684 research outputs found
Ionophore Based Bismuth Film Electrode for Lead
No full textA Nafion/ionophore, 4-tert-butylcalix[4]arene-tetrakis(N,N-dimethylthioacetamide) composite coated and bismuth film modified glassy carbon electrode. (GC/NA-IONO/BiFE) was described to determine trace lead sensitively and selectively. The characteristics of such modified GC/NA-IONO/BiFE were studied by scanning electron microscopy and cyclic voltammetry. The influence of various experimental parameters upon the stripping lead signal at the GC/NA-IONO/BiFE was explored. Under the optimized conditions, the differential pulse voltammetric stripping response is highly linear over the 0.1-8.0 nM lead range examined (180s preconcentration at -1.2V), with a detection limit of 0.044nM and good precision (RSD=5.4% at 0.5nM). Also applicability to seawater samples was demonstrated at such modified electrode. The high selectivity of ionophore coupled with the excellent electrochemical characteristics of bismuth endow the GC/NA-IONO/BiFE a promising and robust tool for monitoring of trace lead rapidly and precisely
CARBON NANOTUBES/IONOPHORE MODIFIED ELECTRODE FOR ANODIC STRIPPING DETERMINATION OF LEAD
No full textBifunctional combination of carbon nanotubes and ionophore is introduced for anodic stripping analysis of lead (Pb(2+)). Carbon nanotubes are employed to improve the detection sensitivity due to their excellent electrical conductivity and strong adsorption ability. An ionophore is utilized for its excellent selectivity toward Pb(2+). The proposed carbon nanotubeslionophore modified electrode shows improved sensitivity and selectivity for Pb(2+). Low detection limit (1 nM), wide linear range (5 nM-8 mu M) and excellent selectivity over other metal ions (Cd(2+), Cu(2+), and Hg(2+)) was obtained. The practical application has been carried out for determination of Pb(2+) in real water samples.Bifunctional combination of carbon nanotubes and ionophore is introduced for anodic stripping analysis of lead (Pb(2+)). Carbon nanotubes are employed to improve the detection sensitivity due to their excellent electrical conductivity and strong adsorption ability. An ionophore is utilized for its excellent selectivity toward Pb(2+). The proposed carbon nanotubeslionophore modified electrode shows improved sensitivity and selectivity for Pb(2+). Low detection limit (1 nM), wide linear range (5 nM-8 mu M) and excellent selectivity over other metal ions (Cd(2+), Cu(2+), and Hg(2+)) was obtained. The practical application has been carried out for determination of Pb(2+) in real water samples
A solid-contact Pb2+-selective polymeric membrane electrode with Nafion-doped poly(pyrrole) as ion-to-electron transducer
No full textConducting polymer poly(pyrrole) (PPy) doped with Nafion was successfully used as ion-to-electron transducer in the construction of a solid-contact Pb2+-selective polymeric membrane electrode. The Nafion dopant can effectively increase the capacitance of the conducting polymer and improve the mechanical robustness of the coating. The transducer layer, PPy-Nafion, characterized by cyclic voltammetry and electrochemical impedance spectroscopy, exhibits a sufficiently high bulk (redox) capacitance and fast ion and electron transport process. The new Pb2+-selective polymeric membrane electrode, based on PPyNafion film as solid contact, shows stable Nernstian characteristics in Pb(NO3)(2) solution within the concentration range of 1.0 x 10(-7)-1.0 x 10(-3) M, and the detection limit is 4.3 x 10(-8) M. The potential stability of the electrode and the influence of the interfacial water layer were also evaluated by chronopotentiometry and potentiometric water layer test, respectively. The results show that the solid-contact Pb2+-selective electrode, based on PPy-Nafion film as ion-toelectron transducer, can effectively overcome the potential drift and reduce the water layer between the PPy-Nafion transducer layer and the ion-selective membrane
Fabrication and Characterization of Carbon Nanotube-Hydroxyapatite Nanocomposite: Application to Anodic Stripping Voltammetric Determination of Cadmium
No full textA novel chemically modified electrode for stripping determination of cadmium is presented in this paper. based on carbon nanotube-hydroxyapatite (CNT-HAP) nanocomposite, which can be prepared by an easy and effective one-step sonication. The newly synthesized nanocomposite was characterized with FTIR, TEM, and electrochemical methods. Due to the combination of the strong absorption ability of HAP and excellent electroanalytical properties of CNTs, the GC/CNT-HAP electrode has been successfully used for determination of Cd(2+) by anodic stripping voltammetry with a linear range of 20 nM -3 mu M. The sensitivity and detection limit are 25.6 mu A/mu M and 4 nM, respectively. The practical application of the proposed electrode has been carried out for the determination of trace levels of Cd(2+) in real water samples
