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2.
Ethn Health ; 28(1): 46-60, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35263206

RESUMO

OBJECTIVES: Previous studies have suggested that often, Black mothers' birthing experiences are not what they expected because of how they were treated by healthcare providers during labor and birth. Our goal in this study was to ask Black mothers who had recently given birth about the quality of their birthing experiences as well as their level of respect from, trust in, and satisfaction with their maternity healthcare providers. DESIGN: This study gathered data from Black mothers (N = 209) who had given birth within the past two years, using a cross-sectional online survey measuring several variables about the birthing experience including types of healthcare provider communication, provider respect for the mother, trust, birth satisfaction, and emotional responses to birth. RESULTS: Provider-centered communication, although preferred by some mothers, was associated with lower birth satisfaction and stronger negative emotions whereas positive birth satisfaction was linked to patient-centered communication which resulted in positive emotions. While most mothers reported overall satisfaction with their birth experience, nearly half reported experiencing some degree of disrespect from their healthcare providers during labor and birth. Moreover, trust and respect mediated the relationship for patient-centered communication with positive emotion and birth satisfaction. Over one-third of participants gave birth with a certified nurse midwife attending. There were no differences in perception of being respected or the quality of birth given the professional identity of the provider as an Obstetrician/Gynecologist or as a midwife. The advice suggested by Black mothers for their healthcare providers was instructive in identifying ways those providers could better serve their patients during birth. CONCLUSION: This study showed that there is still additional work that needs to be done for racial equity and respect during birth. Practical implications for addressing health inequities are discussed.


Assuntos
Tocologia , Mães , Gravidez , Feminino , Humanos , Mães/psicologia , Estudos Transversais , Parto/psicologia , Tocologia/métodos , Comunicação
3.
Artigo em Inglês | MEDLINE | ID: mdl-35805699

RESUMO

The objective of this study was to investigate the therapeutic effect of Wuqinxi Qigong vs. stretching on single- and dual-task gait, motor symptoms, and quality of life in people with mild and moderate Parkinson's disease (PD). This single-blind, randomized control trial included 40 participants with idiopathic PD who were randomized into the Wuqinxi Qigong (WQ) group or stretching group. Participants completed 12 weeks (two sessions/week) of intervention. The primary outcomes were gait parameters when performing single-task (comfortable pace) and dual-task (obstacle crossing, serial-3 subtraction and backward digit span) walking, including gait speed, stride length, and double support percentage. The secondary outcomes were ratings from the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS), results of the timed-up-and-go test (TUGT), results of the Mini-Balance Evaluation Systems Test (MiniBESTest), and responses from the 39-item Parkinson's Disease Questionnaire (PDQ-39). All measures were assessed pre- and post-intervention. The WQ group demonstrated increased gait speed (p = 0.000) during the single task, and increased stride length (p = 0.001, p = 0.021) during the single-task and serial-3 subtraction task. Double support percentage significantly decreased (p = 0.004) in the WQ group during the obstacle crossing task, and also decreased (p = 0.045) in the stretching group during the single-task. TUGT (p = 0.005), MiniBESTest (p = 0.023) and PDQ-39 (p = 0.043) in the WQ group significantly improved, and both groups showed significant improvement in MDS-UPDRS after intervention. Wuqinxi Qigong is an effective method to improve single- and dual-task gait. While both exercises improve motor symptoms, Wuqinxi Qigong results in better mobility, balance and quality of life compared to stretching alone.


