The Impact of Information Flow by Co-Shareholder Relationships on the Stock Returns: A Network Feature Perspective.

One shareholder may invest in different listed energy companies, so the information held by common shareholders can be transmitted among companies. Based on the two-mode complex network method, we construct an information flow shareholder-based network and employ different network indicators representing features of information flow as variables to construct panel regression models to analyze the impact of information flow among listed energy companies on the stock returns. The results indicate that the information flow of listed energy companies are increasingly important and play a significant role over a period. The efficiency of information flow among listed energy companies is increasingly high and the network information is concentrated among a few of these companies. The efficiency of information flow and the independence of listed energy companies are significantly positively related to stock returns, while the listed energy companies' ability to control information is not significantly related to stock returns. We employ a new perspective to analyze the information flow on how to influence stock returns, and offer some related suggestions for investors and policy makers in the future.

Simply translating mercury detection into a temperature measurement: using an aggregation-activated oxidase-like activity of gold nanoparticles.

A novel Hg2+-responsive thermometer system for translating mercury detection into temperature monitoring was developed based on an aggregation-activated oxidase-like activity of gold nanoparticles.

Gold nanozyme as an excellent co-catalyst for enhancing the performance of a colorimetric and photothermal bioassay.

Advanced oxidation processes (AOPs) have recently proposed for advancing colorimetric sensing applications, owing to their excellent performance of sensitive color readout that generated from the oxidation of chromogenic substrates like 3,3',5,5'-tetramethylbenzidine (TMB) by reactive oxygen species (ROS) of AOPs such as ·OH and ·O2- radicals. However, the efficiency of ROS generation and the related H2O2 decomposition in most AOPs is quite low especially at neutral pH, which greatly hampered the practical sensing applications of the AOPs. We herein communicated that ß-cyclodextrin (ß-CD)-capped gold nanoparticles (ß-CD@AuNPs) can promote catalysis at neutral pH for AOP as an excellent co-catalyst. In this strategy, inorganic pyrophosphate (PPi) ions was first used to coordinate with Cu2+ and form Cu2+-PPi complex. In the presence of hydrogen peroxide, target inorganic pyrophosphatase (PPase) can hydrolyze PPi into inorganic phosphate (Pi) and release free Cu2+ simultaneously, resulting in a Cu2+-triggered Fenton-like AOP reaction. The introduced ß-CD@AuNPs acts as a co-catalyst, analogous to mediators in the most co-catalyzed system, to enhance the rate-limiting step of Cu2+/Cu+ conversion in Cu2+/H2O2 Fenton-like AOP and resulting in an efficient generation of ·OH and ·O2- radicals, which further producing an intense blue color by oxidizing TMB into its oxidation product (TMBox) within a short time. Finally, this reaction system was used to simply detecting target PPase with the colorimetric and photothermal readout based on the in-situ generated TMBox indicator. More significantly, we successfully demonstrated nanozyme can serve as a co-catalyst to promote the AOP catalysis at neutral pH, and inspire other strategies to overcome the pH limitation in the AOP catalysis and expand its colorimetric and photothermometric application.

Photothermal and colorimetric dual mode detection of nanomolar ferric ions in environmental sample based on in situ generation of prussian blue nanoparticles.

