Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 17 de 17
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
IEEE Trans Med Imaging ; PP2024 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-38329865

RESUMO

Multi-dimensional analysis in echocardiography has attracted attention due to its potential for clinical indices quantification and computer-aided diagnosis. It can utilize various information to provide the estimation of multiple cardiac indices. However, it still has the challenge of inter-task conflict. This is owing to regional confusion, global abnormalities, and time-accumulated errors. Task mapping methods have the potential to address inter-task conflict. However, they may overlook the inherent differences between tasks, especially for multi-level tasks (e.g., pixel-level, image-level, and sequence-level tasks). This may lead to inappropriate local and spurious task constraints. We propose cross-space consistency (CSC) to overcome the challenge. The CSC embeds multi-level tasks to the same-level to reduce inherent task differences. This allows multi-level task features to be consistent in a unified latent space. The latent space extracts task-common features and constrains the distance in these features. This constrains the task weight region that satisfies multiple task conditions. Extensive experiments compare the CSC with fifteen state-of-the-art echocardiographic analysis methods on five datasets (10,908 patients). The result shows that the CSC can provide left ventricular (LV) segmentation, (DSC = 0.932), keypoint detection (MAE = 3.06mm), and keyframe identification (accuracy = 0.943). These results demonstrate that our method can provide a multi-dimensional analysis of cardiac function and is robust in large-scale datasets.

2.
Angew Chem Int Ed Engl ; 62(37): e202306786, 2023 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-37470313

RESUMO

Although considerable efforts towards directly converting syngas to liquid fuels through Fischer-Tropsch synthesis have been made, developing catalysts with low CO2 selectivity for the synthesis of high-quality gasoline remains a big challenge. Herein, we designed a bifunctional catalyst composed of hydrophobic FeNa@Si-c and HZSM-5 zeolite, which exhibited a low CO2 selectivity of 14.3 % at 49.8 % CO conversion, with a high selectivity of 62.5 % for gasoline in total products. Molecular dynamic simulations and model experiments revealed that the diffusion of water molecules through hydrophilic catalyst was bidirectional, while the diffusion through hydrophobic catalyst was unidirectional, which were crucial to tune the water-gas shift reaction and control CO2 formation. This work provides a new fundamental understanding about the function of hydrophobic modification of catalysts in syngas conversion.

3.
Nanoscale ; 15(14): 6802-6811, 2023 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-36951672

RESUMO

Oxygen reduction reaction (ORR) plays a crucial role in electrochemical energy conversion and storage devices such as metal-air batteries and water electrolyzers. Herein, a hierarchical nanoporous platinum-based metallic glass (NPMG) was developed by a facile fabrication method by dissolving in a liquid. The surface topography of the sample can be easily modulated by controlling the particle size of sodium chloride. As a result, the NPMG was proved to be efficient and robust as the ORR catalysts with super hydrophilicity and self-renewal capacity. The half-wave potential of the platinum-based porous material was 835 mV at 0.1 M KOH, even higher than that of the commercial Pt/C catalyst (823 mV) and the previously reported platinum material. In particular, platinum-based porous materials have extremely long stability (more than 500 h) through the self-renewal surface, which perfectly meets the requirements of catalyst stability in batteries. Our study has a better inspiration for developing and applying novel catalysts to prepare metal-air batteries.

4.
Spectrochim Acta A Mol Biomol Spectrosc ; 287(Pt 1): 122054, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36334416

RESUMO

The issue of disinfection byproducts (DBPs) in the water has received critical attention due to the health effects on humans. In the water environment, interactions between bovine serum albumins (BSA), the most abundant water-soluble protein, and DBPs unavoidably occur. In this study, comparative binding interactions of two aromatic DBPs - 2,4,6-trichlorophenol (TCP) and 2,4,6-tribromophenol (TBP) with BSA were investigated systematically utilizing fluorescence spectrometry, UV absorption spectrometry, isothermal titration calorimetry and molecular docking approach. The fluorescence quenching results indicated that TCP/TBP could quench the endogenous fluorescence of BSA through static quenching mechanisms, and TBP showed a more substantial quenching effect. The binding constants were determined for TCP-BSA (3.638 × 105 L/mol, 303 K) and TBP-BSA (6.394 × 105 L/mol, 303 K) complexes, with TBP showing higher binding affinity than TCP. The thermodynamic study and docking analysis suggested that hydrogen bonding and van der Waals forces were the primary interaction forces. Both of TCP and TBP were located in the subdomain IIIA of BSA, and TBP could form more stable complex than TCP. The results of the present study contributed valuable information on the environmental behaviors of halophenols in water environment from perspectives of binding with BSA.


