. In recent years, graphene quantum dots have been widely used and studied due to their excellent properties such as high stability, low toxicity and water solubility, and have a broad prospect in the field of metal ion detection. A novel high fluorescence Cu2+, Co2+ sensing probe produced by graphene quantum hydrothermal treatment is reported. After heat treatment with hydrazine hydrate, the small-molecule precursor nitronaphthalene synthesized by self-nitrification was transformed from blue fluorescent GQDs to green fluorescent amino-functionalized N-GQDs. Compared with other metal ions, N-GQDs are more sensitive to Cu2+ and Co2+ on the surface, and N-GQDs have much higher selectivity to Cu2+ and Co2+ than GQDs. The strategy proposed here is simple and economical in design.

Fabrication of Orange Fluorescent Boron-Doped Graphene Quantum Dots for Al3+ Ion Detection.

Aluminum is a kind of metal that we often encounter. It can also be absorbed by the human body invisibly and will affect our bodies to a certain extent, e.g., by causing symptoms associated with Alzheimer's disease. Therefore, the detection of aluminum is particularly important. The methods to detect metal ions include precipitation methods and electrochemical methods, which are cumbersome and costly. Fluorescence detection is a fast and sensitive method with a low cost and non-toxicity. Traditional fluorescent nanomaterials have a high cost, high toxicity, and cause harm to the human body. Graphene quantum dots are a new type of fluorescent nanomaterials with a low cost and non-toxicity that can compensate for the defects of traditional fluorescent nanomaterials. In this paper, c-GQDs and o-GQDs with good performance were prepared by a bottom-up hydrothermal method using o-phenylenediamine as a precursor and citric acid or boric acid as modulators. They have very good optical properties: o-GQDs exhibit orange fluorescence under UV irradiation, while c-GQDs exhibits cyan fluorescence. Then, different metal ions were used for ion detection, and it was found that Al3+ had a good quenching effect on the fluorescence of the o-GQDs. The reason for this phenomenon may be related to the strong binding of Al3+ ions to the N and O functional groups of the o-GQDs and the rapid chelation kinetics. During the chelation process, the separation of o-GQDs' photoexcited electron hole pairs leads to their rapid electron transfer to Al3+, in turn leading to the occurrence of a fluorescence-quenching phenomenon. In addition, there was a good linear relationship between the concentration of the Al3+ ions and the fluorescence intensity, and the correlation coefficient of the linear regression equation was 0.9937. This illustrates the potential for the wide application of GQDs in sensing systems, while also demonstrating that Al3+ sensors can be used to detect Al3+ ions.

Laser processing of alumina ceramic by spatially and temporally superposing the millisecond pulse and nanosecond pulse train.

A novel combined laser pulses (CLPs) consisting of a millisecond (ms) pulse and an assisted nanosecond (ns) pulse train was proposed for drilling alumina ceramic. The processing efficiency and quality were well improved by spatially and temporally superposing the ms and ns laser beams. As a result, due to the multi-reflection of keyhole and ejection of melt, the temporally superposed CLPs could decrease the energy consumption of the drilling by an order of magnitude compared with the conventional ms pulse. On the other hand, the spatial distribution of the ns laser on the focal plane was elliptical due to the off-axis distortion of the optical system. However, since the reflection of the laser in the keyhole was non-uniform, the spatially superposed CLPs showed no dependence on the shape of the focused elliptical ns laser spot in terms of the drilling quality. The research results have an important guiding for improving the efficiency and quality of laser processing, especially for the alumina ceramic laser processing.

Nanosecond-millisecond combined pulse laser drilling of alumina ceramic.

