No abstract

Among different nitro compounds, trinitrophenol (TNP) is the most common constituent to prepare powerful explosives all over the world. A few works on the detection of nitro explosives have already been reported in the past few years; however, selectivity is still in its infant stage. As all the nitroexplosives are highly electron deficient in nature, it is very difficult to separate one from a mixture of different nitro compounds by the usual photoinduced electron transfer (PET) mechanism. In the present work, we have used a bright luminescent, 2,6-diamino pyridine functionalized graphene oxide (DAP-RGO) for selective detection of TNP in the presence of other nitro compounds. The major advantage of using this material over other reported materials is not only to achieve very high fluorescence quenching of ∼96% but also superior selectivity >80% in the detection of TNP in aqueous medium via both fluorescence resonance energy transfer and PET mechanisms. Density functional theory calculations also suggest the occurrence of an effective proton transfer mechanism from TNP to DAP-RGO, resulting in this tremendous fluorescence quenching compared to other nitro compounds. We believe this graphene based composite will emerge a new class of materials that could be potentially useful for selective detection, even for trace amounts of nitro explosives in water.

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No abstract

Chemically synthesized amorphous MoSx quantum dots show excellent HER activity in neutral medium during 12 h of electrolysis.

Extraction of hazardous heavy metals like As, Hg, Cd, Cr(VI), etc. for water purification is a great challenge. Exploiting the large surface area of graphene, in the present work, we have synthesized a UV-active 2,6-diamino pyridine-reduced graphene oxide (DAP-RGO) composite to remove Cr(VI) from acidic water solution. Here, the presence of an extra pyridinic-nitrogen lone pair facilitates the removal efficiency of excess Cr(VI) [500 mg L À1 in 3 h only] over reported results so far. In addition to that, the unique advantage of this UV-active material is the enhancement of removal efficiency by 18% at a higher pH value. We believe that this study will bring forth a new class of UV-active graphene based adsorbents with remarkably high removal efficiency for toxic heavy metals from waste-water in future.

To evaluate the effects of green banana and pectin (nondigestible, dietary sources of colonic shortchain fatty acids [SCFA]) on intestinal permeability, 57 boys (5-12 months) with persistent diarrhea (> or = 14 days) were given a week's treatment with a rice-based diet containing either cooked green banana (n = 19), pectin (n = 17), or rice diet alone (n = 21). Intestinal permeability was assessed before and after treatment by giving a lactulose-mannitol (LM) drink and measuring urinary recovery after 5 hr. Treatment with banana significantly (P < 0.05) reduced lactulose recovery, increased mannitol recovery, and decreased the LM ratio, indicating improvement of permeability. Pectin produced similar results. Permeability changes were associated with a 50% reduction in stool weights which correlated strongly (green banana, r2 = 0.84, pectin, r2 = 0.86) with the LM ratio. Green banana-derived and SCFA-mediated stimulation of colonic as well as small bowel absorption is responsible for their antidiarrheal effects. The antidiarrheal effects of green banana and pectin are mediated by improvement of small intestinal permeability in addition to their known colonotrophic effects.

Inspite of being a potential material for electronic applications graphene possesses very poor optical properties, which need to be modified to make it suitable for optoelectronic devices. To achieve superior optical properties, graphene oxide (GO) sheets are functionalized with azo-pyridine to form a new intercalated structure with an interlayer separation of 0.9 nm. These azo-pyridine intercalated GO sheets show superior optical properties with bright blue emission via excited state intra-molecular proton transfer (ESIPT) which have potential applications in graphene based optoelectronic devices.