Assuntos
Soroalbumina Bovina , Água , Humanos , Soroalbumina Bovina/química , Simulação de Acoplamento Molecular , Ligação Proteica , Sítios de Ligação , Calorimetria , Espectrometria de Fluorescência , Termodinâmica , Dicroísmo Circular , Espectrofotometria Ultravioleta
5.
Food Chem ; 382: 132349, 2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35158266

RESUMO

The health effects of disinfection byproducts (DBPs) in drinking water drew great attention recently. Herein, by using in vitro (fluorescence quenching, UV absorbance, circular dichroism) and in silico (molecular docking) method, binding interactions of two halophenolic DBPs (2,4,6-trichlorophenol [TCP] and 2,4,6-tribromophenol [TBP]) with human serum albumin (HSA) and the influence of hydroxypropyl-beta-cyclodextrin (HPCD) on the interactions were investigated. TCP/TBP could form complexes with HSA mainly by hydrogen bonding, while changing its secondary structure, among which TBP showed more influential effect. Interestingly, the binding constants for halophenol-HSA complexes decreased obviously with the involvement of HPCD. Molecular docking results revealed that HPCD could include TCP/TBP into its cavity and change their original binding sites from subdomain IB to IIA, resulting in a more stable binding system. These findings are beneficial for understanding the toxicity of halophenols inside the human body and indicated that HPCD could be a promising detoxication agent for DBPs.


Assuntos
Desinfecção , Albumina Sérica Humana , 2-Hidroxipropil-beta-Ciclodextrina , Sítios de Ligação , Clorofenóis , Dicroísmo Circular , Humanos , Ligação de Hidrogênio , Simulação de Acoplamento Molecular , Fenóis , Ligação Proteica , Espectrometria de Fluorescência , Termodinâmica
6.
Mater Horiz ; 8(6): 1690-1699, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-34846499

RESUMO

Developing materials with tailorable properties has been the long-sought goal of humankind. Forming composite materials with superior properties by combining two or more materials has emerged as a competitive means in the search and design of new materials. However, it is still a grand challenge to use metallic materials as a binder for composites because of their lack of adhesion. In the present work, we proposed a facile and flexible route to synthesize composites using metallic glass as a glue to bond various materials, ranging from conductors to insulators, and metals to nonmetals, together. The mechanical, magnetic and electrical performances of the composites can be manually regulated by changing the addition ratios of the metallic glass glue and the corresponding admixture. In addition, porous structures were also obtained and tuned by dissolving the soluble admixture in water. In principle, our approach provides a new idea for the fabrication and optimization of composites using metallic materials as binders. The outcome of our current research opens up a window not only to synthesize composite materials with tailorable properties universally and flexibly, but also towards the discovery of potential multi-functional metal containing composites.

7.
Artigo em Inglês | MEDLINE | ID: mdl-34444456

RESUMO

Stroke is a devastating condition that may cause upper limb paralysis. Robotic rehabilitation with self-initiated and assisted movements is a promising technology that could help restore upper limb function. Previous studies have established that the tongue motion can be used to communicate human intent and control a rehabilitation robot/assistive device. The goal of this study was to evaluate a tongue-operated exoskeleton system (TDS-KA), which we have developed for upper limb rehabilitation. We adopted a tongue-operated assistive technology, called the tongue drive system (TDS), and interfaced it with the exoskeleton KINARM. We also developed arm reaching and tracking tasks, controlled by different tongue operation modes, for training and evaluation of arm motor function. Arm reaching and tracking tasks were tested in 10 healthy participants (seven males and three females, 23-60 years) and two female stroke survivors with upper extremity impairment (32 and 58 years). All healthy and two stroke participants successfully performed the tasks. One stroke subject demonstrated a clinically significant improvement in Fugl-Meyer upper extremity score after practicing the tasks in six 3-h sessions. We conclude that the TDS-KA system can accurately translate tongue commands to exoskeleton arm movements, quantify the function of the arm, and perform rehabilitation training.


