Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.586
Filtrar
1.
Zhongguo Yi Liao Qi Xie Za Zhi ; 45(2): 145-152, 2021 Apr 08.
Artículo en Chino | MEDLINE | ID: mdl-33825372

RESUMEN

Coagulometer, known as blood coagulation analyzer, is a product that can provide accurate test results for medical diagnosis and treatment analysis by detecting a series of items closely related to thrombosis and hemostasis in coagulation reaction. On the basis of previous traditional methods, and with our deep understanding about the principles of hemagglutination detection, we propose a hemagglutination detection method by using the dual-magnetic circuit beads method. Then, the corresponding hemagglutination detection module is designed. The coagulation time of plasma can be measured by detecting the movement of the magnetic beads when the magnetic field intensity is appropriate. The activated partial thromboplastin time(APTT) of plasma is tested when the most suitable magnetic field intensity is found. The results preliminarily show that this blood coagulation test method is valid and the corresponding test module has a potential value in business.


Asunto(s)
Coagulación Sanguínea , Magnetismo , Pruebas de Coagulación Sanguínea , Fenómenos Magnéticos , Tiempo de Tromboplastina Parcial
2.
Sensors (Basel) ; 21(4)2021 Feb 18.
Artículo en Inglés | MEDLINE | ID: mdl-33670498

RESUMEN

Currently available jaw motion tracking methods require large accessories mounted on a patient and are utilized in controlled environments, for short-time examinations only. In some cases, especially in the evaluation of bruxism, a non-restrictive, 24-h jaw tracking method is needed. Bruxism oriented, electromyography (EMG)-based devices and sensor-enhanced occlusal splints are able to continuously detect masticatory activity but are uninformative in regards to movement trajectories and kinematics. This study explores a possibility to use a permanent magnet and a 3-axial magnetometer to track the mandible's spatial position in relation to the maxilla. An algorithm for determining the sensor's coordinates from magnetic field values was developed, and it was verified via analytical and finite element modeling and by using a 3D positioning system. Coordinates of the cubic test trajectory (a = 10 mm) were determined with root-mean-square error (RMSE) of 0.328±0.005 mm. Possibility for teeth impact detection by accelerometry was verified. Test on a 6 degrees-of-freedom (DOF), hexapod-based jaw motion simulator moving at natural speed confirmed the system's ability to simultaneously detect jaw position and the impacts of teeth. Small size of MEMS sensors is suitable for a wearable intra-oral system that could allow visualization of continuous jaw movement in 3D models and could enable new research on parafunctional jaw activities.


Asunto(s)
Acelerometría , Maxilares , Movimiento , Fenómenos Biomecánicos , Humanos , Fenómenos Magnéticos , Movimiento (Física)
3.
Environ Monit Assess ; 193(4): 179, 2021 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-33751269

RESUMEN

In this paper, Eichhornia Crassipes stems were used as biomass feedstock, and Fe2+ was used as the precursor solution to prepare Fe3O4-modified magnetic mesoporous biochar (Fe3O4@BC). By using Box-Behnken design (BBD) response surface methodology, the influences of three preparation parameters (X1 = Fe2+ concentration, X2 = pyrolysis temperature and X3 = pyrolysis time) on the adsorption of methyl orange (MO) by Fe3O4@BC were investigated, and a reliable response surface model was constructed. The results show that X1X2 and X1X3 have a significant influence on the adsorption of MO by Fe3O4@BC. The surface area and pore volume of Fe3O4@BC are controlled by all preparation parameters. The increase of pyrolysis time will significantly reduce the -OH on the surface of Fe3O4@BC and weaken its MO adsorption capacity. Through the numerical optimization of the constructed model, the optimal preparation parameters of Fe3O4@BC can be obtained as follows: Fe2+ concentration = 0.27 mol/L, pyrolysis temperature = 405 °C, and pyrolysis time = 3.2 h. The adsorption experiment shows that the adsorption of Fe3O4@BC to MO is a spontaneous exothermic process, and the adsorption capacity is maximum when pH = 4. The adsorption kinetics and adsorption isotherms of Fe3O4@BC to MO conform to the pseudo-second-order kinetics and Sips model, respectively. Mechanism analysis shows that electrostatic interaction and H bond formation are the main forces for Fe3O4@BC to adsorb MO. This research not only realizes a new way of resource utilization of Eichhornia Crassipes biomass but also enriches the preparation research of magnetic biochar.


