Semantic Segmentation of Surface Cracks in Urban Comprehensive Pipe Galleries Based on Global Attention.

Cracks inside urban underground comprehensive pipe galleries are small and their characteristics are not obvious. Due to low lighting and large shadow areas, the differentiation between the cracks and background in an image is low. Most current semantic segmentation methods focus on overall segmentation and have a large perceptual range. However, for urban underground comprehensive pipe gallery crack segmentation tasks, it is difficult to pay attention to the detailed features of local edges to obtain accurate segmentation results. A Global Attention Segmentation Network (GA-SegNet) is proposed in this paper. The GA-SegNet is designed to perform semantic segmentation by incorporating global attention mechanisms. In order to perform precise pixel classification in the image, a residual separable convolution attention model is employed in an encoder to extract features at multiple scales. A global attention upsample model (GAM) is utilized in a decoder to enhance the connection between shallow-level features and deep abstract features, which could increase the attention of the network towards small cracks. By employing a balanced loss function, the contribution of crack pixels is increased while reducing the focus on background pixels in the overall loss. This approach aims to improve the segmentation accuracy of cracks. The comparative experimental results with other classic models show that the GA SegNet model proposed in this study has better segmentation performance and multiple evaluation indicators, and has advantages in segmentation accuracy and efficiency.

Identification of critical prognosis signature associated with lymph node metastasis of stomach adenocarcinomas.

Lymph node metastasis (LNM) is an important factor affecting the prognosis of patients with gastric adenocarcinoma (STAD), which is the most common malignancy of the human digestive system. Current detection techniques have limited sensitivity and specificity, and there is a lack of effective biomarkers to screen for LNM. Therefore, it is critical to screen for biomarkers that predict LNM in STAD. Gene expression differential analysis (false discovery rate < 0.05, |log2Fold change| ≥1.5) was performed on 102 LNM samples, 224 non-LNM samples, and 29 normal gastric tissue samples from The Cancer Genome Atlas (TCGA) STAD dataset, and 269 LNM-specific genes (DEGs) were obtained. Enrichment analysis showed that LNM-specific genes functioned mainly in cytokine-cytokine receptor interactions, calcium signaling, and other pathways. Ten DEGs significantly associated with overall survival in STAD patients were screened by multivariate Cox regression, and an LNM-based 10-mRNA prognostic signature was established (Logrank P < 0.0001). This 10-mRNA signature was well predicted in both the TCGA training set and the Gene Expression Omnibus validation dataset (GSE84437) and was associated with survival in patients with LNM or advanced-stage STAD. Using Kaplan-Meier survival, receiver operating characteristic curve, C-index analysis, and decision curve analysis, the 10-mRNA signature was found to be a more effective predictor of prognosis in STAD patients than the other two reported models (P < 0.0005). Protein-protein interaction network and gene set enrichment analysis of the 10-mRNA signature revealed that the signature may affect the expression of multiple biological pathways and related genes. Finally, the expression levels of prognostic genes in STAD tissues and cell lines were verified using qRT-PCR, Western blot, and the Human Protein Atlas database. Taken together, the prognostic signature constructed in this study may become an indicator for clinical prognostic assessment of LNM-STAD and provide a new strategy for future targeted therapy.

Performance Research of Natural Mica Modified with Zirconium-Based Metal-Organic Frameworks for an Epoxy Resin Anti-Corrosion Coating.

A new composite material made from mica and a metal-organic framework (MOF) has been developed to improve the anticorrosive capabilities of epoxy resin coatings. The layered mica was loaded with denser and more uniform UIO-66 nanoparticles after modifying the composite with polyethyleneimine (PEI). The composites were used as fillers to prepare epoxy coatings that exhibited long-lasting active (labyrinth effect produced by mica) and passive (pH-sensitive release of corrosion inhibitors) corrosion protection. Settling experiments showed that polyethyleneimine improved the composites' compatibility in epoxy resin. After being immersed in a 3.5 wt.% NaCl solution for 60 days, the adhesion of PMC-UIO@MBT/EP increases to 9.01 MPa, while the water absorption rate only reaches 2.57%. It indicates that the coating has good barrier properties and stability. After being soaked in a 3.5 wt.% NaCl solution for 60 days at pH = 7, PMC-UIO@MBT/EP exhibits high low-frequency impedance (8.30 × 108 Ω), as demonstrated by the electronic impedance spectrum (EIS). In addition, the coating also exhibited the highest low-frequency impedance after 30 days in 3.5 wt.% NaCl solution at pH = 11.