Assuntos
Exoesqueleto Energizado , Reabilitação do Acidente Vascular Cerebral , Feminino , Humanos , Masculino , Língua , Resultado do Tratamento , Extremidade Superior
8.
Chemosphere ; 245: 125634, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31864047

RESUMO

Road deposited sediments (RDS) is the key carrier of pollutants in the urban road stormwater processes and hence has been seen as an important pollutant source of urban road stormwater. Although many research studies have focused on RDS and pollutants attached to RDS, the investigation on RDS toxicity is very limited. Toxicity test can permit an overall assessment on whether the RDS polluted stormwater can be safely reused. This paper used two living organisms, namely Chinese hamster ovary (CHO) cells, (mammalian cells to indicate human health related toxicity) and Chlorella Pyrenoidosa (algae to indicate ecological health related toxicity) to test RDS toxicity by using an innovative "equivalent toxicity area (ETA)" approach. The outcomes showed that mammalian cells are more sensitive than algae in terms of RDS toxicity. Pb, Cd and Cr primarily contributed to mammalian cell-based toxicity while Zn, Ni, Cu and TOC are primarily toxic to algae. It is also found that road site characteristics such as land uses exerted an important influence on RDS toxicity. Commercial areas tended to generate RDS with higher human health risk related toxicity while industrial areas had a potential to produce RDS with high ecological health risk related toxicity. The research outcomes also showed that solely focusing on pollutant themselves on RDS can not accurately indicate RDS pollution. An approach to considering both pollutant loads and toxicity is preferred. These results were expected to provide a useful insight to enhancing effectiveness of RDS polluted urban road stormwater management and ensuring their reuse safety.


Assuntos
Monitoramento Ambiental/métodos , Poluentes Ambientais/toxicidade , Animais , Células CHO , Chlorella , Cricetinae , Cricetulus , Poluição Ambiental , Sedimentos Geológicos , Humanos , Metais Pesados/análise , Testes de Toxicidade/métodos
9.
Water Res ; 170: 115283, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31739241

RESUMO

Halogenated aromatic disinfection byproducts (DBPs) are a new group of emerging DBPs identified recently. They have been detected in disinfected drinking water, wastewater effluents, recreational water and oil/gas produced water, at concentrations of ng/L to µg/L in general. Previously studies have demonstrated that most of them can induce developmental toxicity and growth inhibition in aquatic organisms based on in vivo bioassays. In this study, to further understand the adverse effects of aromatic DBPs to human health, the comparative cytotoxicity of 15 halogenated aromatic DBPs belonging to four subgroups (i.e., halophenols, halonitrophenols, halohydroxybenzaldehydes and halohydroxybenzoic acids) was evaluated with mammalian Chinese Hamster Ovary cells. The results indicated that the selected aromatic DBPs exhibited an in vitro toxicity rank order of halonitrophenols > halophenols > halohydroxybenzaldehydes > halohydroxybenzoic acids. The potential toxicity mechanisms involved with the antioxidant system were investigated by using molecular docking analysis between key antioxidant enzymes (i.e., catalase, superoxide dismutase, and glutathione S-transferase) and aromatic DBPs. Based on the observed cytotoxicity data and screening the candidate descriptors (including binding energies between the aromatic DBPs and key antioxidant enzymes as well as physical-chemical/quantum-chemical/topological descriptors), a QSAR model was developed as log (LC50) -1 = - 1.050ECAT + 0.300EHOMO - 0.238ELUMO- 0.164, indicating the importance of the interactions of aromatic DBPs towards catalase and the electrophilic/nucleophilic reactivity of aromatic DBPs in the toxicity mechanisms. In addition, the occurrence of the aromatic DBPs in tap water and finished water was studied in a mega city Shenzhen located in South China. Results showed that halogenated aromatic DBPs commonly existed in Shenzhen drinking water at ng/L levels, and three nitrogenous aromatic DBPs were detected in real drinking water for the first time. The major toxicity drivers among the target aromatic DBPs were identified through the integration of the measured concentrations and observed cytotoxicity; notably, DBPs with the highest concentrations may not contribute the highest proportions of overall toxicity.