Assuntos
Doença de Parkinson , Qigong , Marcha/fisiologia , Humanos , Doença de Parkinson/complicações , Equilíbrio Postural , Qigong/métodos , Qualidade de Vida , Método Simples-Cego , Estudos de Tempo e Movimento
4.
Zhongguo Zhong Yao Za Zhi ; 47(2): 412-418, 2022 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-35178983

RESUMO

Farnesyl diphosphate synthase(FPPS) is a key enzyme at the branch point of the sesquiterpene biosynthetic pathway, but there are no reports on the transcriptional regulation of FPPS promoter in Pogostemon cabin. In the early stage of this study, we obtained the binding protein PcFBA-1 of FPPS gene promoter in P. cabin. In order to explore the possible mechanism of PcFBA-1 involved in the regulation of patchouli alcohol biosynthesis, this study performed PCR-based cloning and sequencing analysis of PcFBA-1, analyzed the expression patterns of PcFBA-1 in different tissues by fluorescence quantitative PCR and its subcellular localization using the protoplast transformation system, detected the binding of PcFBA-1 protein to the FPPS promoter in vitro with the yeast one-hybrid system, and verified its transcriptional regulatory function by dual-luciferase reporter gene assay. The findings demonstrated that the cloned PcFBA-1 had an open reading frame(ORF) of 1 131 bp, encoding a protein of 376 amino acids, containing two conserved domains named F-box-like superfamily and FBA-1 superfamily, and belonging to the F-box family. Moreover, neither signal peptide nor transmembrane domain was contained, implying that it was an unstable hydrophilic protein. In addition, as revealed by fluorescence quantitative PCR results, PcFBA-1 had the highest expression in leaves, and there was no significant difference in expression in roots or stems. PcFBA-1 protein was proved mainly located in the cytoplasm. Furthermore, yeast one-hybrid screening and dual-luciferase reporter gene assay showed that PcFBA-1 was able to bind to FPPS promoter both in vitro and in vivo to enhance the activity of FPPS promoter. In summary, this study identifies a new transcription factor PcFBA-1 in P. cabin, which directly binds to the FPPS gene promoter to enhance the promoter activity. This had laid a foundation for the biosynthesis of patchouli alcohol and other active ingre-dients and provided a basis for metabolic engineering and genetic improvement of P. cabin.


Assuntos
Pogostemon , Sequência de Aminoácidos , Clonagem Molecular , Geraniltranstransferase/genética , Fatores de Transcrição/genética
5.
Pain Res Manag ; 2021: 5584997, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34055119

RESUMO

Background: The number of patients with musculoskeletal pain, which seriously affects people's quality of life, has increased. Traditional Chinese exercises are accepted and practiced to strengthen the body. Objective: This study aims to explore the efficacy of traditional Chinese exercises for the treatment of musculoskeletal pain. Methods: A comprehensive search of randomized controlled trials (RCTs) related to traditional Chinese exercises on patients with musculoskeletal pain was completed using PubMed, SinoMed, CNKI, VIP, and Wanfang Med Online databases. All RCTs published until February 2021 were considered. Two researchers independently screened the literature according to the predesigned inclusion and exclusion criteria, and data was extracted and assessed for their risk of bias via the Cochrane collaboration tool. Meta-analysis was performed using RevMan5.2 and Rx64 4.0.2 software. Results: A total of 45 RCT studies with 3178 patients were included. Traditional Chinese exercises were able to effectively alleviate patients with musculoskeletal pain (MD = -1.54, 95% confidence interval (-1.88, -1.19), P < 0.01). Among them, the Yi Jin Jing exercise was superior to other exercises, while Wu Qin Xi showed no significant effects. Besides, traditional Chinese exercises had significant positive effects on the dysfunction and stiffness of the waist and knee joints. Traditional Chinese exercises could effectively relieve the clinical symptoms of patients with musculoskeletal pain. Particularly, the Yi Jin Jing exercise presented the most significant positive effect on pain reduction.