Fabrication of Bismuth/Multi-walled Carbon Nanotube Composite Modified Glassy Carbon Electrode for Determination of Cobalt
No full textA bismuth/multi-walled carbon nanotube (Bi/MWNT) composite modified electrode for determination of cobalt by differential pulse adsorptive cathodic stripping voltammetry is described. The electrode is fabricated by potentiostatic pre-plating bismuth film on an MWNT modified glassy carbon (GC) electrode. The Bi/MWNT composite modified electrode exhibits enhanced sensitivity for cobalt detection as compared with the bare GC, MWNT modified and bismuth film electrodes. Numerous key experimental parameters have been examined for optimum analytical performance of the proposed electrode. With an adsorptive accumulation of the Co(II)-dimethylglyoxime complex at -0.8 V for 200 s, the reduction peak current is proportional to the concentration of cobalt in the range of 4.0x10(-11)-1.0x10(-7) mol/L with a lower detection limit of 8.1x10(-11) mol/L. The proposed method has been applied Successfully to cobalt determination in seawater and lake water samples
Nanomaterial/Ionophore-Based Electrode for Anodic Stripping Voltammetric Determination of Lead: An Electrochemical Sensing Platform toward Heavy Metals
No full textA novel nanomaterial/ionophore-modified glassy carbon electrode for anodic stripping analysis of lead (Pb2+) is described. Nanosized hydroxyapatite (NHAP) with width of 20-25 mn and length of 50-100 nm has been prepared and used to improve the sensitivity for detection of Pb2+ because it provides unique three-dimensional network structure and has strong adsorption ability toward Ph2+. An ionophore, usually used in ion-selective electrodes, is utilized here for its excellent selectivity toward Pb2+. Nafion, a cation-exchange polymer, is employed as the conductive matrix in which NHAP and the ionophore can be tightly attached to the electrode surface. Such a designed NHAP/ionophore/Nafion-modified electrode shows remarkably improved sensitivity and selectivity to Pb2+. The electrode has a linear range of 5.0 nM to 0.8 mu M with a 10 min accumulation time at open-circuit potential. The sensitivity and detection limit of the proposed sensor are 13 mu A/mu M and 1.0 nM, respectively. Interference from other heavy metal ions such as Cd2+, Cu2+, and Hg2+ associated with lead analysis can be effectively diminished. The practical application of the proposed sensor has been carried out for determination of trace levels of Pb2+ in real water samples.A novel nanomaterial/ionophore-modified glassy carbon electrode for anodic stripping analysis of lead (Pb(2+)) is described. Nanosized hydroxyapatite (NHAP) with width of 20-25 mn and length of 50-100 nm has been prepared and used to improve the sensitivity for detection of Pb(2+) because it provides unique three-dimensional network structure and has strong adsorption ability toward Ph(2+). An ionophore, usually used in ion-selective electrodes, is utilized here for its excellent selectivity toward Pb(2+). Nafion, a cation-exchange polymer, is employed as the conductive matrix in which NHAP and the ionophore can be tightly attached to the electrode surface. Such a designed NHAP/ionophore/Nafion-modified electrode shows remarkably improved sensitivity and selectivity to Pb(2+). The electrode has a linear range of 5.0 nM to 0.8 mu M with a 10 min accumulation time at open-circuit potential. The sensitivity and detection limit of the proposed sensor are 13 mu A/mu M and 1.0 nM, respectively. Interference from other heavy metal ions such as Cd(2+), Cu(2+), and Hg(2+) associated with lead analysis can be effectively diminished. The practical application of the proposed sensor has been carried out for determination of trace levels of Pb(2+) in real water samples
On-Line Determination of Lead in Tap Waters at Two-Step Prepared Bismuth Electrode
No full textAn anodic stripping analysis system based on two-step prepared bismuth electrode for on-line determination of lead (Pb2+) in tap water samples is presented here. Such two-step prepared electrode modified in-situ and ex-situ bismuth film shows remarkably improved sensitivity to Pb2+ in acidic solution (pH <= 2). The designed electrode has been successfully used for determination of Pb2+ in acidic solution by anodic stripping voltammetry with a linear range of 1.3-20 mu gL(-1). The sensitivity and detection limit are 19 nAL mu g(-1) and 0.8 mu gL(-1), respectively. The practical application of the proposed electrode has been carried out for the on-line determination of trace levels of Pb2+ in real tap water samples.An anodic stripping analysis system based on two-step prepared bismuth electrode for on-line determination of lead (Pb(2+)) in tap water samples is presented here. Such two-step prepared electrode modified in-situ and ex-situ bismuth film shows remarkably improved sensitivity to Pb(2+) in acidic solution (pH <= 2). The designed electrode has been successfully used for determination of Pb(2+) in acidic solution by anodic stripping voltammetry with a linear range of 1.3-20 mu gL(-1). The sensitivity and detection limit are 19 nAL mu g(-1) and 0.8 mu gL(-1), respectively. The practical application of the proposed electrode has been carried out for the on-line determination of trace levels of Pb(2+) in real tap water samples
