A Circulating Panel of circRNA Biomarkers for the Noninvasive and Early Detection of Pancreatic Ductal Adenocarcinoma.

BACKGROUND & AIMS: Pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal malignancies. Delayed manifestation of symptoms and lack of specific diagnostic markers lead patients being diagnosed with PDAC at advanced stages. This study aimed to develop a circular RNA (circRNA)-based biomarker panel to facilitate noninvasive and early detection of PDAC. METHODS: A systematic genome-wide discovery of circRNAs overexpressed in patients with PDAC was conducted. Subsequently, validation of the candidate markers in the primary tumors from patients with PDAC was performed, followed by their translation into a plasma-based liquid biopsy assay by analyzing 2 independent clinical cohorts of patients with PDAC and nondisease controls. The performance of the circRNA panel was assessed in conjunction with the plasma levels of cancer antigen 19-9 for the early detection of PDAC. RESULTS: Initially, a panel of 10 circRNA candidates was identified during the discovery phase. Subsequently, the panel was reduced to 5 circRNAs in the liquid biopsy-based assay, which robustly identified patients with PDAC and distinguished between early-stage (stage I/II) and late-stage (stage III/IV) disease. The areas under the curve of this diagnostic panel for the detection of early-stage PDAC were 0.83 and 0.81 in the training and validation cohorts, respectively. Moreover, when this panel was combined with cancer antigen 19-9 levels, the diagnostic performance for identifying patients with PDAC improved remarkably (area under the curve, 0.94) for patients in the validation cohort. Furthermore, the circRNA panel could also efficiently identify patients with PDAC (area under the curve, 0.85) who were otherwise deemed clinically cancer antigen 19-9-negative (<37 U/mL). CONCLUSIONS: A circRNA-based biomarker panel with a robust noninvasive diagnostic potential for identifying patients with early-stage PDAC was developed.

Eight-Membered Palladacycle Intermediate Enabled Synthesis of Cyclic Biarylphosphonates.

Transition-metal-catalyzed coupling reactions that involve the direct functionalization of insert C-H bond represent one of the most efficient strategies for forming carbon-carbon bonds. Herein, a palladium-catalyzed intramolecular C-H bond arylation of triaryl phosphates is reported to access seven-membered cyclic biarylphosphonate targets. The reaction is achieved via a unique eight-membered palladacyclic intermediate and shows good functional group compatibility. Meanwhile, the product can be readily converted into other valuable phosphate compounds.

Tf2O-Mediated P(O)-N Bond Formation of Either P(O)-OH or P(O)-H Reagents with Multitype Amines.

We have developed a Tf2O-mediated approach for the direct amination of either P(O)-OH or P(O)-H reagents with a variety of aliphatic or aromatic amines. Without the requirement of precious metals and toxic reagents, this protocol provides an alternative route to various phosphinamides and phosphoramides. The reaction proceeds under simple and mild conditions and can be effectively scaled up with similar efficiency.

Development of a Serum-Based MicroRNA Signature for Early Detection of Pancreatic Cancer: A Multicenter Cohort Study.

BACKGROUND: A grim prognosis of pancreatic cancer (PCa) was attributed to the difficulty in early diagnosis of the disease. AIMS: Identifying novel biomarkers for early detection of PCa is thus urgent to improve the overall survival rates of patients. METHODS: The study was performed firstly by identification of candidate microRNAs (miRNAs) in formalin-fixed, paraffin-embedded tissues using microarray profiles, and followed by validation in a serum-based cohort study to assess clinical utility of the candidates. In the cohorts, a total of 1273 participants from four centers were retrospectively recruited as two cohorts including training and validation cohort. The collected serum specimens were analyzed by real-time polymerase chain reaction. RESULTS: We identified 27 miRNAs expressed differentially in PCa tissues as compared to the benign. Of which, the top-four was selected as a panel whose diagnostic efficacy was fully assessed in the serum specimens. The panel exhibited superior to CA19-9, CA125, CEA and CA242 in discriminating patients with early stage PCa from healthy controls or non-PCa including chronic pancreatitis as well as pancreatic cystic neoplasms, with the area under the curves (AUC) of 0.971 (95% CI 0.956-0.987) and 0.924 (95% CI 0.899-0.949), respectively. Moreover, the panel eliminated interference from other digestive tumors with a specificity of 90.2%. CONCLUSIONS: A panel of four serum miRNAs was developed showing remarkably discriminative ability of early stage PCa from either healthy controls or other pancreatic diseases, suggesting it may be developed as a novel, noninvasive approach for early screening of PCa in clinic.