Assuntos
Desinfetantes , Água Potável , Poluentes Químicos da Água , Purificação da Água , Animais , Células CHO , Catalase , China , Cricetinae , Cricetulus , Desinfecção , Halogenação , Humanos , Simulação de Acoplamento Molecular , Relação Quantitativa Estrutura-Atividade
10.
Ecotoxicol Environ Saf ; 180: 357-365, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31102843

RESUMO

Organic pollutants attached on road deposited sediments (RDS) during dry days can be washed-off into stormwater runoff during rainfall events, undermining stormwater reuse safety. Previous research studies commonly utilized individual pollutant groups and their quantity to evaluate the hazard effect of pollutants attached to RDS in terms of stormwater reuse. Since many types of organic pollutants are present together rather than individually, conventional approaches might not permit a comprehensive understanding of how appropriately the RDS polluted stormwater can be reused. This study undertook a toxicity test of organic pollutants attached to RDS using Chinese hamster ovary cells (CHO), testing a hypothesis that solely focusing on individual pollutant groups are not adequate to represent hazard effects of resulting stormwater and hence their adequacy for reuse. It is noted that comparative toxicity of RDS is not strongly related to total solids (commonly seen as the key carrier of pollutants) and chemical oxygen demand (COD, representing organic matters). Additionally, the comparison results of spatial distributions of toxicity (in this study) and individual pollutants in previous studies did not show a similar trend. These results imply that toxicity should be also used to indicate how stormwater can be safely reused while solely investigating individual pollutants can not adequately show a comprehensive hazard effect in terms of ensuring stormwater reuse safety. Based on study outcomes, a new assessment approach considering both pollutant and toxicity were proposed. This will assist on effective stormwater reuse and ensuring their reuse safety.


Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Chuva/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Animais , Análise da Demanda Biológica de Oxigênio , Células CHO , Sobrevivência Celular/efeitos dos fármacos , China , Cricetinae , Cricetulus , Poluentes Químicos da Água/toxicidade
11.
Annu Int Conf IEEE Eng Med Biol Soc ; 2018: 2158-2161, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30440831

RESUMO

A human-in-the-loop system is proposed to enable collaborative manipulation tasks for person with physical disabilities. Studies show that the cognitive burden of subject reduces with increased autonomy of assistive system. Our framework obtains high-level intent from the user to specify manipulation tasks. The system processes sensor input to interpret the user's environment. Augmented reality glasses provide ego-centric visual feedback of the interpretation and summarize robot affordances on a menu. A tongue drive system serves as the input modality for triggering a robotic arm to execute the tasks. Assistance experiments compare the system to Cartesian control and to state-of-the-art approaches. Our system achieves competitive results with faster completion time by simplifying manipulation tasks.


Assuntos
Língua , Interface Usuário-Computador , Pessoas com Deficiência , Retroalimentação Sensorial , Humanos
12.
Water Res ; 145: 579-587, 2018 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-30199802

RESUMO

Adsorbable organic halogen (AOX) is a parameter conventionally used to indicate the sum of organic halogenated disinfection byproducts (DBPs), which are formed from the reactions of disinfectants with dissolved organic matter, bromide and iodide in water. To overcome the issues of the AOX analytical method, we proposed a new facile and green pretreatment method to enable the analysis of nonionic total organic halogen (NTOX) via the following three steps: 1) separation of NTOX and halides with electrodialysis, 2) conversion of NTOX with ultraviolet (UV) photolysis, and 3) analysis of halides with ion chromatography. To verify this proposal, we mainly evaluated the efficiency of vacuum ultraviolet (VUV) coupled with UV photolysis (VUV-UV) in converting NTOX into halides. Results showed that by applying VUV irradiation for 60 min and UV irradiation at pH 10-11 for another 30 min, over 85.5% of each halide from 20 representative small molecular weight DBPs (each at 100 µg-X/L level) was recovered. The purpose of UV photolysis under alkaline conditions was to reduce oxyhalides (such as bromate and iodate) formed in the VUV process back to halides. With the aid of electrospray ionization-triple quadrupole mass spectrometry, we captured the whole pictures of high molecular weight polar DBPs in a chlorinated drinking water before and after VUV-UV, through which averagely 96.4% of dehalogenation with the VUV-UV treatment was observed. An illustrative comparison of the conventional AOX method and the proposed NTOX method indicates that although the detected NTOX was lower (by 2.3-30.6%) than AOX, the results of the two methods were highly correlated (R2 > 0.97). All these hence verified the photolysis as a mature yet novel tool for sample pretreatment in environmental analytical chemistry.


