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1.
Eur J Nucl Med Mol Imaging ; 51(11): 3235-3251, 2024 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-38730084

RESUMEN

PURPOSE: The value of preoperative multidisciplinary approach remains inadequately delineated in forecasting postoperative outcomes of patients undergoing coronary artery bypass grafting (CABG). Herein, we aimed to ascertain the efficacy of multi-modality cardiac imaging in predicting post-CABG cardiovascular outcomes. METHODS: Patients with triple coronary artery disease underwent cardiac sodium [18F]fluoride ([18F]NaF) positron emission tomography/computed tomography (PET/CT), coronary angiography, and CT-based coronary artery calcium scoring before CABG. The maximum coronary [18F]NaF activity (target-to-blood ratio [TBR]max) and the global coronary [18F]NaF activity (TBRglobal) was determined. The primary endpoint was perioperative myocardial infarction (PMI) within 7-day post-CABG. Secondary endpoint included major adverse cardiac and cerebrovascular events (MACCEs) and recurrent angina. RESULTS: This prospective observational study examined 101 patients for a median of 40 months (interquartile range: 19-47 months). Both TBRmax (odds ratio [OR] = 1.445; p = 0.011) and TBRglobal (OR = 1.797; P = 0.018) were significant predictors of PMI. TBRmax>3.0 (area under the curve [AUC], 0.65; sensitivity, 75.0%; specificity, 56.8%; p = 0.036) increased PMI risk by 3.661-fold, independent of external confounders. Kaplan-Meier test revealed a decrease in MACCE survival rate concomitant with an escalating TBRmax. TBRmax>3.6 (AUC, 0.70; sensitivity, 76.9%; specificity, 73.9%; p = 0.017) increased MACCEs risk by 5.520-fold. Both TBRmax (hazard ratio [HR], 1.298; p = 0.004) and TBRglobal (HR = 1.335; p = 0.011) were significantly correlated with recurrent angina. No significant associations were found between CAC and SYNTAX scores and between PMI occurrence and long-term MACCEs. CONCLUSION: Quantification of coronary microcalcification activity via [18F]NaF PET displayed a strong ability to predict early and long-term post-CABG cardiovascular outcomes, thereby outperforming conventional metrics of coronary macrocalcification burden and stenosis severity. TRIAL REGISTRATION: The trial was registered with the Chinese Clinical Trial Committee (number: ChiCTR1900022527; URL: www.chictr.org.cn/showproj.html?proj=37933 ).


Asunto(s)
Puente de Arteria Coronaria , Radioisótopos de Flúor , Tomografía Computarizada por Tomografía de Emisión de Positrones , Humanos , Masculino , Femenino , Persona de Mediana Edad , Anciano , Enfermedad de la Arteria Coronaria/diagnóstico por imagen , Fluoruro de Sodio , Resultado del Tratamiento , Estudios Prospectivos , Vasos Coronarios/diagnóstico por imagen , Pronóstico
2.
J Oral Pathol Med ; 52(6): 528-538, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37057689

RESUMEN

BACKGROUND: Reports on the proteomic studies of ameloblastoma and other common odontogenic lesions are limited. We thus explored the differential proteins among ameloblastoma, odontogenic keratocyst, dentigerous cyst, and normal gingival tissue using proteomics and identified hub proteins involved in the local aggressiveness and recurrence of ameloblastoma. METHODS: Samples were obtained from 14 patients with ameloblastoma, 6 with odontogenic keratocyst, 9 with a dentigerous cyst, and 5 with normal gingival tissue. Proteins were then extracted, purified, quantified, and analysed using Easy-nLC chromatography and mass spectrometry. Further functional annotation and enrichment analyses were performed using Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes on the target protein collection. Protein clustering and protein-protein interaction network analyses were used to screen the hub proteins. Proteins with significant interactions were screened according to their degree index. These results were verified by immunohistochemical staining. Proteins meeting the screening criteria of expression difference ploidy >1.2-fold (upregulation and downregulation) and p < 0.05 were considered differential proteins. RESULTS: In ameloblastoma, 808 differential proteins were upregulated and 505 were downregulated compared with those in odontogenic keratocyst; 309 were upregulated and 453 were downregulated compared with those in dentigerous cyst; and 2210 were upregulated and 829 were downregulated compared with those in normal gingival tissue. The three groups of differential proteins were associated with cellular exosomes, antigen binding, complement activation, human papillomavirus infection, focal adhesion, cell adhesion molecules, and metabolic pathways. CONCLUSION: CDH3 is associated with the local aggressiveness and recurrence of ameloblastoma and is a potential therapeutic target.


