Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 17 de 17
Filtrar
1.
Reprod Biol Endocrinol ; 22(1): 106, 2024 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-39164703

RESUMO

Hormonal changes in pregnant and lactating women significantly affect bone metabolism and overall stress levels, positioning them as a unique group within the orthodontic population. Fluctuations in estrogen, progesterone, prolactin, and other hormones are closely linked to bone remodeling and the periodontal tissue's response to inflammation caused by dental plaque. Hormones such as thyrotropin, leptin, and melatonin also play crucial roles in pregnancy and bone remodeling, with potential implications for orthodontic tooth movement. Additionally, adverse personal behaviors and changes in dietary habits worsen periodontal conditions and complicate periodontal maintenance during orthodontic treatment. Notably, applying orthodontic force during pregnancy and lactation may trigger stress responses in the endocrine system, altering hormone levels. However, these changes do not appear to adversely affect the mother or fetus. This review comprehensively examines the interaction between hormone levels and orthodontic tooth movement in pregnant and lactating women, offering insights to guide clinical practice.


Assuntos
Lactação , Humanos , Feminino , Lactação/fisiologia , Lactação/metabolismo , Gravidez , Hormônios/metabolismo , Hormônios/sangue , Técnicas de Movimentação Dentária/métodos , Remodelação Óssea/fisiologia
2.
J Biopharm Stat ; : 1-12, 2024 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-39300965

RESUMO

Adverse drug events (ADEs) are one of the major causes of hospital admissions and are associated with increased morbidity and mortality. Post-marketing ADE identification is one of the most important phases of drug safety surveillance. Traditionally, data sources for post-marketing surveillance mainly come from spontaneous reporting system such as the Food and Drug Administration Adverse Event Reporting System (FAERS). Social media data such as posts on X (formerly Twitter) contain rich patient and medication information and could potentially accelerate drug surveillance research. However, ADE information in social media data is usually locked in the text, making it difficult to be employed by traditional statistical approaches. In recent years, large language models (LLMs) have shown promise in many natural language processing tasks. In this study, we developed several LLMs to perform ADE classification on X data. We fine-tuned various LLMs including BERT-base, Bio_ClinicalBERT, RoBERTa, and RoBERTa-large. We also experimented ChatGPT few-shot prompting and ChatGPT fine-tuned on the whole training data. We then evaluated the model performance based on sensitivity, specificity, negative predictive value, positive predictive value, accuracy, F1-measure, and area under the ROC curve. Our results showed that RoBERTa-large achieved the best F1-measure (0.8) among all models followed by ChatGPT fine-tuned model with F1-measure of 0.75. Our feature importance analysis based on 1200 random samples and RoBERTa-Large showed the most important features are as follows: "withdrawals"/"withdrawal", "dry", "dealing", "mouth", and "paralysis". The good model performance and clinically relevant features show the potential of LLMs in augmenting ADE detection for post-marketing drug safety surveillance.

3.
Nanotechnology ; 33(27)2022 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-35313287

RESUMO

Herein, an amphiphilic block copolymer CD44-targeting peptide-conjugated polyethylene glycol-block-hydroxyethyl starch-block-poly (L-lactic acid) (CD44p-conjugated PEG-b-HES-b-PLA) are synthesized, which could self-assemble into the pH-responsive and CD44-targeting polymer micelles against breast cancer cells MDA-MB-231. Emodin (Emo) is a natural anthraquino with pharmacological activities in anti-tumor effects. However, Emo suffers from poor water solubility, low biocompatibility, rapid systemic elimination, and off-target side effects, resulting in unsatisfactory treatment outcomes. Nanotechnology-based drug delivery systems have proven great potential for cancer chemotherapy. The constructed polymeric micelles Emo@CD44p-PM have exhibited an average size of 154.5 ± 0.9 nm characterized by DLS and TEM. Further, the Emo@CD44p-PM have effective Emo-loading capacity, good thermal stability, and pH responsiveness. Intracellular uptake study shows the enhanced cellular internalization of Emo@CD44p-PM due to the increased exposure of CD44p enhances the cellular internalization of Emo@CD44p-PM effectively. Furthermore, thein vitroresults showed Emo@CD44p-PM has been observed good biocompatibility and anti-tumor effects. Therefore, the polymeric micelles Emo@CD44p-PM provide a promising delivery strategy of targeted therapy for breast cancer.


