RESUMO
MicroRNA-218 (miR-218) is a short, noncoding RNA, with multiple biological functions. In this study, we aimed to investigate the potential effects of miR-218 on the apoptosis of human ovarian carcinoma cells and the underlying mechanisms by which miR-218 exerted its actions. After over-expressing miR-218 in human ovarian carcinoma (OVCAR3) cells, cell viability was determined by MTT method, cell apoptosis was observed by flow cytometry (FCM), mRNA expression of miR-218, Bcl2, Bax was measured by RT-PCR and protein expression levels of Wnt, tankyrase and ß-catenin were quantified by Western blots. Over-expression of miR-218 potently suppressed cell viability and promoted the apoptosis of human ovarian carcinoma cells in a time-dependent manner. In addition, the down-regulation of tankyrase expression level was detected in miR-218-over-expressed cells. Following the block of the Wnt/ß-catenin signaling pathway using the inhibitor XAV-939, the effects of miR-218 on the proliferation and apoptosis of human ovarian carcinoma cells were significantly suppressed. Augmenting expression of miR-218 and/or miRNA-218 mimicking therapeutics may provide viable avenue for the treatment of ovarian cancer.
Assuntos
Células Epiteliais/metabolismo , Regulação Neoplásica da Expressão Gênica , MicroRNAs/genética , Proteínas Wnt/genética , beta Catenina/genética , Apoptose/genética , Linhagem Celular Tumoral , Sobrevivência Celular , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/patologia , Feminino , Compostos Heterocíclicos com 3 Anéis/farmacologia , Humanos , MicroRNAs/metabolismo , Ovário/efeitos dos fármacos , Ovário/metabolismo , Ovário/patologia , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Tanquirases/genética , Tanquirases/metabolismo , Proteínas Wnt/antagonistas & inibidores , Proteínas Wnt/metabolismo , Via de Sinalização Wnt , Proteína X Associada a bcl-2/genética , Proteína X Associada a bcl-2/metabolismo , beta Catenina/antagonistas & inibidores , beta Catenina/metabolismoRESUMO
Objective: To explore a registry method for acute cardiovascular events in large-scale fields across China. Methods: This study was based on a community-based Kazakh cohort, including 1 668 persons with complete baseline data, conducted in Altay, Xinjiang. Acute cardiovascular events included acute myocardial infarction(ICD-10: I21-I22), sudden cardiac death (I46.1), and incident stroke (I60-I64) that occurred during the period from Oct 1, 2012 to Jun 30, 2016. There were three stages, a hospital-based search for checking medical records of inpatients in all four local hospitals, a community-based supplementary registry, and an extra survey for reducing false negatives, to complete this registry. The incidence referred to all events within one year per 100 000 people and mortality rate was the number of fatal events within 28 days per 100 000 people. The incidence and mortality was standardized with the weights from distribution of age and gender in the Sixth National Census of China. Results: Forty two cases with 46 acute cardiovascular events including 7 acute myocardial infarctions, 3 sudden cardiac deaths, and 36 incident strokes were found. The ratio of events was 3.6â¶1 for stroke and heart attacks and this ratio was 1.6â¶1 for ischemic or hemorrhagic strokes. A total of 28(60.9%) events and 18(39.1%) events were collected in the hospitals and by community-based supplementary registry physicians, respectively. False negatives were not found at the last stage. The crude and standardized incidence rates were 742 and 926 per 100 000 people and the related mortality rates were 194 and 272 per 100 000 people, respectively. Conclusion: Primary Care physicians are"net bottom" of a monitoring system which needs to combine preventive and clinical medicine with all kinds of governmental resources including health and social benefit.
Assuntos
Infarto do Miocárdio/epidemiologia , Sistema de Registros , Acidente Vascular Cerebral/epidemiologia , China , Humanos , Incidência , Projetos PilotoRESUMO
The construction and analysis of the topic of traditional Chinese medicine is an important social and cultural landscape since the founding of New China, and media for party afairs is an important field for this process. Authoritative media such as People's Daily expressed respect to TCM practitioners, reflected the national system, urban-rural relations, cultural concepts, etc. behind the development of TCM, and clarified the determination and confidence of the Party and the country to adhere to the development of TCM through its content,specific situations and line of reasoning logic.