A nanosecond-millisecond combined pulse laser (CPL) drilling method was proposed for drilling alumina ceramic. The total energy consumption of the CPL drilling was 1/7 of that of a conventional millisecond laser, and the drilling quality was better. The simulation results demonstrated that, due to the nonuniform reflection of the millisecond laser in the keyhole, the ellipse keyhole ablated by the off-axis incident nanosecond pulses had no effect on the circularity of the through hole. In addition, the multireflection of the laser in the keyhole enhanced the absorption, so the keyhole ablated by the nanosecond pulses could be used as a target for limiting the absorption of the subsequent millisecond pulses. In this context, the keyhole could be used to reduce the hole diameter if the subsequent millisecond laser had a bigger spot size, and this CPL drilling method could be used as an effective group hole drilling method.

Laser processing of alumina ceramic by a spatially superposing millisecond laser and a nanosecond laser with different beam shapes.

Advanced combined pulse laser (CPL) processing technology with high processing efficiency is of interest for both academic and engineering prospects. However, the influence of the spatial superposition of the CPL on the processing quality is unclear. Here, we use a CPL composed of a nanosecond and millisecond laser with different beam shapes to drill alumina ceramic. Experimental and simulation results suggest that the CPL drilling process actively homogenizes the laser in the hole through multi-reflection of the laser, and thus holes with high circularity are obtained without the influence of the beam shape of the nanosecond laser. The research shows this to be a novel processing method, and that the processing quality is independent of the laser beam shape.

Evaluation of amplified spontaneous emission in thin disk lasers using the spectral linewidth.

Amplified spontaneous emission (ASE) is important to power scaling of the large-scale, high-gain thin disk laser. In this paper, spectral properties of ASE in Yb:YAG thin disk lasers are deeply studied in both theory and experiment. The experimental results show that the ASE strength is much stronger when emitted from the edge surface than the pumping area. And the spectrum of ASE emitted from the coarsened edge surface is angle independent. Meanwhile, the reabsorption effect in the Yb:YAG crystal on spectral linewidth is analyzed and corrected. Finally, ASE spectral linewidths have been measured. We demonstrate that the spectral linewidths can evaluate ASE strength effectively.

Experimental study on the optimum matching of CW-nanosecond combined pulse laser drilling.

A combined pulse laser (CPL) drilling method that consisted of a continuous wave (CW) laser and an assisted nanosecond laser was used for drilling the Q235B steel. The influence of the repetition rate of the nanosecond laser on the CPL drilling efficiency was analyzed. The results show that the plasma screening threshold during the CPL drilling was about ${1.40} \times {{10}^9}\,\,{\rm W}/{{\rm cm}^2}$1.40×109W/cm2. When the peak power density of the nanosecond laser exceeded the plasma screening threshold, it still could not compensate for the energy loss caused by the plasma screening, even though the high-pressure shock wave introduced by the plasma could improve the drilling efficiency. On the other hand, when the peak power density of the nanosecond laser was lower than the plasma screening threshold, it was shown that the optimum matching between the CW laser and nanosecond laser could be obtained when the repetition rate of the nanosecond laser was between 10 and 25 kHz. Finally, the results show that the CPL drilling method had a better drilling efficiency and quality than conventional millisecond laser drilling.

Reflow soldering method with gradient energy band generated by optical system.

Laser reflow soldering is an important technology in electronic components processing. In this paper, we presented a simple but efficient method to achieve reflow soldering process with gradient energy band created by just two parallel mirrors. The detailed influence of the variety of optical parameters on the soldering process has been analyzed by using the finite element method. And the modulation of the optical parameters on reflow soldering parameters also has been demonstrated. In our experiment, one HR mirror and one-mirror with transmissivity of 10% have been used to create a gradient energy band with an incident laser power of 50W. In summary, both the simulations and the experiments show that the typical reflow soldering profile has been acquired by the optical system. The high quality joints on both the front and rear surface of the capacitor can be acquired by just one surface radiation of the optical system.

Numerical analysis of a multi-pass pumping Yb:YAG thick-disk laser with minimal heat generation.