Asunto(s)
Ameloblastoma , Quiste Dentígero , Quistes Odontogénicos , Tumores Odontogénicos , Humanos , Ameloblastoma/genética , Ameloblastoma/patología , Quiste Dentígero/genética , Quiste Dentígero/patología , Proteómica , Quistes Odontogénicos/genética , Tumores Odontogénicos/genética
3.
Sensors (Basel) ; 22(19)2022 Sep 23.
Artículo en Inglés | MEDLINE | ID: mdl-36236319

RESUMEN

The laser ultrasonic method using the characteristics of transmitted Rayleigh waves in the frequency domain to determine micro-crack depth is proposed. A low-pass filter model based on the interaction between Rayleigh waves and surface cracks is built and shows that the stop band, called the sensitive frequency range, is sensitive to the depth of surface cracks. The sum of transmission coefficients in the sensitive frequency range is defined as an evaluated parameter to determine crack depth. Moreover, the effects of the sensitive frequency range and measured distance on the evaluated results are analyzed by the finite-element method to validate the robustness of this depth-evaluating method. The estimated results of surface cracks with depths ranging from 0.08 mm to ~0.5 mm on the FEM models and aluminum-alloy samples demonstrate that the laser ultrasounds using the characteristics of Rayleigh waves in the frequency domain do work for quantitative crack depth.


Asunto(s)
Aluminio , Ultrasonido , Aleaciones , Rayos Láser , Ultrasonografía
4.
Sensors (Basel) ; 18(9)2018 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-30200505

RESUMEN

The planetary gearbox is at the heart of most rotating machinery. The premature failure and subsequent downtime of a planetary gearbox not only seriously affects the reliability and safety of the entire rotating machinery but also results in severe accidents and economic losses in industrial applications. It is an important and challenging task to accurately detect failures in a planetary gearbox at an early stage to ensure the safety and reliability of the mechanical transmission system. In this paper, a novel method based on wavelet packet energy (WPE) and modulation signal bispectrum (MSB) analysis is proposed for planetary gearbox early fault diagnostics. First, the vibration signal is decomposed into different time-frequency subspaces using wavelet packet decomposition (WPD). The WPE is calculated in each time-frequency subspace. Secondly, the relatively high energy vectors are selected from a WPE matrix to obtain a reconstructed signal. The reconstructed signal is then subjected to MSB analysis to obtain the fault characteristic frequency for fault diagnosis of the planetary gearbox. The validity of the proposed method is carried out through analyzing the vibration signals of the test planetary gearbox in two fault cases. One fault is a chipped sun gear tooth and the other is an inner-race fault in the planet gear bearing. The results show that the proposed method is feasible and effective for early fault diagnosis in planetary gearboxes.

5.
J Hazard Mater ; 475: 134931, 2024 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-38889467

RESUMEN

In this study, oversized microplastics (OMPs) were intentionally introduced into soil containing manure-borne doxycycline (DOX). This strategic approach was used to systematically examine the effects of combined OMP and DOX pollution on the growth of pak choi, analyze alterations in soil environmental metabolites, and explore the potential migration of antibiotic resistance genes (ARGs). The results revealed a more pronounced impact of DOX than of OMPs. Slender-fiber OMPs (SF OMPs) had a more substantial influence on the growth of pak choi than did coarse-fiber OMPs (CF OMPs). Conversely, CF OMPs had a more significant effect on the migration of ARGs within the system. When DOX was combined with OMPs, the negative effects of DOX on pak choi growth were mitigated through the synthesis of indole through the adjustment of carbon metabolism and amino acid metabolism in pak choi roots. In this process, Pseudohongiellaceae and Xanthomonadaceae were key bacteria. During the migration of ARGs, the potential host bacterium Limnobacter should be considered. Additionally, the majority of potential host bacteria in the pak choi endophytic environment were associated with tetG. This study provides insights into the intricate interplay among DOX, OMPs, ARGs, plant growth, soil metabolism, and the microbiome.