A High-Performance Anti-Corrosive Epoxy Coating Based on Ultra-Thin Hydroxyapatite Nanosheets with pH-Responsive Functions.

The changes in the working environment have necessitated greater requirements in terms of the long-term anti-corrosion ability of metal anti-corrosion coatings, and the emergence of intelligent coatings has met this demand. A nanocontainer with a hydrophobic inner cavity and hydrophilic outer cavity called ß-cyclodextrin (ß-CD) was grafted onto the surface of hydroxyapatite (HAp) with a silane coupling agent, encapsulating benzotriazole (BTA) and embedded in epoxy resin to improve the coating anticorrosion performance. The excellent corrosion resistance of the coating in immersion and scratch experiments was derived from the inert protective layer formed by the reaction of the rapidly released corrosion inhibitor with the corrosion products on the metal surface. After 30 days of immersion experiment, the coating could still maintain the low-frequency impedance value of 6.28 × 107 Ω cm2. In this work, the enhancement of the physical barrier function of HAp nanoparticle and the pH-response function conferred by ß-cyclodextrin provided the coating with good passive and active acting abilities in corrosive environments, respectively.

Quantification of pharyngeal airway space changes after two-jaw orthognathic surgery in skeletal class III patients.

BACKGROUND: Skeletal class III malocclusion is a common dentofacial deformity. Orthognathic treatment changes the position of the jaws and affects the shape of the upper airway to some extent. The aim of this study was to use multislice spiral computer tomography data and orthognathic knowledge to quantify the relationship between the amount of surgical movement of the maxilla or mandible in all three spatial planes and the changes in airway volume that occurred. METHODS: A retrospective study of 50 patients was conducted. Preoperative and postoperative linear changes related to skeletal movements of the maxilla and mandible were measured and compared to changes in the most constricted axial level (MCA) and its anteroposterior (MCA-AP) and transverse diameters (MCA-TV). Correlation tests and linear regression analysis were performed. RESULTS: Significant interactions were observed between the anterior vertical movement of the maxilla and the MCA-AP. The anteroposterior movement distance of the mandible was significantly correlated with changes in the oropharyngeal, velopharyngeal, total airway volume, MCA, MCA-AP, and MCA-TV. The change in the mandibular plane angle was significantly correlated with the change in velopharyngeal volume, total airway volume (nasopharynx, oropharynx, velopharynx), and MCA. The linear regression model showed that oropharyngeal volume decreased by 350.04 mm3, velopharyngeal volume decreased by 311.50 mm3, total airway volume decreased by 790.46 mm3, MCA decreased by 10.96 mm2 and MCA-AP decreased by 0.73 mm2 when point B was setback by 1 mm. CONCLUSIONS: Anteroposterior mandibular control is the key to successful airway management in all patients. This study provides estimates of volume change per millimeter of setback to guide surgeons in treatment planning.

Stem cells from human exfoliated deciduous teeth relieve pain via downregulation of c-Jun in a rat model of trigeminal neuralgia.

BACKGROUND: Stem cells from human exfoliated deciduous teeth (SHED) have excellent immunomodulatory and neuroprotective abilities. It is possible that systemic SHED transplantation could ameliorate trigeminal neuralgia. The phosphorylation of c-Jun contributes to the development of hyperalgesia and allodynia. OBJECTIVE: The present study aimed to evaluate whether systemic SHED transplantation could lead to analgesic effects by regulating peripheral c-Jun in the trigeminal ganglia (TG) in a rat model of trigeminal neuralgia. METHODS: Chronic constriction injury of the infraorbital nerve (CCI-ION) was performed to establish a rat pain model. SHED were obtained from discarded exfoliated deciduous teeth from children and transplanted by a single infusion through the tail vein. SHED were labelled with the PKH26 red fluorescent cell linker mini kit for tract distribution. The mechanical threshold was determined using von Frey filaments. The mRNA levels of c-Jun in the ipsilateral TG were quantified. The phosphorylation of c-Jun in the ipsilateral TG was assessed by immunohistochemistry and Western blotting. RESULTS: PKH26-labelled SHED were distributed to both sides of TG, lung, liver and spleen. Systemic SHED transplantation significantly elevated the mechanical thresholds in CCI-ION rats and blocked the upregulation of c-Jun mRNA levels in the TG caused by nerve ligation. The activation of c-Jun in the TG was blocked by SHED transplantation. CONCLUSIONS: These findings demonstrate that systemic SHED administration reverts trigeminal neuralgia via downregulation of c-Jun in the TG.