Assuntos
Exercício Físico , Medicina Tradicional Chinesa/estatística & dados numéricos , Dor Musculoesquelética/terapia , Manejo da Dor/métodos , Humanos
6.
Artigo em Inglês | MEDLINE | ID: mdl-33859712

RESUMO

INTRODUCTION: Parkinson's disease (PD) is a chronic degenerative disease of the central nervous system common in middle-aged and elderly people, which has a serious impact on patients' cognitive and motor functions. Exercise can improve the nonmotor symptoms of PD patients, but the optimal type of exercise for the cognitive function of patients is unclear. Therefore, the purpose of this study is the impact of 12 weeks of Wuqinxi exercise on the cognitive and motor function in PD patients. METHODS: Thirty PD patients participated in the study and were randomly assigned to two groups: Wuqinxi group (n = 15) or stretching group (n = 15). All the participants performed a 12-week exercise program twice a week, 90 min/session. The assessments were conducted before and after exercise intervention, included cognitive function (frontal assessment battery (FAB); Stroop test I and II), motor functions (Unified Parkinson's Disease Rating Scale Part III (UPDRS-III); timed up and go (TUG)). RESULTS: We found the FAB and Stroop I scores were significantly higher in the Wuqinxi group than in the stretching group. Participants in the Wuqinxi group significantly improved their UPDRS-III (17.73 ± 9.88) and TUG (10.50 ± 1.79) score after 12 weeks of training intervention. CONCLUSION: The results show that the use of Wuqinxi for rehabilitation therapy for cognition is feasible, widely accepted, and effective in patients with Parkinson's disease. This study provides preliminary evidence for further large-scale and controlled studies.

7.
Comput Math Methods Med ; 2020: 6056383, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33381220

RESUMO

The motor-imagery brain-computer interface system (MI-BCI) has a board prospect for development. However, long calibration time and lack of enough MI commands limit its use in practice. In order to enlarge the command set, we add the combinations of traditional MI commands as new commands into the command set. We also design an algorithm based on transfer learning so as to decrease the calibration time for collecting EEG signal and training model. We create feature extractor based on data from traditional commands and transfer patterns through the data from new commands. Through the comparison of the average accuracy between our algorithm and traditional algorithms and the visualization of spatial patterns in our algorithm, we find that the accuracy of our algorithm is much higher than traditional algorithms, especially as for the low-quality datasets. Besides, the visualization of spatial patterns is meaningful. The algorithm based on transfer learning takes the advantage of the information from source data. We enlarge the command set while shortening the calibration time, which is of significant importance to the MI-BCI application.


Assuntos
Algoritmos , Interfaces Cérebro-Computador/estatística & dados numéricos , Eletroencefalografia/classificação , Eletroencefalografia/estatística & dados numéricos , Imaginação/fisiologia , Biologia Computacional , Voluntários Saudáveis , Humanos , Aprendizado de Máquina , Destreza Motora/fisiologia , Córtex Sensório-Motor/fisiologia , Processamento de Sinais Assistido por Computador , Análise e Desempenho de Tarefas
8.
Artigo em Inglês | MEDLINE | ID: mdl-33178323

RESUMO

OBJECTIVE: This study was designed to evaluate the effect of Wuqinxi after one session and 12-week intervention on hand dexterity in patients with Parkinson's disease (PD). METHODS: Forty-six elderly participants with mild-to-moderate PD were randomly assigned to the groups trained with Wuqinxi (n = 23) or stretching (n = 23). All participants practiced 60 min session of either of these exercises, 2 sessions a week for 12 weeks in standing position. The score of Purdue Pegboard Test (PPT) and time for Soda Pop Test (SPT) were performed to assess hand dexterity and motor function along assessing the 39 items of Parkinson's Disease Questionnaire before and after 12-week interventions. In addition, the PPT scores were compared before vs. after one session of either of these two exercise modes. RESULTS: Single session with either Wuqinxi or stretching exercise tended to improve PPT scores in PD patients. Furthermore, the improved SPT time was significant (P < 0.01) following 12-week training interventions with Wuqinxi (-1.32 ± 0.38 sec) or stretching (-0.89 ± 0.16 sec), which showed no group difference (P=0.734). However, only the participants in Wuqinxi group significantly improved the PPT scores of the dominant hand (+0.61 ± 1.34), both hand (+1.83 ± 3.13) and assemble (+2.04 ± 3.44) performance after 12-week training intervention. In parallel with improved hand dexterity and motor function, 12-week Wuqinxi training also significantly improved the patient's emotional wellbeing. CONCLUSION: The Wuqinxi intervention could be safely and effectively applied to improve hand dexterity following single-session exercise or 12-week training, which were accompanied by improved quality of life in patients with mild-to-moderate PD.