Asunto(s)
Antibacterianos , Doxiciclina , Estiércol , Microplásticos , Contaminantes del Suelo , Doxiciclina/farmacología , Doxiciclina/toxicidad , Antibacterianos/toxicidad , Antibacterianos/farmacología , Estiércol/microbiología , Contaminantes del Suelo/toxicidad , Microplásticos/toxicidad , Farmacorresistencia Microbiana/genética , Microbiología del Suelo , Bacterias/efectos de los fármacos , Bacterias/genética , Bacterias/metabolismo , Genes Bacterianos/efectos de los fármacos , Farmacorresistencia Bacteriana/genética , Multiómica
6.
J Cancer Res Clin Oncol ; 149(18): 16717-16727, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37725241

RESUMEN

PURPOSE: We used proteomic sequencing and experimental verification to identify the potential ferroptosis-related proteins in ameloblastoma. METHODS: Samples of ameloblastoma (n = 14) and normal gingival tissues (n = 5) were collected for proteomic sequencing to identify differentially expressed proteins (DEPs) in ameloblastoma. Ferroptosis-related genes were downloaded from FerrDb V2, which were then compared with DEPs to obtain ferroptosis-related DEPs (FR-DEPs). A functional enrichment analysis was performed, and a protein-protein interaction network was built. The hub proteins were screened using the Cytoscape software, and potential drugs targeting them were retrieved from the DrugBank database. A hub protein was selected for immunohistochemical validation, and its expression was assessed in ameloblastomas, odontogenic keratocysts, dentigerous cysts, and normal gingival tissues. The primary ameloblastoma cells were cultured to explore the effect of the protein on the migratory properties of the tumour cells. RESULTS: A total of 58 FR-DEPs were screened, and six hub proteins were identified: mTOR, NFE2L2, PRKCA, STAT3, EGFR, and CDH1. Immunohistochemical analysis showed that mTOR expression was upregulated in ameloblastomas compared with that in odontogenic keratocysts, dentigerous cysts, and normal gingival tissues. p-mTOR was highly expressed in ameloblastomas, with a positivity rate of 83.3%. In addition, rapamycin, an inhibitor of mTOR, can inhibit the migratory capacity of primary cultured ameloblastoma cells. CONCLUSION: Our results revealed the ferroptosis-related proteins in ameloblastomas and their underlying biological processes. Additionally, mTOR was overexpressed and was found to be associated with the aggressiveness of ameloblastomas, which may be a potential target for future treatments.


Asunto(s)
Ameloblastoma , Quiste Dentígero , Ferroptosis , Quistes Odontogénicos , Humanos , Quiste Dentígero/metabolismo , Quiste Dentígero/patología , Ameloblastoma/genética , Ameloblastoma/metabolismo , Ameloblastoma/patología , Proteómica , Inmunohistoquímica , Quistes Odontogénicos/metabolismo , Quistes Odontogénicos/patología , Serina-Treonina Quinasas TOR/genética
7.
Arch Oral Biol ; 149: 105662, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-36857877

RESUMEN

OBJECTIVE: To perform an integrated analysis in identifying novel hub genes that could facilitate the diagnosis and targeted therapy of ameloblastoma. DESIGN: The expression profiling dataset, GSE38494, was obtained from the Gene Expression Omnibus database. Differentially expressed genes were identified through GEO2R online tool and characterised via Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The protein-protein interaction network and hub genes were screened using the STRING database and Cytoscape software. Subsequently, an upregulated gene was selected for further validation using the GSE132472 dataset. Further, immunohistochemistry was performed to assess the expression of the selected gene in ameloblastomas, odontogenic keratocysts, dentigerous cysts, and gingival tissues. The diagnostic and therapeutic utility of the selected hub genes were further verified by receiver operating characteristic analysis and the DGIdb database. RESULTS: We identified six hub genes in ameloblastoma, among which the upregulated gene PKD2 and its related gene PKD1 were further validated. GO functional annotation revealed that PKD2 is involved in cell-cell junction, extracellular exosome, cytoplasm, endoplasmic reticulum, and calcium ion transport. The immunohistochemical analysis showed that the expression of polycystin-1 and polycystin-2, encoded by the PKD1 and PKD2 genes, respectively, was upregulated in ameloblastoma. PKD1 and PKD2 had a high diagnostic utility for ameloblastoma, and allopurinol interacted with the PKD2 gene. CONCLUSION: Our research indicates that polycystins are highly expressed in ameloblastoma and might be involved in the oncogenesis of ameloblastoma, thus offering a new perspective on the molecular mechanisms and targeted therapies on ameloblastoma.


Asunto(s)
Ameloblastoma , Humanos , Ameloblastoma/genética , Perfilación de la Expresión Génica , Canales Catiónicos TRPP/genética , Canales Catiónicos TRPP/metabolismo , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Inmunohistoquímica , Biología Computacional , Regulación Neoplásica de la Expresión Génica
8.
J Stomatol Oral Maxillofac Surg ; 124(6): 101472, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37061040

RESUMEN

PURPOSE: To evaluate the effects of concentrated growth factor (CGF), combined with a mixture of iliac cancellous and composite bone materials, on the repair of extensive mandibular defects. PATIENTS AND METHODS: This clinical trial involved patients with mandibular defects caused by large cystic lesions. The test group comprised 16 patients who underwent CGF combined with iliac cancellous bone and composite bone materials to repair extensive mandibular defects, whereas the control group comprised eight patients who underwent vascularised free fibula grafts for mandibular segmental defects. Postoperative exudatum was collected from patients on the 1st, 2nd, 3rd, and 4th days postoperatively, and osteogenic factor, including alkaline phosphatase (ALP), osteocalcin (BGP), and procollagen type I N-terminal propeptide (PINP), and inflammatory cytokines were performed. Additionally, regular cone beam computed tomography (CBCT) scans were conducted before and after surgery. RESULTS: On postoperative days 1-4, the expression levels of ALP, BGP, and PINP were higher in the test group, while those of IL-1α, IL-1ß, IL-6, IL-8, and TNF-α, which were identified as co-differentially expressing inflammatory cytokines, were all down-regulated in the exudatum of the test group. Regular CBCT radiological scans revealed a significant osteogenic effect in the test group. CONCLUSION: The use of CGF combined with iliac cancellous bone and composite bone materials to repair extensive mandibular jaw defects facilitates bone formation and reductions in inflammation in the defect area in the short term, which deserves further research in clinical practice.


Asunto(s)
Hueso Esponjoso , Osteogénesis , Humanos , Péptidos y Proteínas de Señalización Intercelular/farmacología , Citocinas/farmacología , Inflamación/cirugía
9.
Zhonghua Yi Xue Za Zhi ; 92(7): 476-9, 2012 Feb 21.
Artículo en Zh | MEDLINE | ID: mdl-22490970

RESUMEN

OBJECTIVE: To explore the treatment strategies for complicated craniocervical junction malformations with diverse clinical and imaging features. METHODS: The clinical data of 67 cases of complicated craniocervical junction malformation treated between January 2000 to December 2010 were retrospectively analyzed. Based on their clinical manifestations and imaging findings, different operative procedures were adopted, including odontoidectomy via transoral transpharyngeal approach (n = 3), occipito-cervical fusion and(or) suboccipital decompression (n = 19) and odontoidectomy via transoral transpharyngeal approach followed by occipito-cervical fusion in two-stage operation (n = 25). Four cases underwent merely odontoidectomy via transoral transpharyngeal approach and died postoperatively. Sixteen cases had occipito-cervical fusion and(or) transorally surgical release for reduction in one stage. RESULTS: Clinical symptoms significantly improved in 19 cases, partially improved in 21 cases and remained unchanged in 12 cases. Nine cases deteriorated postoperatively and 6 cases died. The effective rate was 59.7%. CONCLUSION: The complexity of craniocervical junction malformations may be fully assessed based on different clinical manifestations and thorough imaging studies. Then personalized operative plans are to be designed.