Assuntos
Neoplasias da Mama , Emodina , Neoplasias da Mama/tratamento farmacológico , Linhagem Celular Tumoral , Portadores de Fármacos , Sistemas de Liberação de Medicamentos , Feminino , Humanos , Receptores de Hialuronatos , Concentração de Íons de Hidrogênio , Micelas , Poliésteres , Polietilenoglicóis , Polímeros
4.
Environ Sci Technol ; 56(6): 3524-3534, 2022 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-35226472

RESUMO

The transport of nanoplastics (NPs) through porous media is influenced by dissolved organic matter (DOM) released from agricultural organic inputs. Here, cotransport of NPs with three types of DOM (biocharDOM (BCDOM), wheat strawDOM (WSDOM), and swine manureDOM (SMDOM)) was investigated in saturated goethite (GT)-coated sand columns. The results showed that codeposition of 50 nm NPs (50NPs) with DOM occurred due to the formation of a GT-DOM-50NPs complex, while DOM loaded on GT-coated sand and 400 nm NPs (400NPs) aided 400NPs transport due to electrostatic repulsion. According to the quantum chemical calculation, humic acid and cellulose played a significant role in 50NPs retardation. Owing to its high concentration, moderate humification index (HIX), and cellulose content, SMDOM exhibited the highest retardation of 50NPs transport and promoting effect on 400NPs transport. Owing to a high HIX, the effect of BCDOM on the mobility of 400NPs was higher than that of WSDOM. However, high cellulose content in WSDOM caused it to exhibit a 50NPs retardation ability that was similar to that of BCDOM. Our results highlight the particle size selectivity and significant influence of DOM type on the transport of NPs and elucidate their quantum and colloidal chemical-interface mechanisms in a typical agricultural environment.


Assuntos
Matéria Orgânica Dissolvida , Microplásticos , Animais , Celulose , Substâncias Húmicas/análise , Compostos de Ferro , Minerais , Tamanho da Partícula , Porosidade , Areia , Suínos
5.
Int J Mol Sci ; 23(7)2022 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-35408870

RESUMO

4-Coumarate:CoA ligase (4CL, EC6.2.1.12), located at the end of the phenylpropanoid metabolic pathway, regulates the metabolic direction of phenylpropanoid derivatives and plays a pivotal role in the biosynthesis of flavonoids, lignin, and other secondary metabolites. In order to understand the molecular characteristics and potential biological functions of the 4CL gene family in the pomegranate, a bioinformatics analysis was carried out on the identified 4CLs. In this study, 12 Pg4CLs were identified in the pomegranate genome, which contained two conserved amino acid domains: AMP-binding domain Box I (SSGTTGLPKGV) and Box II (GEICIRG). During the identification, it was found that Pg4CL2 was missing Box II. The gene cloning and sequencing verified that this partial amino acid deletion was caused by genome sequencing and splicing errors, and the gene cloning results corrected the Pg4CL2 sequence information in the 'Taishanhong' genome. According to the phylogenetic tree, Pg4CLs were divided into three subfamilies, and each subfamily had 1, 1, and 10 members, respectively. Analysis of cis-acting elements found that all the upstream sequences of Pg4CLs contained at least one phytohormone response element. An RNA-seq and protein interaction network analysis suggested that Pg4CL5 was highly expressed in different tissues and may participate in lignin synthesis of pomegranate. The expression of Pg4CL in developing pomegranate fruits was analyzed by quantitative real-time PCR (qRT-PCR), and the expression level of Pg4CL2 demonstrated a decreasing trend, similar to the trend of flavonoid content, indicating Pg4CL2 may involve in flavonoid synthesis and pigment accumulation. Pg4CL3, Pg4CL7, Pg4CL8, and Pg4CL10 were almost not expressed or lowly expressed, the expression level of Pg4CL4 was higher in the later stage of fruit development, suggesting that Pg4CL4 played a crucial role in fruit ripening. The expression levels of 4CL genes were significantly different in various fruit development stages. The results laid the foundation for an in-depth analysis of pomegranate 4CL gene functions.


