Fast and efficient As(III) removal from water by bifunctional nZVI@NBC.

As a notable toxic substance, metalloid arsenic (As) widely exists in water body and drinking As-contaminated water for an extended period of time can result in serious health concerns. Here, the performance of nanoscale zero-valent iron (nZVI) modified N-doped biochar (NBC) composites (nZVI@NBC) activated peroxydisulfate (PDS) for As(III) removal was investigated. The removal efficiencies of As(III) with initial concentration ranging from 50 to 1000 µg/L were above 99% (the residual total arsenic below 10 µg/L, satisfying the contaminant limit for arsenic in drinking water) within 10 min by nZVI@NBC (0.2 g/L)/PDS (100 µM). As(III) removal efficiency influenced by reaction time, PDS dosage, initial concentration, pH, co-existing ions, and natural organic matter in nZVI@NBC/PDS system were investigated. The nZVI@NBC composite is magnetic and could be conveniently collected from aqueous solutions. In practical applications, nZVI@NBC/PDS has more than 99% As(III) removal efficiency in various water bodies (such as deionized water, piped water, river water, and lake water) under optimized operation parameters. Radical quenching and EPR analysis revealed that SO4·- and ·OH play important roles in nZVI@NBC/PDS system, and the possible reaction mechanism was further proposed. These results suggest that nZVI@NBC activated peroxydisulfate may be an efficient and fast approach for the removal of water contaminated with As(III).

Fast T-Type Photochromism of Colloidal Cu-Doped ZnS Nanocrystals.

This paper reports on durable and nearly temperature-independent (at 298-328 K) T-type photochromism of colloidal Cu-doped ZnS nanocrystals (NCs). The color of Cu-doped ZnS NC powder changes from pale yellow to dark gray by UV light irradiation, and the color changes back to pale yellow on a time scale of several tens of seconds to minutes after stopping the light irradiation, while the decoloration reaction is accelerated to submillisecond in solutions. This decoloration reaction is much faster than those of conventional inorganic photochromic materials. The origin of the reversible photoinduced coloration is revealed to be a strong optical transition involving a delocalized surface hole which survives over a minute after escaping from intraparticle carrier recombination due to electron-hopping dissociation. ZnS NCs can be easily prepared in a water-mediated one-pot synthesis and are less toxic. Therefore, they are promising for large-scale photochromic applications such as windows and building materials in addition to conventional photochromic applications. Moreover, the present study demonstrates the importance of excited carrier dynamics and trap depths, resulting in coloration over minutes not only for photochromic nanomaterials but also for various advanced photofunctional materials, such as long persistent luminescent materials and photocatalytic nanomaterials.

[Effect of Tongxinluo superfine on experimental anginal model (contraction of collaterals) in rat with endothelial dysfunction].

OBJECTIVE: To study the effect of Tongxinluo superfine (TXL) on experimental anginal model induced by Arginine Vasopressin in rats with endothelial dysfunction. METHOD: First, the endothelial dysfunction rat model was made by methionine-induced hyperhomocysteinemia (HHcy). The thoracic aorta were excised, and acetylcholine (Ach)-induced endothelium dependent relaxation and sodium nitroprusside (SNP) induced endothelium-independent relaxation were measured. Total plasma homocysteine (Hcy) concentrations were measured with automated fluorescence polarization immunoassay (FPIA). Enzyme-linked immunosorbent assay (ELISA) was used to detect plasma von Willebrand factor (vWF) level. Plasma nitric oxide (NO) contents were assayed by method of nitrate reductase. Then, the rat model of collaterals contraction (model group) was established by AVP intravenous injection in rats with endothelial dysfunction and the S wave change (DeltaS) and T wave depression in Lead II ECG were used as the index of angina severity. The nitric oxide (NO) contents in serum and the expression of myocardium eNOS mRNA were measured. RESULT: Ach (0. 1-1000 nmol L(-1))-induced endothelium dependent relaxation (EDR) of aortic rings was significantly decreased in HHcy group. The endothelium-independent relaxation induced by SNP (0.001-10 micromol L(-1)) was not significantly different between the two groups. Plasma homocysteine concentrations and vWF levels in rats treated with methionine were higher than those of control group, while NO contents were significantly decreased in HHcy group compared with control. The results showed that L-methionine intake induced hyperhomocysteinemia in rats. Impaired EDR, increased vWF and decreased NO suggested the exist of endothelial dysfunction. DeltaS of model group increased from 1 min to 5 min and T wave of model group depressed at 2 min compared with that of control after the administration of vasopressin (0.5 U kg(-1)). The intragastric administration of TXL inhibited vasopressin-induced S wave change at 4 min and 5 min and T wave depression from 30 s to 3 min after AVP injection. The NO contents in serum and the expression of myocardium eNOS mRNA of TXL group were increased compared with model group. CONCLUSION: Experimental angina induced by AVP injection is more severe in rats with endothelial dysfunction. Tongxinluo Superfine can protect against collaterals contraction in rats maybe by increasing the NO contents in serum and the expression of myocardium eNOS mRNA.