Asunto(s)
Articulación Atlantoaxoidea/cirugía , Procedimientos Ortopédicos/métodos , Adolescente , Adulto , Anciano , Articulación Atlantoaxoidea/anomalías , Trasplante Óseo/métodos , Niño , Diagnóstico por Imagen , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Adulto Joven
10.
Ear Nose Throat J ; : 1455613221136671, 2022 Oct 25.
Artículo en Inglés | MEDLINE | ID: mdl-36282816

RESUMEN

BACKGROUND: Based on our cadaveric study findings and the clinical practice, the improved submental island flaps (SIF) used on a case series to reconstruct postoperative defects were reviewed and analyzed, to summarize the technical operation of flap cutting and propose the anterograde anatomical technique of point-line-plane alignment. METHODS: The cadaveric study was carried out first and a case series of about 23 head and neck tumor cases that underwent one-stage SIF repair were reviewed and followed up. The intraoperative anatomy, the technical essentials for vascular pedicle protection and submandibular lymph nodes treatment, and the rational design of flap incisions were analyzed and described. RESULTS: Most patients (21/23, 91.3%), comprising 19 males and 4 females with a mean age of 59 years, recovered completely from the application of SIFs in the repair and reconstruction of head and neck tumors; Only 2 patients experienced partial flap necrosis, which resolved following a local dressing change. The predominant donor site complication was transitory paralysis of the mandibular marginal branch of the facial nerve (MMBFN) (3/23, 13.0%), and the donor site was closed in one stage without skin grafting. The hair growth on skin flaps was not an issue for male patients requiring postoperative radiotherapy. CONCLUSIONS: SIF is a viable choice for correcting abnormalities of the head and neck tumor with the convenience of flap cutting and the effectiveness of the repair. In addition, it permits simultaneous treatment of the lymph nodes in the region I.

11.
Anal Chim Acta ; 1111: 31-39, 2020 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-32312394

RESUMEN

Exhaled hydrogen cyanide (HCN) has been extensively investigated as a promising biomarker of the presence of Pseudomonas aeruginosa in the airways of patients with cystic fibrosis (CF) disease. Its concentration profile for exhalation can provide useful information for medical disease diagnosis and therapeutic procedures. However, the complexity of breath gas, like high humidity, carbon dioxide (CO2) and trace organic compounds, usually leads to quantitative error, poor selectivity and sensitivity for HCN with some of existing analytical techniques. In this work, acetone-assisted negative photoionization (AANP) based on a vacuum ultraviolet (VUV) lamp with a time-of- flight mass spectrometer (AANP-TOFMS) was firstly proposed for online measurement of trace HCN in human breath. In-source collision-induced dissociation (CID) was adopted for sensitivity improvement and the signal response of the characteristic ion CN- (m/z 26) was improved by about 24-fold. For accurate and reliable analysis of the exhaled HCN, matrix influences in the human breath including humidity and CO2 were investigated, respectively. A Nafion tube was used for online dehumidification of breath samples. Matrix-adapted calibration in the concentration range of 0.5-50 ppbv with satisfactory dynamic linearity and repeatability was obtained. The limit of quantitation (LOQ) for HCN at 0.5 ppbv was achieved in the presence of 100% relative humidity and 4% CO2. Finally, the method was successfully applied for online determination of human mouth- and nose-exhaled HCN, and the nose-exhaled HCN were proved to be reliable for assessing systemic HCN levels for individuals. The results are encouraging and highlight the potential of AANP-TOFMS with in-source CID as a selective, accurate, sensitive and noninvasive technique for determination of the exhaled HCN for CF clinical diagnosis and HCN poisoning assessment.


