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This study aims to address the issues of low efficiency and low depth-to-diameter ratio in traditional near-dry electric discharge machining of titanium deep holes. A method which using mixed gas atomized discharge ablation drilling (MA-DAD) to process titanium alloys is proposed. In this method, an atomized high-pressure mixed gas medium (a mixture of high-concentration O2 and low-concentration N2 media) is passed into the inter-electrode space. The atomized medium will react violently with the molten metal material in the inter-electrode, releasing a large amount of chemical energy to efficiently drill deep holes in titanium alloys. Compared to near-dry electric discharge drilling (N-EDD) of titanium alloys, the material removal rate (MRR) of MA-DAD was approximately twice that of N-EDD. Additionally, the depth-diameter ratio reaches 21, and the relative electrode wear rate (REWR) was reduced by 50%. Through orthogonal experiments, the effects of the electrode diameter, atomization amount, rotation speed, current, pulse width, and inter-pulse processing parameters on the process indicators including MRR and over cut (OC), were investigated. The Gray relational analysis technique was used for multi-objective optimization. The optimal combination of processing parameters was obtained, and deep hole processing of titanium alloy with an aspect ratio greater than 28 was achieved under existing conditions. [ABSTRACT FROM AUTHOR]

It may be difficult for existing methods to make full use of the correlation and complementarity of various kinds of information when processing multi-source information. In order to accurately perceive the security situation of distribution automation and ensure the safe and stable operation of distribution network, the multi-source information fusion distribution automation security situation awareness technology based on risk transmission path is studied. Based on the risk transmission path, the distribution automation security situational awareness factors are analyzed, and the main factors affecting the distribution automation security situation are divided into two dimensions: internal source and external source, and eight main awareness factors; Different types of sensors are set in the main areas of security situational awareness factors to collect data of different awareness factors. Using ant colony algorithm to optimize DS evidence fusion method, data with different perception factors are fused, and data fusion results with different perception factors are obtained. The distribution automation security situational awareness model is constructed, and the security situational awareness results are obtained based on the data fusion results of the awareness factors. If the results are higher than the set threshold, the abnormal signal can be output to determine the area where the distribution automation abnormal equipment is located. The experimental results show that the multi-source data fusion effect of this method is good, and it can accurately perceive the security status of different nodes of the experimental object at different time nodes. [ABSTRACT FROM AUTHOR]

Background: Fluorine-18 fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) has some limitations in diagnosis of Intrahepatic cholangiocarcinoma (ICC). Materials and methods: Patients with histologically confirmed ICC who underwent both [18F]FDG and 18F-labeled fibroblast-activation protein inhibitors ([18F]FAPI)-04 PET/CT were prospectively analyzed. The maximum standard uptake value (SUVmax), tumor-to-background ratio (TBR), metabolic tumor volume (MTV), total lesion glycolysis (TLG), [18F]FAPI–avid tumor volume (FTV), total lesion fibroblast activation protein expression (TLF) were compared between the two modalities by paired Wilcoxon signed-rank test and Mann–Whitney U test, and McNemar's test was used to assess the diagnostic accuracy between the two techniques. Results: In total, 23 patients with 389 lesions were included. Compared to [18F]FDG, [18F]F-FAPI-04 PET/CT demonstrated a higher detection rate for intrahepatic lesions (86.3% vs. 78.2% P = 0.040), lymph node metastases (85.2% vs. 68.2%, P = 0.007), peritoneal metastases (100% vs. 93.8%), and bone metastases (100% vs. 70.5%, P < 0.001). [18F]FAPI-04 PET showed higher SUVmax, TBR and greater tumor burden values than [18F]FDG PET in non-cholangitis intrahepatic lesions (SUVmax: 8.7 vs. 6.4, P < 0.001; TBR: 8.0 vs. 3.5, P < 0.001; FTV vs. MTV: 41.3 vs. 12.4, P < 0.001; TLF vs. TLG: 223.5 vs. 57.0, P < 0.001), lymph node metastases (SUVmax: 6.5 vs. 5.5, P = 0.042; TBR: 5.4 vs. 3.9, P < 0.001; FTV vs. MTV: 2.0 vs. 1.5, P = 0.026; TLF vs. TLG: 9.0 vs. 7.8 P = 0.024), and bone metastases (SUVmax: 9.7 vs. 5.25, P < 0.001; TBR: 10.8 vs. 3.0, P < 0.001; TLF vs. TLG: 9.8 vs. 4.2, P < 0.001). However, [18F]FDG showed higher radiotracer uptake (SUVmax: 14.7 vs. 8.4, P < 0.001; TBR: 7.4 vs. 2.8, P < 0.001) than [18F]FAPI-04 PET/CT for 6 patients with obstructive cholangitis. [18F]FAPI-04 PET/CT yielded a change in planned therapy in 6 of 23 (26.1%) patients compared with [18F]FDG. Conclusions: [18F]FAPI-04 PET/CT had higher detection rate and radiotracer uptake than [18F]FDG PET/CT in intrahepatic lesions, lymph node metastases, and distant metastases, especially in bone. Therefore, [18F]FAPI-04 PET/CT may be a promising technique for diagnosis and staging of ICC. Trial registration: Clinical Trials, NCT05485792. Registered 1 August 2022, retrospectively registered, https//clinicaltrials.gov/study/NCT05485792?cond=NCT05485792&rank=1. [ABSTRACT FROM AUTHOR]

In order to minimize the subsequent cutting of aerospace structural parts of difficult-to-machine materials such as high-temperature alloys and to shorten the machining cycle, this paper proposes a machining method that uses electrical discharge machining (EDM) for initial hollowing. The method adopts a U-shaped fine copper tube electrode, with an open row of holes on this electrode in the processing area, and uses deionized water as a working medium to take advantage of the jet effect. The copper tube electrode in the processing area takes part in reciprocating movement to complete the EDM hollowing processing. Three types of feeds—linear feed, S-shaped feed, and lateral reciprocating feed—were designed for the copper tube electrodes. The material removal rate and tool wear ratio of the three feeds are compared and the etching mechanism is analyzed. It is found that the transverse reciprocating feed has the highest material removal rate, 29.99 mm3/min, which is 255% and 135% greater than those of the linear feed and S-shaped feed, respectively. The tool wear ratio of the transverse reciprocating feed is the lowest, at 3%, less by 60% and 46%, respectively, than for the linear feed and the S-shaped feed. The interpolar medium flow field formed by the lateral reciprocating feed is found to be more conducive to chip discharge. At the same time, the lateral reciprocating feed creates a mixed gas-liquid medium environment between the poles, which increases the breakdown voltage and increases the discharge gap. These results are favorable to the discharge of etched products, thus improving the material removal rate and the processing stability. [ABSTRACT FROM AUTHOR]

Purpose: Neoadjuvant PD-1 blockade combined with chemotherapy is a promising treatment for resectable non-small cell lung cancer (NSCLC), yet the immunological mechanisms contributing to tumor regression and biomarkers corresponding to different pathological responses remain unclear. Methods: Using dynamic and paired blood samples from NSCLC patients receiving neoadjuvant chemoimmunotherapy, we analyzed the frequencies of CD8 + T-cell and Treg subsets and their dynamic changes during neoadjuvant treatment through flow cytometry. Cytokine profiles and function-related gene expression of CD8 + T cells and Tregs were analyzed through flow cytometry and mRNA-seq. Infiltrating T-cell subsets in resected tissues from patients with different pathological responses were analyzed through multiplex immunofluorescence. Results: Forty-two NSCLC patients receiving neoadjuvant chemoimmunotherapy were enrolled and then underwent surgical resection and pathological evaluation. Nineteen patients had pCR (45%), 7 patients had MPR (17%), and 16 patients had non-MPR (38%). In patients with pCR, the frequencies of CD137 + CD8 + T cells (P = 0.0475), PD-1 + Ki-67 + CD8 + T cells (P = 0.0261) and Tregs (P = 0.0317) were significantly different from those of non-pCR patients before treatment. pCR patients usually had low frequencies of CD137 + CD8 + T cells, PD-1 + Ki-67 + CD8 + T cells and Tregs, and their AUCs were higher than that of tissue PD-L1 expression. Neoadjuvant chemoimmunotherapy markedly improved CD8 + T-cell proliferation and activation, especially in pCR patients, as the frequencies of CD137 + CD8 + (P = 0.0136) and Ki-67 + CD8 + (P = 0.0391) T cells were significantly increased. The blood levels of cytokines such as IL-2 (P = 0.0391) and CXCL10 (P = 0.0195) were also significantly increased in the pCR group, which is consistent with the high density of activated cytotoxic T cells at the tumor site (P < 0.0001). Conclusion: Neoadjuvant chemoimmunotherapy drives CD8 + T cells toward a proliferative and active profile. The frequencies of CD137 + CD8 + T cells, PD-1 + Ki-67 + CD8 + T cells and Tregs at baseline might predict the response to neoadjuvant chemoimmunotherapy in NSCLC patients. The increase in IL-2 and CXCL10 might reflect the chemotaxis and enrichment of cytotoxic T cells at the tumor site and a better response to neoadjuvant chemoimmunotherapy. [ABSTRACT FROM AUTHOR]