9.
BMJ Open ; 9(9): e028869, 2019 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-31515419

RESUMO

INTRODUCTION: Qigong exercise offers a potentially safe, low-cost and effective mind-body rehabilitative intervention for mitigating the problem of gait interruption among patients with Parkinson's disease (PD) who have frequent freezing of gait (FOG) episodes. However, its clinical effects have not been established. This paper describes the trial protocol of evaluating the clinical efficacy of a newly developed Integrated Qigong in improving gait among patients with PD who have FOG. METHODS AND ANALYSIS: A single-blind randomised controlled trial is designed to compare Integrated Qigong and balance training with an attention control. Participants will be patients with mild to moderate PD who experience FOG and are recruited from local communities in Shanghai, China. Participants will be randomly allocated to one of the three groups: Integrated Qigong group, a balance exercise intervention group, or control group. The total number of participants will be 126, and masked assessments will be made at baseline, 12 weeks (end of intervention) and 12-week follow-up. Both Integrated Qigong group and balance training group will receive a group-based exercise intervention that meets three times per week, 60 min in duration, for 12 weeks. The control group will receive a 60 min weekly group session and monthly health education. The primary outcomes are gait parameters (stride length, gait velocity, stride time variability) and occurrence of FOG. The secondary outcomes are postural instability, walking disability, falling, fear of falling and quality of life. ETHICS AND DISSEMINATION: This study has been approved by the Ethics Committee of Shanghai University of Sport and registered at China Clinical Trial Registry. Participants will sign informed consent prior to the participation of the trial. The findings of the study will be published in peer-reviewed academic journals and disseminated to PD support groups, medical community and media. TRIAL REGISTRATION NUMBER: ChiCTR1800016570.


Assuntos
Transtornos Neurológicos da Marcha/reabilitação , Doença de Parkinson/reabilitação , Qigong/métodos , Fenômenos Biomecânicos , China , Análise da Marcha , Humanos , Método Simples-Cego
10.
Clin Interv Aging ; 9: 131-40, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24453483

RESUMO

This study aimed to evaluate the effectiveness of an innovative exercise program on muscle strength, balance, and gait kinematics in elderly community-dwellers. The exercise program included strength and balance training and the 8-form Tai Chi Chuan. The measurements were carried out at baseline and 12 weeks, and consisted of four physical performance tests, joint isokinetic strength tests, and three-dimensional gait analysis. Fifty-six community-dwelling older adults aged 60-80 years old were randomly assigned to an intervention or control group. After 12 weeks, the intervention group showed a 17.6% improvement in the timed up and go test, accompanied by a 54.7% increase in the 30-second chair stand test score. Significant increases in the score of star excursion balance tests, and the strength of the extensor and flexor muscles at knee and ankle joints were also observed. In addition, the intervention group walked at a faster speed with a longer step length, shorter support phase, and a greater sagittal plane range of motion at the hip and ankle joints. No statistical improvements were seen in the control group. This study provided an effective, evidence-based falls prevention program that can be implemented in community settings to improve physical fitness and reduce fall risks among community-dwelling older adults. The star excursion balance test could be a sensitive measure of physical performance for fall risk assessment in older people.


Assuntos
Acidentes por Quedas/prevenção & controle , Terapia por Exercício/métodos , Aptidão Física , Acidentes por Quedas/estatística & dados numéricos , Idoso , Idoso de 80 Anos ou mais , Feminino , Marcha , Humanos , Masculino , Pessoa de Meia-Idade , Força Muscular , Equilíbrio Postural , Treinamento Resistido/métodos
11.
Cereb Cortex ; 24(4): 908-18, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23250955