Identification of novel biomarkers based on lipid metabolism-related molecular subtypes for moderately severe and severe acute pancreatitis.

BACKGROUND: Acute pancreatitis (AP) is an unpredictable and potentially fatal disorder. A derailed or unbalanced immune response may be the root of the disease's severe course. Disorders of lipid metabolism are highly correlated with the occurrence and severity of AP. We aimed to characterize the contribution and immunological characteristics of lipid metabolism-related genes (LMRGs) in non-mild acute pancreatitis (NMAP) and identify a robust subtype and biomarker for NMAP. METHODS: The expression mode of LMRGs and immune characteristics in NMAP were examined. Then LMRG-derived subtypes were identified using consensus clustering. The weighted gene co-expression network analysis (WGCNA) was utilized to determine hub genes and perform functional enrichment analyses. Multiple machine learning methods were used to build the diagnostic model for NMAP patients. To validate the predictive effectiveness, nomograms, receiver operating characteristic (ROC), calibration, and decision curve analysis (DCA) were used. Using gene set variation analysis (GSVA) and single-cell analysis to study the biological roles of model genes. RESULTS: Dysregulated LMRGs and immunological responses were identified between NMAP and normal individuals. NMAP individuals were divided into two LMRG-related subtypes with significant differences in biological function. The cluster-specific genes are primarily engaged in the regulation of defense response, T cell activation, and positive regulation of cytokine production. Moreover, we constructed a two-gene prediction model with good performance. The expression of CARD16 and MSGT1 was significantly increased in NMAP samples and positively correlated with neutrophil and mast cell infiltration. GSVA results showed that they are mainly upregulated in the T cell receptor complex, immunoglobulin complex circulating, and some immune-related routes. Single-cell analysis indicated that CARD16 was mainly distributed in mixed immune cells and macrophages, and MGST1 was mainly distributed in exocrine glandular cells. CONCLUSIONS: This study presents a novel approach to categorizing NMAP into different clusters based on LMRGs and developing a reliable two-gene biomarker for NMAP.

A prospective prognostic signature for pancreatic adenocarcinoma based on ubiquitination-related mRNA-lncRNA with experimental validation in vitro and vivo.

Ubiquitination-related genes (URGs) exerted a crucial part in a variety of human disease disorders; however, their association with pancreatic adenocarcinoma (PAAD) had yet to be clearly described. We aimed to comprehensively characterize the contributions of URGs in PAAD through in silico analysis and experimental validation, and then identified a robust mRNA-lncRNA-based molecular prognostic panel for patients with PAAD using bulk RNA-sequencing and single-cell RNA-sequencing data. Initially, we collected the multi-omics data from TCGA platform to depict a comprehensive landscape of URGs in pan-cancer. Furthermore, we were accurate to PAAD for in-depth analysis. Significant differences of the activation of ubiquitination pathways and the expression of URGs were detected between normal and malignant cells. Unsupervised hierarchical clustering determined two PAAD subtypes with distinct clinical outcomes, ubiquitination pathway activities, immune microenvironment, and functional annotation characteristics. The expression profiles of ubiquitination-associated mRNAs and lncRNAs in the training and validation datasets were utilized to develop and verify a novel ubiquitination-related mRNA-lncRNA prognostic panel, which had a satisfied prediction efficiency. Our ubiquitination-associated model could function as an effective prognostic index and outperformed four other recognized panels in evaluating PAAD patients' survival status. Tumor immune microenvironment, mutation burden, and chemotherapy response were intensively explored to demonstrate the underlying mechanism of prognostic difference according to our panel. Our findings also revealed that FTI-277, a farnesyltransferase inhibitor, had a better curative effect in high-risk patients, while MK-2206, an Akt allosteric inhibitor, had a superior therapeutic effect in low-risk patients. The real-time PCR results uncovered the RNA expression of AC005062.1 in all the three PAAD cell lines was elevated several thousandfold. In conclusion, our URGs-based classification panel could be triumphantly served as a prediction tool for survival evaluation in patients with PAAD, and the genes in this panel could be developed as a potential target in PAAD therapy.