Iron ions play a key role in many physiological processes, which can provide feedback for the evaluation of biological systems and environmental processes. New strategies for portable determination of Fe3+ therefore are still in urgent need. Here, through an in situ generation of prussian blue nanoparticles (PB NPs) in aqueous solution, we developed a bimodal method for photothermal and colorimetric detection of Fe3+. The sensing mechanism is based on the effective oxidation etching of Au-Cu core-shell nanocubes induced by Fe3+, accompanied by the in situ generation of PB NPs. It can be attributed to the specific reaction between ferrous ions (Fe2+) from the reduction of Fe3+ and potassium ferricyanide (K3[Fe(CN)6]) in the reaction solution. The in situ produced PB NPs show distinct bare-eye-detectable readouts with highly sensitive colorimetric and photothermal responses and thus can be used for Fe3+ determination. Such colorimetric change signals of characteristic absorbance at 740 nm in the UV-vis spectra showed a sensitive response to Fe3+ with a LOD of 210 nM. Moreover, as a sensitive photothermal probe, PB NPs generated in our Fe3+-enabled reaction system also exhibited a sensitive response to Fe3+ with a LOD of 70 nM. In addition, the standard addition experiments demonstrate our photothermal and colorimetric probe has good applicability for Fe3+ detection in the river water sample. What's more, the proposed strategy opens a new horizon for affordable detection of metal ions using a common thermometer, and therefore has a great potential for analytical chemistry and some important applications such as environmental monitoring, disease diagnostics and food analysis.

Target-mediated surface chemistry of gold nanorods for breaking the low color resolution limitation of monocolorimetric sensor.

A long-term limitation of low color resolution in the monocolorimetric sensors seriously restricts its extending application, especially for the traditional organic dyes-based monocolorimetric sensors. Herein, we explore a simple target-mediated surface chemistry-based modulation for regulating the surface of gold nanorods (AuNRs), resulting in a successful multicolorimetric sensor for inorganic pyrophosphatase (PPase) activity. It operates on the principle that PPase modulates the release of Fe3+ free from the ferric-pyrophosphate complex (Fe3+-PPi) through a specific target-catalyzed hydrolysis process, leading to a better mediation for the unique chemical redox reaction between Fe3+ and I-. Subsequently, I- is oxidized into I2, which as a moderate oxidant further regulates the surface of AuNRs due to the rapidly etching reaction between I2 and AuNRs. As a result, the resultant AuNRs surface change further leads to a blue-shift longitudinal LSPR effect of AuNRs, along with a naked-eye-detectable rainbow-like multicolor signal readout. Under optimal conditions, the proposed multicolorimetric sensor exhibits an affordable sensing performance for PPase activity in the range from 1.5 U L-1 to 9 U L-1 with a detection limit of 0.8 U L-1 (S/N = 3). To this point, our strategy not only provides a promising way for breaking the low color resolution limitation of the traditional monocolorimetric sensors, but also broadens the applicability of AuNRs etching-based multicolorimetric sensors.

Molecule-gated surface chemistry of Pt nanoparticles for constructing activity-controllable nanozymes and a three-in-one sensor.

Herein, a simple strategy for constructing activity-controllable nanozymes is proposed based on the glutathione (GSH)-gated surface chemistry of citrate-capped Pt nanoparticles (PtNPs). PtNPs have been shown to have oxidase-like activity that can effectively catalyze the oxidation of 3,3',5,5'-tertamethylbenzidine (TMB) by O2, resulting in a typical color reaction from colorless to blue. We found that GSH can inhibit the oxidase-like activity of PtNPs as a molecule-gated surface chemistry element, resulting in a dramatic decrease of the oxidation of TMB. The addition of copper ions (Cu2+) could oxidize GSH into glutathione disulfide (GSSG), resulting in the distinct suppression of GSH-modulated PtNP surface chemistry and oxidase-like activity inhibition, which further results in a significant acceleration of TMB oxidation and the obvious recovery of intense blue color. Furthermore, the color-based detection signal associated with the redox of TMB indicator here was found to show good fluorescence and a photothermal effect and exhibit sensitive and selective response toward the proposed molecule-gated surface chemistry and Cu2+ target. On the basis of this phenomenon, we successfully constructed a three-in-one sensor for Cu2+ with a triple signal readout, colorimetric, photothermal (temperature), and fluorescence, depending on the proposed in situ modulation method for PtNP catalysis. The applicability of the three-in-one sensor was also demonstrated by measuring Cu2+ in human serum with a standard addition method, and the results are of satisfactory accuracy as confirmed by ICP-MS measurements.