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Medicina Tradicional Chinesa , População Rural , Humanos , ChinaRESUMO
The Houjing River watershed is one of the three major river watersheds in the Kaohsiung City, Taiwan. Based on the recent water quality analysis, the Houjing River is heavily polluted. Both point and non-point source (NPS) pollutants are the major causes of the poor water quality in the Houjing River. Investigation results demonstrate that the main point pollution sources included municipal, agricultural, and industrial wastewaters. In this study, land use identification in the Houjing River watershed was performed by integrating the skills of geographic information system (GIS) and global positioning system (GPS). Results show that the major land-use patterns in the upper catchment of the Houjing River watershed were farmlands, and land-use patterns in the mid to lower catchment were residential and industrial areas. An integrated watershed management model (IWMM) and Enhanced Stream Water Quality Model (QUAL2K) were applied for the hydrology and water quality modeling, watershed management, and carrying capacity calculation. Modeling results show that the calculated NH3-N carrying capacity of the Houjing River was only 31 kg/day. Thus, more than 10,518 kg/day of NH3-N needs to be reduced to meet the proposed water quality standard (0.3 mg/L). To improve the river water quality, the following remedial strategies have been developed to minimize the impacts of NPS and point source pollution on the river water quality: (1) application of BMPs [e.g. source (fertilizer) reduction, construction of grassy buffer zone, and land use management] for NPS pollution control; (2) application of river management scenarios (e.g. construction of the intercepting and sewer systems) for point source pollution control; (3) institutional control (enforcement of the industrial wastewater discharge standards), and (4) application of on-site wastewater treatment systems for the polishment of treated wastewater for water reuse.
Assuntos
Conservação dos Recursos Naturais , Rios/química , Poluição da Água/prevenção & controle , Recuperação e Remediação Ambiental , Geografia , Humanos , Modelos Teóricos , Rios/microbiologia , TaiwanRESUMO
Several bioactive molecules isolated from the saliva of blood-sucking arthropods, such as mosquitoes, have been shown to exhibit potential anticoagulant function. We have previously identified a 30kDa allergen named Aegyptin-like protein (alALP), which is highly homologous to Aegyptin, from the salivary glands of female Aedes albopictus (Asian tiger mosquito). In this study, we identified the conserved functional domain of alALP by using bioinformatic tools, and expressed the His-tagged alALP recombinant protein in sf9 insect cells by generation and transfection of a baculoviral expression plasmid carrying the fulllength cDNA of alALP. We purified this recombinant protein and examined its function on the inhibition of blood coagulation. The results showed that the purified His-alALP prolonged the Activated Partial Thromboplastin Time (APTT), Prothrombin Time (PT) and Thrombin Time (TT) in vitro as well as the Bleeding Time (BT) in vivo, which suggest that alALP could be a novel anticoagulant.
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Aedes/genética , Anticoagulantes/química , Proteínas de Insetos/química , Proteínas e Peptídeos Salivares/química , Sequência de Aminoácidos , Animais , Testes de Coagulação Sanguínea , Clonagem Molecular , Biologia Computacional , Proteínas de Insetos/genética , Camundongos , Tempo de Tromboplastina Parcial , Tempo de Protrombina , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas e Peptídeos Salivares/genéticaRESUMO
BACKGROUND: Tuberculosis (TB) continues to be a major global health problem. Extra-pulmonary TB (EPTB) manifests with protean symptoms, and establishing a diagnosis is more difficult than pulmonary TB (PTB). SETTING: A university-affiliated hospital in southern Taiwan. OBJECTIVE: To analyse the risk factors for EPTB compared with PTB. DESIGN: This retrospective study compared patients with EPTB and PTB in southern Taiwan by analysing their demographic data and clinical underlying diseases. Risk factors for EPTB were further analysed. RESULTS: A total of 766 TB patients were enrolled in this study, with 102 (13.3%) EPTB and 664 (86.7%) PTB cases. Of the 766 patients, 3% of PTB patients had EPTB, while 19.6% of EPTB patients also had PTB. The most frequently involved EPTB site was the bone and joints (24.5%). The incidence of EPTB vs. PTB decreased significantly for each decade increase in patient age. Multivariate logistic regression analysis showed that being female, not being diabetic, having end-stage renal disease and not smoking were independent risk factors for EPTB. CONCLUSION: This study defines the risk factors for EPTB compared with PTB. Awareness of these factors is essential for physicians to have a high index of suspicion for accurate and timely diagnosis.