Tryptophan metabolite norharman secreted by cultivated Lactobacillus attenuates acute pancreatitis as an antagonist of histone deacetylases.

BACKGROUND: Patients with acute pancreatitis (AP) exhibit specific phenotypes of gut microbiota associated with severity. Gut microbiota and host interact primarily through metabolites; regrettably, little is known about their roles in AP biological networks. This study examines how enterobacterial metabolites modulate the innate immune system in AP aggravation. METHODS: In AP, alterations in gut microbiota were detected via microbiomics, and the Lactobacillus metabolites of tryptophan were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). By culturing Lactobacillus with tryptophan, differential metabolites were detected by LC-MS/MS. Lipopolysaccharide (LPS)-stimulated RAW264.7 cells and mice with cerulein plus LPS-induced AP were used to evaluate the biological effect of norharman on M1 macrophages activation in AP development. Further, RNA sequencing and lipid metabolomics were used for screening the therapeutic targets and pathways of norharman. Confocal microscopy assay was used to detect the structure of lipid rafts. Molecular docking was applied to predict the interaction between norharman and HDACs. Luciferase reporter assays and chromatin immunoprecipitation (ChIP) were used to explore the direct mechanism of norharman promoting Rftn1 expression. In addition, myeloid-specific Rftn1 knockout mice were used to verify the role of Rftn1 and the reversed effect of norharman. RESULTS: AP induced the dysfunction of gut microbiota and their metabolites, resulting in the suppression of Lactobacillus-mediated tryptophan metabolism pathway. The Lactobacillus metabolites of tryptophan, norharman, inhibited the release of inflammatory factor in vitro and in vivo, as a result of its optimal inhibitory action on M1 macrophages. Moreover, norharman blocked multiple inflammatory responses in AP exacerbation due to its ability to maintain the integrity of lipid rafts and restore the dysfunction of lipid metabolism. The mechanism of norharman's activity involved inhibiting the enzyme activity of histone deacetylase (HDACs) to increase histone H3 at lysine 9/14 (H3K9/14) acetylation, which increased the transcription level of Rftn1 (Raftlin 1) to inhibit M1 macrophages' activation. CONCLUSIONS: The enterobacterial metabolite norharman can decrease HDACs activity to increase H3K9/14 acetylation of Rftn1, which inhibits M1 macrophage activation and restores the balance of lipid metabolism to relieve multiple inflammatory responses. Therefore, norharman may be a promising prodrug to block AP aggravation.

Nickel-Catalyzed Sodium Hypophosphite-Participated Direct Hydrophosphonylation of Alkyne toward H-Phosphinates.

The traditional methods for the synthesis of phosphinate esters use phosphorus trichloride (PCl3) as the phosphorous source, resulting in procedures that are often highly polluting and energy intensive. The search for an alternative approach that is both mild and environmentally friendly is a challenging, yet highly rewarding task in modern chemistry. Herein, we use an inorganic phosphorous-containing species, NaH2PO2, to serve as the source of phosphorous that participates directly in the nickel-catalyzed selective alkyne hydrophosphonylation reaction. The transformation was achieved in a multicomponent fashion and at room temperature, and most importantly, the H-phosphinate product generated is an advanced intermediate which can be readily converted into diverse phosphinate derivatives, including those bearing new P-C, P-S, P-N, P-Se, and P-O bonds, thus providing a complimentary method to classic phosphinate ester synthesis techniques.

