Large-scale time-lapse scanning electron microscopy image mosaic using a smooth stitching strategy.

Due to the trade-off between the field of view and resolution of various microscopes, obtaining a wide-view panoramic image through high-resolution image tiles is frequently encountered and demanded in numerous applications. Here, we propose an automatic image mosaic strategy for sequential 2D time-lapse scanning electron microscopy (SEM) images. This method can accurately compute pairwise translations among serial image tiles with indeterminate overlapping areas. The detection and matching of feature points are limited by geographical coordinates, thus avoiding accidental mismatching. Moreover, the nonlinear deformation of the mosaic part is also taken into account. A smooth stitching field is utilized to gradually transform the perspective transformation in overlapping regions into the linear transformation in non-overlapping regions. Experimental results demonstrate that better image stitching accuracy can be achieved compared with some other image mosaic algorithms. Such a method has potential applications in high-resolution large-area analysis using serial microscopy images. RESEARCH HIGHLIGHTS: An automatic image mosaic strategy for processing sequential scanning electron microscopy images is proposed. A smooth stitching field is applied in the image mosaic. Improved stitching accuracy is achieved compared with other conventional mosaic methods.

Paper-Based Distance Sensor for the Detection of Lipase via a Phase Separation-Induced Viscosity Change.

Human pancreatic lipase is a symbolic biomarker for the diagnosis of acute pancreatitis, which has profound significance for clinical detection and disease treatment. Herein, we first demonstrate a paper-based lipase sensor via a phase separation-induced viscosity change. Lipase catalyzes triolein to produce oleic acid and glycerol. Adding an excess of Ca2+ produces calcium oleate. The remaining Ca2+ binds with sodium alginate, triggering hydrogelation with an "egg-box" structure. The viscosity change of the aqueous solution induced by the phase separation process can be quantified by measuring the solution flow distance on a pH test paper. The paper-based lipase sensor has high sensitivity with a detection limit of 0.052 U/mL and also shows excellent specificity. Additionally, it is also utilized for quantitative lipase analysis in human serum samples to exhibit its potency in acute pancreatitis detection. This method overcomes the drawbacks of low sensitivity, slow response, and poor reproducibility caused by the nonuniform distribution of the highly viscous hydrogel on the sensing interface in existing approaches. In conclusion, thanks to the prominent characteristics of high portability, low cost, and easy operation, it is prospective for simple quantitative detection of lipase and has great potential for commercialization.

Paper-Based Flow Sensor for the Detection of Hyaluronidase via an Enzyme Hydrolysis-Induced Viscosity Change in a Polymer Solution.

Hyaluronidase (HAase) is implicated in inflammation, cancer development, and allergic reaction. The detection of HAase is significantly important in clinical diagnosis and medical treatment. Herein, we propose a new principle for the development of equipment-free and label-free paper-based flow sensors based on the enzymatic hydrolysis-induced viscosity change in a stimuli-responsive polymer solution, which increases the water flow distance on the pH indicator paper. The detection of HAase is demonstrated as an example. This facile and versatile method can overcome the potential drawbacks of traditional hydrogel-based sensors, including complex preparation steps, slow response time, or low sensitivity. Moreover, it can also avoid the use of specialized instruments, labeled molecules, or functionalized nanoparticles in the sensors developed using the polymer solutions. Using this strategy, the detection of HAase is achieved with a limit of detection as low as 0.2 U/mL. Also, it works well in human urine. Additionally, the detection of tannic acid, which is an inhibitor of HAase, is also fulfilled. Overall, a simple, efficient, high-throughput, and low-cost detection method is developed for the rapid and quantitative detection of HAase and its inhibitor without the use of labeled molecules, synthetic particles, and specialized instruments. As only minimal reagents of HAase, HA, and paper are used, it is very promising in the development of commercial kits for point-of-care testing.

Viscosity-Based Flow Sensor on Paper for Quantitative and Label-Free Detection of α-Amylase and Its Inhibitor.