Asunto(s)
Acetona/química , Pruebas Respiratorias , Cianuro de Hidrógeno/análisis , Humanos , Espectrometría de Masas , Procesos Fotoquímicos , Factores de Tiempo
12.
ISA Trans ; 101: 408-420, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32061355

RESUMEN

Transient impulses are important information for machinery fault diagnosis. However, the transient features contained in the vibration signals generated by planetary gearboxes are usually immersed by a large amount of background noise and harmonic components. Even mathematical morphology (MM) is an excellent anti-noise signal processing method that can directly extract the geometry of impulse features in the time domain, but the four basic operators of MM can only extract one-way impulses while cannot extract the bidirectional impulses effectively at the same time. To accurately extract the impulse feature information, a novel method for fault detection of planetary gearbox based on an enhanced average (EAVG) filter and modulated signal bispectrum (MSB) is proposed. Firstly, the properties of the extracted impulses based on the four basic operators of MM will be divided into two categories of enhanced average operators. The four EAVG filters consist of the average weighted combination of enhanced average operators, and then the best EAVG filter is selected based on correlation coefficient to implement on the original vibration signal. It allows EAVG filter to extract positive and negative impulses of vibration signal, thereby improving the accuracy of planetary gearbox fault detection. Subsequently, the performance of the EAVG filter is influenced by the length of its structural element (SE), which is adaptively determined using an indicator based kurtosis. Then, the EAVG filter selects the optimal SE length to eliminate the interference of background noise and harmonic components to enhance the impulse components of the vibration signal. However, the nonlinear modulation components that are related to the fault types and severities are not extracted exactly and still remained in the filtered signal by EAVG. Finally, the MSB is utilized to the EAVG filtered signal to decompose the modulated components and extract the fault features. The advantages of EAVG over average (AVG) filter are clarified in the simulation study. In addition, the EAVG-MSB is validated by analyzing the vibration signals of planetary gearboxes with sun gear chipped tooth, sun gear misalignment and bearing inner race fault. The results indicate that the EAVG-MSB is effective and accurate in feature extraction compared with the combination morphological filter-hat transform (CMFH) and average combination difference morphological filter (ACDIF), and the feasibility of the EAVG-MSB are proved for planetary gearbox condition monitoring and fault diagnosis.

13.
Talanta ; 201: 33-39, 2019 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-31122430

RESUMEN

High-pressure photoionization time-of-flight mass spectrometry (HPPI-TOFMS) is a versatile and highly sensitive analytical technique for online and real-time analysis of trace volatile organic compounds in complex mixtures. However, discrimination of isomers is usually a great challenge for the soft ionization method, and matrix effect is also inevitable under high pressure in the HPPI source. In this work, we describe a first attempt to develop a two-dimensional (2D) hyphenated instrument by coupling of a multi-capillary column (MCC) with a HPPI-TOFMS to overcome these problems. The capability of the MCC-HPPI-TOFMS for discrimination of isomeric compounds and elimination of the matrix effect was demonstrated by analyzing flavor mixtures. With the merits of fast separation, soft ionization and high detection sensitivity, satisfactory effects in the 2D analysis were achieved, despite the relatively low chromatographic resolution of MCC. As a result, three isomers, eucalyptol, l-menthone and linalool, in a flavor mixture were successfully categorized within 90 s, and the matrix effect caused by solvent ethanol was significantly eliminated as well. The limits of detection (LODs) down to sub-ppbv level were achieved for the investigated five flavor compounds without any enrichment process, and an excellent repeatability was obtained with the relative standard deviations (RSDs) of signal intensities ≤5%. The MCC-HPPI-TOFMS system was preliminarily applied for rapid and online analysis of flavor compounds in the exhaled gas of a volunteer after mouth rinsing with a gargle product. The rapid changes of the three flavor compounds, as well as the steady endogenous metabolite acetone, in the exhaled gas were successfully determined with a time-resolution of only 1.5 min.