A theoretical model is established to describe the dynamic behavior and fractional thermal load of a multi-pass pumping Yb:YAG thick-disk laser, which is pumped at 1030 nm and emits laser radiation at around 1048 nm. The fractional thermal load, the temperature of the thick-disk crystal, and the operational properties for different ambient temperatures and different output coupler transmissions are investigated in detail. The results show that the pump saturation effect and the laser threshold are sensitive to the ambient temperature and the output coupler transmission, which affect the fractional thermal load and the laser extraction efficiency. Furthermore, a new design scheme is proposed to realize "zero thermal load" throughout the output range by dynamically adjusting the output coupler transmission.

Analytical model of amplified spontaneous emission with different thickness anti-ASE caps for thin disk lasers.

The amplified spontaneous emission (ASE) effect is a major factor affecting large, high gain Yb:YAG thin disk lasers. In this paper, the analytical model is built to estimate the ASE photon flux density of thin disk crystals with different thickness anti-ASE caps. Theoretical analysis shows that it is unnecessary to use a critical thickness anti-ASE cap to suppress the ASE effect. At the same time, adjusting the coupler reflectivity of the resonator is an effective way to decrease the ASE effect and decrease the thickness of the anti-ASE cap to effectively suppress the ASE effect. This paper will better reveal how the anti-ASE cap suppresses the ASE effect.

CC-chemokine receptor 7 is overexpressed and correlates with growth and metastasis in prostate cancer.

Multiple studies have shown that CC-chemokine receptor 7 (CCR7) promotes cell proliferation in several human cancers. We investigated the expression and clinical significance of CCR7 in our large collection of prostate cancer (PCa) samples and explored its function on the proliferation and migration of PCa cells. In this study, the expression of CCR7 was examined by immunohistochemical staining and quantitative RT-PCR in primary PCa tissues from 60 patients who underwent radical prostatectomy. Then, we investigated the functional role of CCR7 in PCa cell proliferation and migration by small interfering RNA-mediated depletion. The positive rate of CCR7 staining was 88.33 % (53/60) in the PCa group and 16.67 % (10/60) in cases of benign prostate hyperplasia (BPH); the difference of CCR7 expression between PCa and BPH was statistically significant. The results were confirmed by quantitative real-time PCR. CCR7 was significantly elevated in all five PCa cell lines when compared to the RWPE-1 cells. Silencing of CCR7 inhibited the proliferation of PC3 cells which have a relatively high level of CCR7 in a time-dependent manner, and the invasion and migration of PC3 cells were distinctly suppressed. Our data suggest that the pathogenesis of human PCa maybe mediated by the CCR7, and thus CCR7 could represent selective targets for the molecularly targeted treatments of PCa.

Experimental and Thermal Stress Field Numerical Simulation Study on Laser Metal Deposition of Ti-48Al-2Cr-2Nb Alloy.

The experimental and numerical simulation analysis of a TiAl alloy by laser metal deposition technology is presented in this paper. The research examines the macroscopic morphology, microstructure, and mechanical properties of samples as laser power varies. It also delves into how the temperature field and residual stress evolve under different laser powers. The results reveal that the microstructure of samples is mainly composed of α2-Ti3Al phase and a γ-TiAl phase and that the details of the microstructure are significantly affected by laser power. As laser power increases, coarse lamellar structure content increases, corresponding to a decrease in α2 phase content. The deposited layer hardness ranges from 550 HV to 600 HV, and the average deposition layer hardness decreases with increased laser power. Simulation results predict the molten pool's size, temperature, and residual stresses. A significant increase in the molten pool size is observed when the laser power exceeds 1000 W, and the measured molten pool depths correspond closely to simulation predictions. However, significant tensile stresses are generated in the deposition layer due to high cooling rates, mainly in the x direction. Cracks are observed on the surface of the deposition layer at all laser powers.

Genetic Testing for Global Developmental Delay in Early Childhood.