Diagnostic accuracy of updated risk assessment criteria and development of novel computational prediction models for patients with suspected choledocholithiasis.

BACKGROUND: There are risks of choledocholithiasis in symptomatic gallstones, and some surgeons have proposed the identification of choledocholithiasis before cholecystectomy. Our goal was to evaluate the diagnostic accuracy of the latest guidelines and create computational prediction models for the accurate prediction of choledocholithiasis. METHODS: We retrospectively reviewed symptomatic gallstone patients hospitalized with suspected choledocholithiasis. The diagnostic performance of 2019 and 2010 guidelines of the American Society for Gastrointestinal Endoscopy (ASGE) and 2019 guideline of the European Society of Gastrointestinal Endoscopy (ESGE) in different risks. Lastly, we developed novel prediction models based on the preoperative predictors. RESULTS: A total of 1199 patients were identified and 681 (56.8%) had concurrent choledocholithiasis and were included in the analysis. The specificity of the 2019 ASGE, 2010 ASGE, and 2019 ESGE high-risk criteria was 85.91%, 72.2%, and 88.42%, respectively, and their positive predictive values were 85.5%, 77.4%, and 87.3%, respectively. For Mid-risk patients who followed 2019 ASGE about 61.8% of them did not have CBD stones in our study. On the choice of surgical procedure, laparoscopic cholecystectomy + laparoscopic transcystic common bile duct exploration can be considered the optimal treatment choice for cholecysto-choledocholithiasis instead of Endoscopic Retrograde Cholangio-Pancreatography (ERCP). We build seven machine learning models and an AI diagnosis prediction model (ModelArts). The area under the receiver operating curve of the machine learning models was from 0.77 to 0.81. ModelArts AI model showed predictive accuracy of 0.97, recall of 0.97, precision of 0.971, and F1 score of 0.97, surpassing any other available methods. CONCLUSION: The 2019 ASGE guideline and 2019 ESGE guideline have demonstrated higher specificity and positive predictive value for high-risk criteria compared to the 2010 ASGE guideline. The excellent diagnostic performance of the new artificial intelligence prediction model may make it a better choice than traditional guidelines for managing patients with suspected choledocholithiasis in future.

Identification and immunological characterization of lipid metabolism-related molecular clusters in nonalcoholic fatty liver disease.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is now the major contributor to chronic liver disease. Disorders of lipid metabolism are a major element in the emergence of NAFLD. This research intended to explore lipid metabolism-related clusters in NAFLD and establish a prediction biomarker. METHODS: The expression mode of lipid metabolism-related genes (LMRGs) and immune characteristics in NAFLD were examined. The "ConsensusClusterPlus" package was utilized to investigate the lipid metabolism-related subgroup. The WGCNA was utilized to determine hub genes and perform functional enrichment analysis. After that, a model was constructed by machine learning techniques. To validate the predictive effectiveness, receiver operating characteristic curves, nomograms, decision curve analysis (DCA), and test sets were used. Lastly, gene set variation analysis (GSVA) was utilized to investigate the biological role of biomarkers in NAFLD. RESULTS: Dysregulated LMRGs and immunological responses were identified between NAFLD and normal samples. Two LMRG-related clusters were identified in NAFLD. Immune infiltration analysis revealed that C2 had much more immune infiltration. GSVA also showed that these two subtypes have distinctly different biological features. Thirty cluster-specific genes were identified by two WGCNAs. Functional enrichment analysis indicated that cluster-specific genes are primarily engaged in adipogenesis, signalling by interleukins, and the JAK-STAT signalling pathway. Comparing several models, the random forest model exhibited good discrimination performance. Importantly, the final five-gene random forest model showed excellent predictive power in two test sets. In addition, the nomogram and DCA confirmed the precision of the model for NAFLD prediction. GSVA revealed that model genes were down-regulated in several immune and inflammatory-related routes. This suggests that these genes may inhibit the progression of NAFLD by inhibiting these pathways. CONCLUSIONS: This research thoroughly emphasized the complex relationship between LMRGs and NAFLD and established a five-gene biomarker to evaluate the risk of the lipid metabolism phenotype and the pathologic results of NAFLD.