α-Amylase (AMS) in human serum is a critical biomarker for the early diagnosis of pancreatic damage. In addition, the inhibition of α-amylase has long been thought to decrease the occurrence of diabetes. Thus, it is critical to construct a facile and convenient method for the determination of AMS and its inhibitor. In this study, we demonstrate a novel amylase sensor based on translating the viscosity change of the aqueous solution into the difference of the water diffusion length on a pH paper strip. AMS can be quantitatively detected by measuring the viscosity change of the amylopectin solution in the presence of AMS with different concentrations. The paper-based AMS sensor has a very high sensitivity with a detection limit of 0.017 U/mL and also shows excellent specificity. In addition, the inhibitory effect of acarbose on AMS is demonstrated with the IC50 value determined to be 21.66 ± 1.13 µg/mL. Furthermore, it is also evaluated for the detection of AMS in human serum samples of healthy people and acute pancreatitis patients. The difference in amylase levels between the two groups is unambiguously distinguished. Overall, this study provides a very simple, cost-effective, equipment-free, high-throughput, and label-free method for rapid and quantitative detection of α-amylase and may have significant applications in the diagnosis of acute pancreatitis and the screening of AMS inhibitors.

Effectively Regulating More Robust Amorphous Li Clusters for Ultrastable Dendrite-Free Cycling.

A disordered phase in Li-deposit nanostructure is greatly attractive, but plagued by the uncontrollable and unstable growth, and the nanoscale characterization in the structure. Here, fully characterized in cryogenic transmission electron microscopy (cryo-TEM), more robust amorphous-Li (ALi) clusters are revealed and effectively regulated on heteroatom-activating electronegative sites and an advanced solid electrolyte interphase (SEI) layer. Heteroatom-activating electronegative sites capably enhance the electrostatic interaction of Li+ and heteroatom-doping graphene-like film (HDGs), meaning lower Li diffusion barrier and larger binding energy that is confirmed by small nucleation overpotentials of 13.9 and 10 mV at 0.1 mA cm-2 in the fluoroethylene carbonate-adding ester-based (FEC-ester) and LiNO3 -adding ether-based (LiNO3 -ether) electrolytes. Orderly multilayer SEI structure comprised of inorganic-rich components enables fast ion transports and durable capabilities to construct highly reversible and long-term plating/stripping cycling. ALi cluster anodes exhibit non-crystalline morphologies and perform ultrastable dendrite-free cycling over 2800 times. Stable ALi clusters are also grown in LiFePO4 (LFP) (LFP-ALi-HDGs-N||LiFePO4 [LFP]) full cells with advantageous capacities up to 165.5 and 164.3 mAh g-1 in these optimized electrolytes at 0.1 C; the remarkable capacity retentions maintain to 93% and 91% after 150 cycles at 0.2 C. Structure viability, electrochemical reversibility, and excellent performance in ALi clusters are effectively regulated.

Hydrogel-assisted paper-based lateral flow sensor for the detection of trypsin in human serum.

The detection of trypsin and its inhibitor is significantly important for both clinical diagnosis and disease treatment. Herein, we demonstrate a hydrogel-assisted paper-based lateral flow sensor for the detection of trypsin and its inhibitor for the first time. The gelatin hydrogel is hydrolyzed based on the gel-to-sol transition in the presence of trypsin, which results in the release of the trapped water molecules in the gelatin hydrogel. By placing one end of a pH indicator strip onto the hydrolyzed gelatin hydrogel, water is flowing along the pH indicator strip. However, in the absence of trypsin, water cannot flow along the pH indicator strip as the water molecules are trapped in the gelatin hydrogel. The detection limit of the system reaches as low as 1.0 × 10-6 mg/mL, and it is also applied to the quantitative detection of trypsin in human serum. In addition, the detection of a clinical drug aprotinin that is an inhibitor of trypsin is also successfully achieved. Noteworthy, only the gelatin hydrogel, pH indicator strip, and PS substrate are needed to fulfill the detection of trypsin without the need of other chemicals or reagents. Overall, we develop a particularly simple, elegant, robust, competitive, high-throughput, and low-cost approach for the rapid and label-free detection of trypsin and its inhibitor, which is very promising in the development of commercial products for sensing, diagnostic, and pharmaceutical applications. Besides, the hydrogel-assisted paper-based lateral flow sensor can also be employed to detect other analytes of interest by use of different stimuli-responsive hydrogel systems.