Assuntos
Punica granatum , Aminoácidos/metabolismo , Coenzima A/metabolismo , Coenzima A Ligases/genética , Coenzima A Ligases/metabolismo , Flavonoides , Frutas/genética , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas , Ligases/metabolismo , Lignina/metabolismo , Filogenia , Punica granatum/genética
6.
Cleft Palate Craniofac J ; 59(6): 732-740, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-34128406

RESUMO

OBJECTIVE: We aim to use geometric morphometric methods to analyze the contours of the side face profile and its variations in 116 children in Hunan province, China, in order to reveal common morphological features and growth of the side face profiles of Chinese children. DESIGN: We photographed the side faces with consistent standardized procedures. Thirty-seven landmarks were recorded, which comprehensively reflected the facial sagittal plane. The collection of coordinate data regarding landmarks was conducted by tpsDig software. Other analyses, such as average shape analysis, principal component analysis, variations analysis, and allometric analysis, were conducted using tpsRelw and tpsRegr. RESULT: Based on the 37 landmarks, principal component analysis was used on the profiles of boys and girls. The result shows that PC1 and PC2 account for 35.46% and 27.44% of the side face contour variations, respectively. There is no significant difference in the side profiles of boys and girls. Overlapping distributions between the boys and girls occurred. A significant difference occurs when principal component analysis was used on the side profiles of children and adults. CONCLUSIONS: There is a significant difference in the side face profiles between adult males and females. Adult males have a higher brow (the 8th landmark) than females, and adult females have a more curved forehead. However, the side face profiles of boys and girls around 10 years of age are generally similar, which suggests that the significant difference in side face profiles between adult males and females may be formed after the age of 10. This study is of great significance for both orthodontists and pediatricians to use different norms for kids and adults and different norms for males and females for each of those age groups.


Assuntos
Face , Testa , Adulto , Povo Asiático , Cefalometria/métodos , Criança , Face/anatomia & histologia , Feminino , Testa/anatomia & histologia , Humanos , Masculino , Análise de Componente Principal
7.
Water Sci Technol ; 75(10): 2322-2330, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28541940

RESUMO

Calcium alginate (CaAlg) hydrogel filtration membrane was prepared using urea as pore-forming agent. The effects of preparation and operating conditions on the removal rate of Cd2+ were researched. The removal mechanism of Cd2+ and the anti-fouling property of CaAlg membrane were investigated. The removal rate of the CaAlg filtration membrane reached over 99.5% within 120 min when 20 mg/L Cd2+ was used, and the flux was 15.5 L/m2h at 0.1 MPa when the thickness of the membrane was 0.28 ± 0.08 mm. However, the removal rate of Cd2+ was below 10.0% when the same concentration Cd2+ solution was adsorbed by CaAlg membrane with the same size. Energy dispersive spectroscope analysis demonstrated that the removal of Cd2+ depended on the adsorption and ion exchange of Ca2+ by Cd2+. CaAlg membrane exhibited a higher removal rate for Cd2+ (almost 100%). It was the filtration process that promoted the adsorption and ion exchange of Cd2+ in CaAlg hydrogel.


Assuntos
Cádmio/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Alginatos/química , Cádmio/análise , Cálcio , Filtração/métodos , Hidrogéis/química , Membranas Artificiais , Poluentes Químicos da Água/análise
8.
Int J Nanomedicine ; 19: 5721-5737, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38895153

