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1.
Transl Lung Cancer Res ; 13(2): 321-333, 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38496685

RESUMO

Background: Anaplastic lymphoma kinase (ALK)-targeted tyrosine kinase inhibitors (TKIs) improve patient survival; however, some patients develop ALK-TKI resistance with unidentified mechanisms. We investigated ErbB family and c-MET expression in patients with ALK-positive non-small cell lung cancer (NSCLC) to understand their roles in the ALK-TKI response. Methods: We studied 72 patients with advanced ALK-positive NSCLC with EML4-ALK fusion variant subtyping and immunostaining for c-MET, EGFR, HER2, and HER3 on tissue specimens both pre- (primary) and post-treatment (secondary) with ALK-TKI. We investigated the association of their expression with survival outcomes and assessed the effectiveness of combining ALK and EGFR inhibitors in ALK-positive NSCLC cell lines stimulated with the HER3-specific ligand HRG1. Results: High expression of c-MET, EGFR, HER2, and HER3 was observed in 4.9%, 18.0%, 1.6%, and 25.8% of primary tumors, respectively, and 18.5%, 37.0%, 10.7%, and 35.7% of secondary tumors, respectively. HER3 overexpression in primary tumors showed inferior survival (P=0.132). In the subgroup with EML4-ALK variant 1/2 (V1/V2), HER3 overexpression was significantly associated with inferior survival in both primary and secondary tumors (P=0.022 and P=0.004, respectively). Combination treatment with lorlatinib and erlotinib significantly reduced HRG1-induced activation of RTK signaling in ALK-positive NSCLC cells. Conclusions: HER3 overexpression has potential as a prognostic marker in ALK-positive NSCLCs, including ALK-TKI naïve and treated cases, especially those with EML4-ALK V1/V2. Assessing HER3 expression may be crucial for treatment planning and outcome prediction in these patients.

2.
Endocr Pathol ; 34(2): 247-256, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37040004

RESUMO

Follicular-patterned lesions often have indeterminate results (diagnostic category III or IV) by core needle biopsy (CNB) and fine needle aspiration (FNA). However, CNB diagnoses follicular neoplasm (category IV) more frequently than FNA. Therefore, we aimed to develop a risk stratification system for CNB samples with category III/IV using immunohistochemistry (IHC). The specificity of the RAS Q61R antibody was validated on 58 thyroid nodules with six different types of RAS genetic variants and 40 cases of RAS wild-type. We then applied IHC analysis of RAS Q61R to 207 CNB samples with category III/IV in which all patients underwent surgical resection. RAS Q61R IHC had 98% sensitivity and 98% specificity for detecting the RAS p.Q16R variant. In an independent dataset, the positive rate of RAS Q61R was significantly higher in NIFTP (48%) and malignancies (45%) than in benign tumors (19%). The risk of NIFTP/malignancy was highest in the group with nuclear atypia and RAS Q61R expression (86%) and lowest in the group without both parameters (32%). The high-risk group with either nuclear atypia or RAS Q61R had 67.3% sensitivity, 73.4% specificity, 75.2% positive predictive value, and 65.1% negative predictive value for identifying NIFTP/malignancy. We conclude that RAS Q61R IHC can be a rule-in diagnostic test for NIFTP/malignancy in CNB category III/IV results. Combining of the histologic parameter (nuclear atypia) with RAS Q61R IHC results can further stratify CNB category III/IV into a high-risk group, which is sufficient for a surgical referral, and a low-risk group sufficient for observation.


Assuntos
Neoplasias da Glândula Tireoide , Nódulo da Glândula Tireoide , Humanos , Neoplasias da Glândula Tireoide/diagnóstico , Neoplasias da Glândula Tireoide/genética , Neoplasias da Glândula Tireoide/patologia , Biópsia com Agulha de Grande Calibre , Imuno-Histoquímica , Nódulo da Glândula Tireoide/diagnóstico , Nódulo da Glândula Tireoide/genética , Nódulo da Glândula Tireoide/patologia , Medição de Risco , Estudos Retrospectivos
3.
Sci Rep ; 13(1): 342, 2023 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-36611072