Introduction: Lung cancer (LC) is the most common solid tumor and is currently considered the primary cause of cancer-related deaths worldwide. In clinical efficacy studies, it was not difficult to find that the combination of SFI and chemotherapy could improve the general condition of patients, reduce the side effects of chemotherapy drugs, and have a cooperative antitumor effect in NSCLC patients. However, whether SFI can be used as a novel antitumor drug is still unknown. Methods: First, meta-analysis aimed to explore the efficacy of SFI in NSCLC patients, and SFI was identified by ultra-performance liquid chromatography‒mass spectrometry (UPLC‒MS). Cell proliferation, migration, and invasion were explored by Cell Counting Kit-8 (CCK-8), scratch healing, and Transwell assays, respectively. Cell cycle and apoptosis assays were performed by flow cytometry. Transcriptome sequencing analysis was performed in four NSCLC cell lines. Differential expression analysis was used to identify potential targets. Apoptosis-related protein levels were detected by Western blotting assays. The effects of SFI in NSCLC were further investigated by mouse xenografts. Results: SFI could markedly improve the chemotherapy efficacy of NSCLC patients. The main active ingredients include flavonoids and terpenoids, which can effectively exert antitumor effects. SFI could not only inhibit tumor cell proliferation and cell migration/invasion but also regulate the cell cycle and promote tumor cell apoptosis. In NSCLC, SFI could enhance the transcription level of the CHOP gene, thereby upregulating the expression of the proapoptotic proteins Bax and caspase 3, and inhibiting the expression of the antiapoptotic protein Bcl-2. SFI hindered the growth of mouse NSCLC xenografts in vivo. Conclusions: SFI hindered tumor progression and might promote apoptosis by increasing the expression of Bax, caspase 3 and decreasing the level of Bcl-2 in NSCLC. [ABSTRACT FROM AUTHOR]

Owing to low machining efficiency, poor machining accuracy, and surface quality in traditional electrical discharge machining (EDM) of TC4 titanium alloy holes, an EDM trepanning method was developed using a deionized water medium and a flushing liquid in tube electrodes (denoted by EDM-TFD). Several experiments and research mechanisms were conducted on EDM-TFD. Compared with traditional EDM, ED milling, and EDM trepanning, EDM-TFD featured increased hole machining efficiency by more than five times, improved machining taper by more than 57%, and improved surface quality by more than 40%. The optimal processing technology was determined through process experiments using copper tube electrodes, a flushing liquid with a speed of 2 m/s, pulse width (Ton) of 150 μs, pulse interval (Toff) of 150 μs, and peak current (Ip) of 15 A. Under the optimized process, the hole exhibited a feed rate of 1.1 mm/min, machining efficiency of 38 mm3/min, machining taper of 40 μm, and surface roughness of 5.2 μm. Highlights: An EDM trepanning method was developed using a deionized water medium and a flushing liquid in tube electrodes (denoted by EDM-TFD). This method can process through-hole parts, only a small portion of the material is etched away, and most of the material exists in the form of cores, which can significantly reduce the volume of the etching and improve the processing efficiency. Compared with EDM, ED milling, and EDM-T, the EDM-TFD method featured increased machining efficiency by more than five times, increased machining taper by more than 57%, and improved surface quality by more than 40%. The effects of flushing speed and electrical parameters on the machining of titanium alloy holes were studied. The optimal processing technology was determined through process experiments using copper tube electrodes, a flushing liquid with a speed of 2 m/s, pulse width (Ton) of 150 μs, pulse interval (Toff) of 150 μs, and peak current (Ip) of 15 A. [ABSTRACT FROM AUTHOR]

Background: Diffuse large B-cell lymphoma (DLBCL) exhibits remarkable heterogeneity but still remains undiagnosed in identifying the subpopulation of DLBCL to predict the prognosis and guide clinical treatment. Methods: Molecular subgroups were identified in gene expression data from GSE10846 by a consensus clustering algorithm. And gene set enrichment analysis, immune infiltration, and the proposed cell cycle algorithm were applied to explore the biological functions of different subtypes. Meanwhile, univariate and multivariate Cox regression analyses were used to evaluate independent prognostic factors of DLBCL. Finally, the prognostic model, including some key genes screened by Lasso regression, Random Forest algorithm, and point-biserial correlation, was constructed by an optimal classifier from seven machine learning algorithms and validated by another three external datasets (GSE34171, GSE87371, GSE31312). Results: Comprehensive genomic analysis of 1,143 DLBCL samples identify 2 molecularly, prognostically relevant subtypes: immune-enriched (IME) and cell-cycle-enriched (CCE). Then a new predictive model including seven key genes (SERPING1, TIMP2, NME1, DCTPP1, RFC4, POLE2, and SNRPD1) was developed with high prediction accuracy (88.6%) and strong predictive power (AUC = 0.973) based on the Support Vector Machine (SVM) algorithm in 414 patients from GSE10846. The predictive power was similar in another three testing sets (HR > 1.400, p < 0.05). Conclusion: This model could evaluate survival independently with strong predictive power compared with other clinical risk factors. Our study constructed a reliable model to predict two new subtypes of DLBCL patients, which could guide the implementation of individualized treatment. [ABSTRACT FROM AUTHOR]

The heterogeneous CoS and WS2 composites were prepared via the simple hydrothermal method. The introduction of WS2 can reinforce the electrical conductivity of the composites. The introduction of WS2 can augment the specific surface area and pore space of the composite; polarization occurring in the two different materials results in enhanced absorption of electromagnetic waves. By changing the mass fraction of WS2 in CoS/Co9S8 materials, the composites can absorb electromagnetic waves to the greatest extent possible. When the CoS/Co9S8/WS2 composite containing 10 wt% of WS2, attains the minimum reflection loss (RLmin) of − 29.3 dB at the thickness of 1.3 mm in 16.9 GHz when the filler loading is 50 wt%. The results of the above experimental data prove that the prepared CoS/Co9S8/WS2 composites have the superiority of simple preparation, low weight, strong absorption capacity, thin thickness and wide bandwidth, which has high research value in microwave absorption field. [ABSTRACT FROM AUTHOR]

In China, post-loan management is usually executed in the form of a visit survey conducted by a credit manager. Through a quarterly visit survey, a large number of loan audit short texts, which contain valuable information for evaluating the credit status of small and micro-enterprises, are collected. However, methods for analysing this type of short text remain lacking. This study proposes a method for processing short loan audit texts called fuzzy clustering analysis (FCA). This method first transforms short texts into a fuzzy matrix through lexical analysis; it then calculates the similarity between records based on each fuzzy matrix and constructs an association graph with this similarity. Finally, it uses a prism minimum spanning tree to extract clusters based on different α cuts. Experiments using actual data from a commercial bank in China revealed that the FCA yields suitable clustering results when handling loan audit briefs. Moreover, it exhibited superior performance compared to BIRCH, k-means, and fuzzy c-means. [ABSTRACT FROM AUTHOR]

The long-existing contradiction between cutting speed and surface quality in wire electrical discharge machining (WEDM) detrimentally hinders its further development and application. To address this problem, this work proposed a multi-channel discharge method that performs WEDM on several workpieces, each electrically insulated and connected to a pulse power supply with a resistor. As a result, the machining energy normally exerted on one plasma channel can be dispersed into multiple discharge channels when each pulse voltage is applied. Firstly, the mechanism of multi-channel discharge was theoretically illustrated. Secondly, machining waveforms and high-speed imaging of gap phenomena were captured to prove the feasibility of multi-channel discharge in high-speed WEDM (HSWEDM). Although the multi-channel discharge is stochastic, a certain probability exists due to the vibration of wire electrodes. Lastly, verification experiments were conducted to investigate the performance of multi-channel discharge. The results indicate that the multi-channel discharge can significantly improve surface quality without reducing cutting speed, thus achieving a better balance between productivity and surface quality. [ABSTRACT FROM AUTHOR]

Objectives: Lung cancer is the most common form of cancer and the leading cause of cancer death. For familial lung cancer, identification of causing genetic factors is essential for prevention and control of non-lung cancer in carriers. Materials and methods: We studied two generations of a family with suspected inherited lung cancer susceptibility. Four individuals in this family had lung adenocarcinoma. To identify the gene(s) that cause the lung cancer in this pedigree, we extracted DNA from the peripheral blood of four cancer individuals and blood from three cancer-free family members as the control and performed whole-genome sequencing. Our filtering strategy includes, assessment of allele frequency, functional affection on amino acids, mutation accumulation, phased blocks and evolution analysis towards the alterations. Results: We identified two possible mutations, including PLEKHM2 (D134N) and MCC (R448Q) in all affected family members but did not found in the control group. Then, we performed a genetic susceptibility screening for 10 non-lung cancer relatives and found two individuals with PLEKHM2 (D134N) mutation, two with MCC (R448Q) mutation and one carrying both mutations. 3 carriers performed LDCT scan and 2 of them carried MCC (R448Q) also had ground-glass opacity (GGO) lesion in their lung. Conclusion: Our data suggested that WGS together with our filtering strategy was successful in identifying PLEKHM2 (D134N) and MCC (R448Q) as the possible driver mutations in this family. Genetic susceptibility screening of non-lung cancer carriers will be a useful approach to prevent and control lung cancer in families with high-risk for the disease. [ABSTRACT FROM AUTHOR]

Uneven distribution of discharge energy exists in high-speed wire electrical discharge machining (WEDM) when high-thickness workpiece (greater than 400 mm) is machined. To tackle this problem, a resistance model of the discharge circuit, considering the resistance of the wire electrode, is established to analyze the equivalent resistance of the circuit. When the conventional feeding circuit is used for machining, the discharge point moves from the middle part to the upper and lower ends along the thickness direction of the workpiece. This yields to a gradual decrease in the equivalent resistance in the discharge circuit and to an increase in the discharge energy, which results in a difference in the material removal at each workpiece section. In order to reduce the difference in discharge energy at the different discharge points, a rear-end feeding circuit, consisting of two separate feeding points with controllable discharge energy, is proposed. The number of MOSFETs that are turned on at the upper and lower feeding points will vary to adjust the discharge energy along the thickness direction of the workpiece. Moreover, it is verified through experiments that the change of discharge peak current is consistent with the workpiece material erosion. The conventional feeding circuit and the rear-end feeding circuit are used to cut the workpiece with a thickness of 400 mm, respectively. Compared to the conventional feeding circuit, when the wire electrode is in the positive traveling direction, the number of MOSFETs that are turned on at the upper feeding point is greater than those at the lower feeding point in the rear-end feeding circuit, and the material erosion at each workpiece section is more uniform; when the wire electrode is in the positive and negative traveling directions, the number of MOSFETs that are turned on at the upper and lower feeding points is equal in the rear-end feeding circuit, and the straightness error of the workpiece decreases by 36.36%. [ABSTRACT FROM AUTHOR]

In the work, heterophase nickel sulfide absorbers with wave absorption properties were prepared by a simple hydrothermal method. The nickel sulfide samples with the best wave absorption properties were obtained by adjusting the hydrothermal temperature. The results show that the nickel sulfide samples had excellent wave absorption performance by adjusting the hydrothermal temperature of 210 °C. Nickel sulfide has the best microwave absorption performance when it is filled with 50%. Among them, the corresponding minimum reflection loss value is -25.41 dB at 15.04 GHz, the effective absorption bandwidth is 4.24 GHz, and the thickness is 1.5 mm. Meanwhile, the particle size of nickel sulfide was changed by adjusting the reaction temperature. The enhanced absorption capacity of nickel sulfide is due to its reduced particle size and increased specific surface area. The results indicate that the nickel sulfide absorbing material prepared under the optimal reaction temperature conditions has the advantages of good absorption capacity, light weight, wide bandwidth, thin thickness and simple preparation. Thus, nickel sulfide is a promising wave-absorbing material. [ABSTRACT FROM AUTHOR]

Traditional electrochemical discharge machining (ECDM) is a hybrid of electrical discharge machining (EDM) and electrochemical machining (ECM). Electrical discharge erosion and electrochemical dissolution occur simultaneously in low-conductivity salt solution. It is very difficult to reduce the recast layers because of the low ratio of electrochemical dissolution. A novel combined machining approach combining electrical discharge ablation machining and electrochemical machining (EDAM-ECM) is proposed and the "electrolyte-oxygen" aerosol is used as the medium in this study. First, the electrical discharge ablation machining (EDAM) process is performed with oxygen in the aerosol medium to attain a higher material removal rate (MRR). Second, the electrochemical reaction current is increased by using a droplet of the electrolyte with higher conductivity. Third, the ratio of electrochemical dissolution is increased in an aerosol medium. The mechanism of conventional ECDM milling and EDAM-ECM milling was analyzed and comparable experiments were performed. Results show that EDAM-ECM milling has advantages of higher MRR, lower relative electrode wear ratio (REWR), and higher surface quality. Under the prescribed test conditions, the MRR increased by more than five times and the REWR is reduced by 94.1% compared with ECDM milling, and the recast layer is completely removed. [ABSTRACT FROM AUTHOR]

The use of a liquid medium in near-dry electrical discharge machining (EDM) with a two-phase gas‒liquid medium endows it with desirable characteristics such as a stable discharge process and high material removal rate. However, the effect mechanism of the liquid medium in near-dry EDM is not well understood, which limits its development. In this present, a variant of the near-dry EDM technology, namely, mixed-gas atomization discharge ablation processing (MA-DAP) of titanium alloy, is used to reveal the effect mechanism of a liquid medium in the process of near-dry EDM. This technology uses a mixed gas containing oxygen and a liquid medium to form the dielectric medium, so as to obtain a higher effective material erosion ability than near-dry EDM. Through the combination of experimental and theoretical modeling and analysis, it can be concluded that liquid dielectric water has the functions of endothermic cooling, inducing an intermittent gas supply environment between electrodes, efficient etching product removal, improving oxygen utilization efficiency, controlling oxygen diffusion speed, and increasing the discharge gap between electrodes, which can significantly improve the inter-electrode discharge state and material removal rate. Compared with conventional EDM, the material removal rate associated with MA-DAP technology increases by 16 times, and the relative wear rate of the electrode is reduced by more than 93%. [ABSTRACT FROM AUTHOR]

