RESUMO
In order to assess the colonization efficacy of the oral probiotic Streptococcus salivarius K12, a rapid method for specific detection and enumeration of the strain was developed. Here, we describe a two-step TaqMan™ quantitative PCR assay using primer-probe combinations targeting genes of the locus encoding the lantibiotic bacteriocin salivaricin B.
Assuntos
Carga Bacteriana/métodos , Streptococcus salivarius/classificação , Streptococcus salivarius/genética , Proteínas de Bactérias/genética , Humanos , Plasmídeos/genética , Probióticos , Reação em Cadeia da Polimerase em Tempo Real , Streptococcus salivarius/isolamento & purificaçãoRESUMO
Hydrothermal carbonization (HTC) of biomass such as glucose and cellulose typically produces micrometer-sized carbon spheres that are insulating. Adding a very small amount of Graphene oxide (GO) to glucose (e.g., 1:800 weight ratio) can significantly alter the morphology of its HTC product, resulting in more conductive carbon materials with higher degree of carbonization. At low mass loading level of GO, HTC treatment results in dispersed carbon platelets of tens of nanometers in thickness, while at high mass loading levels, free-standing carbon monoliths are obtained. Control experiments with other carbon materials such as graphite, carbon nanotubes, carbon black, and reduced GO show that only GO has significant effect in promoting HTC conversion, likely due to its good water processability, amphiphilicity, and two-dimensional structure that may help to template the initially carbonized materials. GO offers an additional advantage in that its graphene product can act as an in situ heating element to enable further carbonization of the HTC products very rapidly upon microwave irradiation. Similar effect of GO is also observed for the HTC treatment of cellulose.
Assuntos
Carbono/química , Grafite/química , Óxidos/química , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier , TermogravimetriaRESUMO
Unprecedented adsorption of chlorpyrifos (CP), endosulfan (ES), and malathion (ML) onto graphene oxide (GO) and reduced graphene oxide (RGO) from water is reported. The observed adsorption capacities of CP, ES, and ML are as high as ~1200, 1100, and 800 mg g(-1) , respectively. Adsorption is found to be insensitive to pH or background ions. The adsorbent is reusable and can be applied in the field with suitable modifications. A first-principles pseudopotential-based density functional analysis of graphene-water-pesticide interactions showed that the adsorption is mediated through water, while direct interactions between graphene and the pesticides is rather weak or unlikely.