Asunto(s)
Aguas Residuales , Contaminantes Químicos del Agua , Adsorción , Compuestos Azo , Carbón Orgánico , Monitoreo del Ambiente , Cinética , Fenómenos Magnéticos , Contaminantes Químicos del Agua/análisis
4.
Chemosphere ; 270: 128640, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33757273

RESUMEN

This study assessed the convenience of using magnetic particles (MPs) to reduce phosphorus (P) concentration in treated wastewater. The working hypothesis is that MP addition increases P removal in artificial wastewater treatment ponds. Water samples were collected at the inlet and outlet of a semi-natural pond receiving secondary municipal effluent that is discharged in a Ramsar site (Fuente de Piedra, Málaga, Spain). Then, laboratory batch experiments were run to (i) assess the effect of adding MPs on the chemical composition of treated wastewater, (ii) identify the number of adsorption cycles (by reusing MPs) which are able to trap a high percentage of P (>50%) and (iii) select the optimum ratio between MP mass and initial dissolved inorganic P (DIP) concentration. The results show the suitability of using MPs to remove P in treated wastewater due to both their high equilibrium adsorption capacity (q) and P removal efficiency. Lastly, considering its practical and economical relevance, based on the advantages (P removal efficiency) and disadvantages (economic price), the optimum dose of MPs (0.16 g MP mg-1 P) to achieve a high P removal efficiency (>50%) was identified.


Asunto(s)
Contaminantes Químicos del Agua , Purificación del Agua , Fenómenos Magnéticos , Fosfatos , Fósforo/análisis , España , Eliminación de Residuos Líquidos , Aguas Residuales , Contaminantes Químicos del Agua/análisis , Humedales
5.
J Environ Manage ; 285: 112155, 2021 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-33652186

RESUMEN

Fenton reaction is an oxidation process of interest in wastewater treatment because of its ability to degrade organic compounds. Iron-based magnetic particles can be a very useful catalyst when using heterogeneous Fenton process. The major problem of this heterogeneous process is the saturation of the Fe 3+ on the surface, which limits the process. In this study, the possibility of using magnetite particles as a substrate is presented, increasing its degradation efficiency by Fenton reaction through a regeneration process that achieves the electronic reduction of its surface using reducing agents. The results indicate that the regeneration process is quite effective, increasing the efficiency of the degradation of Methylene Blue up to 99%. The concentration of magnetite is the most influential factor in the efficiency of the reaction, while the regeneration time and the concentration of reducing agent do not significantly affect the results considering the range used. The presence of mechanical stirring may adversely affect the reaction in the long term. Increasing the oxidant agent concentration reduces the initial speed of the reaction but not the long-term efficiency. The use of hydrazine in this process allows the successive reuse of these particles maintaining a high percentage of elimination of methylene blue, above 70% even after 10 uses, compared to an elimination below 20% for particles not regenerated after the second use and for particles regenerated with ascorbic acid after the eighth use.


Asunto(s)
Contaminantes Químicos del Agua , Purificación del Agua , Catálisis , Peróxido de Hidrógeno , Fenómenos Magnéticos , Oxidación-Reducción , Agua , Contaminantes Químicos del Agua/análisis
6.
J Environ Manage ; 285: 112177, 2021 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-33662763

RESUMEN

Magnetic sorption process is applied to real wastewater effluents from a Wastewater Treatment Plant. The complex media sorption is done by using different types of magnetic particles (resin and polymeric covered magnetite) giving good results for removing detergents, phosphates and COD and moderate results for the sorption of nitrogen and several heavy metals. Important kinetic parameters were obtained by data fitting for the pseudo first and second order, and for simplified Elovich models. Regeneration and reuse of the magnetic particles using a chemical-free method was also tested, as well as the effect of the concentration of the particles in the removal efficiency (which proved to be relevant).