RESUMO

NEK9 is a key player in the NEK9-EG5 axis for microtubule polymerization, chromosome alignment, and mitosis. In present study, we investigated the altered expression of the NEK9, EG5 and acetyl-α-tubulin as well as common epithelial-mesenchymal transition (EMT) markers (E-cadherin, vimentin, claudin-1, and ß-catenin) through the immunohistochemistry analysis of 138 patients with pathologic T3 (pT3) stage colon cancers, and evaluated their metastatic potential. NEK9 expression showed an association with distant metastasis (P = 0.032) and was an independent predictive factor for distant metastasis (HR = 3.365, P < 0.001) by multivariate analysis, which was more significant than either the regional nodal metastasis (HR = 2.496, P = 0.007) or lymphovascular invasion (HR = 2.090, P = 0.153). Positive correlations were observed between NEK9 and EG5 or acetyl-α-tubulin (r = 0.236 and P = 0.007; r = 0.181 and P = 0.038, respectively) and concordant overexpression of the NEK9-EG5 axis was further confirmed in colon cancer cell lines. These findings collectively suggest that the overexpression of the NEK9-EG5 axis is present and associated with distant metastasis in colon cancer. These biomarkers might be useful for predicting metastatic potential among the patients with pT3 colon cancers.


Assuntos
Neoplasias do Colo , Tubulina (Proteína) , Humanos , Biomarcadores Tumorais/metabolismo , Caderinas/metabolismo , Neoplasias do Colo/genética , Transição Epitelial-Mesenquimal/genética , Mitose , Quinases Relacionadas a NIMA/genética , Tubulina (Proteína)/genética
4.
Leuk Lymphoma ; 63(13): 3072-3081, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36167334

RESUMO

The clinical significance of extra copy (EC) genotypes of BCL2, MYC, and BCL6 have not been fully elucidated. We evaluated the EC and translocation statuses of BCL2, MYC, and BCL6 in 190 diffuse large B-cell lymphoma (DLBCL) cases using fluorescence in situ hybridization. EC genotype was sub-classified according to copy number-gained tumor cell ratio (EC1, >20% but ≤50%; EC2, >50%). Only the BCL2-EC groups, not MYC-EC or BCL6-EC groups, displayed significantly increased immunoreactivity of the corresponding protein. Moreover, the BCL2-EC2 group was significantly associated with poor overall survival (OS) and progression-free survival (PFS) in a 147 R-CHOP-treated patient subset, which was also statistically significant as per the multivariate survival analysis for PFS. No significant differences in the survival of MYC, BCL6, concurrent BCL2/MYC, BCL6/MYC, BCL2/BCL6, or triple EC groups were observed. BCL2-EC may contribute to increased BCL-2 protein expression and serve as a predictor of treatment outcomes in DLBCL.


Assuntos
Variações do Número de Cópias de DNA , Linfoma Difuso de Grandes Células B , Humanos , Proteínas Proto-Oncogênicas c-bcl-6/genética , Hibridização in Situ Fluorescente , Proteínas Proto-Oncogênicas c-myc/genética , Prognóstico , Linfoma Difuso de Grandes Células B/diagnóstico , Linfoma Difuso de Grandes Células B/tratamento farmacológico , Linfoma Difuso de Grandes Células B/genética , Proteínas Proto-Oncogênicas c-bcl-2/genética
5.
Med Image Anal ; 80: 102482, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35688048

RESUMO

In digital pathology, segmentation is a fundamental task for the diagnosis and treatment of diseases. Existing fully supervised methods often require accurate pixel-level annotations that are both time-consuming and laborious to generate. Typical approaches first pre-process histology images into patches to meet memory constraints and later perform stitching for segmentation; at times leading to lower performance given the lack of global context. Since image level labels are cheaper to acquire, weakly supervised learning is a more practical alternative for training segmentation algorithms. In this work, we present a weakly supervised framework for histopathology segmentation using only image-level labels by refining class activation maps (CAM) with self-supervision. First, we compress gigapixel histology images with an unsupervised contrastive learning technique to retain high-level spatial context. Second, a network is trained on the compressed images to jointly predict image-labels and refine the initial CAMs via self-supervised losses. In particular, we achieve refinement via a pixel correlation module (PCM) that leverages self-attention between the initial CAM and the input to encourage fine-grained activations. Also, we introduce a feature masking technique that performs spatial dropout on the compressed input to suppress low confidence predictions. To effectively train our model, we propose a loss function that includes a classification objective with image-labels, self-supervised regularization and entropy minimization between the CAM predictions. Experimental results on two curated datasets show that our approach is comparable to fully-supervised methods and can outperform existing state-of-the-art patch-based methods. https://github.com/PhilipChicco/wsshisto.