Assuntos
Mycobacterium tuberculosis/isolamento & purificação , Tuberculose/epidemiologia , Adolescente , Adulto , Fatores Etários , Criança , Pré-Escolar , Diagnóstico Diferencial , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Morbidade/tendências , Prognóstico , Estudos Retrospectivos , Fatores de Risco , Fatores Sexuais , Taiwan/epidemiologia , Tuberculose/diagnóstico , Tuberculose/microbiologia , Tuberculose Pulmonar/diagnóstico , Tuberculose Pulmonar/epidemiologia , Tuberculose Pulmonar/microbiologia , Adulto JovemRESUMO
The industrial solvent trichloroethylene (TCE) is among the most ubiquitous chlorinated solvents found in groundwater contamination. The main objectives of this study were to evaluate the feasibility of using non-ionic surfactant Simple Green (SG) to enhance the oxidative dechlorination of TCE by potassium permanganate (KMnO4) employing a continuous stir batch reactor system (CSBR) and column experiments. The effect of using surfactant SG to enhance the biodegradation of TCE via aerobic cometabolism was also examined. Results from CSBR experiments revealed that combination of KMnO4 with surfactant SG significantly enhanced contaminant removal, particularly when the surfactant SG concentrated at its CMC. TCE degradation rates ranged from 74.1% to 85.7% without addition of surfactant SG while TCE degradation rates increased to ranging from 83.8% to 96.3% with presence of 0.1wt% SG. Furthermore, results from column experiments showed that TCE was degraded from 38.1microM to 6.2microM in equivalent to 83.7% of TCE oxidation during first 560min reaction. This study has also demonstrated that the addition of surfactant SG is a feasible method to enhance bioremediation efficiency for TCE contaminated groundwater. The complete TCE degradation was detected after 75 days of incubation with both 0.01 and 0.1wt% of surfactant SG addition. Results revealed that surfactant enhanced chemical oxidation and bioremediation technology is one of feasible approaches to clean up TCE contaminated groundwater.
Assuntos
Técnicas de Química Analítica/métodos , Compostos de Manganês/química , Óxidos/química , Tensoativos/química , Tricloroetileno/química , Poluentes Químicos da Água/química , Água/análise , Água/química , Técnicas de Química Analítica/instrumentação , Oxirredução , SoluçõesRESUMO
The objective of this study was to evaluate the feasibility of using ferrous ion-activated persulfate oxidation to remediate groundwater contaminated with methyl tert-butyl ether (MTBE). In this study, batch experiments were conducted to evaluate the effects of various factors on the efficiency of MTBE degradation including persulfate concentrations, ferrous ion concentrations, and persulfate coupled with hydrogen peroxide. Results show that ferrous ion-activated persulfate oxidation was capable of degrading MTBE efficiently. Persulfate and ferrous ion concentrations correlated with MTBE degradation rates. However, excess addition of ferrous ion resulted in decreased MTBE degrading rates most likely because of competition for sulfate free radicals between ferrous ion and MTBE. Two main byproducts of MTBE degradation, tert-butyl formate and tert-butyl alcohol, were detected in the experiments; both were, however, subsequently degraded. Results of sulfate analysis show that proper addition of ferrous ion could prevent unnecessary persulfate decomposition.
Assuntos
Poluentes Atmosféricos/química , Compostos Ferrosos/química , Éteres Metílicos/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Formiatos/química , Íons , Cinética , Oxirredução , terc-Butil Álcool/químicaRESUMO
[This corrects the article DOI: 10.1016/j.sna.2007.06.006.].
RESUMO
BACKGROUND: A child's diagnosis of autism impacts their whole family, in both positive and negative ways, that may be influenced by cultural beliefs. AIMS: We aimed to describe the experiences of mothers and typically-developing siblings of children with autism in two cultural contexts. METHODS: Fourteen mother-sibling dyads from Taiwan and the UK participated in semi-structured interviews. RESULTS: Whilst there were similarities in sibling experiences, a negative tone regarding the influence of autism was more evident in Taiwan, where families also cited societal judgement and cultural-specific expectations. In the UK, a more balanced tone was apparent: mothers emphasised educating and involving the siblings. It is speculated that UK siblings had a greater understanding of their parents' stress, leading to more adaptive family dynamics. Various types of support service were mentioned in the UK, whereas the availability of social services and support appeared to be relatively limited in Taiwan. IMPLICATIONS: Our data suggest that cultural context may have a significant impact on the responses of the family members. This is mediated by both differences in attitudes and traditions, and availability of resources. Support for family members needs to be sensitive to such cultural differences, as well as recognising positive experiences.