Purpose: This prospective study was aimed to investigate the potential utility of [18F]fibroblast activation protein inhibitor (FAPI) PET/CT for evaluating focal liver lesions (FLLs) with [18F]FDG non-avidity. Methods: From January 2021 to March 2022, this prospective study included 80 FLLs that were not avid on [18F]FDG PET/CT from 37 patients, then underwent [18F]FAPI PET/CT. All patients with FLL(s) with biopsy-proof or follow-up confirmation were categorized into four subgroups (20 hepatocellular carcinomas [HCCs]/5 non-HCC malignancies/4 inflammatory FLLs/8 benign noninflammatory FLLs). The diagnostic value of [18F]FAPI for detecting liver malignancy was determined by visual evaluation. Differences in the maximum standardized uptake value (SUVmax) and lesion-to-background ratio (LBR) obtained from [18F]FAPI PET/CT among the four subgroups were analyzed by semiquantitative analysis. Results: Among the thirty-seven enrolled participants (34 males; median age 57 years, range 48–67 years), on visual evaluation, the sensitivity, specificity, and accuracy of [18F]FAPI PET for detecting liver malignancy in the patient-based analysis were 96.0% (24/25), 58.3% (7/12), and 83.8% (31/37), respectively. On semiquantitative analysis, the SUVmax and LBR of [18F]FAPI PET in liver malignancy (33 HCC lesions; 19 non-HCC malignant lesions) were significantly higher than those in 11 benign noninflammatory FLLs [HCC: SUVmax: 6.4 vs. 4.5, P = 0.017; LBR: 5.1 vs. 1.5, P = 0.003; non-HCC: SUVmax: 5.5 vs. 4.5, P = 0.008; LBR: 4.4 vs. 1.5, P = 0.042]. Notably, there was no significant difference in the SUVmax of [18F]FAPI PET between 33 HCC lesions and 17 inflammatory FLLs (6.4 vs. 8.2, P = 0.37), but the LBR of [18F]FAPI PET in HCC were significantly lower than that in inflammatory FLLs (5.1 vs. 9.1, P = 0.003). Conclusions: [18F]FAPI PET/CT shows high sensitivity in detecting HCC and non-HCC malignancy with [18F]FDG non-avidity. [18F]FAPI might be a promising radiopharmaceutical for the differential diagnosis of benign noninflammatory FLLs and liver malignancy with [18F]FDG non-avidity. [ABSTRACT FROM AUTHOR]

To eliminate the recast layer on the surface machined by multi-pass wire electrical discharge machining (WEDM), hence improving the surface integrity, the present paper proposed and investigated a new combined machining process of performing wire electrochemical machining (WECM) after multi-pass WEDM on the same machine tool by utilizing the slight conductivity of the compound working fluid. A theoretical model based on the electric double layer and Faraday's law of electrolysis was established to calculate the wire feed rate for WECM finishing. Due to the exclusive film protection of the compound working fluid, the theoretical model was modified according to the experimental results under different electrolyte concentrations. Afterward, the optimized model was applied to guide the experiments of the combined process. An electrolyte concentration of 1:5 was used to facilitate the electrochemical reaction. The experimental results showed that the remaining recast layer after multi-pass WEDM could be completely removed at a wire feed rate of 10 µm/s, and a fine surface finish could be obtained. In addition, the surface roughness of the machined part was improved from 1.458 µm Ra to 0.683 µm Ra. [ABSTRACT FROM AUTHOR]

Baicalin (BA)-berberine (BBR) have been proposed as the couple in the prevention and treatment of numerous diseases due to their multiple functional attributes. However, with regard to certain factors involving unsatisfactory aqueous solubility and low bioavailability associated with its clinical application, there is need for continuous researches by scientist. In this study, after successfully preparing BA-BBR complex, BA-BBR complex nanocrystals were obtained through high-pressure homogenization and evaluated (in vitro and in vivo). The particle size, distribution, morphology, and crystalline properties for the optimal BA-BBR complex nanocrystals were characterized by the use of scanning electron microscope, dynamic light scattering, powder X-ray diffraction, and differential scanning calorimetry. The particle size and poly-dispersity index of BA-BBR complex nanocrystals were 318.40 ± 3.32 nm and 0.26 ± 0.03, respectively. In addition, evaluation of the in vitro dissolution extent indicated that BA and BBR in BA-BBR complex nanocrystals were 3.30- and 2.35-fold than BA-BBR complex. Subsequently, single-pass intestinal perfusion combined with microdialysis test and oral pharmacokinetics in SD rats was employed to evaluate the in vivo absorption improvement of BA-BBR complex nanocrystals. The pharmacokinetics results exhibited that the area under curve of BA and BBR in the BA-BBR complex nanocrystals group were 622.65 ± 456.95 h·ng/ml and 167.28 ± 78.87 h·ng/ml, respectively, which were separately 7.49- and 2.64-fold than the complex coarse suspension. In conclusion, the above results indicate that the developed and optimized BA-BBR complex nanocrystals could improve the dissolution rate and extent and oral bioavailability, as well as facilitate the co-absorption of the drug prescriptions BA and BBR. [ABSTRACT FROM AUTHOR]

Severe uneven wire tension occurs during super-high-thickness (more than 1000 mm) cutting in high-speed wire electrical discharge machining, resulting in different discharge regularities between electrodes when the wire electrode is in the positive and negative traveling directions. Regarding the specific performance, a certain proportion of no-load pulses will appear between electrodes when the wire electrode is in the positive traveling direction, resulting in the feeding of the machine tool; when the wire electrode is in a negative traveling direction after feeding, a large number of short-circuit pulses will be formed, which seriously affect the continuous and stable feeding and the cutting speed. According to these different regularities, this work proposes the use of different reference objects as the basis of servo feeding in the positive and negative traveling directions. A pulse probability detection servo control method based on the discharge peak current is designed, and different control objects for the positive and negative traveling direction are used as the target probabilities of the proportional integral derivative algorithm. The results of experiments demonstrate that the proposed servo control method can significantly improve the cutting stability and cutting speed for super-high-thickness cutting. When cutting a workpiece with a thickness of 1000 mm, the surface machined by the average voltage detection-based servo method with the fixed threshold and the conventional pulse probability-based servo control method was found to exhibit obvious streaks, and the cutting speed was respectively 53.75 mm2/min and 63.6 mm2/min. Finally, the surface machined by the proposed servo control method was even, and the cutting speed was 77.78 mm2/min, thereby exhibiting an improvement of 44.71% as compared to that of the average voltage detection method with a fixed threshold, and the surface evenness was greatly improved. Thus, the proposed servo control method for super-high- thickness cutting was found to achieve a faster cutting speed and higher surface quality. [ABSTRACT FROM AUTHOR]

Psoriasis, an autoimmune inflammatory skin disorder, is one of the commonest immune-mediated disease conditions affecting individuals globally. At the moment, the conventional methods applied against psoriasis treatment have various drawbacks involving limited efficacy, skin irritation, immunosuppression, etc. Therefore, it is important for scientists to find a more potent and alternative drug approach towards psoriasis therapeutics. Natural medicine still remains an important source for new drug discovery due to its therapeutical significance in various drug administration routes. However, the traditional formulation of topical therapies for psoriasis is limited in efficacy, which limits the use of natural medicine. Based on the aforementioned limitations, the use of nanocarriers in preparation of these topical herbal products could be tremendously beneficial in enhancing the efficacy of topical medications. Growing pieces of evidence have proposed that the utilization of nanocarriers in transdermal preparation as a prospective technique, with regards to better potency, directs drug absorption to site of action, and minimum toxicity effect respectively. In the course of this review, we emphasized the pathological mechanism of psoriasis, natural medicine formula, active components of natural medicine, and nanopreparations used in the treatment of psoriasis. [ABSTRACT FROM AUTHOR]

Electrical discharge machining ablation (EDMA) technology is an EDM processing method that uses oxygen as the discharge medium. Compared with traditional EDM, EDMA can greatly improve the machining efficiency but is prone to combustion and explosion phenomena when machining titanium alloy and cannot obtain stable continuous processing. Therefore, this present first analyzes the oxidation characteristics of titanium alloy from the oxidation thermodynamics and kinetics of the material. Then, the structural characteristics of the oxide layer formed on the surface of the titanium alloy where combustion and explosion phenomena occur are analyzed, and the effects of the metal elements that constitute the titanium alloy on the oxide layer structure are studied to reveal the reasons for the explosions. Finally, a method of mixed-gas electrical discharge ablation processing for titanium alloy to avoid explosions is proposed. The material removal rate in the proposed approach is 10 times and 3.5 times greater than that of conventional nitrogen- and argon-assisted submersed gas-flushing EDM, respectively. This provides a new electric machining technology for the high-efficiency and sustainable processing of titanium alloy. [ABSTRACT FROM AUTHOR]