Assuntos
Algoritmos , Aprendizado de Máquina Supervisionado , Humanos
7.
J Pathol Transl Med ; 55(5): 330-337, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34465079

RESUMO

BACKGROUND: Follicular lymphoma (FL) is the second most common non-Hodgkin lymphoma (NHL) in Western countries. However, it is relatively rare in Asia. This study examined epidemiologic characteristics of FL in South Korea, with an emphasis on recent trends of increase in cases. METHODS: We retrospectively examined 239 cases of newly diagnosed FL at a large tertiary institution in Korea (Asan Medical Center, Seoul, Republic of Korea) between 2008 and 2017. Age-adjusted incidence rates and clinicopathological variables were analyzed, and joinpoint regression analysis was used to identify the changes. RESULTS: The age-adjusted incidence of FL significantly increased during the study period (p = .034), and the ratio of (relative incidence) patients with FL to patients with NHL increased from 4.28% to 9.35% in the same period. Over the 10-year study assessment duration, the proportion of patients with stage III/IV FL (p = .035) and expression of BCL2 (p = .022) or BCL6 (p = .039) significantly increased. From 2013-2017, the proportion of patients with highrisk Follicular Lymphoma International Prognostic Index (FLIPI) score increased (21.5% to 28.7%), whereas that of low-risk FLIPI decreased (55.4% to 38.6%), although those results were not statistically significant (p = .066). CONCLUSIONS: We found an increasing incidence of FL, with a disproportionate increase in the incidence of high-stage disease and recent changes in the clinicopathologic features of the Korean patient population.

8.
Asian J Surg ; 44(6): 848-853, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33622598

RESUMO

BACKGROUND: Pseudomyxoma peritonei (PMP) is a rare disease characterized by mucinous ascites and deposits on the peritoneal surfaces. The study aimed to assess PMP patients according to the Peritoneal Surface Oncology Group International (PSOGI) classification, as a part of standardization of this rare disease. METHODS: This retrospective study analyzed PMP patients who underwent surgery between January 2007 and December 2017. All histologic slides were re-evaluated and the clinical data were collected. According to the PSOGI, PMP was retrospectively classified into three categories: low-grade (LG-PMP), high-grade (HG-PMP), and signet-ring cells (SRC-PMP). The extent of peritoneal involvement was quantified by the peritoneal cancer index (PCI). The completeness of cytoreduction (CCR) was dichotomized as complete or incomplete. RESULTS: Fifty-seven patients were included in this study, consisted of 39 patients with LG-PMP (74.0%), 14 with HG-PMP (20.8%), and 4 with SRC-PMP (5.2%). There was no operative mortality and major complications occurred in 24 patients (31.2%). The 5-year overall survival was 56.2% ± 8.1% for LG-PMP, 37.5% ± 12.1% for HG-PMP, and 25.0% ± 21.7% for SRC-PMP. Concerning CCR, the 5-year overall (complete: 59.5% ± 8.4% vs. incomplete: 12.7% ± 8.1%, p = 0.001) and disease-free survival (complete: 38.6% ± 8.9% vs. incomplete: 7.7% ± 6.8%, p = 0.001) were significantly different. In a multivariable analysis, PSOGI classification and CCR independently correlated with survival (p = 0.011 and 0.018, respectively). CONCLUSIONS: The PSOGI classification provides prognostic stratification, hopefully requiring further validation including every single case of PMP established as a standard criteria.


Assuntos
Neoplasias Peritoneais , Pseudomixoma Peritoneal , Procedimentos Cirúrgicos de Citorredução , Humanos , Prognóstico , Pseudomixoma Peritoneal/diagnóstico , Pseudomixoma Peritoneal/cirurgia , Estudos Retrospectivos
9.
Cancer Res Treat ; 53(1): 270-278, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32972046

