Thermostability Improvement of the d‑Allulose 3‑Epimerase from <i>Dorea</i> sp. CAG317 by Site-Directed Mutagenesis at the Interface Regions

d-Allulose is a low-calorie sweetener and has broad applications in the food, cosmetics, and pharmaceutical industries. Recently, most studies focus on d-allulose production from d-fructose by d-allulose 3-epimerase (DAEase). However, the major blocker of industrial production of d-allulose is the poor thermostability. In this study, site-directed mutagenesis at the interface regions of <i>Dorea</i> sp. DAEase was carried out, and the F154Y/E191D/I193F mutation was obtained. The mutant protein displayed much higher thermostability, with a <i>t</i>_1/2 value of 20.47 h (50 °C) and a <i>T</i>_m value of 74.18 °C. Compared with the wild-type DAEase, the <i>t</i>_1/2 value at 50 °C increased by 5.4-fold, and the <i>T</i>_m value increased by 17.54 °C. In the d-allulose production from 500 g/L d-fructose, 148.2 g/L d-allulose could be obtained by F154Y/E191D/I193F mutant protein. The results suggest that site-directed mutagenesis at the interface regions is an efficient approach for improving the thermostability of DAEase

Aluminum Impurity from Current Collectors Reactivates Degraded NCM Cathode Materials toward Superior Electrochemical Performance

The huge amount of degraded NCM (LiNi0.5Co0.2Mn0.3O2) cathode materials from spent lithium-ion batteries is arising as a serious environmental issue as well as a severe waste of metal resources, and therefore, direct recycling of them toward usable electrode materials again is environmentally and economically more attractive in contrast to present metallurgical treatments. In this work, we design a robust two-step method for direct recycling of degraded NCM materials, which uses the aluminum impurity from the attached current collector to supplement the transition metal vacancies for simultaneous elemental compensation and structural restoration. This single-element compensation strategy leads to the regeneration of high-quality NCM material with depressed cation disordering and stabilized layered structure. Moreover, the regenerated NCM material with controllable Al doping delivered an outstanding electrochemical performance; specifically, the capacity (158.6 mAh g–1), rate capability (91.6 mAh g–1 at 5 C), and cycling stability (89.6% capacity retention after 200 cycles) of the regenerated NCM material are even comparable with those of fresh materials. The as-established regeneration protocol has its chance in simplifying the industrial recycling process of degraded NCM materials

Graphene Oxide Thin Film with Dual Function Integrated into a Nanosandwich Device for in Vivo Monitoring of Interleukin‑6

Graphene oxide (GO), with its exceptional physical and chemical properties and biocompatibility, holds a tremendous potential for sensing applications. In this study, GO, acting both as the electron-transfer bridge and the signal reporter, was attached on the interface to develop a label-free electrochemical nanosandwich device for detection of interleukin-6 (IL-6). First, a single layer of GO was covalently modified on gold electrodes, followed by attachment of anti-IL-6 capture antibody to form the sensing interface. The 4-aminophenyl phosphorylcholine was further attached to the surface of GO to minimize nonspecific protein adsorption. For reporting the presence of analyte, the anti-IL-6 detection antibody was covalently modified to the GO, which has been integrated with the redox probe Nile blue (NB). Finally, a nanosandwich assay was fabricated on gold surfaces for detection of IL-6 on the basis of the electrochemical signal of NB. The prepared nanosandwiches demonstrated high selectivity and stability for detection of IL-6 over the range of 1–300 pg mL^–1 with the lowest detectable concentration of 1 pg mL^–1. The device was successfully used for monitoring of IL-6 secretion in RAW cells and live mice. By tailoring the GO surface with functional components, such devices were able to detect the analyte in vivo without causing inflammatory response

Exfoliation of Stable 2D Black Phosphorus for Device Fabrication

Discovering stabilizers that protect phosphorene from oxidative degradation is critically required for dispersion processing of black phosphorus (BP). It is equally important to also find environmentally friendly, low-cost, and practical exfoliating media. Herein, we demonstrate the yield of remarkably stable phosphorene by coating with a polymer to shield the nanosheets from reaction with water and air. The polymer shell suppresses the rate of BP degradation more efficiently than previously reported systems. We present for the first time a simple kinetic model for exfoliation of BP in polyvinylpyrrolidone (PVP) ethanol solution that appears to quantitatively fit BP exfoliation data, and it illuminates mechanistic aspects of exfoliation. Exfoliated flakes consist of a high level of 51% crystalline single layers that are free from structural disorder or oxidation. A successive centrifugation and redispersion strategy is developed affording dispersions with high phophorene-to-stabilizer ratio, which is very useful for further applications. We also demonstrate that PVP-stabilized phosphorene dispersions possess saturable absorption at both 515 and 1030 nm, which have potential use as ultrafast broadband absorbers. Furthermore, such phosphorene dispersions were processed to prepare new metal/phosphorene nanocomposites that have potential for use as electrocatalysts in electrolytic cells

Daily number of streets with DF cases in Guangzhou city, China, between 1 January 2006 and 31 December 2014.

<p>Daily number of streets with DF cases in Guangzhou city, China, between 1 January 2006 and 31 December 2014.</p

The spatial distributions of high and low DF risk streets and the counts of daily indigenous DF cases in high and low risk streets.

<p>Fig 4A was generated by ArcGIS 10.0 (Environmental Systems Research Institute, RedLands, California, U.S.A). (A) High risk streets with RRs>1 and low risk streets with RRs≤1. (B) The epidemic pattern of daily accumulative dengue cases in high-risk clustering streets and the low-risk clustering streets in Guangzhou city, 2006–2014.</p

The average DF incidence rates and increment of average DF incidence rates.

<p>A, B, &C were generated by ArcGIS 10.0 (Environmental Systems Research Institute, RedLands, California, U.S.A.). The spatial distributions for annual mean DF incidence rates during 2006±2011; (B) The spatial distributions for annual mean DF incidence rates during 2012±2014; (C) The spatial distribution for increment of annual mean DF incidence rates from 2006±2011 to 2012±2014.</p

Location of Guangzhou city in Guangdong province, China.

<p>Fig 1 was generated by ArcGIS 10.0 (Environmental Systems Research Institute, RedLands, California, U.S.A).</p

The spatial and temporal clusters of daily indigenous DF cases in Guangzhou city, 2006–2014.

<p>A&C were produced by ArcGIS 10.0 (Environmental Systems Research Institute, RedLands, California, U.S.A). (A) Spatial cluster circles of each year produced by SaTScan were displayed in different color. Both the most likely cluster and the secondary subcluster were displayed. Only the most likely clusters were displayed in the enlarged map. (B) Time clusters of each significant cluster of each year were plotted by different color and a dot in the earliest date denote the date of the onset of the first case of each year. In the year 2006 and 2013, “1” is the most likely cluster and “2” is the secondary likely cluster. (C) The streets where the first cases occur were plotted in different color and the date of onset were labeled below the legend.</p

The association between DF incidence rates and longitude and latitude geographically in each street during the study period.

<p>The association between DF incidence rates and longitude and latitude geographically in each street during the study period.</p