Fine particulate matter exposure disturbs autophagy, redox balance and mitochondrial homeostasis via JNK activation to inhibit proliferation and promote EMT in human alveolar epithelial A549 cells.

Epidemiologic studies have demonstrated a direct correlation between fine particulate matter (FPM) exposure and the high risk of respiratory diseases. FPM can penetrate deep into the lung and deposit in the alveoli with breath, where it directly interacts with alveolar epithelial cell (APC). However, we know little about the effects nor mechanisms of FPM on APC. Here, using human APC A549 cells, we found that FPM resulted in blockade of autophagic flux, redox imbalance and oxidative stress, mitochondrial fragmentation, increased mitophagy and impaired mitochondrial respiration. Further we showed that activation of JNK signaling (c-Jun N-terminal kinase) and excessive ROS (reactive oxygen species) release contribute to these adverse effects, with the former being upstream of the latter. More importantly, we found that scavenging ROS or inhibiting JNK activation could restore those effects as well as ameliorate FPM-induced inhibition of cell proliferation, and epithelial-mesenchymal transformation (EMT) in A549 cells. Taken together, our findings indicate that FPM leads to toxicity in alveolar type II cells via JNK activation, and JNK-targeting or antioxidant strategies might be beneficial for prevention or treatment of FPM-related pulmonary diseases.

Debranching Thoracic Endovascular Aortic Repair Combined with Ascending Aortic Banding: Analysis of a New Surgical Procedure.

BACKGROUND: To analyze the clinical effect of debranching thoracic endovascular aortic repair combined with ascending aortic banding. METHODS: The clinical data of patients who underwent a debranching thoracic endovascular aortic repair combined with ascending aortic banding at Anzhen Hospital (Beijing, China) between January 2019 and December 2021 were reviewed to evaluate the occurrence and outcomes of postoperative complications. RESULTS: A total of 30 patients underwent a debranching thoracic endovascular aortic repair combined with ascending aortic banding. There were 28 male patients (93.3%) with an average age of 59.9 ± 11.8 years. Twenty-five patients underwent simultaneous surgery and five patients had staged surgery. Postoperatively, two patients developed complete paraplegia (6.7%), three patients developed incomplete paraplegia (10%), two patients developed cerebral infarction (6.7%), and one patient developed femoral artery thromboembolism (3.3%). No patient died during the perioperative period, and one patient (3.3%) died during the follow-up period. None of the patients underwent retrograde type A aortic dissection during the perioperative and postoperative follow-up periods. CONCLUSIONS: Banding the ascending aorta with a vascular graft to restrict its movement and to serve as the proximal anchoring area of the stent graft can reduce the risk of retrograde type A aortic dissection.

Qingyi granules ameliorate severe acute pancreatitis in rats by modulating the gut microbiota and serum metabolic aberrations.