Assuntos
Desinfetantes , Poluentes Químicos da Água , Purificação da Água , Desinfecção , Halogenação , Halogênios , Fotólise , Água
13.
Environ Pollut ; 224: 7-15, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28288352

RESUMO

Developmental neurobehavioral toxicity of Dechlorane Plus (DP) was investigated using the embryo-larval stages of zebrafish (Danio rerio). Normal fertilized embryos were waterborne exposed to DP at 15, 30, 60 µg/L beginning from 6 h post-fertilization (hpf). Larval teratology, motor activity, motoneuron axonal growth and muscle morphology were assessed at different developmental stages. Results showed that DP exposure significantly altered embryonic spontaneous movement, reduced touch-induced movement and free-swimming speed and decreased swimming speed of larvae in response to dark stimulation. These changes occurred at DP doses that resulted no significant teratogenesis in zebrafish. Interestingly, in accord with these behavioral anomalies, DP exposure significantly inhibited axonal growth of primary motoneuron and induced apoptotic cell death and lesions in the muscle fibers of zebrafish. Furthermore, DP exposure at 30 µg/L and 60 µg/L significantly increased reactive oxygen species (ROS) and malondialdehyde (MDA) formation, as well as the mRNA transcript levels of apoptosis-related genes bax and caspase-3. Together, our data indicate that DP induced neurobehavioral deficits may result from combined effects of altered neuronal connectivity and muscle injuries.


Assuntos
Axônios/efeitos dos fármacos , Hidrocarbonetos Clorados/toxicidade , Atividade Motora/efeitos dos fármacos , Neurônios Motores/efeitos dos fármacos , Compostos Policíclicos/toxicidade , Peixe-Zebra , Animais , Caspase 3/metabolismo , Embrião não Mamífero/efeitos dos fármacos , Larva/efeitos dos fármacos , Malondialdeído/metabolismo , Natação
14.
J Rehabil Res Dev ; 53(6): 989-1006, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28475207

RESUMO

Stroke survivors with severe upper limb (UL) impairment face years of therapy to recover function. Robot-assisted therapy (RT) is increasingly used in the field for goal-oriented rehabilitation as a means to improve function in ULs. To be used effectively for wrist and hand therapy, the current RT systems require the patient to have a minimal active range of movement in the UL, and those that do not have active voluntary movement cannot use these systems. We have overcome this limitation by harnessing tongue motion to allow patients to control a robot using synchronous tongue and hand movement. This novel RT device combines a commercially available UL exoskeleton, the Hand Mentor, and our custom-designed Tongue Drive System as its controller. We conducted a proof-of-concept study on six nondisabled participants to evaluate the system usability and a case series on three participants with movement limitations from poststroke hemiparesis. Data from two stroke survivors indicate that for patients with chronic, moderate UL impairment following stroke, a 15-session training regimen resulted in modest decreases in impairment, with functional improvement and improved quality of life. The improvement met the standard of minimal clinically important difference for activities of daily living, mobility, and strength assessments.