RESUMO

Purpose: Curcumin nanocrystals (Cur-NCs) were prepared by hot melt extrusion (HME) technology to improve the dissolution and bioavailability of curcumin (Cur). Methods: Cur-NCs with different drug-carrier ratios were prepared by one-step extrusion process with Eudragit® EPO (EEP) as the carrier. The dispersed size and solid state of Cur in extruded samples were characterized by dynamic light scattering (DLS), scanning electron microscope (SEM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). The thermal stability of Cur was analyzed by thermogravimetric analysis (TGA) and high performance liquid chromatography (HPLC). Dissolution and pharmacokinetics were studied to evaluate the improvement of dissolution and absorption of Cur by nano-preparation. Results: Cur-NCs with particle sizes in the range of 50~150 nm were successfully prepared by using drug-carrier ratios of 1:1, 2:1 and 4:1, and the crystal form of Cur was Form 1 both before and after HME. The extrudate powders showed very efficient dissolution with the cumulative dissolution percentage of 80% in less than 2 min, and the intrinsic dissolution rates of them were 13.68 ± 1.20 mg/min/cm2, 11.78 ± 0.57 mg/min/cm2 and 4.35 ± 0.20 mg/min/cm2, respectively, whereas that of pure Cur was only 0.04 ± 0.00 mg/min/cm2. The TGA data demonstrated that the degradation temperature of Cur was about 250 °C, while the HPLC results showed Cur was degraded when extruded at the temperature over 150 °C. Pharmacokinetic experiment showed a significant improvement in the absorption of Cur. The Cmax of Cur in the Cur-NC group was 1.68 times that of pure Cur group, and the Cmax and area under the curve (AUC0-∞) of metabolites were 2.79 and 4.07 times compared with pure Cur group. Conclusion: Cur-NCs can be prepared by HME technology in one step, which significantly improves the dissolution and bioavailability of Cur. Such a novel method for preparing insoluble drug nanocrystals has broad application prospects.


Assuntos
Disponibilidade Biológica , Curcumina , Tecnologia de Extrusão por Fusão a Quente , Nanopartículas , Tamanho da Partícula , Solubilidade , Curcumina/farmacocinética , Curcumina/química , Curcumina/administração & dosagem , Nanopartículas/química , Animais , Tecnologia de Extrusão por Fusão a Quente/métodos , Portadores de Fármacos/química , Portadores de Fármacos/farmacocinética , Masculino , Varredura Diferencial de Calorimetria , Estabilidade de Medicamentos , Liberação Controlada de Fármacos , Difração de Raios X , Ácidos Polimetacrílicos
9.
Sci Total Environ ; 864: 161078, 2023 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-36565862

RESUMO

The wide use of plastic film mulch has led to the release of phthalate esters (PAEs), which seriously threatens the soil environment and the safety of crop production. However, it is unknown whether there is a maximum threshold of soil PAEs accumulation induced by plastic film residue, and the dynamic changes of soil PAEs under field conditions are still unclear. To address these issues, a field experiment was conducted to investigate the temporal fluctuations of soil PAEs content and the response of microbial community structure in the field with plastic film residue. Results showed that the content of soil PAEs fluctuated during an observation period of one year, had a periodical peak in winter and summer, and was exacerbated by the increase in the aging degree and residual amount of plastic films. The PAEs content in soil with black films was higher than the US soil allowable criteria. High-throughput sequencing analysis showed that the addition of residual film significantly increased the alpha diversity of bacterial communities, changed the structure of bacterial community, and generated significant disturbances in bacterial function. Besides, the residual film recruited more microbiota related to plastic film and PAEs degradation. Results of the present study provide insight into the dynamic variation of soil PAEs caused by plastic film residue in one year, which is important to help evaluate the pollution risk of PAEs on soils and crops caused by residual plastic film.


Assuntos
Ácidos Ftálicos , Poluentes do Solo , Solo/química , Ácidos Ftálicos/análise , Poluentes do Solo/análise , Verduras/química , Plásticos/química , China , Ésteres/análise , Dibutilftalato/análise
10.
J Hazard Mater ; 447: 130788, 2023 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-36682251

RESUMO

Combined pollution from microplastics (MPs) and cadmium (Cd) can influence soil environment and soil biota, altering plant growth and development, and Cd mobilization. We investigated the effects of polystyrene (PS) and polypropylene (PP) MPs alongside Cd on soil Cd bioavailability, rhizosphere soil metabolomics, bacterial community structure, and maize (Zea mays L.) growth in two soil types (red soil and cinnamon soil). Although the addition of PS/PP-Cd promoted Cd accumulation in maize plants overall, there were large-particle-size- and small-particle-size-dependent effects in the red soil and cinnamon soil, respectively. The difference is mainly due to the capacity of the large particle size MPs to significantly reduce soil pH, improve soil electrical conductivity (EC), promote active Cd, and intensify Cd mobilization in red soil. In contrast, small-size MPs in cinnamon soil promoted the synthesis and secretion of rhizosphere amino acids and soil metabolites, thus promoting Cd absorption by maize roots. Soil microorganisms also improved Cd bioavailability via C-related functional bacteria. Overall, our study provides novel insights on the potential effects of combined MPs and Cd pollution on soil ecology and agricultural production, enhancing our understanding of rhizosphere metabolites in different soils.