14.
Huan Jing Ke Xue ; 34(1): 34-8, 2013 Jan.
Artículo en Zh | MEDLINE | ID: mdl-23487915

RESUMEN

With the features of a broad range of ionizable compounds, reduced fragments and simple mass spectrum, a homemade magnetic field enhanced photoelectron ionization (MEPEI) source combined with single photon ionization (SPI) for time-of-flight mass spectrometer was built and applied to analyze thermal decomposition/combustion products of polyvinyl chloride (PVC). The combined ion source can be switched very fast between SPI mode and SPI-MEPEI mode for detecting different targeted compounds, and only adjusting the voltage of the electrode in the ionization region to trigger the switch. Among the PVC thermal decomposition/combustion products, HCl and CO2, which ionization energies (12.74 eV, 13.77 eV respectively) were higher than the energy of photon (10.60 eV), were ionized by MEPEI, while alkenes, dichloroethylene, benzene and its homologs, monochlorobenzene, styrene, indane, naphthalene and its homologs were ionized by SPI and MEPEI simultaneously. Spectra of interested products as a function of temperatures indicated that products are formed via two main mechanisms: (1) dechlorination and intramolecular cyclization can lead to the formation of HCl, benzene and naphthalene at 250-370 degrees C; (2) intermolecular crosslinking leads to the formation of alkyl aromatics such as toluene and xylene/ethylbenzene at 380-510 degrees C. The experimental results show that the combined ion source of SPI/ SPI-MEPEI for TOF-MS has broad application prospects in the online analysis field.


Asunto(s)
Calor , Cloruro de Polivinilo/análisis , Cloruro de Polivinilo/aislamiento & purificación , Espectrometría de Masa por Ionización de Electrospray/métodos , Diseño de Equipo , Incineración , Sistemas en Línea , Fotones , Cloruro de Polivinilo/química , Espectrometría de Masa por Ionización de Electrospray/instrumentación
15.
Talanta ; 98: 241-6, 2012 Aug 30.
Artículo en Inglés | MEDLINE | ID: mdl-22939154

RESUMEN

The concentration of propofol in patient's exhaled air is an indicator of the anesthetic depth. In the present study, a membrane inlet ion mobility spectrometer (MI-IMS) was built for the on-line measurement of propofol. Compared with the direct sample introduction, the membrane inlet could eliminate the interference of moisture and improve the selectivity of propofol. Effects of membrane temperature and carrier gas flow rate on the sensitivity and response time have been investigated experimentally and theoretically. Under the optimized experimental conditions of membrane temperature 100 °C and carrier gas flow rate 200 mL min(-1), the calculated limit of detection (LOD) for propofol was 1 ppbv, and the calibration curve was linear in the range of 10-83 ppbv with a correlation coefficient (R(2)) of 0.993. Finally, the propofol concentration in an anaesthetized mouse exhaled air was monitored continuously to demonstrate the capability of MI-IMS in the on-line measurement of propofol in real samples.


Asunto(s)
Anestésicos Intravenosos/análisis , Propofol/análisis , Anestésicos Intravenosos/administración & dosificación , Anestésicos Intravenosos/farmacocinética , Animales , Pruebas Respiratorias , Calibración , Espiración , Calor , Humanos , Cinética , Límite de Detección , Membranas Artificiales , Ratones , Propofol/administración & dosificación , Propofol/farmacocinética , Silicio , Espectrometría de Masa de Ion Secundario
16.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 46(4): 245-7, 2011 Apr.
Artículo en Zh | MEDLINE | ID: mdl-21612717

RESUMEN

OBJECTIVE: To analyze the amount and tendency of methyl methacrylate (MMA) released from autopolymerized denture base polymer (self-curing resin) during processing using time-of-flight mass spectrometer (TOF-MS). METHODS: Self-curing resin was mixed in the container using a ratio of 2 g of powder to 1 g of liquid in accordance with the manufacturer's instructions for 40 s as a specimen. The amount of MMA released from the specimen was continuously monitored and simultaneously recorded every minute by TOF-MS since immediately after mixing. A total of five specimens were monitored. RESULTS: The amount of MMA increased dramatically at 11 min [(45.2 ± 3.5) mg/L] after mixing, and reached the highest level at 13 min [(228.9 ± 22.6) mg/L], then become stable at 23 min [(8.8 ± 2.3) mg/L] after mixing. CONCLUSIONS: The releasing tendency of MMA could be analyzed accurately with continuously monitoring during processing. The amount of MMA released from self-curing resin changed rapidly and the processing was complicated and changeful.


Asunto(s)
Bases para Dentadura , Espectrometría de Masas/métodos , Metilmetacrilato/química , Polímeros/química , Ensayo de Materiales , Metilmetacrilato/análisis
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