Asunto(s)
Metales Pesados , Contaminantes Químicos del Agua , Purificación del Agua , Adsorción , Concentración de Iones de Hidrógeno , Cinética , Fenómenos Magnéticos , Aguas Residuales , Contaminantes Químicos del Agua/análisis
7.
Molecules ; 26(4)2021 Feb 18.
Artículo en Inglés | MEDLINE | ID: mdl-33670484

RESUMEN

In this mini-review of our research group's activity, the application of 57Fe Mössbauer spectroscopy in studies of electronic structure, coordination environment, and magnetic interactions in an interesting series of Fe(II/III) compounds selected is discussed. We selected two prominent phenomena that arose during investigations of selected groups of compounds carried out at different periods of time: (1) very high magnetic hyperfine fields observed at low temperatures; (2) changes in the oxidation state of the central iron atom of complexes in the solid state during interactions with gaseous O2/H2O mixtures, resulting in spin crossover (SCO).


Asunto(s)
Química Inorgánica , Fenómenos Magnéticos , Espectroscopía de Mossbauer , Marcadores de Spin , Modelos Moleculares , Conformación Molecular
8.
Molecules ; 26(4)2021 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-33672016

RESUMEN

Reaction of 2,2'-bipyridine (2,2'-bipy) or 1,10-phenantroline (phen) with [Mn(Piv)2(EtOH)]n led to the formation of binuclear complexes [Mn2(Piv)4L2] (L = 2,2'-bipy (1), phen (2); Piv- is the anion of pivalic acid). Oxidation of 1 or 2 by air oxygen resulted in the formation of tetranuclear MnII/III complexes [Mn4O2(Piv)6L2] (L = 2,2'-bipy (3), phen (4)). The hexanuclear complex [Mn6(OH)2(Piv)10(pym)4] (5) was formed in the reaction of [Mn(Piv)2(EtOH)]n with pyrimidine (pym), while oxidation of 5 produced the coordination polymer [Mn6O2(Piv)10(pym)2]n (6). Use of pyrazine (pz) instead of pyrimidine led to the 2D-coordination polymer [Mn4(OH)(Piv)7(µ2-pz)2]n (7). Interaction of [Mn(Piv)2(EtOH)]n with FeCl3 resulted in the formation of the hexanuclear complex [MnII4FeIII2O2(Piv)10(MeCN)2(HPiv)2] (8). The reactions of [MnFe2O(OAc)6(H2O)3] with 4,4'-bipyridine (4,4'-bipy) or trans-1,2-(4-pyridyl)ethylene (bpe) led to the formation of 1D-polymers [MnFe2O(OAc)6L2]n·2nDMF, where L = 4,4'-bipy (9·2DMF), bpe (10·2DMF) and [MnFe2O(OAc)6(bpe)(DMF)]n·3.5nDMF (11·3.5DMF). All complexes were characterized by single-crystal X-ray diffraction. Desolvation of 11·3.5DMF led to a collapse of the porous crystal lattice that was confirmed by PXRD and N2 sorption measurements, while alcohol adsorption led to porous structure restoration. Weak antiferromagnetic exchange was found in the case of binuclear MnII complexes (JMn-Mn = -1.03 cm-1 for 1 and 2). According to magnetic data analysis (JMn-Mn = -(2.69 ÷ 0.42) cm-1) and DFT calculations (JMn-Mn = -(6.9 ÷ 0.9) cm-1) weak antiferromagnetic coupling between MnII ions also occurred in the tetranuclear {Mn4(OH)(Piv)7} unit of the 2D polymer 7. In contrast, strong antiferromagnetic coupling was found in oxo-bridged trinuclear fragment {MnFe2O(OAc)6} in 11·3.5DMF (JFe-Fe = -57.8 cm-1, JFe-Mn = -20.12 cm-1).


