Over the past decade, many efforts have been devoted to designing and fabricating substrates for surface-enhanced Raman spectroscopy (SERS) with abundant hot spots to improve the sensitivity of detection. However, there have been many difficulties involved in causing molecules to enter hot spots actively or effectively. Here, we report a general SERS method for actively capturing target molecules in small gaps (hot spots) by constructing a nanocapillary pumping model. The ubiquity of hot spots and the inevitability of molecules entering them lights up all the hot spots and makes them effective. This general method can realize the highly sensitive detection of different types of molecules, including organic pollutants, drugs, poisons, toxins, pesticide residues, dyes, antibiotics, amino acids, antitumor drugs, explosives, and plasticizers. Additionally, in the dynamic detection process, an efficient and stable signal can be maintained for 1–2 min, which increases the practicality and operability of this method. Moreover, a dynamic detection process like this corresponds to the processes of material transformation in some organisms, so the method can be used to monitor transformation processes such as the death of a single cell caused by photothermal stimulation. Our method provides a novel pathway for generating hot spots that actively attract target molecules, and it can achieve general ultratrace detection of diverse substances and be applied to the study of cell behaviors in biological systems.

Asphaltene with high aromaticity derived from coal direct liquefaction residue is a favorable precursor to prepare new carbon materials because it is easy to polymerize or cross link. Here, asphaltene was used as a carbon precursor for synthesis of porous carbon nanosheets via an in situ sheetstructure-directing agent from urea thermal polymerization. The porous carbon nanosheet with controllable thickness and a graphitized-like ribbon structure was obtained after KOH activation. As supercapacitor electrode materials, the asprepared porous carbon nanosheets demonstrated a specific capacitance of 282.9 F/g even at 100 A/g in a three-electrode test and 186.7 F/g at 20 A/g in a two-electrode test. The electrolyte was a KOH aqueous solution in both tests; the specific capacitance of the device retained 89.6% after 10,000 cycles showing a good lifetime and durability. The specific capacitance of the device was 135.4 and 119.1F/g at 1 A/g, respectively, in ionic liquid and organic electrolyte; its highest energy density reached 53.5 Wh/kg (at 159.9 W/kg) and 35.9 Wh/kg (at 134.9 W/kg), respectively. The synergism of high specific surface area to volume ratio developed micromesoporous structure, graphitized-like conduction paths, resulting in excellent specific capacitance and outstanding cycle life and rate performance capability of the prepared porous carbon nanosheets as supercapacitor electrodes.

A stable transparent electromagnetic interference shielding film is realized based on silver nanowires by integrating a polymer layer.

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The flexible transparent electromagnetic interference (EMI) shielding materials in visual windows is essential for the innovation of optoelectronic devices. Herein, we demonstrate the fabrication of the flexible EMI shielding films...

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The use of nuclear magnetic resonance (NMR) imaging techniques for determination of porosity and saturation distributions is investigated. Difficulties in quantitation which arise from the short transverse relaxation times exhibited by fluids in porous media are addressed. Procedures are presented whereby transverse relaxation during the signal acquisition process is modeled so that accurate estimates of intrinsic magnetization intensity, and thus porosity and saturation, can be obtained. Special consideration is given t o saturation/position dependence and multi-exponential behavior of transverse relaxation. These procedures are validated with results for longitudinal profile images. The use of thin-slice cross sectional profile images are demonstrated by observing fluid displacement in a rock sample with structural heterogeneities.