Assuntos
Exoesqueleto Energizado , Robótica , Reabilitação do Acidente Vascular Cerebral/instrumentação , Língua , Atividades Cotidianas , Adulto , Idoso , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Qualidade de Vida , Recuperação de Função Fisiológica , Acidente Vascular Cerebral , Resultado do Tratamento , Adulto Jovem
15.
Talanta ; 144: 836-43, 2015 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-26452898

RESUMO

A novel method for the simultaneous determination of 9-ethylphenanthrene (9-EP), pyrene (Pyr) and 1-hydroxypyrene (1-OH-Pyr) in an aqueous solution using hydroxyl-propyl ß-cyclodextrin (HPCD) as a sensitizer has been established. The overlap of the conventional fluorescence spectra of these molecules is resolved using synchronous fluorescence spectrometry with the double scans method. The simultaneous quantitative determination of three compounds was carried out with Δλ=36 nm and Δλ=55 nm. The signals detected at these three wavelengths (i.e., 298 nm, 337 nm and 351 nm) vary linearly when the concentrations of 9-EP, Pyr and 1-OH-Pyr were in the range of 5.00×10(-8)-1.60×10(-6) mol L(-1), 2.00×10(-8)-1.80×10(-6) mol L(-1), and 2.00×10(-8)-1.20×10(-5) mol L(-1), respectively. The limits of detection (LOD) for 9-EP, Pyr and 1-OH-Pyr were 3.97×10(-9) mol L(-1), 5.25×10(-)(9) mol L(-1), 4.20×10(-9) mol L(-1), respectively, with relative standard deviations (R.S.D.) of 1.62%, 2.45% and 1.73% (n=9), respectively. The inclusion behaviors between HPCD and the guest molecules were observed by synchronous fluorimetry and the association constants for the 1:1 complexes with HPCD were determined. The binding and complexation energies for different orientations are discussed. The proposed method was successfully applied to the analysis of 9-EP, Pyr and 1-OH-Pyr in tap and lake water with good recoveries in the range of 92.9-110.0%.

16.
J Hazard Mater ; 243: 139-45, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23107290

RESUMO

Bioremediation of surface waters contaminated with polycyclic aromatic hydrocarbons (PAHs) is a serious problem, often limited by the low bioavailability of contaminants as a result of their low aqueous solubility. In this study, we studied the influence of hydroxypropyl-ß-cyclodextrin (HPCD) addition on the biodegradation of dissolved pyrene in aqueous solution. Five types of unidentified bacterial strains were used with a concentration of pyrene under its solubility limit. The reduction of pyrene content was monitored during the biodegradation process using synchronous fluorimetry. The presence of HPCD changed the rate of pyrene biodegradation by microorganisms due to the formation of an inclusion complex between pyrene and HPCD. The hydrophobicity and the emulsifying activity of microorganisms relative to their biodegrading capacity were investigated. The results indicated that hydrophobicity and emulsifying activity of the microorganisms were important factors that can influence the biodegradation process. The hydrophobicity and emulsifying activity were strongly correlated with the biodegrading capacity of the microorganisms toward pyrene in the presence of solubilizing agents or organized media.


Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Carcinógenos/metabolismo , Pirenos/metabolismo , beta-Ciclodextrinas/farmacologia , 2-Hidroxipropil-beta-Ciclodextrina , Bactérias/metabolismo , Disponibilidade Biológica , Biomassa , Carcinógenos/química , Emulsões , Hidrocarbonetos Policíclicos Aromáticos/química , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Pirenos/química , Microbiologia do Solo , Espectrometria de Fluorescência
17.
Spectrochim Acta A Mol Biomol Spectrosc ; 79(3): 599-602, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21530377

RESUMO

Boron determination by a charge transfer spectrophotometric method is described. Accompanied the reaction, a charge transfer complex can be formed by lysine with sodium 1, 2-naphthoquinone-4-sulfonate and boron in alkaline solution (pH 12.00). Subsequently, a new reaction mechanism has been proposed and discussed. The absorbance at the maximal absorption wavelength is 574 nm and boron concentration agrees well with Beer's law in a range of 2.16-43.24 µg mL(-1). The linear regression equation is A=-0.01867+0.01326C (µg mL(-1)), with a linearly correlation coefficient of 0.9935. The relative standard deviation (R.S.D.) of eleven parallel determinations is 2.1% with a detection limit (3σ/k) of 2.00 µg mL(-1). The recovery ranges from 96.4% to 104.5% with the satisfactory results. This method has been successfully applied to determine boron in pharmaceutical samples directly.


Assuntos
Boro/análise , Espectrofotometria/métodos , Calibragem , Concentração de Íons de Hidrogênio , Limite de Detecção , Lisina/química , Naftoquinonas/química , Soluções , Temperatura
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...