Assuntos
Transtorno Autístico/psicologia , Crianças com Deficiência/psicologia , Relações Familiares/psicologia , Comportamento Materno , Irmãos/psicologia , Estresse Psicológico , Adaptação Psicológica , Adulto , Atitude Frente a Saúde , Criança , Etnopsicologia , Saúde da Família , Feminino , Acessibilidade aos Serviços de Saúde/estatística & dados numéricos , Humanos , Masculino , Avaliação das Necessidades , Sistemas de Apoio Psicossocial , Taiwan/etnologia , Reino Unido/etnologiaRESUMO
The helix-loop-helix protein Id-1 inhibits the activity of basic helix-loop-helix transcription factors, and is an important regulator of cell growth and tissue-specific differentiation. We have shown (P. Y. Desprez et al., Mol. Cell. Biol., 18: 4577-4588, 1998) that ectopic expression of Id-1 inhibits differentiation and stimulates the proliferation and invasiveness of mouse mammary epithelial cells, and that there is a correlation between the levels of Id-1 protein and the aggressiveness of several human breast cancer cell lines. Here, we show that aggressive and metastatic breast cancer cells express high levels of Id-1 mRNA because of a loss of serum-dependent regulation that is mediated by a 2.2-kb region of the human Id-1 promoter. Three lines of evidence suggest that unregulated Id-1 expression may be an important regulator of the aggressive phenotype of a subset of human breast cancer cells: (a) a constitutively expressed Id-1 cDNA, when introduced into a nonaggressive breast cancer cell line (T47D), conferred a more aggressive phenotype, as measured by growth and invasiveness; (b) Id-1 was an important mediator of the effects of sex steroid hormones on T47D cell proliferation. Estrogen stimulated proliferation and induced Id-1 expression, whereas progesterone inhibited proliferation and repressed Id-1 expression. Progesterone repressed Id-1 expression, at least in part by repressing transcription. Most importantly, an antisense oligonucleotide that reduced Id-1 protein levels reduced the ability of estrogen to stimulate cell proliferation, whereas constitutive Id-1 expression rendered cells refractory to growth inhibition by progesterone; and (c) using a limited number of breast cancer biopsies, we showed that Id-1 was more frequently expressed in infiltrating carcinomas compared with ductal carcinomas in situ. Our results suggest that Id-1 can control the malignant progression of breast cancer cells, particularly that mediated by sex steroid hormones. Moreover, Id-1 has the potential to serve as a marker for aggressive breast tumors.
Assuntos
Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Estrogênios/farmacologia , Glândulas Mamárias Animais/patologia , Proteínas Repressoras , Fatores de Transcrição/genética , Animais , Divisão Celular/genética , Transformação Celular Neoplásica/genética , Estrogênios/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica , Sequências Hélice-Alça-Hélice , Humanos , Proteína 1 Inibidora de Diferenciação , Glândulas Mamárias Animais/metabolismo , Camundongos , Neoplasias Hormônio-Dependentes/genética , Neoplasias Hormônio-Dependentes/patologia , Fatores de Transcrição/biossíntese , Células Tumorais CultivadasRESUMO
Monoclonal antibody (mAb) 425 (IgG2a) binds to the external domain of the epidermal growth factor receptor. This determinant is highly expressed by human glioma tissues but rarely by normal brain tissues, and is absent on peripheral blood lymphocytes and bone marrow cells. The mAb exerts variable cytotoxic effects against cultured human glioma cells in conjunction with human and murine effector cells. Inhibition of growth of s.c. glioma xenografts in nude mice by the mAb may be mediated by murine macrophages or may be related to the capacity of the mAb to antagonize growth stimulation of glioma cells by epidermal growth factor. In approaches to radioimmunotherapy of human glioma with mAb 425, the 125I-labeled mAb 425 exhibited more significant antitumor effects than the 131I-labeled mAb both in vitro and in vivo in xenotransplanted nude mice. These differences may be due to enhanced nuclear damage caused by 125I-labeled versus 131I-labeled fragments following their internalization into the glioma cells. Our studies provide the rationale for immunotherapy of glioma patients with either unlabeled or 125I-labeled anti-epidermal growth factor receptor mAb 425.