As a variant of highly efficient electrical discharge machining (EDM), the die-sinking mixed-gas atomization discharge ablation process (DMA-DAP) uses an atomized dielectric formed by a mixed gas, which mainly composed of oxygen and supplemented by nitrogen, and water medium as the discharge medium. In this technology, the oxygen in the medium is used for exothermic oxidation, and the vaporization and explosion of the water generates a chip removal force for highly efficient erosion. The present work uses single-factor tests to compare the characteristics of processing the difficult-to-machine material titanium-alloy special-shaped cavities using either DMA-DAP or EDM. The current, pulse width, pulse interval, and dielectric pressure are selected as the single-factor processing parameters, and how they influence the material removal rate (MRR), electrode relative wear rate (ERWR) and the surface morphology of the processed square cavities is analyzed. The results show that with DMA-DAP, the MRR is more than 12 times that of EDM, the ERWR is reduced by more than 98%, and the surface morphology is relatively good. Finally, taking an aero-engine radial diffuser as the profiling object, DMA-DAP realizes a profiling sample in the form of a variable-cross-section cavity that EDM cannot process, and the efficient die-sinking processing ability of DMA-DAP is verified. [ABSTRACT FROM AUTHOR]

Further understanding the mechanism for microglia activation is necessary for developing novel anti-inflammatory strategies. Our previous study found that the activation of sigma-1 receptor can effectively inhibit the neuroinflammation, independent of the canonical mechanisms, such as NF-κB, JNK and ERK inflammatory pathways. Thus, it is reasonable that an un-identified, non-canonical pathway contributes to the activation of microglia. In the present study, we found that a sigma-1 receptor agonist of 2-morpholin-4-ylethyl 1-phenylcyclohexane-1-carboxylate (PRE-084) suppressed lipopolysaccharide (LPS) elevated nitric oxide (NO) content in BV-2 microglia culture supernatant and LPS-raised mRNA levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS) in BV-2 microglia. Moreover, PRE-084 alleviated LPS-increased Ser 9 de-phosphorylation of glycogen synthase kinase-3 beta (GSK-3β), LPS-elevated catalytic activity of calcineurin, and LPS-raised percent and frequency of Ca2+ oscillatory BV-2 cells. We further found that the inhibitory effect of PRE-084 was reversed by a calcineurin activator of chlorogenic acid and a GSK-3β activator of pyrvinium. Moreover, an IP3 receptor inhibitor of 2-aminoethoxydiphenyl borate mimicked the anti-inflammatory activity of PRE-084. Thus, we identified a noncanonical pro-neuroinflammary pathway of Ca2+ oscillation/Calcineurin/GSK-3β and the inhibition of this pathway is necessary for the anti-inflammatory activity of sigma-1 receptor activation. [ABSTRACT FROM AUTHOR]

Surface machined by high-speed wire electrical discharge machining (HS-WEDM) at super-high thickness (more than 1000 mm) cutting suffers from uneven surface, a major problem that has been investigated in this paper. According to the analysis, as wire frame span increases, the rigidity of the wire electrode decreases, and under the action of discharge explosive force, wire electrode vibration intensifies. As a result, the machining stability inevitably decreases. However, the core problem is whether there is enough working fluid in the slit to dampen and absorb the vibration of the wire electrode so as to ensure the positional stability of the wire electrode. To verify the above point of view: first, the wire guide and gravity take-up with bidirectional tension in the wire feeding system were installed to improve the positional accuracy of the wire electrode; second, to improve the flow of the working fluid into the slit, the slit width was increased by improving the working fluid and a medium carrier with a higher melting point and vaporization point can reduce the vaporization of the working fluid in the slit as much as possible. The experiment showed that the outlet flow of the improved working fluid is 56.72% higher than that of the original working fluid when cutting a 750-mm thick workpiece, which increases the damping and vibration absorption effect of the working fluid on the wire electrode in the long and narrow gap. After the above measures were implemented, super-high thickness cutting can be carried out continuously and steadily, the surface evenness was significantly improved, and the workpiece with a thickness of 2000 mm was cut successfully. [ABSTRACT FROM AUTHOR]

In order to reveal the microscopic mechanism of the titanium alloy die-sinking mixed-gas atomization discharge ablation process (MA-DAP), a single-pulse discharge test was performed using a needle electrode discharge device. According to the step-like characteristic of the single discharge waveform, the micro-erosion process could be divided into four stages: preparation for oxidation ablation; oxidation occurrence and oxide layer generation; oxidation-ablation dynamic balance and oxide layer prototype formation; and oxidation-ablation termination and integral oxide layer formation. Theoretical analysis showed that the violent exothermic oxidation reaction between the oxygen medium and the high-temperature melting material introduced a large quantity of external chemical energy into the sparking region. Fast vaporization and explosion of the atomized medium after heating gave MA-DAP high particle removal power. The technological experimental results showed MA-DAP provides high material removal efficiency and strong deep-hole machining ability. The depth-to-diameter ratio of the specially shaped titanium alloy MA-DAF blind hole was 11 times that from traditional electrical discharge machining, while the cross-sectional hardness can be reduced by 45%. [ABSTRACT FROM AUTHOR]

The vapor-cell rubidium atomic clock is widely used in Global Navigation Satellite System (GNSS) and telecommunications. The sensitivity of temperature is one of the most important factors affecting the performance of rubidium Atomic Frequency Standards (RAFS). It plays a significant role in the long-term frequency stability of the rubidium atomic clock, and largely depends on the Physics Package (PP). In this paper, we attempt to reduce the temperature sensitivity of RAFS in a specific environment of vacuum and extraterrestrial temperature. We achieve this by studying the theory of light shift, collision shift, and magnetic frequency shift in RAFS. By combining this with our engineering expertise, we have proposed a single method on three parameters to optimize the temperature coefficient of PP of the rubidium atomic clock, which can not only optimize the temperature coefficient of PP, but can also improve the long-term frequency stability of the rubidium atomic clock. Some related experiments, by the proposed method, further demonstrate a significant reduction in the temperature coefficient of PP, suggesting that the performance of RAFS can be improved. [ABSTRACT FROM AUTHOR]

To meet the increasing demand for wire electrical discharge machining (WEDM) under extreme conditions such as ultra-high thickness cutting, micro-wire cutting, micro-energy finishing, and ceramic composites machining, a concept of multichannel discharge WEDM under semiconductor characteristics was proposed. The essence of this conception is that under these extreme machining conditions, the electrode wire or workpiece — or even both of the two electrodes — cannot be treated as electrically conductive materials of the conventional WEDM due to their high electrical resistance. However, they can exhibit electrical discharge behavior like semiconductors, which is defined as semiconductor characteristics. The conventional WEDM theory and related technologies cannot be applied to extreme WEDM because conventional WEDM only has one discharge channel per pulse, whereas multiple discharge channels can be generated by each pulse in extreme WEDM. Therefore, a suitable theory needs to be developed for extreme WEDM under semiconductor characteristics. Based on the multichannel discharge behavior of semiconductors, experiments were conducted on high-efficiency machining with multichannel discharge by stacking several workpieces as an assembly with semiconductor characteristics. It was proved that the multichannel discharge WEDM is capable of achieving high machining efficiency, as well as enhanced surface quality and lower wear of electrode wire. The proposed multichannel discharge WEDM sets up the foundation for the establishment of the theoretical system of EDM under semiconductor characteristics. [ABSTRACT FROM AUTHOR]