RESUMO

PURPOSE: In contrast to the Western diffuse large B-cell lymphoma (DLBCL), prognostic impact of age in a Korean population with DLBCL has not been fully evaluated. MATERIALS AND METHODS: Six hundred and eight DLBCL patients treated with rituximab-containing chemotherapeutic regimens from January 2002 to March 2012 in Asan Medical Center were enrolled. Survival models using the restricted cubic spine-transformed age variable were constructed to evaluate non-linear relationships between age and survival outcome. Finally, age was categorized according to the conventional international prognostic index (IPI), National Comprehensive Cancer Network (NCCN)-IPI, and Grupo Español de Linfomas/Trasplante Autólogo de Médula Ósea (GELTAMO)-IPI schemes and the prognostic implications were evaluated. RESULTS: The relative hazard did not change significantly during the first to fifth decades, but began to increase exponentially in patients aged over 62 years. This pattern or relationship was also retained in a multivariate model fitted to the age-adjusted IPI and relative dose intensity. Multivariate survival analysis revealed that age > 75 years, but not age > 60 years, was associated independently with poor overall and progression-free survival when the relative dose intensity and age-adjusted IPI were taken into account. CONCLUSION: The outcome of DLBCL in Korean populations may deteriorate rapidly as age exceeds 62 years. Therefore, a consensus cutoff value for age in Korean DLBCL patients should be determined to better predict prognosis.


Assuntos
Antineoplásicos Imunológicos/uso terapêutico , Linfoma Difuso de Grandes Células B/tratamento farmacológico , Rituximab/uso terapêutico , Antineoplásicos Imunológicos/farmacologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , República da Coreia , Rituximab/farmacologia
10.
Leuk Lymphoma ; 61(14): 3342-3350, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32921221

RESUMO

BCL2 translocation is the genetic hallmark of follicular lymphoma (FL). Besides BCL2 translocation, copy number (CN) gains and translocations of BCL6, MYC, and IRF4 have also been detected in FL, but there is little information regarding their prognostic significance. This retrospective study used fluorescence in situ hybridization (FISH) to analyze BCL2, BCL6, MYC, and IRF4 translocations and CN gains in 105 FL cases. Genetic translocations were detected for BCL2 (n = 64; 72.7%), BCL6 (n = 14; 15.9%), and MYC (n = 2; 2.3%); no case showed IRF4 translocation. Overall, 23 (26.1%), 30 (34.1%), 12 (13.8%), and 10 (11.0%) cases showed CN gains in BCL2, BCL6, MYC, and IRF4, respectively. BCL6 CN gain was a prognostic factor for worse overall survival, demonstrating a trend toward significance in multivariate analysis (HR =8.769, p = 0.056). BCL6 CN gain in FL might be associated with aggressive biologic behavior.


Assuntos
Genes myc/genética , Hibridização in Situ Fluorescente/métodos , Fatores Reguladores de Interferon/genética , Linfoma Folicular/genética , Linfoma Folicular/patologia , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-6/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Variações do Número de Cópias de DNA , DNA de Neoplasias/análise , Feminino , Humanos , Fatores Reguladores de Interferon/metabolismo , Masculino , Pessoa de Meia-Idade , Prognóstico , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Proteínas Proto-Oncogênicas c-bcl-6/metabolismo , Estudos Retrospectivos , Análise Serial de Tecidos , Translocação Genética
11.
Am J Clin Pathol ; 153(6): 760-771, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32010932

RESUMO

OBJECTIVES: Histopathologic characteristics of choledochal cysts and their clinical implications have not been previously comprehensively studied. METHODS: Smooth muscle distribution patterns and other histologic findings (inflammation, metaplasia, dysplasia, and heterotopia) in 233 surgically resected choledochal cysts were evaluated. RESULTS: Mean patient age was 23.3 ±â€…19.8 years, with male:female ratio of 0.3. Most cases were Todani type I (175 cases, 75.1%) or IVa (56 cases, 24.1%). Choledochal cysts with thin scattered/no muscle fiber (175 cases, 75.1%) were the predominant pattern and were associated with more frequent postoperative biliary stricture (P = .031), less frequent pyloric metaplasia (P = .016), and mucosal smooth muscle aggregates (P < .001) compared to cysts with thick muscle bundles. Severe chronic cholangitis (P = .049), pyloric metaplasia (P = .019), mucosal smooth muscle aggregates (P < .001), biliary intraepithelial neoplasia (P = .021), and associated bile duct (P = .021) and gallbladder carcinomas (P = .03) were more common in adults (age >20 years vs ≤20 years), suggesting that chronic irritation in association with developmental anomalies involves tumorigenesis from choledochal cysts. CONCLUSION: Smooth muscle distribution pattern of choledochal cyst may predict postoperative complication, raising clinical implications of smooth muscle patterns in postoperative management of choledochal cysts.


