RESUMEN
In this work, new thermosensitive copolymers bearing phosphonated groups were synthesized and used to remove metal pollution. Sorption properties are brought by hydrolyzed (dimethoxyphosphoryl)methyl 2-methylacrylate (hMAPC1) monomer. N-n-propylacrylamide (NnPAAm) led to the thermoresponsive properties of the copolymers. Low lower critical solution temperature (LCST) values were observed, ranging between 20 and 25 °C depending on the molar ratio of each monomer in the copolymer. Sorption properties of these copolymers towards nickel ions were evaluated for increasing temperatures (10-40 °C), Ni ion concentrations of 20 mg L(-1) and pH values between 3 and 7. Best results were observed for temperatures just lower than the LCST (20 °C), when the copolymer was fully soluble in water solution. For temperature higher than the LCST, phosphonic diacid groups accessibility was considerably reduced by the precipitation of the thermosensitive part of the copolymer leading to lower sorption properties. In these conditions, the highest Ni removal by the copolymer was observed for pH = 7, when there was almost no competition between the sorption of H(+) and Ni(2+) ions on the phosphonic acid groups. These optimal conditions enabled removal of about 70% of the nickel in the synthetic effluent.
Asunto(s)
Metacrilatos/química , Níquel/aislamiento & purificación , Polímeros/síntesis química , Contaminantes Químicos del Agua/aislamiento & purificación , Acrilamidas/química , Adsorción , Concentración de Iones de Hidrógeno , TemperaturaRESUMEN
The use of a multiple attachment sites strategy is considered in order to improve the stability of monomolecular adlayers. The hypothesis was tested in the case of PEG-ylated compounds carrying phosphonate groups, known for their affinity toward titanium oxide surfaces. As a result, a new class of co- and terpolymers were synthesized by free-radical polymerization of three different monomers: dialkyl(methacryloyloxyalkyl)phosphonates, PEG methyl ether methacrylate, and/or butyl methacrylate monomers. Adlayers were formed following a simple dip-and-rinse protocol using diluted aqueous polymer solutions and were characterized by evaluating their thicknesses with variable angle spectroscopic ellipsometry (VASE) and their elemental compositions with X-ray photoelectron spectroscopy (XPS). The same techniques were used to determine changes of the adlayer as a function of exposure to electrolytes at different pH values and to monitor nonspecific protein adsorption upon serum exposures. The results indicated that the poly(alkyl-phosphonate)-based adlayers combine multiple site attachment of phosphonic groups and presentation of PEG side chains to the aqueous environment, resulting in both improved stability over a wide pH range in comparison to the tested reference surfaces and excellent resistance to protein adsorption when exposed to full human serum.
Asunto(s)
Organofosfonatos/química , Titanio/química , Espectroscopía de Resonancia Magnética , Propiedades de SuperficieRESUMEN
This study reports a 10-year experience of the USAF School of Aerospace Medicine with spike waves of focal spikes on a screening electroencephalogram in aviators who did not have a history of seizure, unexplained loss of consciousness, or significant neurologic abnormality at the time of the first abnormal electroencephalogram. Only one of 20 patients went on to develop a seizure disorder 4 years after his first abnormal electroencephalogram.
Asunto(s)
Medicina Aeroespacial , Electroencefalografía , Adolescente , Adulto , Epilepsia/diagnóstico , Humanos , Masculino , Persona de Mediana EdadRESUMEN
A 33-year-old man developed paroxysmal choreoathetosis following a severe head injury. Phenobarbital therapy was promptly effective. The family history as well as physical examinations and laboratory studies were unremarkable.
Asunto(s)
Atetosis/etiología , Corea/etiología , Traumatismos Craneocerebrales/complicaciones , Adulto , Atetosis/tratamiento farmacológico , Corea/tratamiento farmacológico , Humanos , Masculino , Fenobarbital/uso terapéuticoRESUMEN
A 46-year-old man had metastasis to the central tegmental tract of the pons with ipsilateral olivary hypertrophy. Although the phenomenon of palatal myochlonus has been repeatedly correlated with the finding of olivary hypertrophy, no palatal myoclonus was noted on repeated examinations. The clinical pathologic correlates and literature of similar cases are reviewed.