RESUMO

Cognitive models claim that spoken words are recognized by an optimally efficient sequential analysis process. Evidence for this is the finding that nonwords are recognized as soon as they deviate from all real words (Marslen-Wilson 1984), reflecting continuous evaluation of speech inputs against lexical representations. Here, we investigate the brain mechanisms supporting this core aspect of word recognition and examine the processes of competition and selection among multiple word candidates. Based on new behavioral support for optimal efficiency in lexical access from speech, a functional magnetic resonance imaging study showed that words with later nonword points generated increased activation in the left superior and middle temporal gyrus (Brodmann area [BA] 21/22), implicating these regions in dynamic sound-meaning mapping. We investigated competition and selection by manipulating the number of initially activated word candidates (competition) and their later drop-out rate (selection). Increased lexical competition enhanced activity in bilateral ventral inferior frontal gyrus (BA 47/45), while increased lexical selection demands activated bilateral dorsal inferior frontal gyrus (BA 44/45). These findings indicate functional differentiation of the fronto-temporal systems for processing spoken language, with left middle temporal gyrus (MTG) and superior temporal gyrus (STG) involved in mapping sounds to meaning, bilateral ventral inferior frontal gyrus (IFG) engaged in less constrained early competition processing, and bilateral dorsal IFG engaged in later, more fine-grained selection processes.


Assuntos
Mapeamento Encefálico , Encéfalo/fisiologia , Idioma , Reconhecimento Psicológico , Comportamento Verbal/fisiologia , Estimulação Acústica , Adulto , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Vias Neurais/fisiologia , Tempo de Reação/fisiologia , Adulto Jovem
12.
J Cereb Blood Flow Metab ; 34(2): 235-41, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24192639

RESUMO

SMTP-7 (Stachybotrys microspora triprenyl phenol-7), a small molecule that promotes plasminogen activation through the modulation of plasminogen conformation, has excellent therapeutic activity against cerebral infarction in several rodent models. Detailed evaluations of SMTP-7 in a primate stroke model are needed for effective, safe drug development. Here we evaluated SMTP-7 in a monkey photochemical-induced thrombotic middle cerebral artery (MCA) occlusion model (n=6), in which MCA occlusion was followed by recanalization/reocclusion. SMTP-7 (10 mg/kg, intravenous infusion) significantly increased the postinfusion MCA recanalization rate (32.5-fold, P=0.043) and ameliorated the post-24-h neurologic deficit (by 29%, P=0.02), cerebral infarct (by 46%, P=0.033), and cerebral hemorrhage (by 51%, P=0.013) compared with the vehicle control animals. In normal monkeys, SMTP-7 did not affect general physiologic or hemostatic variables, including coagulation and platelet parameters. Investigations in rodent models of transient and permanent focal cerebral ischemia, as well as arterial thrombosis and bleeding tests, suggest a role for SMTP-7's regulated profibrinolytic action and neuroprotective properties in the monkey MCA occlusion model. In conclusion, SMTP-7 is effective in treating thrombotic stroke in monkeys. SMTP-7 is thus a promising candidate for the development of alternative therapy for ischemic stroke.


Assuntos
Hemorragia Cerebral/tratamento farmacológico , Fibrinolíticos/farmacologia , Infarto da Artéria Cerebral Média/tratamento farmacológico , Fenóis/farmacologia , Stachybotrys/química , Acidente Vascular Cerebral/tratamento farmacológico , Terapia Trombolítica/métodos , Animais , Hemorragia Cerebral/fisiopatologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Fibrinolíticos/química , Infarto da Artéria Cerebral Média/fisiopatologia , Macaca fascicularis , Masculino , Camundongos , Camundongos Endogâmicos ICR , Fenóis/química , Ratos , Ratos Sprague-Dawley , Acidente Vascular Cerebral/fisiopatologia , Trombose/tratamento farmacológico , Trombose/fisiopatologia
14.
Planta Med ; 76(8): 786-92, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20033864