Research on Improvement of College Students' Trust in Counselors under the Guidance of qFive Development Conceptsq
No full textStudies on College Students’ Entrepreneurial Ability Under Internet Environment
No full textWith the emerging of “mass entrepreneurship and innovation” and deep integration of “Internet +” with different industries, entrepreneurship is stepping into the golden era. Under the Internet, college students are provided with numerous platforms and opportunities which have lowered the entrepreneurship threshold and stimulated college students’ entrepreneurial passion. On the basis of analyzing entrepreneurial opportunities brought by internet, this article has combined with problems of college students’ entrepreneurship to propose some methods to improve college students’ entrepreneurial ability under internet environment
Towards a competency-based healthcare management: The case of the attending physician
No full textThe reform of the healthcare system in China opened room for the creation of the position of the attending physician, being entrusted with critical clinical functions. This position is crucial, but traditional hospital human resource evaluation in China mostly focuses on qualifications rather than competencies to select and evaluate attending physicians. However, a competency-based management offers better guarantees for high professional level.
Therefore, there is a need to build a competency-based management of attending physicians and research is lacking in China. This study is set to fill this research gap.
To achieve this, three empirical studies were conducted. The first, qualitative, identified a list of primary competencies for the attending physicians through interviews, reaching consensus via Delphi technique. Based on a sample of 406 healthcare professionals as well as patients, study 2 report findings from a conjoint analysis and questionnaire survey on rankings of the framework of competencies and other aspects generated by the first study. This produced a weighted evaluation index for attending physicians. The last study tested the predictive validity of such competency framework with a sample of 183 director-physician dyads, testing a moderated mediation model that linked competency and performance via work engagement while testing for the interaction effect with perceived organizational support. Findings supported the conceptual model thus indicating the competency framework proposed for attending physicians is robust in grasping their primary competencies, and that it can be used to conduct further research as well as to manage and improve professionalism throughout the healthcare system.A reforma do sistema de saúde na China abriu espaço para a criação do cargo de médico assistente, sendo-lhe confiadas funções clínicas críticas. Esta posição é crucial, mas a avaliação tradicional dos recursos humanos hospitalares na China centra-se sobretudo nas qualificações e não nas competências para seleccionar e avaliar os médicos assistentes. Contudo, uma gestão baseada nas competências oferece melhores garantias para um elevado nível profissional.
Assim, afigura-se necessário promover uma gestão dos médicos assistentes, baseada nas competências e falta investigação na China. Este estudo destina-se a preencher esta lacuna de investigação.
Para o efeito, foram realizados três estudos empíricos. O primeiro, qualitativo, identificou uma lista de competências primárias dos médicos assistentes através de entrevistas, chegando a consenso através da técnica Delphi. Com base numa amostra de 406 profissionais de saúde, bem como pacientes, o estudo 2 relatou os resultados de uma análise conjoint sobre rankings do quadro de competências e outros aspetos gerados pelo primeiro estudo. Isto produziu um índice de avaliação ponderada para os médicos assistentes. O último estudo testou a validade preditiva desse quadro de competências com uma amostra de 183 díades director-médico assistente, testando um modelo de mediação moderada que liga competência e desempenho através do envolvimento no trabalho enquanto testou o efeito de interacção com o apoio organizacional percebido. Os resultados apoiam o modelo conceptual, indicando assim que o quadro de competências proposto para os médicos assistentes é robusto para retratar as suas competências primárias, e que pode ser utilizado para conduzir mais investigação, bem como para gerir e melhorar o profissionalismo em todo o sistema de saúde
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