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A highly sensitive flow-injection chemiluminescence immunoassay is first established based on resin beads and ZIF-L-Hemin nanozyme for the detection of OTA in foods. Based on the similarity of the coordination state and catalytic mechanism between ZIF-L-Hemin and natural HRP, the active site luminal microenvironment of axially coordinated histidine and distal histidine of HRP was simulated by using ZIF-L to replace the protein backbone. [Display omitted] • A novel FI-CLIA based on carboxyl resin beads and ZIF-L-Hemin catalytic amplification is proposed for the first time. • ZIF-L-Hemin synthesized by a green one-pot method is considered as one of the competitive alternatives to natural enzymes. • Carboxyl resin beads as an important carrier in molecular biology can be well covalently coupled with biological ligands such as antigens and antibodies. • The CL immunosensor provides an economical, sensitive and specific method for Ochratoxin A detection. Compared with natural enzymes, nanozymes have the advantages of easy preparation, low cost and high stability. With the booming development of nanozymes, scientists have further defined them as "nanomaterials with enzyme-like properties". Here, on the one hand, ZIF-L has the characteristics of simple preparation, good stability and large specific surface area. Meanwhile, the array structure of Zn2+ and imidazole in the ZIF-L can replace the amino acids precisely located in the natural enzymes, thus mimicking the microenvironment of the natural peroxidase. On the other hand, based on the chemical similarity of hemin to natural heme, we encapsulated hemin into the ZIF-L backbone by a straightforward "green" one-pot technique. According to the symbiotic stability-enhancing effect, the encapsulated biomolecules can make the ZIF-L matrix more stable while the ZIF-L backbone protects the enzyme from denaturation. Based on this, ZIF-L-Hemin composites with excellent peroxidase properties was successfully prepared. Using ZIF-L-Hemin composites, we constructed a flow-injection chemiluminescence immunoassay for the quick and ultrasensitive detection of ochratoxin A (OTA) in food. The experimental results showed that the detection range of OTA was 0.0015 ∼ 1500 ng mL−1, and the limit of detection (LOD) was 0.47 pg mL−1 (S/N = 3). The OTA analysis of wheat, corn and feed samples showed that the recoveries ranged from 80.83 % to 115.54 %, which successfully demonstrated the usability and potential applications of immunosensor. [ABSTRACT FROM AUTHOR]

• A two-bacterium coupled catalytic system was employed to produce D -PLA from L -Phe, with amorphous ZIF-90 being the encapsulating material for this system. • aZIF-90@ E. coli were equipped with excellent resistance to harsh environment and enhanced recyclability and storage ability • aZIF-90@ E. coli was applied to the fed-batch catalysis of D -PLA, achieving efficient transformation and practical application. D-phenyllactic acid is an important medical intermediate and a potential green preservative. Due to its extensive use and high demand, there has been significant research interest in developing efficient synthesis methods. In this study, we aimed to efficiently produce D -phenyllactic acid from L -phenylalanine through a two-step cascade reaction using a coupled catalytic system consisting of two bacteria strains (E. coli /pET28a- lrldh and E. coli /pET28a- ladd 2). To enhance the stability of this catalytic system, we encapsulated the two recombinant E. coli strains with amorphous ZIF-90, which was thoroughly characterized using various methods including SEM, FT-IR, TGA, XRD, XPS, and CLSM analysis. Compared to free cells, the immobilized living materials (amorphous ZIF-90@ E. coli) showed good stability in harsh environments and superior recyclability. When applied to the production of D -PLA, the amorphous ZIF-90@ E. coli system achieved a yield of 9.00 g/L and a conversion of 89.4 %. This successful coupling catalysis from L-phenylalanine to D -PLA indicates the potential of aZIF-90@ E. coli for biosynthesis of D -phenyllactic acid in future industrial applications. Synthesis of aZIF-90@ E. coli applied to the production of D -phenyllactic acid [Display omitted] [ABSTRACT FROM AUTHOR]