Importance: Global developmental delay (GDD) is characterized by a complex etiology, diverse phenotypes, and high individual heterogeneity, presenting challenges for early clinical etiologic diagnosis. Cognitive impairment is the core symptom, and despite the pivotal role of genetic factors in GDD development, the understanding of them remains limited. Objectives: To assess the utility of genetic detection in patients with GDD and to examine the potential molecular pathogenesis of GDD to identify targets for early intervention. Design, Setting, and Participants: This multicenter, prospective cohort study enrolled patients aged 12 to 60 months with GDD from 6 centers in China from July 4, 2020, to August 31, 2023. Participants underwent trio whole exome sequencing (trio-WES) coupled with copy number variation sequencing (CNV-seq). Bioinformatics analysis was used to unravel pathogenesis and identify therapeutic targets. Main Outcomes and Measures: The main outcomes of this study involved enhancing the rate of positive genetic diagnosis for GDD, broadening the scope of genetic testing indications, and investigating the underlying pathogenesis. The classification of children into levels of cognitive impairment was based on the developmental quotient assessed using the Gesell scale. Results: The study encompassed 434 patients with GDD (262 [60%] male; mean [SD] age, 25.75 [13.24] months) with diverse degrees of cognitive impairment: mild (98 [23%]), moderate (141 [32%]), severe (122 [28%]), and profound (73 [17%]). The combined use of trio-WES and CNV-seq resulted in a 61% positive detection rate. Craniofacial abnormalities (odds ratio [OR], 2.27; 95% CI, 1.45-3.56), moderate or severe cognitive impairment (OR, 1.69; 95% CI, 1.05-2.70), and age between 12 and 24 months (OR, 1.57; 95% CI, 1.05-2.35) were associated with a higher risk of carrying genetic variants. Additionally, bioinformatics analysis suggested that genetic variants may induce alterations in brain development and function, which may give rise to cognitive impairment. Moreover, an association was found between the dopaminergic pathway and cognitive impairment. Conclusions and Relevance: In this cohort study of patients with GDD, combining trio-WES with CNV-seq was a demonstrable, instrumental strategy for advancing the diagnosis of GDD. The close association among genetic variations, brain development, and clinical phenotypes contributed valuable insights into the pathogenesis of GDD. Notably, the dopaminergic pathway emerged as a promising focal point for potential targets in future precision medical interventions for GDD.

[Association between mutations of SCN9A gene and pain related to Parkinsonism].

OBJECTIVE: To screening mutations of exons 15, 18 and 26 of sodium channel Nav1.7 (SCN9A) gene, and to assess its association with pain related to Parkinsonism. METHODS: Respectively, 101 patients with primary Parkinson's disease (PD) and 104 similar-aged volunteers without PD were recruited from March, 2008 to January, 2011. Mutations of above 3 exons in SCN9A gene was detected with PCR and direct sequencing. For 100 patients with Parkinsonism, the pain was scored with a McGill pain rating scale. Statistical analysis was performed with SPSS. RESULTS: The prevalence of pain in Parkinsonian was 57%. 43.86% patients with pain were males, and 56.14% were females. Based on Chaudhuri criteria, the pain symptoms may be classified as musculoskeletal pain (10.52%), radicular pain (10.52%), dyskinesis pain (54.38%), pain from akathisia and restlessness (14.04%), dyskinesis combined with radicular pain (5.26%), skeletal muscles pain and headache (1.75%), and arthralgia (3.50%). Two missense mutations were identified, which included 2794A/C (0.941/0.059) (rs12478318) (M932L) in exon 15 and 3448C/T (0.988/0.012) (rs6746030) (R1150W) in exon 18. The wild type A/C for the 2794 locus had a higher prevalence in PD patients with pain, but this was not statistically different. All of the 5 heterozygotes for 3448 (C/T) were found in Parkinsonian patients with pain. No homozygotes were found. CONCLUSION: The prevalence of pain was higher in Parkinsonian patients than general population, and the proportion of males to females was similar. More patients have suffered dyskinesis pain. A 3448 (C/T) mutation of SCN9A gene may be related to pathogenesis of pain in Parkinsonism.

Direct Write Printing of Ultraviolet-Curable Bulk Superhydrophobic Ink Material.

Although superhydrophobic surfaces have various promising applications, their fabrication methods are often limited to 2D plane surfaces that are vulnerable to abrasion and have limited adhesion to the substrate. Herein, an ultraviolet (UV) curable ink with bulk superhydrophobicity, consisting of poly(dimethylsiloxane) (PDMS) resins, hydrophobic silica, and solvent (porogen), was successfully developed for UV-assisted direct write printing processing. After UV curing of the ink followed by solvent evaporation, the generated porous structure cooperates with silica particles to form a self-similar and hierarchical structure throughout the bulk material, which can keep its original morphology even after cyclic abrasion (over 1000 times) and thus exhibits durable superhydrophobicity. With this unique ink, UV-assisted direct write printing can not only create 2D superhydrophobic surfaces on various substrates (e.g., paper and wire mesh) but also fabricate self-supporting 3D superhydrophobic objects for various applications such as waterproofing and oil-water separation. The printed objects exhibited a stable superhydrophobicity against liquid corrosion and mechanical damage. In addition, the 3D printing approach can be used to optimize the oil-water separation performance of the superhydrophobic porous materials by tuning the pore size, thus presenting promising applications.

Effect of new nurse-led healthcare collaborative model on self-efficacy, compliance and quality of life in patients with chronic diseases.

OBJECTIVE: To explore the impact of routine management compared to case management on social support and self-efficacy of patients with chronic diseases and assess the new nurse-led healthcare collaborative model. METHODS: This is a prospective study which was approved by the Biomedical Ethics Committee of Anhui Medical University. A total of 100 patients with chronic diseases who received treatment and care in Hefei First People's Hospital from January 2020 to December 2021 were selected as the study subjects and divided into a control group and an observation group according to the numerical table method, with 50 cases in each group. In the control group, conventional management was implemented, while the observation received a nurse-led healthcare collaborative care, which included community doctors providing treatment services and family doctors contracting to manage care. The patients in the two groups were compared in terms of self-efficacy, self-management ability, social support, and their attendance. RESULTS: Before the intervention, there was no statistically significant difference in self-efficacy, compliance and quality of life scores between the two groups (P>0.05). After the intervention, self-efficacy, compliance and quality of life scores were significantly higher in the observation group than those in the control group, with statistically significant differences (P<0.05). A statistical assessment of the transfer of patients from the community to the hospital was also conducted for both groups, and it was found that the proportion of patients transferred from the community to the hospital was significantly higher in the observation group compared to that in the control group after surgery, with statistically significant differences in hospital costs, hospital days and readmission rates between the two groups (P<0.05). The proportion of patients transferred from the hospital to nursing home increased by 72.2% in the observation group compared to only 35.5% in the control group, and the discharge rate (home care) was significantly higher in the observation group (P<0.05). CONCLUSION: This study provides some references for the effective management of patients with chronic diseases. By comparing the data from the conventional and case care management models, it can be found that the use of a nurse-led healthcare collaborative model meets the acute medical and nursing service needs of older people, improves timely access to medical and nursing resources, and effectively improves self-efficacy, compliance and quality of life in patients with chronic diseases.

Numerical Simulation of Temperature Characteristics and Graphitization Mechanism of Diamond in Laser Powder Bed Fusion.