Mapping research trends of temporomandibular disorders from 2010 to 2019: A bibliometric analysis.

BACKGROUND: Because of various clinical manifestations and complicated courses, temporomandibular disorders (TMDs) are difficult to treat. Current knowledge about this disease remains insufficient for precise treatment after diagnosis. OBJECTIVES: The objective of this study is to obtain and map the overall literature trends and most cited keywords in TMDs research. METHODS: Many indicators, including annual number of publications, country distribution, global cooperations, author contributions, original journals, cited references and keywords, were calculated and evaluated using VOSviewer v.1.6.13, which visualised many results, from the WoSCC database. RESULTS: A total of 3121 papers on TMDs research were retrieved from 2010 to 2019. The United States produced the most articles published, but the most productive institution was the University of Sao Paulo (Brazil). Researchers and institutions conducting TMDs research have shown a very widespread and close connection. TMDs have been studied worldwide by many research centres. Professor Svensson P was the most published researcher in TMDs research and the Journal of Oral Rehabilitation published the most TMDs research articles. The top cited references mainly presented diagnostic criteria of TMDs. The most cited keywords formed clusters: (a) Anatomical factor of TMDs, (b) Symptoms of TMDs and (c) RDC/TMD, the risk factors, biopsychosocial factors and epidemiology of TMDs. CONCLUSIONS: The research results provide very valuable data for a thorough understanding of the research status of TMDs and demonstrated international cooperation.

Rapid human-derived iPSC osteogenesis combined with three-dimensionally printed Ti6Al4V scaffolds for the repair of bone defects.

Human-induced pluripotent stem cells (iPSCs) are an alternative source of mesenchymal stem cells used for bone regeneration. However, the current osteogenically induced methods for iPSCs are slow and complex. We have used retinoic acid (RA) to induce osteogenic iPSCs within 10 days and assess whether a rapid differentiation could improve the osteogenic potential of the three-dimensionally printed Ti6Al4V (3DTi) scaffolds. First, the osteogenic differentiation of iPSCs was induced with RA, and the osteogenic potential of iPSCs was evaluated using standard assays. In addition, a 5-mm mandibular bone defect was generated in rats and was repaired with 3DTi scaffolds that were seeded with iPSC-induced osteoblasts. The capacity of seeded scaffolds for the enhancement of bone regeneration in vivo was assessed. Finally, we tested the potential mechanisms of RA-dependent iPSC bone induction and its effect on the Wnt/ß-catenin pathway. The results showed that iPSCs could form osteocytes within 10 days. Animal experiments confirmed that rapid osteo-induced iPSCs could enhance the bone regeneration and osteointegration capacity of the 3DTi scaffolds. Mechanistically, RA could activate the AKT/GSK3ß/ß-catenin pathway during the process of iPSCs osteogenesis. The rapid osteoinduction of iPSCs combined with 3DTi scaffolds is a safe, effective, and reproducible method for repairing mandibular bone defects.

Tunable-liquid-crystal-filter-based low-light-level color night vision system and its image processing method.

We introduce and verify a single-channel time-division filtering low-light-level (LLL) color night vision system (3LCNV). The imaging scheme, comprising a tunable liquid crystal filter, three-generation GaAsP image intensifier, and CMOS camera, achieves LLL color imaging and ensures sensitivity. The image enhancement and color reconstruction algorithm flow suitable for LLL night vision combines overexposure-against white balance, color correction matrix (CCM) color correction, and color image denoising to improve color visibility and reduce color difference and image noise. The proposed night vision system extends the minimum working illuminance to 10-4 lx and achieves natural and clear color LLL imaging, improving night-time observations.

Improvement of Aesthetic and Nasal Airway in Patients With Cleft Lip Nasal Deformities: Rhinoplasty With Septal Cartilage Graft and Septoplasty.