Assuntos
Cisto do Colédoco/patologia , Músculo Liso/patologia , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Cisto do Colédoco/cirurgia , Feminino , Humanos , Hiperplasia/patologia , Lactente , Recém-Nascido , Inflamação/patologia , Masculino , Metaplasia/patologia , Pessoa de Meia-Idade , Adulto Jovem
12.
J Pathol Transl Med ; 53(2): 125-128, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30424589

RESUMO

Type 1 autoimmune pancreatitis (AIP1) is an IgG4-related systemic disease that mimics tumors. We report a rare case of AIP1 accompanied by mucinous cystic neoplasm (MCN). A pancreatic lesion was incidentally detected in a woman in her 60s. After 6 years of follow-up, the lesion abruptly increased in size. Computed tomography showed a 3.5 cm unilocular cyst in the tail of the pancreas and distal pancreatectomy was performed. On microscopic examination, the cyst was lined by mucinous and non-mucinous epithelial cells with mild cytologic atypia. The surrounding stroma comprised ovarian-type spindle cells with progesterone receptor positivity. The pericystic pancreas exhibited multifocal lymphoid follicles, lymphoplasmacytic infiltrations, obliterative phlebitis, and storiform fibrosis. IgG4-positive plasma cell infiltration (215 cells high-power field) and the IgG4/IgG ratio (57%) were increased. Cases of MCN coexisting with AIP1 are extremely rare; only two such cases have been reported in the English-language literature. This third case featured low-grade MCN with AIP1.

13.
Biomol Ther (Seoul) ; 26(6): 539-545, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-29665659

RESUMO

4-Hydroxy-2-(4-hydroxyphenethyl)isoindoline-1,3-dione (PD1) is a synthetic phthalimide derivative of a marine compound. PD1 has peroxisome proliferator-activated receptor (PPAR) γ agonistic and anti-inflammatory effects. This study aimed to investigate the effect of PD1 on allergic asthma using rat basophilic leukemia (RBL)-2H3 mast cells and an ovalbumin (OVA)-induced asthma mouse model. In vitro, PD1 suppressed ß-hexosaminidase activity in RBL-2H3 cells. In the OVA-induced allergic asthma mouse model, increased inflammatory cells and elevated Th2 and Th1 cytokine levels were observed in bronchoalveolar lavage fluid (BALF) and lung tissue. PD1 administration decreased the numbers of inflammatory cells, especially eosinophils, and reduced the mRNA and protein levels of the Th2 cytokines including interleukin (IL)-4 and IL-13, in BALF and lung tissue. The severity of inflammation and mucin secretion in the lungs of PD1-treated mice was also less. These findings indicate that PD1 could be a potential compound for anti-allergic therapy.

14.
Chemosphere ; 73(5): 813-9, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18597815

RESUMO

Reactive reductants of cement/Fe(II) systems in dechlorinating chlorinated hydrocarbons are unknown. This study initially evaluated reactivities of potential reactive agents of cement/Fe(II) systems such as hematite (alpha-Fe(2)O(3)), goethite (alpha-FeOOH), lepidocrocite (gamma-FeOOH), akaganeite (beta-FeOOH), ettringite (Ca(6)Al(2)(SO(4))(3)(OH)(12)), Friedel's salt (Ca(4)Al(2)Cl(2)(OH)(12)), and hydrocalumite (Ca(2)Al(OH)(6)(OH).3H(2)O) in reductively dechlorinating trichloroethylene (TCE) in the presence of Fe(II). It was found that a hematite/Fe(II) system shows TCE degradation characteristics similar to those of cement/Fe(II) systems in terms of degradation kinetics, Fe(II) dose dependence, and final products distribution. It was therefore suspected that Fe(III)-containing phases of cement hydrates in cement/Fe(II) systems behaved similarly to the hematite. CaO, which was initially introduced as a pH buffer, was observed to participate in or catalyze the formation of reactive reductants in the hematite/Fe(II) system, because its addition enhanced the reactivities of hematite/Fe(II) systems. From the SEM (scanning electron microscope) and XRD (X-ray diffraction) analyses that were carried out on the solids from hematite/Fe(II) suspensions, it was discovered that a sulfate green rust with a hexagonal-plate structure was probably a reactive reductant for TCE. However, SEM analyses conducted on a cement/Fe(II) system showed that hexagonal-plate crystals, which were presumed to be sulfate green rusts, were much less abundant in the cement/Fe(II) than in the hematite/Fe(II) systems. It was not possible to identify any crystalline minerals in the cement/Fe(II) system by using XRD analysis, probably because of the complexity of the cement hydrates. These observations suggest that major reactive reductants of cement/Fe(II) systems may differ from those of hematite/Fe(II) systems.