Most existing algorithms of anomaly detection are suitable for static data where all data are available during detection but are incapable of handling dynamic data streams. In this study, we proposed an improved iLOF (incremental local outlier factor) algorithm based on the landmark window model, which provides an efficient method for anomaly detection in data streams and outperforms conventional methods. What is more, data windows as updating units are introduced to reduce the false alarm rate, and multiple tests are taken here to identify candidate anomalies and real anomalies. The improved iLOF shows its obvious advantage with its false positive rate. Furthermore, the proposed algorithm instantly deletes data points of identified real anomalies. We analyzed the performance of the improved algorithm and the sensitivity of certain parameters via empirical experiments using synthetic and real data sets. The experimental results demonstrate that the proposed improved algorithm achieved better performance on the higher detection rate and the lower false alarm rate compared with the original iLOF algorithm and its improvements. [ABSTRACT FROM AUTHOR]

Titanium alloy is widely used in aerospace and other industry fields because of its excellent physical and chemical properties. However, the fabrication process is still a challenge for the traditional machining processes due to the ultra hardness and chemical reactivity properties of titanium alloy. Electrical discharge machining (EDM) is a significant processing approach to machine titanium alloy regardless of hardness, while accompanied by disadvantages such as electrode wear and low machining efficiency. This paper proposed a novel mixed-gas atomization discharge ablation process (MA-DAP) method for high-efficiency machining titanium alloy with low tool wear. An atomized dielectric formed by a mixed gas, which mainly composed of oxygen and supplemented by nitrogen, and water medium was used in the machining process. The exothermic oxidation between the oxygen component in the atomized dielectric and high-temperature molten material activated by spark discharges could multiply accelerate material removal of workpiece. The explosive effect generated by the vaporization expansion of the water component in the dielectric would improve the machining quality and the processing capability of large depth-to-diameter ratio holes. To investigate the machining characteristics of the new approach, comparative experiments were conducted in terms of material removal rate, electrode relative wear rate, machining accuracy, surface morphology, and recast layer. The experimental results showed that, compared with traditional EDM, the material removal rate of MA-DAP was dramatically increased by more than an order of magnitude, and other technological indexes are greatly improved simultaneously. A deep-shaped blind hole with a depth-to-diameter ratio greater than 12 was obtained by the MA-DAP. [ABSTRACT FROM AUTHOR]

Malaria is a climate-sensitive infectious disease. Many ecological studies have investigated the independent impacts of ambient temperature on malaria. However, the optimal temperature measures of malaria and its interaction with other meteorological factors on malaria transmission are less understood. This study aims to investigate the effect of ambient temperature and its interactions with relative humidity and rainfall on malaria in Suzhou, a temperate climate city in Anhui Province, China. Weekly malaria and meteorological data from 2005 to 2012 were obtained for Suzhou. A distributed lag nonlinear model was conducted to quantify the effect of different temperature measures on malaria. The best measure was defined as that with the minimum quasi-Akaike information criterion. GeoDetector and Poisson regression models were employed to quantify the interactions of temperature, relative humidity, and rainfall on malaria transmission. A total of 13,382 malaria cases were notified in Suzhou from 2005 to 2012. Each 5 °C rise in average temperature over 10 °C resulted in a 22% (95% CI: 17%, 28%) increase in malaria cases at lag of 4 weeks. In terms of cumulative effects from lag 1 to 8 weeks, each 5 °C increase over 10 °C caused a 175% growth in malaria cases (95% CI: 139%, 216%). Average temperature achieved the best performance in terms of model fitting, followed by minimum temperature, most frequent temperature, and maximum temperature. Temperature had an interactive effect on malaria with relative humidity and rainfall. High temperature together with high relative humidity and high rainfall could accelerate the transmission of malaria. Meteorological factors may affect malaria transmission interactively. The research findings could be helpful in the development of weather-based malaria early warning system, especially in the context of climate change for the prevention of possible malaria resurgence. [ABSTRACT FROM AUTHOR]

Tool wear inevitably occurs during electrical discharge milling (ED milling), adversely affecting the form precision of machined features. Specifically, radial tool wear negatively influences copying precision. In this study, electrical discharge ablation milling (EDA milling) with a microcutting depth was investigated to improve the machining precision of discharge milling. In the proposed method, the cutting depth of a single layer was kept at the micron level, which is smaller than the discharge gap, and the electrode was set to a fast feeding rate at a constant speed. The microcutting depth of a single layer made the discharge concentrate at the end of the electrode while avoiding the side. Under this method, radial tool wear is prevented to realize high-precision discharge milling. The discharge state and high-precision mechanism of the proposed method were analyzed. Contrast experiments were conducted to compare conventional electrical discharge milling (ED milling), conventional electrical discharge ablation milling with a large cutting depth (EDA milling with a large cutting depth), and EDA milling with a microcutting depth. Results indicated that when peak current was 30A (pulse duration was 150 μs and pulse interval was 120 μs), the machining efficiency of the proposed method (18.8 mm3/min) was 9.5 times that of ED milling (1.97 mm3/min) and was 62% higher than that of EDA milling with a large cutting depth (11.6 mm3/min). Besides, the surface quality and cross-sectional shape precision of the straight groove were significantly improved compared with EDA milling with a large cutting depth. [ABSTRACT FROM AUTHOR]

This paper proposes a combined milling process of electrical discharge ablation machining (EDAM) and electrochemical machining (ECM) as an alternative to the low efficiency problem of less efficient electrical discharge machining (EDM) and to reduce the recast layer of EDAM. The working medium was a mixed aerosol of NaCl solution and oxygen, which has electrolytic and dielectric characteristics. The mechanism was analyzed: the combined milling process was a mixed process of EDAM, ECM, and EDAM-ECM combined machining. The EDAM-ECM combined machining can be divided into three stages: the electrolysis stage, discharge channel formation stage, and rapid ablative removal stage of metal substrate. Experiments were performed to compare conventional EDM milling, EDAM milling, and combined milling of EDAM and ECM. Results showed that the material removal rate (MRR) of the combined milling was 11.5 times that of EDM milling, and it increased by 18.7% compared with EDAM milling. The relative tool wear ratio (RTWR) decreased by 46.6%, and the thicknesses of the recast layer on the bottom and side were reduced by 61.2% and 49.2%, respectively, compared with EDAM milling. [ABSTRACT FROM AUTHOR]

This study aims to develop an artificial intelligence (AI)-based model to assist radiologists in pneumoconiosis screening and staging using chest radiographs. The model, based on chest radiographs, was developed using a training cohort and validated using an independent test cohort. Every image in the training and test datasets were labeled by experienced radiologists in a double-blinded fashion. The computational model started by segmenting the lung field into six subregions. Then, convolutional neural network classification model was used to predict the opacity level for each subregion respectively. Finally, the diagnosis for each subject (normal, stage I, II, or III pneumoconiosis) was determined by summarizing the subregion-based prediction results. For the independent test cohort, pneumoconiosis screening accuracy was 0.973, with both sensitivity and specificity greater than 0.97. The accuracy for pneumoconiosis staging was 0.927, better than that achieved by two groups of radiologists (0.87 and 0.84, respectively). This study develops a deep learning-based model for screening and staging of pneumoconiosis using man-annotated chest radiographs. The model outperformed two groups of radiologists in the accuracy of pneumoconiosis staging. This pioneer work demonstrates the feasibility and efficiency of AI-assisted radiography screening and diagnosis in occupational lung diseases. [ABSTRACT FROM AUTHOR]

The electrical resistance of wire electrode increases with the decrease of the wire diameter. It is difficult to use the voltage threshold method to distinguish the spark and short-circuit states according to the discharge voltage, so it cannot meet the requirements of normal machining. In this study, a gap discharge state identification and servo control method based on discharge current are proposed in high-speed reciprocating microwire-EDM. The synchronous pulse can improve the stability of the system by reducing the disturbance of the discharge frequency and deionization. The experimental results show that a high wire speed is beneficial to the introduction of dielectric and the removal of erosion particles. When the target probability is set at 90%, the processing stability is higher. By using Φ 0.08 mm molybdenum wire electrode, the stable cutting of a 1250 height-diameter ratio (the ratio of cutting height to electrode wire diameter) workpiece is realized with an average cutting efficiency of 32.08 mm2/min. This study is a useful exploration of the machining of high height-diameter ratio workpieces by using a microwire electrode in high-speed wire-cut electrical discharge machining (HSWEDM). [ABSTRACT FROM AUTHOR]