Asunto(s)
Acetatos/química , Complejos de Coordinación/química , Compuestos Heterocíclicos/química , Manganeso/química , Valeratos/química , Adsorción , Complejos de Coordinación/síntesis química , Cristalografía por Rayos X , Espectroscopía de Resonancia por Spin del Electrón , Fenómenos Magnéticos , Conformación Molecular , Temperatura , Termogravimetría , Valeratos/síntesis química , Difracción de Rayos X
9.
Bioresour Technol ; 329: 124904, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33676354

RESUMEN

An integration of two processes, magnetic coagulation (MC) and short-cut biological nitrogen removal (SBNR), coupled with a sequencing batch membrane bioreactor (SMBR) controlled by an automatic real-time control strategy (RTC), was developed to treat different characteristics of high strength wastewater. The treatment efficiency and microbial community-diversity of the proposed method was evaluated and investigated using swine wastewater and food waste (FW) digestate. The MC showed high removal of TSS (89.1 ± 1.5%, 92.21 ± 1.8%), turbidity (90.58 ± 2.1%, 95.1 ± 2.1%), TP (88.5 ± 1.9%, 92.1 ± 1.5%), phosphate (87.76 ± 1.6%, 91.22 ± 1.5%), and SMBR achieved stable and excellent removal of COD (96.05 ± 0.2%, 97.39 ± 0.2%), TN (97.30 ± 0.3%, 97.44 ± 0.3%) andNH4+-N (99.07 ± 0.2%, 98.54 ± 0.2%) for swine wastewater and FW digestate, respectively. The effluent COD andNH4+-N concentrations were found to meet their discharge standards. The microbial community comparison showed similar diversity and richness, and genus Diaphorobacter and Thaurea were dominant in denitritation, and Nitrosomonas was dominant in nitritation treating both swine wastewater and FW digestate.


Asunto(s)
Eliminación de Residuos , Aguas Residuales , Animales , Reactores Biológicos , Desnitrificación , Alimentos , Fenómenos Magnéticos , Nitrógeno , Porcinos , Eliminación de Residuos Líquidos
10.
Molecules ; 26(5)2021 Feb 26.
Artículo en Inglés | MEDLINE | ID: mdl-33652868

RESUMEN

Three new 3D metal-organic porous frameworks based on Co(II) and 2,2'-bithiophen-5,5'-dicarboxylate (btdc2-) [Co3(btdc)3(bpy)2]·4DMF, 1; [Co3(btdc)3(pz)(dmf)2]·4DMF·1.5H2O, 2; [Co3(btdc)3(dmf)4]∙2DMF∙2H2O, 3 (bpy = 2,2'-bipyridyl, pz = pyrazine, dmf = N,N-dimethylformamide) were synthesized and structurally characterized. All compounds share the same trinuclear carboxylate building units {Co3(RCOO)6}, connected either by btdc2- ligands (1, 3) or by both btdc2- and pz bridging ligands (2). The permanent porosity of 1 was confirmed by N2, O2, CO, CO2, CH4 adsorption measurements at various temperatures (77 K, 273 K, 298 K), resulted in BET surface area 667 m2⋅g-1 and promising gas separation performance with selectivity factors up to 35.7 for CO2/N2, 45.4 for CO2/O2, 20.8 for CO2/CO, and 4.8 for CO2/CH4. The molar magnetic susceptibilities χp(T) were measured for 1 and 2 in the temperature range 1.77-330 K at magnetic fields up to 10 kOe. The room-temperature values of the effective magnetic moments for compounds 1 and 2 are µeff (300 K) ≈ 4.93 µB. The obtained results confirm the mainly paramagnetic nature of both compounds with some antiferromagnetic interactions at low-temperatures T < 20 K in 2 between the Co(II) cations separated by short pz linkers. Similar conclusions were also derived from the field-depending magnetization data of 1 and 2.