OBJECTIVE: To assess the improvement of nasal morphologies and ventilation after septal cartilage graft and septoplasty of patients with unilateral cleft lip and palate (UCLP). DESIGN: Retrospective case-control study. SETTING: Tertiary stomatology hospital. PATIENTS: In total, 118 patients with UCLP who had been diagnosed with a secondary nasal deformity and had reconstructive rhinoplasty and/or septoplasty between 2010 and 2015. MAIN OUTCOME MEASURES: Nasal Obstruction Symptoms Evaluation (NOSE) questionnaire, septum deviated angle, rhinoplasty satisfaction questionnaire, and 3-dimensional photographs. RESULTS: Average follow-up period was approximately 12 months for both groups. NOSE and 3-dimensional computed tomography (3DCT) analysis demonstrated postoperative improvement in nasal airway function of those patients who underwent rhinoplasty and septoplasty simultaneously ( P < .05). Subjective assessment by patients' visual analog scale (VAS) and objective assessment by 3-dimensional stereophotography demonstrated postoperative improvement in nasal morphologies, particularly the columella deviation angle and nasal depth (representing nasal tip height), which are crucial parameters of nasal aesthetics ( P < .05). CONCLUSIONS: In patients who underwent simultaneous rhinoplasty and septoplasty, nasal symmetry and ventilation function were significantly improved compared to the control group. Septum grafts could provide nasal tip support for patients with cleft lip. Three-dimensional stereophotogrammetry helped us to better visualize the surgical results. Although the septal cartilage of Asian patients is sometimes insufficient for simultaneous use for multiple grafts, septum grafts in rhinoplasty of patients with cleft lip nasal deformities could give support for nasal tips.

Overexpression of 3-phosphoinositide-dependent protein kinase-1 is associated with prognosis of gastric carcinoma.

This study investigated the correlation between the expression of 3-phosphoinositide-dependent protein kinase-1 (PDK1) and the prognosis of gastric carcinoma patients. A total of 156 paired tumor and matched normal samples were collected from patients of gastric carcinoma who underwent surgical resection. The expression of PDK1 was analyzed by real-time quantitative PCR and immunohistochemistry method. Potential correlation between PDK1 protein expression and the clinicopathological characteristics was determined by chi-square test and Spearman correlation analysis. The influence of PDK1 expression on 5-year survival rate and survival length was determined by Kaplan-Meier analysis. The expression of PDK1 mRNA and protein were significantly higher in tumor samples comparing to those in adjacent normal samples (paired t test, P = 0.007). Immunohistochemical staining results indicated that PDK1 protein level was positively correlated with infiltration (P = 0.006). However, no associations with age, sex, clinical stage, lymph node metastasis, and distant metastasis were observed (P > 0.05). The 5-year survival rate was 20.1 and 63.4 % of the patients with high and low expression level of PDK1, respectively (P < 0.05). The median survival length was 32.5 months (95 % CI 22.8-37.6) for patients with high level of PDK1 and 63.1 months (95 % CI 52.3-64.7) for patients with low level of PDK1 (×2 = 20.153, P < 0.05). Kaplan-Meier survival curves demonstrated that elevated expression of PDK1 was an independent negative prognostic factor of gastric carcinoma (P<0.05). Our study indicated that PDK1 might serve as a candidate pro-oncogene and a potential prognostic biomarker for gastric carcinoma.

MicroRNA expression profile of surgical removed mandibular bone tissues from patients with mandibular prognathism.

BACKGROUND: Mandibular prognathism (MP) or skeletal class III malocclusion with a prognathic mandible is one of the most severe facial deformities. Recent work has revealed certain circulating microRNAs (miRNAs) are associated with MP, we conducted this study to characterize the miRNAs expression profile in surgically removed mandibular bone tissue in patients with MP and explored the role of miRNA regulation in the pathogenesis of MP. METHODS: Affymetrix GeneChip miRNA 3.0 Array was used to examine the miRNA expression in mandibular bone tissues from MP patients and control subjects. A variety of bioinformatic approaches were used to predict the target genes of the miRNAs, find the potential functions and pathways of the target genes, analyze their intersection with differentially expressed mRNAs, and establish miRNA-gene network. RESULTS: Eleven upregulated and 11 downregulated miRNAs with a fold change ≥ 2 and a P value <0.05 were identified in bone specimens of MP patients. A total of 3569 genes were predicted as targets of hsa-miR-10a-5p, hsa-miR-150-5p, hsa-miR-192-5p, hsa-miR-194-5p, hsa-miR-197-3p, hsa-miR-30 d-5p, hsa-miR-342-5p and hsa-miR-629-5p, hsa-miR-1202, and hsa-miR-638. The target genes were predicted to be involved in biological functions and signaling pathways related to osteogenesis. Hsa-miR-30 d-5p was the key node of miRNA-gene network. CONCLUSIONS: Our results indicated a possible association between the differentially expressed miRNAs and MP pathogenesis, and the precise mechanisms are needed to be further validated.