CONTEXT: Qingyi granules can be used to effectively treat patients with severe acute pancreatitis (SAP). OBJECTIVE: To elucidate the role of gut microbiota-mediated metabolism in the therapeutic effects of Qingyi granules. MATERIALS AND METHODS: Sprague-Dawley rats were grouped into the sham operation, SAP model, Qingyi granule intervention (Q, 1.8 g/kg) and emodin intervention (E, 50 mg/kg) groups and observed for 24 h. H&E staining and ELISA were used for histopathological analysis and serum enzyme and cytokine assays. 16S rDNA sequencing and UHPLC-HRMS were used for gut microbiota analysis and untargeted metabolomics. RESULTS: In SAP rats, Qingyi granules decreased the pancreatic pathological score (Q, 7.4 ± 1.14; SAP, 11.6 ± 1.14, p < 0.01); serum amylase (Q, 121.2 ± 6.7; SAP, 144.3 ± 8.86, p < 0.05), lipase (Q, 566 ± 20.34; SAP, 656.7 ± 29.32, p < 0.01), and diamineoxidase (Q, 492.8 ± 26.08; SAP, 566.1 ± 26.83, p < 0.05) activities; and IL-1ß (Q, 29.48 ± 0.88; SAP, 36.17 ± 1.88, p < 0.01), IL-6 (Q, 112.2 ± 3.57; SAP, 128.9 ± 9.09, p < 0.05) and TNF-α (Q, 215.3 ± 8.67; SAP, 266.4 ± 28.03, p < 0.05) levels. SAP induced Helicobacter and Lactobacillus overgrowth and suppressed Romboutsia and Allobaculum growth and caused aberrations in bacterial metabolites, which were partly reversed by Qingyi granules. DISCUSSION AND CONCLUSIONS: Qingyi granules can modulate the gut microbiota and metabolic abnormalities to ameliorate SAP. Multi-omics approaches allow systematic study of the pharmacological mechanisms of compound prescriptions for critical illnesses.

Infection with a human-derived enteroinvasive Escherichia coli strain altered intestinal barrier function in guinea pigs.

BACKGROUND/AIMS: The aim was to characterize a bacterium causing intestinal mucosal barrier damage and to identify the possible invasion mechanism. MATERIALS AND METHODS: The intestinal permeability and tight junction protein levels were detected in guinea pigs infected with Escherichia coli D-09 via immunofluorescence analysis and western blotting. In order to explain this invasion mechanism at the gene level, whole genome sequencing analysis was performed on this bacterium. RESULTS: The results showed an increased intestinal permeability and upregulated expression of the leaky protein claudin-2 in both the colon and liver of the infected animals. In addition, the draft genome of E. coli D-09 comprised 42 scaffolds (size, > 645 bp) with a total size of 4,679,567 bp. A total of 4379 protein coding genes were identified, which contained 45 antibiotic resistance and 86 virulence-related genes and covered 88.0% of the whole genome. CONCLUSIONS: This study verified that the human-derived enteroinvasive E. coli strain could destroy intestinal barrier function in guinea pigs. Additionally, our data first characterized the genome features of E. coli O124:K72 D-09, which may provide new insights into the possible invasion mechanism.

Primary Amination of Ar2P(O)-H with (NH4)2CO3 as an Ammonia Source under Simple and Mild Conditions and Its Extension to the Construction of Various P-N or P-O Bonds.

A facile and efficient method for the synthesis of primary phosphinamides from Ar2P(O)-H reagents with stable and readily available ammonium carbonate as an ammonia source is disclosed herein for the first time. This ethyl bromoacetate-mediated primary amination proceeds smoothly under mild and simple conditions, without any metal catalyst or oxidant. Moreover, this method is also appropriate for the reaction of Ar2P(O)-H with a variety of amines, alcohols, and phenols to construct P-N or P-O bonds, with features of handy operation, good functional group tolerance, and broad substrate scope.

Visible-Light-Mediated Tandem Difluoromethylation/Cyclization of Alkenyl Aldehydes toward CF2H-Substituted Chroman-4-one Derivatives.

An efficient and facile visible-light-mediated tandem difluoromethylation/cyclization of alkenyl aldehydes, with easily accessible and air-stable [Ph3PCF2H]+Br- as the difluoromethylation reagent, has been established. A range of CF2H-substituted chroman-4-one skeletons and their derivatives, such as 2,3-dihydroquinolin-4(1H)-ones, chroman, 3,4-dihydronaphthalen-1(2H)-one, 2,3-dihydrobenzofuran, and 2,3-dihydro-1H-inden-1-one, are efficiently produced in moderate to good yields with excellent chemoselectivity under mild reaction conditions.

Transition-metal-free three-component coupling approach to QUINAP derivatives.

The aluminum(III) triflate catalyzed three-component coupling reaction of alkynes, amines and phosphorylated aryl aldehydes to access phosphoryl quinoline derivatives has been developed. The reaction proceeds in a simple system without the use of transition metals, ligands or additives, thus making it attractive for the fast preparation of a variety of new potential N-P bidentate ligands.

Challenges in treatment of a patient suffering from neuroendocrine tumor G1 of the hilar bile duct: a case report.

BACKGROUND: Neuroendocrine tumors (NETs) arise from neuroendocrine cells and are extremely rare in the biliary tract. Currently, there are no guidelines for the diagnosis and treatment of biliary NETs. We presented a case with NETs G1 of the hilar bile duct and the challenges for her treatment. CASE PRESENTATION: A 24-year-old woman was presented to our department with painless jaundice and pruritus, and the preoperative diagnosis was Bismuth type II hilar cholangiocarcinoma. She underwent Roux-en-Y hepaticojejunostomy with excision of the extrahepatic biliary tree and radical lymphadenectomy. Unexpectedly, postoperative pathological and immunohistochemical examination indicated a perihilar bile duct NETs G1 with the microscopic invasion of the resected right hepatic duct. Then the patient received 3 cycles of adjuvant chemotherapy (Gemcitabine and tegafur-gimeracil-oteracil potassium capsule). At present, this patient has been following up for 24 months without recurrence or disease progression. CONCLUSION: We know little of biliary NETs because of its rarity. There are currently no guidelines for the diagnosis and treatment of biliary NETs. We reported a case of perihilar bile duct NETs G1 with R1 resection, as far as we know this is the first report. More information about biliary NETs should be registered.

Efficient weakly supervised LIBS feature selection method in quantitative analysis of iron ore slurry.

On-stream analysis of the element content in ore slurry plays an important role in the control of the mineral flotation process. Therefore, our laboratory developed a LIBS-based slurry analyzer named LIBSlurry, which can monitor the iron content in slurries in real time. However, achieving high-precision quantitative analysis results of the slurries is challenging. In this paper, a weakly supervised feature selection method named spectral distance variable selection was proposed for the raw spectral data. This method utilizes the prior information that multiple spectra of the same slurry sample have the same reference concentration to assess the important weight of spectral features, and features selected by this prior can avoid over-fitting compared with a traditional wrapper method. The spectral data were collected on-stream of iron ore concentrate slurry samples during the mineral flotation process. The results show that the prediction accuracy is greatly improved compared with the full-spectrum input and other feature selection methods; the root mean square error of the prediction of iron content can be decreased to 0.75%, which helps to realize the successful application of the analyzer.

Model transfer method based on piecewise direct standardization in laser-induced-breakdown spectroscopy.

A large number of certified samples are usually required to build models in the quantitative analysis of complicated matrices in laser-induced-breakdown spectroscopy (LIBS). Because of differences among instruments, including excitation and collection efficiencies, a quantitative model made on one instrument is difficult to apply directly to other instruments. Each instrument requires a large number of samples to model, which is very labor intensive and will hinder the rapid application of the LIBS technique. To eliminate the differences in spectral data from different instruments and reduce the cost of building new models, a piecewise direct standardization method combined with partial least squares (PLS_PDS) is studied in this work. Two portable LIBS instruments with the same configuration are used to obtain spectral data, one of which is called a master instrument because its calibration model is directly built on a large number of labeled samples, and the other of which is called a slave instrument because its model is obtained from the master instrument. The PLS_PDS method is used to build a transfer function of spectra between the master instrument and slave instrument to reduce the spectral difference between two instruments, and thus one calibration model can adapt to different instruments. Results show that for multiple elemental analyses of aluminium alloy samples, the number of samples required for slave modeling was reduced from 51 to 14 after model transferring by PLS_PDS, and the quantitative performance of the slave instrument was close to that of the master instrument. Therefore, the model transfer method can obviously reduce the sample number of building models for slave instruments, and it will be beneficial to advance the application of LIBS.