Assuntos
Cádmio , Poluentes do Solo , Cádmio/metabolismo , Microplásticos/análise , Zea mays/metabolismo , Plásticos/análise , Raízes de Plantas/metabolismo , Solo/química , Aminoácidos/metabolismo , Poluentes do Solo/metabolismo , Rizosfera
11.
Chemosphere ; 286(Pt 3): 131965, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34449324

RESUMO

The production and degradation of plastic remains can result in nanoplastics (NPs) formation. However, insufficient information regarding the environmental behaviors of NPs impedes comprehensive assessment of their significant threats. In this study, the transport behavior of unmodified NPs (PSNPs), carboxyl-modified NPs (PSNPs-COOH), and amino-modified NPs (PSNPs-NH2) was investigated using column experiments in the presence and absence of goethite (GT) and diethylhexyl phthalate (DEHP). Quantum chemical computation was performed to reveal the transport mechanisms. The results showed that GT decreased the transport of NPs and the presence of DEHP decreased it further. Van der Waals forces and small electrostatic interactions coexisted between the PSNPs and GT and caused deposition. Ligand exchange caused greater deposition of PSNPs-COOH on GT-coated sand than that of PSNPs. Although hydrogen bonding existed between the DEHP and NPs with functional groups, an increase in the positive charge and chemical heterogeneity of the collector was the main reason for DEHP promoting the deposition of NPs. Because of low absolute negative zeta potential values, PSNPs-NH2 was sensitive to chemical heterogeneity, and thus fully deposited (over 96.9%) in GT and GT-DEHP-coated columns. Generally, the deposition of NPs due to chemical heterogeneity was more significant than that due to the formation of chemical bonds and van der Waals, electrostatic, and hydrogen interactions. Our results highlight that the surface charge and functional groups significantly influence the transport behaviors of NPs and elucidate the fate of NPs in the terrestrial environment.


Assuntos
Dietilexilftalato , Microplásticos , Plásticos , Poliestirenos , Areia
12.
Colloids Surf B Biointerfaces ; 217: 112669, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35810613

RESUMO

Biologically fixed arthroplasty is limited in its development by the long postoperative recovery time and the low quality of solidity of the fixed interface in the short postoperative period. Therefore, fretting stimulation is used to accelerate the combination between bone tissue and the biological fixation interface of artificial joint prostheses. The effects of different compression loads and tangential micro-motion amplitude on the growth rate of bone tissue and the firm quality of fixation interface were studied by using two kinds of micro-motion stimuli: compression and tangential micro-motion. The mechanism of micro-motion stimulation to promote bone growth at the fixation interface was revealed. The results of binding force detection of biological fixation interface and bone tissue section staining showed that the bone tissue and hydroxyapatite coating interface had the most tendency to produce new bone tissue under compression load of 4 N. In the tangential fretting environment, the tangential fretting amplitude of ± 40 µm and the normal load of 7.5 N were the most conducive to bone growth, making the combination of bone tissue and titanium alloy prosthesis coated with hydroxyapatite more firm. The study is important for accelerating the integration and shortening the rehabilitation time after artificial joint replacement.