Thermal damage to diamonds is a major limitation in laser powder bed fusion (LPBF) processing of metal matrix diamond composites. In this paper, a numerical simulation model was established to describe the thermal effect of the Diamond-CuSn10 composite on the LPBF process. The simulation results show that the temperature of the diamond presents a double-peak structure, and the double-peak temperature curve shape can be modulated by modifying the laser scanning offset and the size of the diamond powder. And it suggests that the heat of the diamond mainly comes from the transfer of the molten pool. Then, combined with the experimental phenomenon, the mechanism of diamond graphitization in the LPBF process is analyzed. It indicates that since the surface defects of the diamond inhibit the heat conduction of the diamond, the temperature accumulates on the surface, leading to the graphitization of the diamond. Finally, based on this model, the potential of Ti-coated diamonds to prevent and reduce thermal damage in the LPBF process has been extensively studied. It is found that a Ti coating with low thermal conductivity can effectively reduce diamond temperature and improve diamond graphitization resistance. This study can provide a good method and basis for the preliminary selection of LPBF process parameters and the understanding of the graphitization mechanism of diamond tools.

Advances in Laser Drilling of Structural Ceramics.

The high-quality, high-efficiency micro-hole drilling of structural ceramics to improve the thermal conductivity of hot-end parts or achieve high-density electronic packaging is still a technical challenge for conventional processing techniques. Recently, the laser drilling method (LDM) has become the preferred processing tool for structural ceramics, and it plays an irreplaceable role in the industrialized processing of group holes on structural ceramic surfaces. A variety of LDMs such as long pulsed laser drilling, short pulsed laser drilling, ultrafast pulsed laser drilling, liquid-assisted laser drilling, combined pulse laser drilling have been developed to achieved high-quality and high-efficiency micro-hole drilling through controlling the laser-matter interaction. This article reviews the characteristics of different LDMs and systematically compares the morphology, diameter, circularity, taper angle, cross-section, heat affect zone, recast layer, cracks, roughness, micro-nano structure, photothermal effect and photochemical reaction of the drilling. Additionally, exactly what processing parameters and ambient environments are optimal for precise and efficient laser drilling and their recent advancements were analyzed. Finally, a summary and outlook of the LDM technology are also highlighted.

Knockdown of circ-FURIN suppresses the proliferation and induces apoptosis of granular cells in polycystic ovary syndrome via miR-195-5p/BCL2 axis.

BACKGROUND: Polycystic ovary syndrome (PCOS) is an endocrine disease that increases the risk of infertility. Circular RNAs (circRNAs) play important roles in regulating the biological processes of PCOS. Our study was designed to explore the function of circ-FURIN in PCOS. METHODS: Circ-FURIN expression was detected using RT-qPCR. The protein expression of AVEN, BCL2, XIAP and AREL1 was measured using western blot. Dual-luciferase reporter and RNA pull-down assays were applied to clarify the interaction between miR-195-5p and circ-FURIN or BCL2. Functionally, cell proliferation was assessed by MTT and colony formation assays. Cell apoptosis was analyzed by flow cytometry. RESULTS: Circ-FURIN was upregulated in PCOS patients and granular cells (GCs). Knockdown of circ-FURIN inhibited cell proliferation and promoted apoptosis of KGN cells, along with the increased expression of caspase-3 and Bax and the decreased levels of p-PI3K. Gene ontology (GO) analysis indicated circ-FURIN is associated with apoptotic signaling pathway and cell death. Subsequently, BCL2 expression was elevated in patients with PCOS and positively regulated by circ-FURIN. Furthermore, circ-FURIN was served as a sponge of miR-195-5p to directly target to BCL2. The levels of miR-195-5p were reduced in PCOS and KGN cells. Knockdown of circ-FURIN decreased the expression of BCL2, which was abolished by miR-195-5p inhibitor. At last, rescue experiments revealed that overexpression of BCL2 reversed the effects of circ-FURIN knockdown on cell proliferation and apoptosis of KGN cells. CONCLUSIONS: Loss of circ-FURIN alleviated the development of PCOS via miR-195-5p/BCL2 axis. Circ-FURIN may be the novel biomarker for PCOS.