Asunto(s)
Cobalto/química , Estructuras Metalorgánicas/ultraestructura , Conformación Molecular , Compuestos Organometálicos/química , Adsorción/efectos de los fármacos , Cristalografía por Rayos X , Ligandos , Fenómenos Magnéticos , Estructuras Metalorgánicas/química , Porosidad , Propiedades de Superficie
11.
Talanta ; 227: 122207, 2021 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-33714475

RESUMEN

Since December 2019, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has caused millions of deaths and seriously threatened the safety of human life; indeed, this situation is worsening and many people are infected with the new coronavirus every day. Therefore, it is very important to understand patients' degree of infection and infection history through antibody testing. Such information is useful also for the government and hospitals to formulate reasonable prevention policies and treatment plans. In this paper, we develop a lateral flow immunoassay (LFIA) method based on superparamagnetic nanoparticles (SMNPs) and a giant magnetoresistance (GMR) sensing system for the simultaneously quantitative detection of anti-SARS-CoV-2 immunoglobulin M (IgM) and G (IgG). A simple and time-effective co-precipitation method was utilized to prepare the SMNPs, which have good dispersibility and magnetic property, with an average diameter of 68 nm. The Internet of Medical Things-supported GMR could transmit medical data to a smartphone through the Bluetooth protocol, making patient information available for medical staff. The proposed GMR system, based on SMNP-supported LFIA, has an outstanding advantage in cost-effectiveness and time-efficiency, and is easy to operate. We believe that the suggested GMR based LFIA system will be very useful for medical staff to analyze and to preserve as a record of infection in COVID-19 patients.


Asunto(s)
Anticuerpos Antivirales/sangre , Inmunoensayo/métodos , Inmunoglobulina G/sangre , Inmunoglobulina M/sangre , /inmunología , Animales , Anticuerpos Inmovilizados/química , Anticuerpos Inmovilizados/inmunología , Anticuerpos Antivirales/inmunología , Bovinos , Teléfono Celular , Humanos , Inmunoglobulina G/inmunología , Inmunoglobulina M/inmunología , Internet de las Cosas , Límite de Detección , Fenómenos Magnéticos
12.
Int J Nanomedicine ; 16: 1051-1066, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33603368

RESUMEN

Background: This study was aimed to prepare a novel magnetic thermosensitive cationic liposome drug carrier for the codelivery of Oxaliplatin (OXA) and antisense lncRNA of MDC1 (MDC1-AS) to Cervical cancer cells and evaluate the efficiency of this drug carrier and its antitumor effects on Cervical cancer. Methods: Thermosensitive magnetic cationic liposomes were prepared using thin-film hydration method. The OXA and MDC1-AS vectors were loaded into the codelivery system, and the in vitro OXA thermosensitive release activity, efficiency of MDC1-AS regulating MDC1, in vitro cytotoxicity, and in vivo antitumor activity were determined. Results: The codelivery system had desirable targeted delivery efficacy, OXA thermosensitive release, and MDC1-AS regulating MDC1. Codelivery of OXA and MDC1-AS enhanced the inhibition of cervical cancer cell growth in vitro and in vivo, compared with single drug delivery. Conclusion: The novel codelivery of OXA and MDC1-AS magnetic thermosensitive cationic liposome drug carrier can be applied in the combined chemotherapy and gene therapy for cervical cancer.


Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/genética , Proteínas de Ciclo Celular/genética , Portadores de Fármacos/química , Sistemas de Liberación de Medicamentos , Fenómenos Magnéticos , Terapia Molecular Dirigida , Oxaliplatino/uso terapéutico , ARN Largo no Codificante/administración & dosificación , Neoplasias del Cuello Uterino/terapia , Animales , Apoptosis/efectos de los fármacos , Apoptosis/genética , Cationes , Línea Celular Tumoral , Movimiento Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Proliferación Celular/genética , Liberación de Fármacos , Femenino , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Liposomas , Ratones Endogámicos BALB C , Ratones Desnudos , Oxaliplatino/farmacología , Tamaño de la Partícula , Electricidad Estática , Temperatura , Neoplasias del Cuello Uterino/genética , Neoplasias del Cuello Uterino/patología
13.
J Chromatogr A ; 1639: 461921, 2021 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-33524931