Assuntos
Anticorpos Monoclonais/uso terapêutico , Receptores ErbB/imunologia , Glioma/terapia , Imunoterapia/métodos , Radioisótopos do Iodo/uso terapêutico , Animais , Citotoxicidade Celular Dependente de Anticorpos , Glioma/radioterapia , Humanos , Camundongos , Camundongos Nus , Transplante de Neoplasias , Radioimunoterapia/métodos , Células Tumorais CultivadasRESUMO
It has been reported that Lysine-305 is needed for the nuclear import of the p53 protein (Liang et al., 1998). In the present study, further mutagenesis analyses were carried out between Lys-305 and the major nuclear localization signal (NLS I) of p53. It was found that a single mutation of Arg-306 resulted in the defect of p53 nuclear import. This effect is the same as that of Lys-305 mutation. Other mutations between Arg-306 and NLS I have no effect on the nuclear import of p53. However, deletions of more than two amino acids between this region abolished the transport of p53 into the nucleus. These results indicate that a basic domain other than the well defined NLS is required for the nuclear import of p53. A spacer between this basic domain and NLS I is necessary for the entrance of p53 into the cell nucleus.
Assuntos
Núcleo Celular/metabolismo , Sinais de Localização Nuclear , Proteína Supressora de Tumor p53/metabolismo , Arginina/genética , Transporte Biológico , Análise Mutacional de DNA , Lisina/genética , Deleção de Sequência , Proteína Supressora de Tumor p53/genéticaRESUMO
Assisted by ab initio calculations, an n-body Cu-Re potential is first constructed for the equilibrium-immiscible Cu-Re system under the second moment approximation of a tight-binding scheme. The proven realistic Cu-Re potential is then applied to perform the molecular dynamics simulations using the Cu-Re sandwich model. The simulations reveal that the interfacial free energy stored in the Cu/Re interfaces plays an important role in facilitating the spontaneous solid-state amorphization and that the amorphous interlayer grows in a layer-by-layer mode featuring an asymmetric behavior, i.e., the growth of the amorphous interlayer advances faster toward the Cu lattice than toward the Re direction. It is also found that with increasing the simulation time, the growth speed of the amorphous interlayer gradually slows down and eventually becomes zero when the interlayer reaches a thickness of about 1.47 nm. Interestingly, according to a recently proposed thermodynamic and kinetic model, the maximum thickness of the growing amorphous layer is limited by the available interfacial free energy and in the Cu-Re system, it is estimated to be around 1.35 nm, which is comparable with that observed from the simulations.
RESUMO
Anti-idiotypic antibodies (Ab2) binding to the antigen-combining site of other antibodies may functionally and even structurally mimic antigen. Ab2 to antibodies directed against the lymphocyte CD4 receptor for human immunodeficiency virus type 1 (HIV-1) may mimic the receptor and therefore inhibit viral infectivity. We have produced Ab2 against monoclonal anti-CD4 receptor antibodies (Ab1). The Ab1 strongly inhibit HIV-1 binding to the receptor. Six monoclonal rat Ab2 and two polyclonal rabbit Ab2 were produced against the Ab1 MT151 and nine monoclonal Ab2 against the Ab1 OKT4A. These Ab2 bound only to Ab1 and not to a panel of nine unrelated murine monoclonal antibodies (MAbs). The Ab2 completely inhibited the binding of the homologous Ab1 to CD4-positive target cells, and recombinant soluble CD4 inhibited binding of Ab2 to Ab1. Thus, the Ab2 seemed to mimic the Ab1-binding site of the CD4 receptor, although the results of inhibition assays did not exclude steric hindrance of antibody-combining sites. However, none of the 17 Ab2 bound to gp120 of HIV-1 envelope or inhibited syncytia formation between cells infected and uninfected with HIV-1. These results suggest that the Ab2 do not mimic the HIV-1 binding site of the CD4 receptor. They further suggest that the Ab1 may not bind within the virus-binding site of the CD4 receptor.