Acoustofluidics inside the microchannel has already found its wide applications recently. Acoustic streaming and radiation force are two underlying mechanisms that determine the trajectory of microparticles and cells in the manipulation. Critical particle size of viscous effects is found to be about 1.6 µm in the conventional rectangular microchannel (W × H = 380 m × 160 m) at the frequency of 2 MHz, below which the acoustic streaming dominants, and is independent of the driving voltage. In order to effectively adjust such a critical size, a approach is proposed and evaluated numerically to enhance the acoustic streaming by adding some protrusions (i.e., in the shape of a wedge, rod, half-ellipse) to the middle of the top or bottom wall. It is found that the resonant frequency and acoustic pressure will decrease and the acoustic streaming velocity will increase significantly, respectively, with the increase of protrusion height (up to 30 µm while keeping the width the same as 8 µm). Subsequently, trajectory motion patterns of microparticles have apparent changes in comparison to those inside the rectangular microchannel, and acoustic streaming can even dominate the motion of large microparticles (i.e., 10 µm). As a result, the critical particle size could be increased up to 72.5 µm. Furthermore, different protrusion shapes (i.e., wedge, rod, half-ellipse) on the top wall were compared. The sharpness of protrusion at its tip seems to determine the acoustic streaming velocity. The wedge attached to the bottom wall had higher resonant frequency and lower acoustic streaming velocity compared with the top wedge in the same dimension. The patterns of acoustic streaming and microparticle trajectory motion in the microchannel with dual wedges on the top and bottom walls are not the superposition of those of the top and bottom wedge individually. In summary, the geometry of the microchannel has a significant effect on the induced acoustofluidics by the bulk acoustic waves. A much larger acoustic streaming velocity is produced at the tip of the protrusion to change the critical size of microparticles between acoustic streaming and radiation force. It suggests that more applications of acoustofluidics (i.e., mixing and sonoporation) to microparticles and cells in various sizes are feasible by designing an appropriate geometry of the microchannel. [ABSTRACT FROM AUTHOR]

Topography plays a critical role in the growth, development, and carbon accumulation of Moso bamboo. However, it is still unknown whether the effects of topography on the newly sprouted culms, the diameter at breast height (DBH) and the carbon stocks of newly sprouted culms (called carbon stocks below) vary temporally following Moso bamboo afforestation. In this study, thirty-one 20 × 20 m long-term sample plots were established and the DBH, age, height, and coordination of every newly sprouted culm were measured from 2009 to 2018. Four Moso bamboo expansion periods (rhizome expansion period, early period, middle period, and stable period) were divided according to the patterns of change of newly sprouted culms. Structural equation modeling and univariate analysis were combined to assess the dynamic effects of topographic factors (slope, aspect, slope position, and topographic complexity) and the effect of single topographic factors and their interactions on the carbon stocks during the four expansion periods. The result showed that the leading topographic factors influencing DBH, newly sprouted culms and carbon stocks were depended on the expansion period. Furthermore, the effective degree of leading topographic factor, aspect, decreased from the early period to a stable period. The four topographic factors studied here did not influence carbon stocks and newly sprouted culms during the stable period. The optimal interactions between carbon stocks and slope position and aspect (an east aspect of lower and upper slope positions) were relatively larger than those of a single aspect (east aspect), and significantly decreased in a stable period. Low topographic complexity was beneficial to the carbon accumulation under abrupt slopes but middle topographic complexity was needed under steeper slopes (steep and dangerous slope). Overall, this study offers a greater understanding of the effect of topography on Moso bamboo growth and provides a scientific basis for the selection of suitable afforestation locations for forest management. [ABSTRACT FROM AUTHOR]

The initial period after the earthquake is the prime time for disaster relief. During this period, it is of great value to rationally locate the transfer facilities of relief materials and effectively arrange the transportation of relief materials. Considering the characteristics of the two-level emergency logistics system including uncertain demand, uncertain transportation time, multiple varieties of relief materials, shortage of supply, multi-transportation modes and different urgencies of relief material demand, the integrated issue with the concern of transfer facility location and relief material transportation is studied. Then, this problem is formulated as a grey mixed integer bi-level nonlinear programming in which the upper-level aims at the shortest relief material transportation time and the lower-level aims at the maximum fairness of relief material distribution. According to the characteristics of the model, a hybrid genetic algorithm is designed to solve the proposed model. Finally, a numerical simulation is carried out on the background of 5.12 Wenchuan Earthquake. In addition, the validation of the proposed model and algorithm is verified. [ABSTRACT FROM AUTHOR]

The bacterial potassium channel KcsA binds lipid molecules and are involved in the in vitro refolding of the tetramer channel protein. Data indicate that negatively charged lipids mediate ion conduction through these channels.

Author(s): Yufeng Zhou; João H. Morais-Cabral [1]; Amelia Kaufman; Roderick MacKinnon Potassium channels control the electric potential across cell membranes by catalysing the rapid, selective diffusion of K[sup.+] ions down [...]

Author(s): João H. Morais-Cabral [1]; Yufeng Zhou; Roderick MacKinnon (corresponding author) The KcsA K[sup.+] channel contains multiple K[sup.+] ions in its conduction pore (Fig. 1a). One ion resides at the [...]