RESUMEN

Present study described a sensitive and efficient method for determination of heterocyclic aromatic hydrocarbons using multiwalled carbon nanotubes modified magnetic polyamido-amine dendrimers (MNPs@PAMAM-Gn@MWCNTs) as adsorbent for magnetic solid-phase extraction (MSPE) coupled with gas chromatography-triple quadrupole mass spectrometer (GC-MS/MS). Some pivotal parameters including PAMAM generation, adsorbent dosage, adsorption time, elution time and volume, pH and humic acid concentration were investigated to achieve the best adsorption efficiencies. Under the optimal conditions, 7-methylquinoline, dibenzothiophene and carbazole had good linearity in the concentration range of 0.005-20 µg L - 1, 9-methylcarbazole, 4-methyldibenzothiophene and 4,6-dimethyl dibenzothiophene had good linearity in the concentration range of 0.001-20 µg L - 1. All the correlation coefficients were higher than 0.996. The detection limits of the targets were in the range of 2.2 × 10-4-1.8 × 10-3 µg L - 1 with precisions less than 8.28% (n = 6). The enrichment factors were in the range of 141-147. The spiked recoveries were in the range of 87.0%-115.1% (n = 3). These results indicated that the method could be a reliable alternative tool for monitoring trace heterocyclic aromatic hydrocarbons in environmental water samples.


Asunto(s)
Aminas/química , Dendrímeros/química , Cromatografía de Gases y Espectrometría de Masas/métodos , Fenómenos Magnéticos , Nanotubos de Carbono/química , Nylons/química , Hidrocarburos Policíclicos Aromáticos/análisis , Extracción en Fase Sólida/métodos , Adsorción , Nanotubos de Carbono/ultraestructura , Espectroscopía Infrarroja por Transformada de Fourier , Espectrometría Raman , Espectrometría de Masas en Tándem , Contaminantes Químicos del Agua/análisis , Difracción de Rayos X
14.
Zhongguo Yi Liao Qi Xie Za Zhi ; 45(1): 22-25, 2021 Feb 08.
Artículo en Chino | MEDLINE | ID: mdl-33522171

RESUMEN

OBJECTIVE: In the context of coronavirus disease 2019 (COVID-19) pandemic, the subject was designed to develop a new tracheal intubation device based on magnetic navigation technology to improve the success rate of tracheal intubation and reduce the risk of occupational exposure of medical staff. METHODS: The new tracheal intubation device was designed with the uniqueness of the magnetic field environment and magnetic steering of magnetic navigation technology. And preliminary magnetic navigation tracheal intubation experiments were performed on the tracheal intubation simulator. RESULTS: Magnetic navigation tracheal intubation can successfully implement tracheal intubation, and the time required is lower than that of traditional laryngoscopy. CONCLUSIONS: The tracheal intubation based on magnetic navigation technology is feasible, with high efficiency and easy operation. That is expected to be widely used for tracheal intubation during treatment of patients outside the hospital in the future. At the same time, magnetic navigation endotracheal intubation technology will be the key technology for the development of endotracheal intubation robots.


Asunto(s)
/terapia , Diseño de Equipo , Estudios de Factibilidad , Humanos , Intubación Intratraqueal , Fenómenos Magnéticos , Tecnología
15.
Zhongguo Yi Liao Qi Xie Za Zhi ; 45(1): 32-36, 2021 Feb 08.
Artículo en Chino | MEDLINE | ID: mdl-33522173

RESUMEN

The magnetic anchoring lung nodule positioning device is composed of a target magnet, an anchor magnet, a coaxial puncture needle and a puncture navigation template, through these, a new type of accurate positioning technology for small pulmonary nodules is derived. The device inserts the target magnet into the both sides nearby the lung nodule under the guidance of CT. Helped by the mutual attraction of the two target magnets, they can be fixed in the lung tissue, avoiding the movement in the lung, and accurately positioning the target lung nodule before surgery. In thoracoscopic surgery, the anchor magnet and the target magnet attract each other to achieve the purpose of positioning the target nodule. The device uses the characteristics of non-contact suction of magnetic materials biomedical engineering technology, eliminating the previous procedure of direct interaction with the positioning marks, finally achieves the target of precise positioning of lung nodules and rapid surgical removal.