Assuntos
Síndrome da Imunodeficiência Adquirida/imunologia , Anticorpos Anti-Idiotípicos/imunologia , Antígenos CD4/imunologia , Epitopos/imunologia , HIV-1/imunologia , Anticorpos Monoclonais , Linhagem Celular , Avaliação Pré-Clínica de Medicamentos , Humanos , Receptores de HIV/imunologia , Proteínas Recombinantes/imunologia , Linfócitos T Auxiliares-Indutores/imunologiaRESUMO
The objective of this study was to develop a controlled-oxidant-release technology combining in situ chemical oxidation (ISCO) and permeable reactive barrier (PRB) concepts to remediate trichloroethene (TCE)-contaminated groundwater. In this study, a potassium permanganate (KMnO4)-releasing composite (PRC) was designed for KMnO4 release. The components of this PRC included polycaprolactone (PCL), KMnO4, and starch with a weight ratio of 1.14:2:0.96. Approximately 64% (w/w) of the KMnO4 was released from the PRC after 76 days of operation in a batch system. The results indicate that the released KMnO4 could oxidize TCE effectively. The results from a column study show that the KMnO4 released from 200 g of PRC could effectively remediate 101 pore volumes (PV) of TCE-contaminated groundwater (initial TCE concentration = 0.5 mg/L) and achieve up to 95% TCE removal. The effectiveness of the PRC system was verified by the following characteristics of the effluents collected after the PRC columns (barrier): (1) decreased TCE concentrations, (2) increased ORP and pH values, and (3) increased MnO2 and KMnO4 concentrations. The results of environmental scanning electron microscope (ESEM) analysis show that the PCL and starch completely filled up the pore spaces of the PRC, creating a composite with low porosity. Secondary micro-scale capillary permeability causes the KMnO4 release, mainly through a reaction-diffusion mechanism. The PRC developed could be used as an ISCO-based passive barrier system for plume control, and it has the potential to become a cost-effective alternative for the remediation of chlorinated solvent-contaminated groundwater.
Assuntos
Água Subterrânea/química , Permanganato de Potássio/química , Tricloroetileno/química , Poluentes Químicos da Água/química , Dicloroetilenos/química , Condutividade Elétrica , Concentração de Íons de Hidrogênio , Compostos de Manganês/química , Microscopia Eletrônica de Varredura , Oxirredução , Óxidos/química , Oxigênio/análise , Solo/química , Cloreto de Vinil/química , Eliminação de Resíduos LíquidosRESUMO
In this study, an in situ slow polycolloid-releasing substrate (SPRS) biobarrier system was developed to continuously provide biodegradable substrates for the enhancement of trichloroethylene (TCE) reductive dechlorination. The produced SPRS contained vegetable oil (used as a slow-released substrate), cane molasses [used as an early-stage (fast-degradable) substrate], and surfactants [Simple Green (SG) and soya lecithin (SL)]. An emulsification study was performed to evaluate the globule droplet size and stability of SPRS. The distribution and migration of the SPRS were evaluated in a column experiment, and an anaerobic microcosm study was performed to assess the capability of SPRS to serve as a slow and long-term carbon-releasing substrate for TCE dechlorination. The results show that a stable oil-in-water (W/O, 50/50) emulsion (SPRS) with uniformly small droplets (D10, 0.93 µm) has been produced, continuously supplying primary substrates. The emulsion containing the surfactant mixture (with 72 mg/L SL and 71 mg/L SG) had a small absolute value of the zeta potential, which reduced the inter-particle repulsion, leading the emulsion droplets to adhere to one another after collision. The addition of SPRS creates anaerobic conditions and leads to a more complete and thorough removal of TCE through biodegradation and sorption mechanisms.
Assuntos
Tricloroetileno/metabolismo , Poluentes Químicos da Água/metabolismo , Adsorção , Bactérias/metabolismo , Biodegradação Ambiental , Emulsões , Ácidos Graxos Voláteis/metabolismo , Água Subterrânea , Lecitinas/química , Lipídeos/química , Melaço , Tensoativos/química , Tricloroetileno/química , Poluentes Químicos da Água/químicaRESUMO
The objective of this study was to assess the potential of using an in situ oxidation barrier system to remediate gasoline-contaminated groundwater. The passive remedial system included a persulfate-releasing barrier containing persulfate-releasing materials to release persulfate for contaminant oxidation. Bench experiments were performed to determine the components and persulfate-releasing rate of the persulfate-releasing materials. Column experiments were conducted to evaluate the effectiveness of the designed persulfate-releasing materials on the control of petroleum-hydrocarbon plume. In this study, methyl tert-butyl ether (MTBE) and benzene were used as the target compounds. The optimal persulfate releasing rate was obtained when the mass ratio of persulfate/cement/sand/water was 1/1/0.16/0.5, and the rate varied from 31 to 8 mg persulfate per day per g of material. Significant amounts of MTBE and benzene were removed through the oxidation process due to the release of persulfate, and the produced tert-butyl formate (TBF) and tert-butyl alcohol (TBA), byproducts of MTBE, were further oxidized in the system. Results suggest that the oxidation rate would be affected by the oxidant reduction potential and concentrations of ferrous iron and persulfate.