SARS-CoV-2, a β-coronavirus, has rapidly spread across the world, highlighting its high transmissibility, but the underlying morphogenesis and pathogenesis remain poorly understood. Here, we characterize the replication dynamics, cell tropism and morphogenesis of SARS-CoV-2 in organotypic human airway epithelial (HAE) cultures. SARS-CoV-2 replicates efficiently and infects both ciliated and secretory cells in HAE cultures. In comparison, HCoV-NL63 replicates to lower titers and is only detected in ciliated cells. SARS-CoV-2 shows a similar morphogenetic process as other coronaviruses but causes plaque-like cytopathic effects in HAE cultures. Cell fusion, apoptosis, destruction of epithelium integrity, cilium shrinking and beaded changes are observed in the plaque regions. Taken together, our results provide important insights into SARS-CoV-2 cell tropism, replication and morphogenesis. Here, the authors characterize replication of SARS-CoV-2 in human airway epithelial (HAE) cultures and show that it can infect ciliated and secretory cells, affects transepithelial electrical resistance and causes plaque-like cytopathic effects associated with apoptosis. [ABSTRACT FROM AUTHOR]

The vaporization of dielectric fluid between electrodes is very significant in high speed–wire cut electrical discharge machining (HS-WEDM) under high-energy conditions. Inter-polar corrosion products cannot be expelled in time, resulting in serious burn on the surface of the workpiece. To solve this problem, a certain proportion of kerosene is added to the dielectric fluid. The heat absorbed by kerosene chemical decomposition can effectively reduce the gasification of inter-electrode dielectric fluid. This ensures that there is sufficient dielectric fluid between the poles, and guarantees that the corrosion products produced between electrodes can be expelled in time, reducing the burn on the workpiece surface. Through theoretical calculation and comparative analysis, it is concluded that the heat absorbed by kerosene chemical decomposition is 24 to 211 times that absorbed by dielectric fluid gasification under the same volume condition. In this research, two cooling modes, kerosene chemical decomposition endothermic cooling and physical gasification endothermic cooling, are proposed. The important role of chemical decomposition endothermic cooling in inter-pole cooling is proved. The optimum proportion of kerosene in dielectric fluid is about 1%, as determined by experimentation. When the kerosene content exceeds 1%, carbon deposition will occur. When the kerosene content is around 1%, the cutting efficiency is 23% higher than that when kerosene is not added, and the burn area of the workpiece surface is reduced by 91%. [ABSTRACT FROM AUTHOR]

This paper analyzes the high-performance efficiency of atomized electric discharge machining (EDM) ablation using quantitative analysis of discharge and combustion erosion. Using an argon-atomizing medium and an oxygen-atomizing medium, a comparative experiment is performed to calculate the amount of material erosion generated by discharge and combustion during EDM ablation. Then, by collecting the single-pulse discharge waveform and the discharge rate, comparative experiments are carried out between EDM and EDM ablation to study the influence of electrical parameters on the ratio of discharge to combustion erosion in EDM ablation process. The reasons for the efficiency of EDM ablation are determined to be the higher discharge probability when compared to conventional EDM and the introduced oxygen which reacts with the activated material, increasing combustion effectiveness. The results show that under different pulse width, pulse interval, and average current experimental conditions, the combustion erosion in the atomization ablation process accounts for 67–78% of the total erosion, and the efficiency of atomization EDM ablation is over 8 times that of traditional EDM. [ABSTRACT FROM AUTHOR]

The local excessive ablation of Ti6Al4V by electrical discharge machining ablation (EDMA) is investigated in the present work. In order to achieve the high efficiency and stable ablation machining of Ti6Al4V, a method of diluting the concentration of oxygen medium by the nitrogen is proposed; that is, a mixed gas medium composed of nitrogen and oxygen is used as a gas medium for EDMA. Firstly, the effects of the oxygen concentration, discharge energy, and gas pressure on the excessive ablation of Ti6Al4V are theoretically analyzed. Then, the quantitative correlation between the above three factors and the excessive ablation phenomenon is established through the experimental exploration. Finally, the Taguchi orthogonal method is applied to systematically investigate the effects of the mentioned factors on the material removal rate (MRR) and electrode wear rate (EWR), and compared with the conventional electrical discharge machining (EDM). The experimental results show that the discharge energy and the gas pressure decrease parabolically as the oxygen concentration increases, while discharge current decreases linearly as the gas pressure increases. Moreover, the pulse width decreases exponentially as the gas pressure increases. It is observed that the discharge current and oxygen concentration have significant effects on MRR, while pulse width has significant effects on EWR. The present work shows that the processing efficiency of EDMA is more than 9 times of that for EDM with solid electrode in water. [ABSTRACT FROM AUTHOR]

High-speed wire electrical discharge machining (HS-WEDM) using hard water working liquid results in the machined surface losing metallic luster and reducing the cutting speed comparing with distilled water working fluid. Scanning electron microscopy (SEM) was used to observe the microscopic surface of the workpiece. The chemical composition of the machined surface was analyzed via energy-dispersive X-ray spectroscopy (EDS). Results indicated that the primary cause for lost metallic luster of the machine's surface was the Cl− present in hard water, which was easily adsorbed on the surface of the workpiece under high-temperature and pressure inter-electrode conditions, resulting in pitting corrosion. By analyzing the conductivity and the continuous discharge waveforms of distilled water and hard water working liquid, it was determined that the reduced cutting speed was because the hard water working liquid contained ions such as Ca2+ and Mg2+, which were adsorbed by the colloid in the working fluid. This resulted in the loss of dielectric property for the working fluid. Furthermore, the conductivity of hard water working fluid is higher, making it easier to be broken down under the same voltage, which results in a larger discharge gap and reduced cutting speed. A method of distilling the hard water to remove the ions was presented to circumvent this; after which, the cutting surface recovered metallic luster and the general machining speed increased. [ABSTRACT FROM AUTHOR]

Drum-shaped inaccuracy increases dramatically in high-speed wire electrical discharge machining (HS-WEDM) after multiple cuts when very thick workpiece (> 100 mm) are used. To tackle this problem, a positional change model of the wire electrode was established to analyze the main causes of the drum-shaped inaccuracy. In HS-WEDM, the conductivity of the working fluid is very high. As the workpiece thickness increases, the "leakage current" at the machining gap increases, and more energy is required for the trim cuts. In addition, to maintain stable trim cuts, a long pulse-on time is needed. As a result, the high discharge energy inevitably results in a large explosive force, which increases the wire bending deformation due to long durations under this force. To solve these problems, novel measures were taken in this study. First, an improved working fluid was proposed to reduce the conductivity so that the energy loss between the electrodes can be decreased. The discharge energy used for the trim cuts was diminished to reduce the impact of the discharge explosive force. Second, a short pulse-on time and a high peak current were utilized for the trim cuts to reduce the impulse from the effect of the discharge explosive force on the wire electrode. Third, a closed-loop tension mechanism was designed to increase the wire tension, thereby improving the stability and rigidity of wire electrode. Finally, the rigidity of wire electrode was further improved by utilizing a unique trim-cut method proposed in this study. The experimental results showed that the drum-shaped inaccuracy of a workpiece with a thickness of 150 mm was reduced to 10 μm from 25 μm after three cuts (one roughing cut and two finish/trim cuts) under normal machining and the quality and uniformity of the machined surface were improved. [ABSTRACT FROM AUTHOR]

To improve the surface quality of multiple cutting and eliminate the recast layer in high-speed wire-cut electrical discharge machining (HSWEDM), a novel combined processing based on diamond wire saw and molybdenum twisted wire is proposed in this paper. This closed-loop tension control system can detect tension to stabilize the spatial position of the electrode wire in real time. Compared with molybdenum wire, experimental results show machining status between gaps are superior, with more breakdown delay. Surface roughness (Ra) is reduced from 0.902 to 0.552 μm with combined processing of the twisted wire. The thickness of the recast layer is also reduced by 62% compared with multiple cutting of molybdenum wire, and the straightness error is significantly reduced. [ABSTRACT FROM AUTHOR]