RESUMO

The aims of this study were to investigate the effect of ligusticum chuanxiong volatile oil (CVO) on the oral absorption of hydroxysafflor yellow A (HSYA). The effects were studied both IN VITRO and IN VIVO. The contents of CVO were measured by GC-MS. The Caco-2 cell model was used to evaluate HSYA permeation with or without the presence of CVO. Transepithelial electrical resistance (TEER) of the Caco-2 cell monolayers was monitored and the alteration in the subcellular localization of claudin-1, the tight junction protein, was observed by immunofluorescence. The irritation of CVO on rat intestine was studied by paraffin slice technology. Our results demonstrated that CVO mainly contained ligustilide (47.82 %). The Papp of HSYA was improved by 5.34-fold and 4.62-fold in the presence of 0.02 mg/mL and 0.01 mg/mL of CVO, respectively. After opening of the tight junctions of the Caco-2 cell monolayer, TEER decreased, the position of claudin-1 changed, and its expression increased. CVO at different concentrations (10, 25, 100 and 200 mg/kg) caused no significant irritation on rat intestine. The bioavailability of HSYA in rats was increased by 6.48-fold and 4.91-fold when 100 and 25 mg/kg of CVO were co-administrated, respectively. CVO was an effective absorption enhancer for oral delivery of BCS III drugs. It can cause redistribution of claudin-1 proteins and open the tight junctions.


Assuntos
Chalcona/análogos & derivados , Medicamentos de Ervas Chinesas/farmacologia , Quinonas/farmacocinética , Administração Oral , Animais , Área Sob a Curva , Células CACO-2 , Chalcona/administração & dosagem , Chalcona/farmacocinética , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Ligusticum , Masculino , Potenciais da Membrana , Quinonas/administração & dosagem , Ratos , Ratos Wistar
15.
Zhongguo Zhong Yao Za Zhi ; 34(17): 2241-6, 2009 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-19943495

RESUMO

OBJECTIVE: To study the effect of combination components on pharmacokinetics of Shuxiong tablet to provide evidence for the new recipe. METHOD: Six groups of rats (6 for each group) were orally administered with co-extractum of chuanxiong and honghua (CHE), mixed solution of hydroxysafflor yellow A (HSYA) and ferulic acid (FA) (HFM). Panax notoginseng saponins solution (PNS), mixed solution of PNS and CHE (PCHE), mixed solution of PNS and HFM (PHFM) and mixed emulsion of Chuanxiong volatile oil (CVO) and PHFM (CVO-PHFM), respectively. The concentrations of HSYA, FA, ginsnenoside Rg1 and Rb1 in rat plasma were determined by HPLC. Pharmacokinetic parameters (Ka, Kel, Cmax, Tmax and AUC) were calculated by model simulation. The differences of HSYA, FA, Rg1 and Rb1 in pharmacokinetics parameters after administration of six preparations were demonstrated by statistical analysis. RESULT: After oral administration of six preparations to rats, the concentration-time curve of HSYA and Rg1 fitted to one-compartment model, and that of FA fitted to double-compartment model. After oral administration of CHE, Kel of FA reduced; Cmax decreased; but K12 increased, significantly, compared with oral administration of HFM. Other parameters were not significant differences. After co-administration of PNS and CHE (PCHE) or PNS and HFM (PHFM), Ka of HSYA increased; Tmax reduced, significantly. After oral administration of PNS and HFM (PHFM), Ka of Rg1 improved, Tmax decreased, significantly. However, the parameters of FA and Rb1 were not significantly changed. After co-administration of CVO and PHFM (CVO-PHFM), Cmax of Rb1 decreased, K12 improved, significantly. Meanwhile, the oral bioavailability of HSYA, FA and Rg1 was improved by 6.056, 2.854 and 2.055 folds, respectively. CONCLUSION: After oral administration of different combinations of Shuxiong tablet constituents, some pharmacokinetics parameters of active ingredients are significantly changed, but the bioavailability is improved only when CVO is co-administered.