Assuntos
Benzeno/isolamento & purificação , Éteres Metílicos/isolamento & purificação , Sulfatos/química , Poluentes Químicos da Água/isolamento & purificaçãoRESUMO
The objective of this study was to evaluate the effectiveness of in situ bioremediation of trichloroethylene (TCE)-contaminated groundwater using specific gene analyses under the following conditions: (1) pretreatment with biodegradable surfactants [Simple Green™ (SG) and soya lecithin (SL)] to enhance TCE desorption and dissolution, and (2) supplementation with SG, SL, and cane molasses as primary substrates to enhance the aerobic cometabolism of TCE. Polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), and nucleotide sequence analysis were applied to monitor the variations in specific activity-dependent enzymes and dominant microorganisms. Results show that TCE-degrading enzymes, including toluene monooxygenase, toluene dioxygenase, and phenol monooxygenase, were identified from sediment samples collected from a TCE-spill site. Results from the microcosm study show that addition of SG, SL, or cane molasses can enhance the aerobic cometabolism of TCE. The TCE degradation rates were highest in microcosms with added SL, the second highest in microcosms containing SG, and lowest in microcosms containing cane molasses. This indicates that SG and SL can serve as TCE dissolution agents and act as primary substrates for indigenous microorganisms. Four dominant microorganisms (Rhodobacter sp., Methyloversatilis sp., Beta proteobacterium sp., and Hydrogenophaga pseudoflava) observed in microcosms might be able to produce TCE-degrading enzymes for TCE cometabolic processes.
Assuntos
Tensoativos/química , Tricloroetileno/metabolismo , Poluentes Químicos da Água/metabolismo , Sequência de Bases , Primers do DNA , Eletroforese em Gel de Poliacrilamida , Reação em Cadeia da PolimeraseRESUMO
Groundwater contamination by gasoline spill is a worldwide environmental problem. Gasoline contains methyl tertiary-butyl ether (MTBE) (a fuel oxygenates) and benzene, which are the chemicals of concerns among the gasoline components. In this study, an in situ chemical oxidation (ISCO) barrier system was developed to evaluate the feasibility of applying this passive system on the control of MTBE and benzene plume in aquifer. The developed ISCO barrier contained oxidant-releasing materials, which could release oxidants (e.g., persulfate) when contact with water for the contaminants' oxidation in groundwater. In this study, laboratory-scale fill-and-draw experiments were conducted to determine the component ratios of the oxidant-releasing materials and evaluate the persulfate release rates. Results indicate that the average persulfate-releasing rate of 7.26 mg S(2)O(8)(2-)/d/g was obtained when the mass ratio of sodium persulfate/cement/sand/water was 1/1.4/0.24/0.7. The column study was conducted to evaluate the efficiency of in situ application of the developed ISCO barrier system on MTBE and benzene oxidation. Results from the column study indicate that approximately 86-92% of MTBE and 95-99% of benzene could be removed during the early persulfate-releasing stage (before 48 pore volumes of groundwater pumping). The removal efficiencies for MTBE and benzene dropped to approximately 40-56% and 85-93%, respectively, during the latter part of the releasing period due to the decreased persulfate-releasing rate. Results reveal that acetone, byproduct of MTBE, was observed and then further oxidized completely. Results suggest that the addition of ferrous ion would activate the persulfate oxidation. However, excess ferrous ion would compete with organic contaminants for persulfate, and thus, cause the decrease in contaminant oxidation rates. The proposed treatment scheme would be expected to provide a more cost-effective alternative to remediate MTBE, benzene, and other petroleum-hydrocarbon contaminated aquifers. Results from this study will be useful in designing a scale-up system for field application.