Asunto(s)
Nódulo Pulmonar Solitario , Humanos , Pulmón , Neoplasias Pulmonares , Fenómenos Magnéticos , Imanes , Cirugía Torácica Asistida por Video , Tomografía Computarizada por Rayos X
16.
Environ Pollut ; 275: 116485, 2021 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-33556732

RESUMEN

Magnetic biochars were prepared by chemical co-precipitation of Fe3+/Fe2+ onto rice straw (M-RSB) and sewage sludge (M-SSB), followed by pyrolysis treatment, which was also used to prepare the corresponding nonmagnetic biochars (RSB and SSB). The comparison of adsorption characteristics between magnetic and nonmagnetic biochars was investigated as a function of pH, contact time, and initial Cd2+ concentration. The adsorption of nonmagnetic biochars was better described by pseudo-second-order kinetic model, and the adsorption of RSB and SSB was better described by Langmuir and Freundlich models, respectively. Magnetization of the biochars did not change the applicability of their respective adsorption models, but reduced their adsorption capabilities. The maximum capacities were 42.48 and 4.64 mg/g for M-RSB and M-SSB, respectively, underperforming their nonmagnetic counterparts of 58.65 and 7.22 mg/g for RSB and SSB. Such a reduction was fundamentally caused by the decreases in the importance of cation-exchange and Cπ-coordination after magnetization, but the Fe-oxides contributed to the precipitation-dependent adsorption capacity for Cd2+ on magnetic biochars. The qualitative and quantitative characterization of adsorption mechanisms were further analyzed, in which the contribution proportions of cation-exchange after magnetization were reduced by 31.9% and 12.1% for M-RSB and M-SSB, respectively, whereas that of Cπ-coordination were reduced by 3.4% and 31.1% for M-RSB and M-SSB, respectively. These reductions suggest that for adsorbing Cd2+ the choice of conventional biochar was more relevant than whether the biochar was magnetized. However, magnetic biochars are easily separated from treated solutions, depending largely on initial pH. Their easy of separation suggests that magnetic biochars hold promise as more sustainable alternatives for the remediation of moderately Cd-contaminated environments, such as surface water and agriculture soil, and that magnetic biochars should be studied further.


Asunto(s)
Cadmio , Carbón Orgánico , Adsorción , Fenómenos Magnéticos , Agua
17.
Environ Pollut ; 275: 116613, 2021 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-33609857

RESUMEN

In this research, an efficient (94.9-99.4%) and fast (5 min) method has been developed and validated for simultaneous identification and quantification of phenolic endocrine disrupting compounds with an emphasis on bisphenol A (BPA) and 4-cumylphenol (4-CP) in food stuffs using a dual-template magnetic, molecularly-imprinted polymer (dt-MMIP). The dt-MMIP was synthesized by a sol-gel method using Fe3O4@SiO2 (as the core) and BPA and 4-CP (as templates). The dt-MMIP was coupled with magnetic solid phase extraction to simultaneously detect BPA and 4-CP in food samples. BPA was measured from bottled water and fruit juice samples samples at 0.36 and 0.24 ng mL-1, respectively, while 4-CP in those samples was 0.33 and 0.16 ng mL-1, respectively. Their detection limits were estimated as 0.04 and 0.05 ng mL-1, respectively. The developed dt-MMIP method was highly reproducible, while maintaining a good cyclability up to 20 cycles.


Asunto(s)
Impresión Molecular , Fenómenos Magnéticos , Dióxido de Silicio , Extracción en Fase Sólida
18.
J Environ Sci (China) ; 102: 64-73, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33637266

RESUMEN

Organochlorine pesticides (OCPs) have received much attention due to their toxicity. Reliable methods to monitor their residues in the environment are needed. Here, magnetic polyamidoamine dendrimers were prepared by co-precipitation, Michael addition, and amidation. The magnetic polyamidoamine dendrimers demonstrated good adsorption ability for OCPs-this feature was utilized to construct a sensitive tool for monitoring OCPs in water samples. The proposed method provided remarkable linearity from 0.1 to 500 µg/L and satisfactory limits of detection from 0.012 to 0.029 µg/L. The spiked recoveries of the four target analytes were 91.8%-103.5% with relative standard deviations less than 4.5%. The magnetic materials had good reusability. The results indicated that the resulting method was an efficient, easy, rapid, economical, and eco-friendly tool for monitoring OCPs in aqueous samples.