Assuntos
Medicamentos de Ervas Chinesas/farmacocinética , Animais , Disponibilidade Biológica , Medicamentos de Ervas Chinesas/administração & dosagem , Masculino , Distribuição Aleatória , Ratos , Ratos Sprague-Dawley , Comprimidos/administração & dosagem , Comprimidos/farmacocinética
16.
J Contam Hydrol ; 60(3-4): 193-209, 2003 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-12504359

RESUMO

Knowledge of the factors that influence the fate and transport of viruses in porous media is very important for accurately determining groundwater vulnerability and for developing protective regulations. In this study, six saturated sand column experiments were performed to examine the effects of a positively charged Al-oxide, which was coated on sand particles, on the retention and transport of viruses (phiX174 and MS-2) in background solutions of different ionic strength and composition. We found that the Al-oxide coating on sand significantly removed viruses during their transport in a phosphate buffered saline (PBS) solution. Mass balance calculations showed that 34% of the input MS-2 was inactivated/irreversibly sorbed on the surface of Al-oxide coated sand whereas 100% of phiX174 was recovered. Results from this study also indicated that higher ionic strength facilitated the transport of both phiX174 and MS-2 through the Al-oxide coated sand. This was attributed to the effect of ion shielding, which at higher ionic strength decreased the electrostatic attraction between the viral particles and the sand surface and consequently decreased virus sorption. Strong effect of the ionic strength indicates that an outer-sphere complexation mechanism was responsible for the virus sorption on the Al-oxide coated sand. Ion composition of the background solutions was also found to be a significant factor in influencing virus retention and transport. Virus transport was enhanced in the presence of phosphate (HPO(4)(2-)) as compared to bicarbonate (HCO(3)(-)), and the effect of HPO(4)(2-) was more significant on MS-2 than on phiX174. The presence of bivalent cations (Ca(2+) and Mg(2+)) increased virus transport because the cations partially screened the negative charges on the viruses therefore decreased the electrostatic attraction between the positively charged sand surface and the negatively charged viruses. Mass recovery data indicated that bivalent cations gave rise to a certain degree of inactivation/irreversibly sorption of phiX174 on the surface of Al-oxide coated sand. On the contrary, the bivalent cations appeared to have protected MS-2 from inactivation/irreversibly sorption. This study provides some insights into the mechanisms responsible for virus retention and transport in porous media.


Assuntos
Óxido de Alumínio/química , Microbiologia do Solo , Vírus , Porosidade , Dióxido de Silício , Movimentos da Água
17.
Chemosphere ; 49(6): 619-28, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12430649

RESUMO

Surface charges play a major role in determining the interactions of contaminants with soils. The most important sources of soil charges are clay mineral colloids, whose electrochemical properties are usually modified by metal-oxides and organic matter in natural environments. In this study, effects of coatings of organic matter and Fe- and Al-oxides on a series of electrochemical properties and heavy metal sorption of three clay minerals (kaolinite, montmorillonite and illite) predominant in natural soils were investigated using batch techniques. The results indicate that the coatings increased the specific surface area of the clay minerals, except for the Al-oxide coated montmorillonite and organic matter coated 2:1 clay minerals. The sesquioxide coatings increased amount of positive charges but decreased negative charges. This causes great reduction of the negative potential on the clay surfaces, shift of the zero point of charge to a higher pH, and promotion of fluoride sorption due to presence of more OH- and OH2 on the oxide surfaces than on the clay surfaces. In contrast, the organic coating significantly increased the negativity of surface charges, and thus the zero point of charge and zeta-potential of the clays dropped down. The organic coating also induced a reduction of fluoride sorption on the clays. With respect to the sorption of lead and cadmium, the sesquioxide coatings produced insignificant effects. The experiments of lead/cadmium competitive sorption show that on both the oxide-coated surface and the original clay surface there exist different types of sites, each of which preferentially binds with a heavy metal.


Assuntos
Silicatos de Alumínio/química , Minerais/química , Poluentes do Solo/análise , Adsorção , Óxido de Alumínio/química , Cádmio/química , Argila , Eletroquímica , Compostos Férricos/química , Fluoretos/química , Concentração de Íons de Hidrogênio , Radical Hidroxila/química , Chumbo/química , Propriedades de Superfície
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