Assuntos
Ligas , Durapatita , Desenvolvimento Ósseo , Osso e Ossos , Durapatita/farmacologia , Titânio/farmacologia
13.
J Hazard Mater ; 440: 129726, 2022 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-35988495

RESUMO

Combined pollution from microplastics (MPs) and other environmental pollutants has attracted considerable attention. Few studies have investigated the effects of polyurethane (PU) and polypropylene (PP) MPs on available Cadmium(Cd) in different soil types. Here, PU and PP additions affected available Cd and reduced its concentration in soil (P > 0.05). PU and PP reduced available Cd more strongly in clay soil than that in sandy soil. PU and PP improved the soil porous structure and voids and significantly increased the Zeta potential in clay soil (P < 0.05). Dissolved organic carbon and pH in clay soil were significantly negatively correlated with available Cd after PU and PP addition, and Fe(Ⅱ) was significantly negatively correlated with available Cd in sandy soil. PU and PP addition promoted the C-C, CO32-, and C-H functional groups and FeO, FeOOH, and Fe3O4 formation and influenced the effective Cd through adsorption and precipitation. CdCO3 formation and clay mineral adsorption, and iron oxide formation, influenced the effective Cd in clay and sandy soils, respectively. PU and PP influenced the effective state of Cd by affecting bacterial communities related to carbon and iron cycles. This study is significant for assessing the environmental risks of MPs combined with heavy metals in different soils and their mechanisms.


Assuntos
Poluentes Ambientais , Metais Pesados , Poluentes do Solo , Agricultura , Cádmio/química , Carbono , Argila , Compostos Ferrosos , Ferro , Metais Pesados/análise , Microplásticos , Minerais/química , Plásticos , Polipropilenos , Poliuretanos , Solo/química , Poluentes do Solo/análise
14.
Sci Total Environ ; 850: 157886, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-35952884

RESUMO

Microplastics (MPs) affect the accumulation of heavy metals by regulating the soil environment. However, studies on the dynamic effects of microplastics on the available states of heavy metals in soil are lacking. In particular, how controlled-release fertilizer coated microplastics can synergistically change the avsilable states of heavy metals in soil by affecting soil physical and chemical properties and microbial community structure is still lacking. The dynamic effect of polyurethane (PU) MPs on the effective state of soil cadmium (Cd; DGTCd), at different particle sizes and concentrations, was studied in situ by diffusive gradient in thin-films (DGT) for the first time. The bioavailability, soil chemical properties, and microbial effects of PU MPs on Cd depend on PU particle size and concentration; high-concentration (1 %) PU MPs cause a significant increase in DGT-Cd concentration. The addition of PU MPs decreased soil pH and dissolved organic carbon (DOC), while increasing the absolute zeta value, Fe(II) and Mn(II), in a manner dependent on particle size, concentration, and culture time. Correlation analysis combined with path analysis showed that PU MPs affected the effective state of Cd by changing soil properties, among which Fe(II) content and DOC were important factors controlling the activation of Cd. Meanwhile, changes in soil properties and heavy metal availability correlated significantly with microbial community composition, suggesting that PU MPs may indirectly impact heavy metal activity by affecting microorganisms and functional genes associated with C and Fe cycling. Therefore, when the concentration of PU MPs is higher than 1 %, we should strengthen ecological risk prevention and control of the compound pollution of controlled-release fertilizer coated microplastics and heavy metals in farmland soil.


Assuntos
Metais Pesados , Poluentes do Solo , Cádmio/análise , Preparações de Ação Retardada , Compostos Ferrosos , Fertilizantes/análise , Metais Pesados/análise , Microplásticos , Plásticos , Poliuretanos , Solo/química , Poluentes do Solo/análise
15.
Chemosphere ; 251: 126231, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32169713

RESUMO

In this work, a composite resin gel incorporating thiol-modified metal double hydroxide (TM-MDH) nanoparticles is developed for application in diffusive gradients in thin films (DGT) devices to sample and concentrate divalent Hg (Hg(II)) in water and sediment samples. The DGT device uses the TM-MDH resin as a sorption layer and an agarose gel as a diffusive layer. Complete digestion of the TM-MDH resin after sampling can be achieved in 5 mL of 12 N HCl solution for 30 min for direct aqueous Hg(II) analysis. The recovery of Hg(II) uptake onto the resin in aqueous solution reaches 95.4 ± 1.9%. The effect of ionic strength and pH on the performance of DGT device for Hg(II) is assessed. It is found that there is no significant difference on Hg(II) uptake over a pH range of 3.5-8.5 and an ionic strength range of 1-500 mM NaCl. The diffusion coefficient of Hg(II) at 25 °C was estimated to be 9.48 × 10-6 cm2/s at 50 µg/L solution. The sorption capacity of TM-MDH-DGT for Hg(II) reaches 41.0 µg/cm2. Field validations performed in reservoir water and in contaminated paddy soil demonstrate that the developed TM-MDH DGT device can accurately determine Hg(II) concentrations in these samples and outperform traditional sampling methods for both high and low Hg(II) concentrations.