Comparative research on phosphorus removal by pilot-scale vertical flow constructed wetlands using steel slag and modified steel slag as substrates.

This research mainly focused on the phosphorus removal performance of pilot-scale vertical flow constructed wetlands with steel slag (SS) and modified steel slag (MSS). First, bench-scale experiments were conducted to evaluate the phosphorus adsorption capacity. Results showed that the Langmuir model could better describe the adsorption characteristics of the two materials; the maximum adsorption of MSS reached 12.7 mg/g, increasing by 34% compared to SS (9.5 mg/g). Moreover, pilot-scale constructed wetlands with SS and MSS were set up outdoors. Then, the influence of hydraulic retention time (HRT) and phosphorus concentration in phosphorus removal for two wetlands were investigated. Results revealed that better performance of the two systems could be achieved with an HRT of 2 d and phosphorus concentration in the range of 3-4.5 mg/L; the system with MSS had a better removal efficiency than the one with SS in the same control operation. Finally, the study implied that MSS could be used as a promising substrate for wetlands to treat wastewater with a high phosphorus concentration. However, considering energy consumption, SS could be regarded as a better alternative for substrate when treating sewage with a low phosphorus concentration.

First-aid treatments of crush injuries after earthquake: 2 special cases.

Hyperkalemia and acute renal failure are the life-threatening complications of crush injuries. Vigilant prehospital emergency care is vital to reduce the complications. We report and discuss 2 cases diagnosed as crush syndrome after earthquake, in order to illustrate the value of prehospital application of tourniquets to prevent hyperkalemia accompanying extremity crush injuries. The victim in case 1 died of hyperkalemia shortly after extrication without tourniquet. The prehospital tourniquet had been used to avoid uncontrollable hemorrhage and release of toxic metabolites into the circulation in case 2. Providers need to be fully aware of the risk of hyperkalemia in the field for patients with crush syndrome. Tourniquet application is strongly recommended in the prehospital setting for severe crush injuries.

Anthropometric analysis of the maxillary bone and the alar base in unilateral cleft lip with secondary nasal deformity: classification of a piriform margin bony depression.

OBJECTIVES: This study was conducted to measure the soft tissue of the alar base and the piriform aperture area of the maxillary bone of unilateral cleft lips with secondary nasal deformities when secondary operation are necessary to classify the alar base depression and to provide a clinical reference for the second surgery. METHODS: Twenty-six patients with unilateral cleft lip with secondary nasal deformity were treated at the Department of Oral and Maxillofacial Surgery, School of Stomatology, China Medial University. Nose data were attained preoperatively and postoperatively. Correlations were made between the soft tissue and the bony depression and patient satisfaction with the nasi basis. Classifications were then made based on these data. RESULTS: When the distance discrepancy of the bilateral piriform aperture depression was less than 4.5 mm, we obtained a fine appearance for the nose by repairing only the soft tissues. When it was more than 5 mm, we had to combine repair of the soft tissue with a bone graft or the restitution of the alveolar cleft. When the distance was between 4.5 mm and 5 mm, the surgeon considered both the wishes of the patient and the clinic's standard procedure. CONCLUSIONS: For patients with cleft lips and palates, the bony depression was not the only factor that resulted in postoperative alar depression. Anthropometry of the nose prior to surgery was important for choosing the methods that would yield satisfactory results.

The safety and efficacy of intranasal dexmedetomidine during electrochemotherapy for facial vascular malformation: a double-blind, randomized clinical trial.