Asunto(s)
Dendrímeros , Hidrocarburos Clorados , Plaguicidas , Contaminantes Químicos del Agua , Cromatografía Líquida de Alta Presión , Hidrocarburos Clorados/análisis , Fenómenos Magnéticos , Plaguicidas/análisis , Poliaminas , Agua , Contaminantes Químicos del Agua/análisis
19.
ACS Appl Mater Interfaces ; 13(7): 7966-7976, 2021 Feb 24.
Artículo en Inglés | MEDLINE | ID: mdl-33566573

RESUMEN

Nowadays, there is an increasing demand for more accessible routine diagnostics for patients with respect to high accuracy, ease of use, and low cost. However, the quantitative and high accuracy bioassays in large hospitals and laboratories usually require trained technicians and equipment that is both bulky and expensive. In addition, the multistep bioassays and long turnaround time could severely affect the disease surveillance and control especially in pandemics such as influenza and COVID-19. In view of this, a portable, quantitative bioassay device will be valuable in regions with scarce medical resources and help relieve burden on local healthcare systems. Herein, we introduce the MagiCoil diagnostic device, an inexpensive, portable, quantitative, and rapid bioassay platform based on the magnetic particle spectrometer (MPS) technique. MPS detects the dynamic magnetic responses of magnetic nanoparticles (MNPs) and uses the harmonics from oscillating MNPs as metrics for sensitive and quantitative bioassays. This device does not require trained technicians to operate and employs a fully automatic, one-step, and wash-free assay with a user friendly smartphone interface. Using a streptavidin-biotin binding system as a model, we show that the detection limit of the current portable device for streptavidin is 64 nM (equal to 5.12 pmole). In addition, this MPS technique is very versatile and allows for the detection of different diseases just by changing the surface modifications on MNPs. Although MPS-based bioassays show high sensitivities as reported in many literatures, at the current stage, this portable device faces insufficient sensitivity and needs further improvements. It is foreseen that this kind of portable device can transform the multistep, laboratory-based bioassays to one-step field testing in nonclinical settings such as schools, homes, offices, etc.


Asunto(s)
Bioensayo , Nanopartículas de Magnetita/química , Teléfono Inteligente , Estreptavidina/análisis , Bioensayo/instrumentación , Humanos , Hidrodinámica , Gripe Humana/diagnóstico , Fenómenos Magnéticos , Tamaño de la Partícula , Propiedades de Superficie
20.
Bioresour Technol ; 327: 124818, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33581375

RESUMEN

Magnetic porous biochars (MCHCl, MCHAc) with nanostructure on surfaces were prepared from penicillin fermentation dregs by pyrolysis with K2FeO4 activation and used in penicillin adsorption. MCHCl and MCHAc had high BET surface areas of 672 and 735 m2/g, respectively; mainly be attributed to the activation of K2FeO4 as well as acid pickling. Saturation magnetizations of MCHCl and MCHAc were 75.29 and 42.45 emu/g, respectively; the magnetism was mainly derived from the Fe3O4 and Fe3C in magnetic biochars. MCHCl had nano sticks of ~ 80 nm and MCHAc had petal-like slice of ~ 30 nm on surfaces. The maximum adsorption capacities of penicillin on MCHCl and MCHAc were 196 and 322 mg/g at 308 K, respectively. The adsorptions of penicillin on MCHCl and MCHAc were consistent with pseudo primary kinetics and the Langmuir adsorption isotherm model, and thermodynamic analysis indicated that the adsorption mechanism included physical and chemical adsorption.


Asunto(s)
Nanoestructuras , Contaminantes Químicos del Agua , Adsorción , Carbón Orgánico , Fermentación , Cinética , Fenómenos Magnéticos , Penicilinas , Porosidad , Pirólisis
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...