Assuntos
Compostos Férricos/química , Tricloroetileno/química , Materiais de Construção , Compostos Ferrosos/química , Compostos de Ferro/química , Cinética , Microscopia Eletrônica de Varredura , Minerais , Oxirredução , Difração de Raios X
15.
Artigo em Inglês | MEDLINE | ID: mdl-18172806

RESUMO

The feasibility of using zero-valent iron (ZVI) and peat mixture as in situ barriers for contaminated sediments and groundwater was investigated. Trichloroethylene (TCE) and nitrate (NO(3)(-)), redox sensitive contaminants were reduced by ZVI and peat soil mixture under anaerobic condition. Peat was used to support the sorption of TCE, microbial activity for biodegradation of TCE and denitrification while TCE and nitrate were reduced by ZVI. Decreases in TCE concentrations were mainly due to ZVI, while peat supported denitrifying microbes and further affected the sorption of TCE. Due to the competition of electrons, nitrate reduction was inhibited by TCE, while TCE reduction was not affected by nitrate. From the results of peat and sterilized peat, it can be concluded that peat was involved in both dechlorination and denitrification but biological reduction of TCE was negligible compared to that of nitrate. The results from hydrogen and methane gas analyses confirmed that hydrogen utilization by microbes and methanogenic process had occurred in the ZVI-peat system. Even though effect of the peat on TCE reduction were quantitatively small, ZVI and peat contributed to the removal of TCE and nitrate independently. The 16S rRNA analysis revealed that viable bacterial diversity was narrow and the most frequently observed genera were Bacillus and Staphylococcus spp.


Assuntos
Ferro/química , Nitratos/análise , Microbiologia do Solo , Poluentes do Solo/análise , Solo/análise , Tricloroetileno/análise , Poluentes Químicos da Água/análise , Biodegradação Ambiental , DNA Bacteriano/análise , Cinética
16.
J Contam Hydrol ; 56(1-2): 75-98, 2002 May.
Artigo em Inglês | MEDLINE | ID: mdl-12076024

RESUMO

The gel barrier formation by a gelling liquid (Colloidal Silica) injection in an unsaturated porous medium is investigated by developing a mathematical model and conducting numerical simulations. Gelation process is initiated by adding electrolytes such as NaCl, and the gel phase consisting of cross-linked colloidal silica particles grows as the gelation process proceeds. The mathematical model describing the transport and gelation of Colloidal Silica (CS) is based on coupled mass balance equations for the gel mixture (the sol phase plus the gel phase), gel phase (cross-linked colloidal silica particles plus water captured between cross-linked particles), and colloidal silica particles (discrete and cross-linked) and NaCl in the sol (suspension of discrete colloidal silica particles in water) and gel phases. The solutions in terms of volumetric fraction of the gel phase yield the gel mixture viscosity via the dependency on the volumetric fraction of gel phase. This dependency is determined from a kinetic gelation model with time-normalized viscosity curves. The proposed model is verified by comparing experimentally and numerically determined hydraulic conductivities of gel-treated soil columns at different CS injection volumes. The numerical experiments indicate that an impermeable gel layer is formed within the time period twice the gel-point in a one-dimensional flow system. At the same normalized time corresponding to twice the gel-point, the CS solutions with lower NaCl concentrations result in further migration and poor performance in plugging the pore space. The viscosity computation proposed in this study is compared with another method available in the literature. It is observed that the other method estimates the viscosity at the mixing zone higher than the one proposed by the authors. The proposed model can simulate realistic injection scenarios with various combinations of operating parameters such as NaCl concentration and NaCl mixing time, and thus providing guidelines in performing this technology on site.


Assuntos
Coloides/química , Géis/química , Modelos Teóricos , Dióxido de Silício/química , Análise Numérica Assistida por Computador , Propriedades de Superfície , Viscosidade
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