PURPOSE: Intranasal dexmedetomidine is noninvasive and has been reported as premedication for children undergoing surgery. The aim of this study was to evaluate the safety and efficacy of intranasal dexmedetomidine during electrochemotherapy for facial vascular malformation under local anesthesia. MATERIALS AND METHODS: A placebo-controlled randomized clinical trial was designed. Patients with facial vascular malformation scheduled for electrochemotherapy under local anesthesia were randomly assigned to 1 of 3 groups (group IN, IV, or C). Patients in group IN received dexmedetomidine 1 µg/kg intranasally. Patients in group IV received dexmedetomidine 1 µg/kg intravenously. Patients in group C received 0.9% saline intranasally and intravenously. Sedation status and vital signs were assessed at baseline, 15 and 30 minutes after drug administration, before surgery, and 15 minutes after the start of surgery. Midazolam was used as a rescue. Data were analyzed by 2-way repeated measures analysis of variance. RESULTS: Sixty patients with American Society of Anesthesiologists physical status I or II were enrolled. Patients in groups IN and IV were significantly more sedated than those in group C before the beginning of surgery (P < .001 for the 2 comparisons). After nasal administration, adequate sedation was achieved within 30 to 45 minutes. In group IV, the onset of sedation was 15 to 20 minutes. There were no clinically significant adverse effects. CONCLUSIONS: Intranasal dexmedetomidine has a sedative effect under local anesthesia and offers a noninvasive, better-tolerated alternative to intravenous administration.

Three-dimensional finite element analysis of the craniomaxillary complex during maxillary protraction with bone anchorage vs conventional dental anchorage.

INTRODUCTION: The aim of this study was to explore the biomechanical effects on the craniomaxillary complex of bone anchorage and dental anchorage during maxillary protraction. METHODS: We established 2 finite element models. One simulated maxillary protraction with dental anchorage in the maxillary first molars and the other with bone anchorage in the infrazygomatic buttresses of the maxilla. The magnitude of the applied forces was 500 g per side, and the force directions were 0°, 10°, 20°, and 30° forward and downward relative to the occlusal plane. RESULTS: The finite element model of the craniomaxillary complex could displace in an almost translatory manner when the force direction was about 20° in the bone anchorage model and about 30° in the dental anchorage model. The nodes representing the sutures at the back of the maxilla showed greater stress in the bone anchorage model than in the dental anchorage model in the same force direction. It is the opposite at the front of the maxilla. CONCLUSIONS: We should determine the direction of applied force according to the anchorage location and skeletal characteristics of patients before maxillary protraction. The dramatic effects of maxillary protraction with bone anchorage can be based on the advantages of bone anchorage, not on the changes in the region of the applied force.

[Feasibility of 13th lymph nodes as sentinels for periampullary carcinoma].

OBJECTIVE: To study the feasibility and clinical value of 13th lymph nodes in predicting general lymph nodes metastases for periampullary carcinoma. METHODS: A total of 77 patients with pathologically confirmed periampullary carcinoma were recruited. And 26 (18 males and 8 females, age 38-79 years) of them underwent Whipple procedures during which 1% methylene blue or nanogate carbon was injected into tumor bed. The other 51 patients as controls (33 males, 18 females, age 38-78 years) . The dyed 13th lymph nodes were biopsied. Then routine lymphadenectomy was performed and their pathological results were analyzed. RESULTS: In the experimental group, the lymph node drainage area of cancer was identified. However, in contrast with 51 patients in the control group, the labeling of 13th lymph nodes did not significantly increase the number of cleaned lymph nodes (15.8 (3-54) vs 17.6 (6-40) , P = 0.460). CONCLUSION: 13th lymph nodes are non-suitable as sentinels for predicting general lymph nodes metastases of periampullary carcinoma.

[Experimental investigation of the chemical effect of direct current arc plasma igniter].

To study the chemical effect of direct current arc plasma igniter, the emission spectrum of plasma jet was measured, and the active particles produced by the interaction of plasma jet with atmospheric air were analyzed. The NO and CO volume fractions were measured quantificationally by smoke analyzer at the 8cm downstream the plasma igniter exit, and the changing law between arc current and NO, CO volume fractions was obtained. The results show that the plasma jet interacting with atmospheric air produced active particles (H, O, N), charged particles (O2 +, N2+), and excited particles (N2 (A3), N2 (B3), N2 (C3), N2 (a1), O2 (a1), O2 (b1)). The NO and CO volume fractions increased with rising of are current and feedstock argon flow rate.