Advances in Artificial Layers for Stable Lithium Metal Anodes.

Lithium (Li) metal is considered as the most promising anode material for rechargeable high-energy batteries. Nevertheless, the practical implement of Li anodes is significantly hindered by the growth of Li dendrites, which can cause severe safety issues. To inhibit the formation of Li dendrites, coating an artificial layer on the Li metal anode has been shown to be a facile and effective approach. This review mainly focuses on recent advances in artificial layers for stable Li metal anodes. It summarizes the progress in this area and discusses the different types of artificial layers according to their mechanisms for Li dendrite inhibition, including regulation of uniform deposition of Li metal and suppression of Li dendrite growth. By doing this, it is hoped that this contribution will provide instructional guidance for the future design of new artificial layers.

MoS2 Nanosheets Vertically Grown on Carbonized Corn Stalks as Lithium-Ion Battery Anode.

In this study, MoS2 nanosheets are vertically grown on the inside and outside surfaces of the carbonized corn stalks (CCS) by a simple hydrothermal reaction. The vertically grown structure can not only improve the transmission rate of Li+ and electrons but also avoid the agglomeration of the nanosheets. Meanwhile, a new approach of biomass source application is presented. We use CCS instead of graphite powders, which can not only avoid the exploitation of graphite resources, but also be used as a matrix for MoS2 growth to prevent the electrode from being further decomposed during long cycles and at high current densities. Meanwhile, lithium-ion batteries show remarkable electrochemical performance. They demonstrate a high specific capacity of 1409.5 mA g-1 at 100 mA g-1 in the initial cycle. After 250 cycles, the discharge capacity is still as high as 1230.9 mAh g-1. Even at 4000 mA g-1, they show a high specific capacity of 777.7 mAh g-1. Furthermore, the MoS2/CCS electrodes show long cycle life, and the specific capacity is still up to ∼500 mAh g-1 at 5000 mA g-1 after 1000 cycles.

Unique Reversible Conversion-Type Mechanism Enhanced Cathode Performance in Amorphous Molybdenum Polysulfide.

A unique reversible conversion-type mechanism is reported in the amorphous molybdenum polysulfide (a-MoS5.7) cathode material. The lithiation products of metallic Mo and Li2S2 rather than Mo and Li2S species have been detected. This process could yield a high discharge capacity of 746 mAh g-1. Characterizations of the recovered molybdenum polysulfide after the delithiaiton process manifests the high reversibility of the unique conversion reaction, in contrast with the general irreversibility of the conventional conversion-type mechanism. As a result, the a-MoS5.7 electrodes deliver high cycling stability with an energy-density retention of 1166 Wh kg-1 after 100 cycles. These results provide a novel model for the design of high-capacity and long-life electrode materials.

Adsorption behavior of light green anionic dye using cationic surfactant-modified wheat straw in batch and column mode.

An agricultural by-product, natural wheat straw (NWS), was soaked in 1 % cationic surfactant (hexadecylpyridinium bromide, CPB) solution for 24 h (at 293 K), and modified wheat straw (MWS) was obtained. Analysis of FTIR, XFR, and nitrogen element showed that CPB was adsorbed onto surface of NWS. Then, MWS was used as adsorbent for the removal of light green dye (LG, anionic dye) from aqueous solution. The experiment was performed in batch and column mode at room temperature (293 K). Sodium chloride (up to 0.1 mol/L) existed in solution was not favor of LG dye adsorption. The equilibrium data were better described by Langmuir isotherm, and adsorption capacity of q m from Langmuir model was 70.01 ± 3.39 mg/g. In fixed-bed column adsorption mode, the effects of initial LG concentration (30, 50, 70 mg/L) and flow rate (6.5, 9.0, 14.5 mL/min) on adsorption were presented. Thomas and modified dose-response models were used to predict the breakthrough curves using nonlinear analysis method, and both models can fit the breakthrough curves. Theoretical and experimental breakthrough curves were drawn and compared. The results implied that MWS can be used as adsorbent material to remove LG from aqueous solution.