Assuntos
Monitoramento Ambiental/métodos , Mercúrio/análise , Poluentes Químicos da Água/análise , Resinas Compostas , Difusão , Metais/análise , Concentração Osmolar , Água/análise
16.
Huan Jing Ke Xue ; 33(10): 3562-8, 2012 Oct.
Artigo em Zh | MEDLINE | ID: mdl-23233989

RESUMO

The diffusive gradients in thin films (DGT) technique with solid-state binding phases has been widely used for in situ collection and measurement of available heavy metals in waters, soils or sediments, whereas DGT with liquid binding phase is primarily used in the in situ analysis of heavy metals in waters. In this paper, rhizosphere soils of sugarcane were collected in Guangxi and the concentrations of cadmium (Cd) were determined by DGT with a solid-state binding phase of chelex100 (chelex100-DGT) and modified DGT with a liquid binding phase of sodium polyacrylate (CDM-PAAS-DGT). The result showed that the Cd contents in soils measured by DGT with both binding phases and Cd in the roots, leaves and unpolished stems of sugarcane had significant positive correlation. The extraction ability of the CDM-PAAAS-DGT was much higher than that of the chelex100-DGT. In addition, multivariate analyses were used to assess the impact of pH, cation exchange capacity (CEC), soil organic matter (OM) and texture. Two principal components were extracted and the linear regression models were established. The Cd bioavailability in soils could be accurately predicted by the CDM-PAAAS-DGT technique, which expanded its applicable area.


Assuntos
Resinas Acrílicas/química , Cádmio/análise , Saccharum/crescimento & desenvolvimento , Poluentes do Solo/análise , Solo/química , Disponibilidade Biológica , Difusão , Monitoramento Ambiental/instrumentação , Monitoramento Ambiental/métodos , Modelos Lineares , Resinas Sintéticas/química
17.
Biomaterials ; 32(28): 6719-28, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21703681

RESUMO

Patterned two-component, self-assembled monolayers on gold were produced by UV lithography. An oligo(ethylene glycol) terminated disulfide served as inert matrix reducing unspecific protein adsorption and cell adhesion. The second component of the self-assembled monolayer (SAM) presented a benzylguanine moiety for the immobilization of Sonic hedgehog (Shh) fused to a mutant O(6)-alkylguanine-DNA alkyltransferase (SNAP-tag™). The enzymatic activity of the SNAP-tag allows selective and covalent immobilization of the linked Shh. Time-of-flight secondary ion mass spectrometry verified the correct lateral distribution of the benzylguanine head groups in the patterned SAM. The quantification of unspecific and specific protein binding to mixed SAMs showed increased adsorption of albumin with increasing benzylguanine/(ethylene glycol) ratios. However, the immobilization of SNAP-tagged Shh was not blocked by pre-adsorbed albumin. Furthermore, the obtained micro-patterned substrates permitted direct immobilization of SNAP-tagged Shh even in the presence of many competing proteins from conditioned media of transfected HEK293 cells. Therefore, the presented system is suited for the controlled immobilization of fusion proteins from complex mixtures avoiding purification steps.


Assuntos
Guanina/química , Proteínas Hedgehog/metabolismo , Adsorção , Materiais Biocompatíveis/química , Materiais Biocompatíveis/metabolismo , Adesão Celular , Ouro/química , Células HEK293 , Células HeLa , Proteínas Hedgehog/química , Proteínas Hedgehog/genética , Humanos , Espectrometria de Massas/métodos , Teste de Materiais , Estrutura Molecular , O(6)-Metilguanina-DNA Metiltransferase/química , O(6)-Metilguanina-DNA Metiltransferase/genética , O(6)-Metilguanina-DNA Metiltransferase/metabolismo , Ligação Proteica , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Propriedades de Superfície
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA