1.IMM-H007 promotes hepatic cholesterol and triglyceride metabolism by activating AMPKα to attenuate hypercholesterolemia.
Jiaqi LI ; Mingchao WANG ; Kai QU ; Yuyao SUN ; Zequn YIN ; Na DONG ; Xin SUN ; Yitong XU ; Liang CHEN ; Shuang ZHANG ; Xunde XIAN ; Suowen XU ; Likun MA ; Yajun DUAN ; Haibo ZHU
Acta Pharmaceutica Sinica B 2025;15(8):4047-4063
Hypercholesterolemia is a significant risk factor for the development of atherosclerosis. 2',3',5'-Tri-O-acetyl-N 6-(3-hydroxyphenyl) adenosine (IMM-H007), a novel AMPK agonist, has shown protective effects in metabolic diseases. However, its impact on cholesterol and triglyceride metabolism in hypercholesterolemia remains unclear. In this study, we aimed to elucidate the effects and specific mechanisms by which IMM-H007 regulates cholesterol and triglyceride metabolism. To achieve this goal, we used Apoe -/- and Ldlr -/- mice to establish a hypercholesterolemia/atherosclerosis model. Additionally, hepatocyte-specific Ampka1/2 knockout mice were subjected to a 5-week high-cholesterol diet to establish hypercholesterolemia, while atherosclerosis was induced via AAV-PCSK9 injection combined with a 16-week high-cholesterol diet. Our results demonstrated that IMM-H007 improved cholesterol and triglyceride metabolism in mice with hypercholesterolemia. Mechanistically, IMM-H007 modulated the AMPKα1/2-LDLR signaling pathway, increasing cholesterol uptake in the liver. Furthermore, IMM-H007 activated the AMPKα1-FXR pathway, promoting the conversion of hepatic cholesterol to bile acids. Additionally, IMM-H007 prevented hepatic steatosis by activating the AMPKα1/2-ATGL pathway. In conclusion, our study suggests that IMM-H007 is a promising therapeutic agent for improving hypercholesterolemia and atherosclerosis through the activation of AMPKα.
2.Buqi-Tongluo Decoction inhibits osteoclastogenesis and alleviates bone loss in ovariectomized rats by attenuating NFATc1, MAPK, NF-κB signaling.
Yongxian LI ; Jinbo YUAN ; Wei DENG ; Haishan LI ; Yuewei LIN ; Jiamin YANG ; Kai CHEN ; Heng QIU ; Ziyi WANG ; Vincent KUEK ; Dongping WANG ; Zhen ZHANG ; Bin MAI ; Yang SHAO ; Pan KANG ; Qiuli QIN ; Jinglan LI ; Huizhi GUO ; Yanhuai MA ; Danqing GUO ; Guoye MO ; Yijing FANG ; Renxiang TAN ; Chenguang ZHAN ; Teng LIU ; Guoning GU ; Kai YUAN ; Yongchao TANG ; De LIANG ; Liangliang XU ; Jiake XU ; Shuncong ZHANG
Chinese Journal of Natural Medicines (English Ed.) 2025;23(1):90-101
Osteoporosis is a prevalent skeletal condition characterized by reduced bone mass and strength, leading to increased fragility. Buqi-Tongluo (BQTL) decoction, a traditional Chinese medicine (TCM) prescription, has yet to be fully evaluated for its potential in treating bone diseases such as osteoporosis. To investigate the mechanism by which BQTL decoction inhibits osteoclast differentiation in vitro and validate these findings through in vivo experiments. We employed MTS assays to assess the potential proliferative or toxic effects of BQTL on bone marrow macrophages (BMMs) at various concentrations. TRAcP experiments were conducted to examine BQTL's impact on osteoclast differentiation. RT-PCR and Western blot analyses were utilized to evaluate the relative expression levels of osteoclast-specific genes and proteins under BQTL stimulation. Finally, in vivo experiments were performed using an osteoporosis model to further validate the in vitro findings. This study revealed that BQTL suppressed receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis and osteoclast resorption activity in vitro in a dose-dependent manner without observable cytotoxicity. The inhibitory effects of BQTL on osteoclast formation and function were attributed to the downregulation of NFATc1 and c-fos activity, primarily through attenuation of the MAPK, NF-κB, and Calcineurin signaling pathways. BQTL's inhibitory capacity was further examined in vivo using an ovariectomized (OVX) rat model, demonstrating a strong protective effect against bone loss. BQTL may serve as an effective therapeutic TCM for the treatment of postmenopausal osteoporosis and the alleviation of bone loss induced by estrogen deficiency and related conditions.
Animals
;
NFATC Transcription Factors/genetics*
;
Drugs, Chinese Herbal/pharmacology*
;
Ovariectomy
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Osteoclasts/metabolism*
;
Female
;
Osteogenesis/drug effects*
;
Rats, Sprague-Dawley
;
Rats
;
NF-kappa B/genetics*
;
Osteoporosis/genetics*
;
Signal Transduction/drug effects*
;
Bone Resorption/genetics*
;
Cell Differentiation/drug effects*
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Humans
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RANK Ligand/metabolism*
;
Mitogen-Activated Protein Kinases/genetics*
;
Transcription Factors
3.Environmental Temperature and the Risk of Hand, Foot, and Mouth Disease Transmission in the Yangtze River Region of China.
Yan Qing YANG ; Min CHEN ; Jin LI ; Kai Qi LIU ; Xue Yan GUO ; Xin XU ; Qian LIANG ; Xing Lu WU ; Su Wen LEI ; Jing LI
Biomedical and Environmental Sciences 2025;38(3):290-302
OBJECTIVE:
To assess health equity in the Yangtze River region to improve understanding of the correlation between hand, foot, and mouth disease (HFMD) and socioeconomic factors.
METHODS:
From 2014-2016, data on HFMD incidence, population statistics, economic indicators, and meteorology from 26 cities along the Yangtze River were analyzed. A multi-city random-effects meta-analysis was performed to study the relationship between temperature and HFMD transmission, and health equity was assessed with respect to socio-economic impact.
RESULTS:
Over the study period, 919,458 HFMD cases were reported, with Shanghai (162,303) having the highest incidence and Tongling (5,513) having the lowest. Males were more commonly affected (male-to-female ratio, 1.49:1). The exposure-response relationship had an M-shaped curve, with two HFMD peaks occurring at 4 °C and 26 °C. The relative risk had two peaks at 1.30 °C (1.834, 95% CI: 1.204-2.794) and 31.4 °C (1.143, 95% CI: 0.901-1.451), forming an M shape, with the first peak higher than the second. The most significant impact of temperature on HFMD was observed between -2 °C and 18.1 °C. The concentration index (0.2463) indicated moderate concentration differences, whereas the Theil index (0.0418) showed low inequality in distribution.
CONCLUSION
The incidence of HFMD varied across cities, particularly with changes in temperature. Economically prosperous areas showed higher risks, indicating disparities. Targeted interventions in these areas are crucial for mitigating the risk of HFMD.
Female
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Humans
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Male
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China/epidemiology*
;
Cities/epidemiology*
;
Hand, Foot and Mouth Disease/transmission*
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Incidence
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Risk Factors
;
Temperature
4.Construction of a Prognostic Model for Lysosome-dependent Cell Death in Gastric Cancer Based on Single-cell RNA-seq and Bulk RNA-seq Data.
Peng NI ; Kai Xin GUO ; Tian Yi LIANG ; Xin Shuang FAN ; Yan Qiao HUA ; Yang Ye GAO ; Shuai Yin CHEN ; Guang Cai DUAN ; Rong Guang ZHANG
Biomedical and Environmental Sciences 2025;38(4):416-432
OBJECTIVE:
To identify prognostic genes associated with lysosome-dependent cell death (LDCD) in patients with gastric cancer (GC).
METHODS:
Differentially expressed genes (DEGs) were identified using The Cancer Genome Atlas - Stomach Adenocarcinoma. Weighted gene co-expression network analysis was performed to identify the key module genes associated with LDCD score. Candidate genes were identified by DEGs and key module genes. Univariate Cox regression analysis, and least absolute shrinkage and selection operator regression and multivariate Cox regression analyses were performed for the selection of prognostic genes, and risk module was established. Subsequently, key cells were identified in the single-cell dataset (GSE183904), and prognostic gene expression was analyzed. Cell proliferation and migration were assessed using the Cell Counting Kit-8 assay and the wound healing assay.
RESULTS:
A total of 4,465 DEGs, 95 candidate genes, and 4 prognostic genes, including C19orf59, BATF2, TNFAIP2, and TNFSF18, were identified in the analysis. Receiver operating characteristic curves indicated the excellent predictive power of the risk model. Three key cell types (B cells, chief cells, and endothelial/pericyte cells) were identified in the GSE183904 dataset. C19orf59 and TNFAIP2 exhibited predominant expression in macrophage species, whereas TNFAIP2 evolved over time in endothelial/pericyte cells and chief cells. Functional experiments confirmed that interfering with C19orf59 inhibited proliferation and migration in GC cells.
CONCLUSION
C19orf59, BATF2, TNFAIP2, and TNFSF18 are prognostic genes associated with LDCD in GC. Furthermore, the risk model established in this study showed robust predictive power.
Stomach Neoplasms/pathology*
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Humans
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Prognosis
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Lysosomes/physiology*
;
RNA-Seq
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Cell Death
;
Single-Cell Analysis
;
Gene Expression Regulation, Neoplastic
;
Cell Proliferation
;
Single-Cell Gene Expression Analysis
5.Analysis of related indicators and interventions in apheresis platelet donors with low ferritin
Jie PAN ; Liang GUAN ; Danhong WANG ; Yunming LIN ; Wanping CHEN ; Kai ZHANG ; Mengsha XIANG
Chinese Journal of Blood Transfusion 2025;38(11):1586-1591
Objective: To analyze characteristics of iron-deficient blood donors, implement targeted interventions, and evaluate their effectiveness, thereby providing a reference for formulating blood donor recruitment and care strategies. Methods: Based on serum ferritin (SF) test results, the apheresis platelet donors were divided into the low SF group (n=90; 45 males and 45 females) and the normal SF group (n=651; 510 males and 141 females). The results of related indicators of the two groups were compared and analyzed. Interventions for the low SF group included extending the blood donation interval to at least 45 days (group A) and oral iron supplementation combined with the extended donation interval implemented in group A (group B). Pre-intervention and post-intervention SF results were compared. Results: For both male and female donors, serum iron levels were significantly lower in the low SF group than those of the normal SF group, while the levels of transferrin, unsaturated iron binding capacity (UIBC) and total iron binding capacity (TIBC) were higher in the low SF group compared to the normal SF group. Some indicators related to red blood cells showed changes, with more evident alterations in females than in males. Twenty-eight donors in group A and 39 donors in group B completed the study after intervention. SF value in group A was (18.32±8.09) μg/L at baseline and (26.21±17.30) μg/L after intervention. Similarly, SF value in group B was (15.87±7.69) μg/L at baseline and (26.24±15.55) μg/L after intervention. In both groups, SF values after intervention were significantly higher than baseline values. However, the magnitude of change did not significantly differ between groups A and B. Conclusion: Other related indicators in blood donors with low ferritin have also experienced some changes, suggesting that some blood donors may have entered the stage of iron-deficient erythropoiesis. Extending blood donation interval facilitates the recovery of iron storage in low-ferritin apheresis platelet donors. Blood stations should develop care strategies for apheresis platelet donors, including, at a minimum, the prolonged blood donation interval for donors with low ferritin.
6.Predict the effect of the number of positive preoperative serum tumor markers on the surgical method and prognosis of intrahepatic cholangiocarcinoma patients based on mediation analysis
Zonglong LI ; Jialu CHEN ; Yue TANG ; Delong QIN ; Chen CHEN ; Yinghe QIU ; Hong WU ; Yu HE ; Xianhai MAO ; Wenlong ZHAI ; Jingdong LI ; Xiao LIANG ; Chuandong SUN ; Kai MA ; Zhimin GENG ; Zhaohui TANG ; Zhiwei QUAN
Chinese Journal of Surgery 2024;62(7):685-696
Objective:To investigate the effect of the number of positive preoperative serological tumor markers on the surgical approach and prognosis of patients with intrahepatic cholangiocarcinoma.Methods:This is a retrospective case-series study. Data from 548 patients with intrahepatic cholangiocarcinoma after radical resection from October 2010 to April 2019 were retrospectively collected in 10 hospitals of China. There were 277 males and 271 females with an age of (57.8±10.2)years(range:23 to 84 years). Four hundred and twenty-six patients(77.7%) had at least one positive preoperative serum tumor marker. The data collection included the results of 4 preoperative serological tumor markers,other preoperative indicators(5 prodromal symptoms, 6 medical history,8 preoperative serological indicators,5 preoperative imaging indicators,and 14 preoperative pathological examination indicators),baseline data (gender and age),surgical methods,and prognostic follow-up data. Four preoperative results of serologic tumor marker and surgical procedure were converted into categorical variables. The number of positive preoperative serum tumor markers was used as the treatment variable,the surgical method was used as the mediating variable,and the survival time was used as the outcome variable. Univariate and multivariate analysis were used to screen for other preoperative indicators which were independent factors that influenced the surgical procedure and the prognosis of patients as covariates to analyze the mediating effect.Results:Of the 548 patients included in the study, 176 patients (32.1%) underwent partial hepatectomy,151 patients(27.5%) underwent hemihepatectomy, and 221 patients(40.3%) underwent partial hepatectomy or hemihepatectomy combined with other treatments. The results of the univariate and multivariate analysis showed that the number of positive serum tumor markers,intrahepatic bile duct dilatation,portal vein invasion,pathological differentiation,pathological type,vascular invasion,T stage,N stage and maximum tumor diameter were independent factors influencing the surgical procedure(all P<0.05). Intrahepatic bile duct dilatation,pathological differentiation and T stage were independent prognostic factors for patients with intrahepatic cholangiocarcinoma(all P<0.05). Intrahepatic bile duct dilatation,differentiation and T stage were included as covariates in the mediation effect model. The results showed that the number of positive serum tumor markers before surgery had a negative predictive effect on the survival time of patients with intrahepatic cholangiocarcinoma ( β=-0.092, P=0.039),and had a positive predictive effect on the surgical method ( β=0.244, P<0.01). The number of positive serum tumor markers had a negative predictive effect on the survival time of patients with intrahepatic cholangiocarcinoma ( β=-0.151, P=0.002). Direct and indirect effects accounted for 71.3% and 28.7% of total effects,respectively. Conclusions:The higher the positive number of preoperative tumor markers,the worse the prognosis of patients with intrahepatic cholangiocarcinoma. The number of positive cells not only directly affects the prognosis of patients,but also indirectly affects the prognosis of patients by affecting the surgical method.
7.Effect of different blood pressure stratification on renal function in diabetic population
Yong-Gang CHEN ; Shou-Ling WU ; Jin-Feng ZHANG ; Shuo-Hua CHEN ; Li-Wen WANG ; Kai YANG ; Hai-Liang XIONG ; Ming GAO ; Chun-Yu JIANG ; Ye-Qiang LIU ; Yan-Min ZHANG
Medical Journal of Chinese People's Liberation Army 2024;49(6):663-669
Objective To investigate the effect of varying blood pressure stratification on renal function in the diabetic population.Methods A prospective cohort study was conducted,enrolling 9 489 diabetic patients from a total of 101 510 Kailuan Group employees who underwent health examinations between July 2006 and October 2007.The follow-up period was(8.6±4.0)years.Participants were categorized into four groups based on their baseline blood pressure levels:normal blood pressure(systolic blood pressure<120 mmHg and diastolic blood pressure<80 mmHg),elevated blood pressure(systolic blood pressure 120-130 mmHg and diastolic blood pressure<80 mmHg),stage 1 hypertension(systolic blood pressure 130-140 mmHg and/or diastolic blood pressure 80-90 mmHg),and stage 2 hypertension(systolic blood pressure≥140 mmHg and/or diastolic blood pressure≥90 mmHg).The incidence density of chronic kidney disease(CKD)was compared among these groups.A multivariate Cox proportional hazards regression model was employed to assess the effects of different blood pressure levels on renal function in diabetic patients,with the stability of the results confirmed using a multivariate time-dependent Cox proportional hazards model.Sensitivity analysis was conducted after excluding cases of cardiovascular disease(CVD)during follow-up,and cases using antihypertensive and antidiabetic medications at baseline.Results(1)At baseline,stage 1 hypertension patients demonstrated statistically significant higher differences with age and body mass index(BMI)compared to normal blood pressure group(P<0.05).(2)By the end of the follow-up,2 294 cases of CKD were identified,including 1 117 cases of estimated glomerular filtration rate(eGFR)decline and 1 575 cases of urinary protein.The incidences density of CKD,eGFR decline and urinary protein for stage 1 hypertension group were 39.4,16.3 and 25.5 per thousand person-years,respectively,all of which were statistically significant different from normal blood pressure group(log-rank test,P<0.01).(3)Multivariate Cox regression analysis revealed that,compared to the normal blood pressure group,stage 1 hypertension was associated with a 29%increased risk of CKD(HR=1.29,95%CI 1.09-1.52)and a 40%increased risk of eGFR decline(HR=1.40,95%CI 1.08-1.80)in diabetic individuals.Conclusion Stage 1 hypertension significantly increases the risk of CKD and eGFR decline in diabetic individuals,with a particularly notable effect on the risk of eGFR decline.
8.Effects of 1α,25-dihydroxyvitamin D3 on expression of SIRT1,GATA-3 and airway inflammation in asthmatic mice
Xin WANG ; Wei-Ying LIU ; Chen WU ; Xue-Jie LIANG ; Jin-Jun KAI
Medical Journal of Chinese People's Liberation Army 2024;49(6):686-693
Objective To explore the effects of 1α,25-dihydroxyvitamin D3 on airway inflammation in asthmatic mice and the potential mechanisms.Methods Twenty-four female BALB/c mice in SPF grade were randomly divided into three groups(n=8):control group,asthma group,and asthma+VD3 group.On the 1st,8th,and 15th day,asthma group and asthma+VD3 group were given 0.2 ml ovalbumin(OVA)suspension for sensitization,while control group received 0.2 ml normal saline.On the 22-28th day,asthma group and asthma+VD3 group were challenged with 1%OVA atomization inhalation,while control group received an equal amount of normal saline atomization,for 30 minutes each time,once a day,for a continuous 7 days.Asthma+VD3 group was given intraperitoneal injection of 1α,25-dihydroxyvitamin D3 injection(4 μg/kg)30 minutes before each atomization,while control group and asthma group were given an equal dose of normal saline.After the last challenge,all mice were anesthetized,and serum,bronchoalveolar lavage fluid(BALF)and lung tissue samples were collected.HE staining and Periodic Acid Schiff(PAS)staining were used to observe the pathological changes in lung tissue and changes in airway mucus levels.ELISA was employed to detect serum IgE and inflammatory cytokines IL-4,IL-5 and IL-13 in BALF.Immunohistochemical technique and Western blotting were used to detect the expressions of SIRT1 and GATA-3 in mouse lung tissue.Results Compared with control group,asthma group had a significant increase in inflammatory cell infiltration around lung tissue,bronchia and accompanying perivascular,mainly characterized by eosinophils.Bronchial lumen stenosis,airway mucosal epithelial hyperplasia,and increased tracheal mucus secretion were also observed.The above changes in asthma+VD3 group were reduced compared with asthma group.Compared with control group,serum levels of IgE,and IL-4,IL-5,IL-13 inflammatory factors in BALF and GATA-3 in lung tissue were increased in asthma group(P<0.05),and SIRT1 level in lung tissue was significant decreased(P<0.05).Compared with asthma group,IgE level in serum,inflammatory factors of IL-4,IL-5 and IL-13 in BALF,and GATA-3 in lung tissue in asthma+VD3 group were decreased(P<0.05),and SIRT1 level in lung tissue was increased(P<0.05).Correlation analysis showed that the expression level of lung tissue SIRT1 was negatively correlated with the expression of GATA-3,serum IgG,and the levels of IL-4,IL-5,and IL-13 in BALF(P<0.05);the expression level of lung tissue GATA-3 was positively correlated with serum IgG and the levels of IL-4,IL-5,and IL-13 in BALF(P<0.05).Conclusion 1α,25-dihydroxyvitamin D3 can alleviate airway inflammation in asthmatic mice,possibly by upregulating the expression of SIRT1 in lung tissue and inhibiting the expression of GATA-3,thereby inhibiting inflammatory factors(IL-4,IL-5,IL-13).
9.Predict the effect of the number of positive preoperative serum tumor markers on the surgical method and prognosis of intrahepatic cholangiocarcinoma patients based on mediation analysis
Zonglong LI ; Jialu CHEN ; Yue TANG ; Delong QIN ; Chen CHEN ; Yinghe QIU ; Hong WU ; Yu HE ; Xianhai MAO ; Wenlong ZHAI ; Jingdong LI ; Xiao LIANG ; Chuandong SUN ; Kai MA ; Zhimin GENG ; Zhaohui TANG ; Zhiwei QUAN
Chinese Journal of Surgery 2024;62(7):685-696
Objective:To investigate the effect of the number of positive preoperative serological tumor markers on the surgical approach and prognosis of patients with intrahepatic cholangiocarcinoma.Methods:This is a retrospective case-series study. Data from 548 patients with intrahepatic cholangiocarcinoma after radical resection from October 2010 to April 2019 were retrospectively collected in 10 hospitals of China. There were 277 males and 271 females with an age of (57.8±10.2)years(range:23 to 84 years). Four hundred and twenty-six patients(77.7%) had at least one positive preoperative serum tumor marker. The data collection included the results of 4 preoperative serological tumor markers,other preoperative indicators(5 prodromal symptoms, 6 medical history,8 preoperative serological indicators,5 preoperative imaging indicators,and 14 preoperative pathological examination indicators),baseline data (gender and age),surgical methods,and prognostic follow-up data. Four preoperative results of serologic tumor marker and surgical procedure were converted into categorical variables. The number of positive preoperative serum tumor markers was used as the treatment variable,the surgical method was used as the mediating variable,and the survival time was used as the outcome variable. Univariate and multivariate analysis were used to screen for other preoperative indicators which were independent factors that influenced the surgical procedure and the prognosis of patients as covariates to analyze the mediating effect.Results:Of the 548 patients included in the study, 176 patients (32.1%) underwent partial hepatectomy,151 patients(27.5%) underwent hemihepatectomy, and 221 patients(40.3%) underwent partial hepatectomy or hemihepatectomy combined with other treatments. The results of the univariate and multivariate analysis showed that the number of positive serum tumor markers,intrahepatic bile duct dilatation,portal vein invasion,pathological differentiation,pathological type,vascular invasion,T stage,N stage and maximum tumor diameter were independent factors influencing the surgical procedure(all P<0.05). Intrahepatic bile duct dilatation,pathological differentiation and T stage were independent prognostic factors for patients with intrahepatic cholangiocarcinoma(all P<0.05). Intrahepatic bile duct dilatation,differentiation and T stage were included as covariates in the mediation effect model. The results showed that the number of positive serum tumor markers before surgery had a negative predictive effect on the survival time of patients with intrahepatic cholangiocarcinoma ( β=-0.092, P=0.039),and had a positive predictive effect on the surgical method ( β=0.244, P<0.01). The number of positive serum tumor markers had a negative predictive effect on the survival time of patients with intrahepatic cholangiocarcinoma ( β=-0.151, P=0.002). Direct and indirect effects accounted for 71.3% and 28.7% of total effects,respectively. Conclusions:The higher the positive number of preoperative tumor markers,the worse the prognosis of patients with intrahepatic cholangiocarcinoma. The number of positive cells not only directly affects the prognosis of patients,but also indirectly affects the prognosis of patients by affecting the surgical method.
10.Prediction of Wind Turbine Lubricating Oil's Acid Value by Ordinary Least Square Method Based on Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy Through Higher-Order Derivative Combined with Angular Metric
Chun-Hui GE ; Yan-Jun LIU ; Meng-Shi CHEN ; Ce YANG ; Pei-Pei LIANG ; Zhi-Xiang YAO ; Kai ZHANG
Chinese Journal of Analytical Chemistry 2024;52(9):1254-1265,中插1-中插4
To address the key challenges in multivariate statistical modeling,a higher-order derivative approach combined with vector space angle multiplicative error correction was proposed for establishing an acid value prediction ordinary least squares(OLS)regression model based on attenuated total reflectance-Fourier transform infrared(ATR-FTIR)spectroscopy.By using acid values measured by potentiometric titration as reference,ATR-FTIR spectroscopy was utilized for direct calibration and prediction of acid values on 96 kinds of lubricating oil samples from a wind turbine.Firstly,the simulated hyperbolic(SH)method was employed to obtain accurate fourth derivative spectrum,resolving overlapping bands and enhancing spectral selectivity.Then,from the calibration set(48 samples),informative spectral regions were identified based on correlation coefficients.Next,the sample with the highest acid value was selected as the reference and1/(1+tan(θ/2))was used as the metric relation of the spectrum to suppress the multiplicity error caused by factors such as the change of effective optical path in ATR-FTIR spectroscopy.After pretreatment of the spectrum by the method of fourth-order derivative combined with angular quantity,the number of variables decreased from 1737 to 8,and the matrix condition number decreased from 1.85×1015 to 56.34,which effectively eliminated the collinearity issue for OLS regression.Direct OLS modeling on spectral preprocessed data achieved a determination coefficient of 0.981 for 47 validation samples,with a relative error range of-8.38%-8.22%,outperforming the commonly used partial least squares(PLS)method(Determination coefficient of 0.865,relative error of-27.82%-22.38%).It was proved that effective data preprocessing significantly improved the prediction accuracy of the model.Furthermore,when the number of calibration set was compressed to 25 and the number of validation set was expanded to 70,the model retained 8 variables with a condition number of 42.60,the determination coefficient of validation set was 0.972,and the relative error ranged from-10.80%to 12.31%.Comparing with the PLS method(Determination coefficient of 0.724,relative error of-34.26%-53.84%),the improvement was more obvious,which showed that the method could still have high prediction accuracy even with fewer modeling samples as well as robustness against multiplicative error interference.

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