To further improve the technological indexes of high-speed wire electrical discharge machining (HS-WEDM) under conditions of high energy and high thickness while also solving the problem of an absent liquid medium and unsteady processing in the inter-electrode gap, a new type of stranded wire electrode used in HS-WEDM was designed to enhance the flow of the liquid medium and debris removal during the machining process. First, a simulation model of the inter-electrode gap flow field is established; the simulation analysis indicates that the capacity of carrying liquid medium with a stranded wire electrode is approximately 65% higher than with a normal wire electrode at a high workpiece thickness of 400 mm. Next, the special discharge characteristic of stranded wire electrode is summarized from the two aspects of effective discharge area and high-thickness workpiece. Third, a comparative experiment on cutting a high-thickness workpiece at high energy demonstrates a greater threshold of stable cutting speed (over 250 mm2/min) and stable material removal rate (142 mm3/min) at an average cutting current of 18 A with a stranded wire electrode, whereas the maximum cutting speed (155 mm2/min) at an average cutting current of 8 A with a normal wire electrode. Experiments prove that using a stranded wire electrode can significantly increase cutting speed and improve processing stability in the electrode gap under high-energy and high-thickness conditions. [ABSTRACT FROM AUTHOR]

When machining Ti-6Al-4V, electrical discharge machining ablation (EDMA) using a pure oxygen medium can greatly improve the relatively low machining efficiency in EDM, especially when machining a deep-type blind hole. However, Ti-6Al-4V is prone to an explosive phenomenon in the process of ablation, which makes stable processing unsustainable. In this paper, the relations of this phenomenon to the oxide layer and to oxygen concentration were revealed by analyzing the formation process of the surface oxide layer, the explosion mechanism, and the oxygen diffusion mechanism. The results show that high-concentration oxygen enters the alloy substrate through the broad and deep crack channel on the oxide layer, inducing an explosion phenomenon given the high temperature of the discharge. To reduce the oxygen concentration and the crack width and depth, nitrogen is added to the oxygen medium, which prevents the oxygen from entering the matrix and allows stable processing. Experimental results showed that the crack width and depth increase with the increase of the oxygen concentration. Stable and efficient processing can be achieved when the concentration ratio of oxygen to nitrogen is 5:1, and the machining efficiency is more than 8 times higher than in the air medium. Finally, a deep-type blind hole with a deep diameter ratio of 10 was machined continuously and stably. [ABSTRACT FROM AUTHOR]

To reduce the recast layer and cracks formed during the small hole, electrical discharge machining (EDM) of the TC4 alloy, negative polarity EDM, and electrical discharge machining/electrochemical machining combined process (EDM/ECM) were carried out. The machining efficiency, the recast layer, and the cracks were studied. The experimental results showed that when compared with common positive polarity EDM under the specific processing condition, the recast layer of the negative polarity EDM decreased by 65% in thickness but the material removal rate (MRR) decreased by 31%. In EDM/ECM, MMR was 18% higher than the positive polarity EDM, and the majority of the recast layer and the cracks were removed. However, issues including the low efficiency occur during the penetration period. The following paper analyzed the causes of these problems and proposed a novel unitized hole drilling process. In this unitized process, EDM/ECM was initially used and then converted to negative polarity EDM with external flushing water during the penetration period. The general machining efficiency of a single hole increased by 73% over conventional EDM/EDM. Furthermore, only a 7-μm thick recast layer remained at the hole’s outlet, with no obvious cracks found. [ABSTRACT FROM AUTHOR]

To improve the efficiency of conventional electrical discharge machining (EDM) milling, this study proposes a highly efficient machining method that employs continuous oxygen feeding and fast-moving electrode. High-efficiency machining is achieved by the method of feeding with small thickness, allowing the electrode suspended above the workpiece to reduce short circuit and using a high discharge probability to ignite the workpiece in order to realizing high efficiency machining with great chemical energy released from metal combustion. Comparative tests for conventional EDM milling, EDM ablation milling, and ablation milling by fast-moving electrode were performed in the milling process. In this study, we analyzed the mechanism, machining efficiency, electrode relative wear ratio, and machining quality. The machining efficiency of EDM ablation milling was 6.8 times higher than that of conventional EDM milling, and the relative tool wear ratio was 20% of conventional EDM milling; the machining efficiency of ablation milling by fast-moving electrode can reach 11.2 times higher than that of conventional EDM milling, and the electrode relative wear ratio decreased by 86%. [ABSTRACT FROM AUTHOR]

In this study, the problem of poor precision and low efficiency in shape-cutting hard, brittle semiconductor materials with traditional fixed abrasive diamond wire sawing (DWS) is investigated experimentally and a novel approach, which combines electric discharge and diamond abrasive grinding into a single process, is proposed. Experiments with polycrystalline silicon materials are conducted to contrast abrasive-spark hybrid machining, diamond wire sawing, and wire electricaldischarge machining (WEDM). The results show that, under the same processing conditions, the shape accuracy of abrasive-spark hybrid machining is the highest and cylindricity error is as the lowest, at 11 μm. In comparison with WEDM, the damage-layer thickness of machined surfaces is reduced by 10 μm. Among three processing methods, hybrid machining has the minimum wire bending and wider kerf. The thickness of damage layer and the surface roughness of hybrid machining are in the middle. The surface topography is composed of shallow discharge pits and grinding areas, and there are few scratches on the cut surface compared to diamond wire-cut surfaces, such that this new machining method is found to be more suitable for shape-cutting hard and brittle semiconductor materials. [ABSTRACT FROM AUTHOR]

This study analyzes the limitations of servo control systems for high-speed wire cut electrical discharge machining (HSWEDM). The discharge gap cannot be adjusted in real time during large energy cutting, as this will prevent interelectrode dielectric liquid from entering the discharge gap steadily, leading to violent vaporization and resulting in surface burning of the workpiece. This study proposes a new servo control system for HSWEDM based on discharge probability detection. The system collects the interelectrode discharge signal by dividing and comparing voltage circuits and then calculating discharge probability in a field-programmable gate array (FPGA), after which the machine tool adjusts feed rate by comparing the actual and initial target discharge probability. Thus, proper and stable discharge gap are ensured, enabling the interelectrode dielectric liquid to remain constant, increasing efficiency and stability, and decreasing surface burning effectively. Experiments prove that a servo control method based on discharge probability detection can increase stable cutting speed to 180 mm/min and workpiece surfaces show no apparent burning stripes. In addition, the highest cutting speed can be increased to 208 mm/min. [ABSTRACT FROM AUTHOR]

Surface machined by high-speed wire electrical discharge machining (HS-WEDM) at high energy (average current >8 A) suffers from surface burn and reduced cutting speed increase-rate, a major problem which is investigated in this paper. According to the study, the debris is mainly expelled out of the inter-electrode gap by the liquid medium. When machining at low energy, the gap is full of water-based medium, and the debris is mainly expelled by this medium. However, at high energy the medium in the gap is enormously vaporized and is then reduced due to a thermal load at high energy. Thus, the debris cannot be removed from the gap in time, resulting in its deposition and eventually leading to the surface burn. To overcome this limitation, it is suggested that within a range of discharge energy levels, the erosion products of the HS-WEDM process should be driven by a medium carrier with a higher melting point and vaporization point to ensure that there is sufficient liquid medium in the gap at high energy to carry and expel the debris out of the machining zone. Experiments were conducted by increasing the JR1A (traditionally used dielectric medium) -to-water ratio to increase the content of high-melting-point medium, thus validating the theory. Based on the experimental results, a new type of dielectric medium, JR1H, was formulated to ensure that there is still sufficient liquid medium to expel the debris at large energy machining. A greater threshold of stable cutting speed (more than 330 mm/min) was achieved with the machining current of 15 A using JR1H, which is a significant breakthrough in higher efficiency HS-WEDM. [ABSTRACT FROM AUTHOR]