Rapid and efficient removal of multiple heavy metals from diverse types of water using magnetic biochars derived from antibiotic fermentation residue.

Pyrolysis is a promising method to treat antibiotic fermentation residue (AFR), a hazardous waste in China, with the benefits of detoxification and resource recycling. However, the application of the AFR-derived biochar has been limited yet, restricting the use of pyrolysis to treat AFR. Herein, for the first time, we reported the use of magnetic biochars derived from vancomycin fermentation residue to rapidly and efficiently co-adsorb multiple heavy metals from diverse types of water with complex matrices. The biochar prepared at 700 °C (labeled as VBC700) exhibited high affinity and selectivity for multiple heavy metals, especially for Ag(I), Hg(II), Pb(II), and Cu(II). The kinetics for Ag(I), Hg(II), and Pb(II) were ultrafast with an equilibrium time of only 5 min, while those for Cu(II) were relatively slower. The maximum adsorption capacity calculated from the Langmuir model for Ag(I), Hg(II), Pb(II), and Cu(II) reached 177.4, 105.9, 387.1, 124.5 mg/g, respectively, which were superior to much previously reported adsorbents. Impressively, Na(I), K(I), Ca(II), Mg(II), and salinity did not affect the capture of these heavy metals, and thus >99% of Ag(I), Pb(II), and Cu(II) were concurrently removed from complex water matrices including seawater, which has rarely been reported before. Furthermore, VBC700 remained high adsorption performance at pH ≥ 3. The adsorption mechanisms included ion exchange, precipitation, and inner-sphere complexation. Overall, the results demonstrate that VBC700 would be an excellent adsorbent to co-capture multiple heavy metals from diverse types of water, highlighting the feasibility of using pyrolysis to achieve a win-win goal for AFR management and heavy metal pollution control.

Effect of indwelling depth of peripheral intravenous catheters on thrombophlebitis.

To clarify the effect of catheter indwelling depth on the occurrence of thrombophlebitis, a total of 339 hospitalized patients were randomly enrolled and divided by the catheter indwelling depth into 2 groups. Then the effect of indwelling depth on thrombophlebitis was analyzed, and the independent influence factors on the occurrence of thrombophlebitis were clarified. There were 49 cases of thrombophlebitis, including 8 tumor-bearing patients and 41 patients with lung infection. Thirteen of the 135 patients with indwelling depth of 1 cm, and 36 of the 204 patients with indwelling depth of 1.9 cm suffered thrombophlebitis. The relationship between incidence rate of thrombophlebitis and clinicopathological parameters was analyzed. It was found the incidence of thrombophlebitis was significantly correlated with males (X2 = 5.77), lung infection (X2 = 7.79), and indwelling depth of 1.9 cm (X2 = 4.223). Multifactor analysis of variance showed the significant independent risk factors of thrombophlebitis were male [hazard ratio (HR) 3.12 (1.39-6.98)], and lung infection (HR 0.22 [0.06-0.69]), and the indwelling depth of 1.9 cm affected the occurrence of thrombophlebitis (HR 0.79 [0.42 -3.09]) but was not an independent risk factor. In our treatment center, while appropriate fixation was ensured, the catheter indwelling depth shall be as short as possible, so as to reduce the occurrence of thrombophlebitis. For patients with lung infection, nursing at the intubation site shall be strengthened, so as to decrease thrombophlebitis.

Temperature Rise Associated with Adiabatic Shear Band: Causality Clarified.

One of the most important issues related to adiabatic shear failure is the correlation among temperature elevation, adiabatic shear band (ASB) formation and the loss of load capacity of the material. Our experimental results show direct evidence that ASB forms several microseconds after stress collapse and temperature rise reaches its maximum about 30 µs after ASB formation. This observation indicates that temperature rise cannot be the cause of ASB. Rather, it might be the result of adiabatic shear localization. As such, the traditional well-accepted thermal-softening mechanism of ASB needs to be reconsidered.

Flow of quasi-two dimensional water in graphene channels.

When liquids confined in slit channels approach a monolayer, they become two-dimensional (2D) fluids. Using molecular dynamics simulations, we study the flow of quasi-2D water confined in slit channels featuring pristine graphene walls and graphene walls with hydroxyl groups. We focus on to what extent the flow of quasi-2D water can be described using classical hydrodynamics and what are the effective transport properties of the water and the channel. First, the in-plane shearing of quasi-2D water confined between pristine graphene can be described using the classical hydrodynamic equation, and the viscosity of the water is ∼50% higher than that of the bulk water in the channel studied here. Second, the flow of quasi-2D water around a single hydroxyl group is perturbed at a position of tens of cluster radius from its center, as expected for low Reynolds number flows. Even though water is not pinned at the edge of the hydroxyl group, the hydroxyl group screens the flow greatly, with a single, isolated hydroxyl group rendering drag similar to ∼90 nm2 pristine graphene walls. Finally, the flow of quasi-2D water through graphene channels featuring randomly distributed hydroxyl groups resembles the fluid flow through porous media. The effective friction factor of the channel increases linearly with the hydroxyl groups' area density up to 0.5 nm-2 but increases nonlinearly at higher densities. The effective friction factor of the channel can be fitted to a modified Carman equation at least up to a hydroxyl area density of 2.0 nm-2. These findings help understand the liquid transport in 2D material-based nanochannels for applications including desalination.