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Lipase is an industrial enzyme, the catalytic efficiency of which is restricted by various environmental factors. To improve this efficiency, immobilization technology has been utilized in the past to improve the stability of lipase in harsh conditions. Immobilization technology can be divided into physical methods and chemical methods. Some unsolved problems remain in current immobilization technology. The interaction between enzyme and immobilization support is weak and reversible during physical adsorption, resulting in poor stability of the immobilized enzyme and the contamination of substrate solution by leached enzymes. In chemical methods, enzyme-active sites might be inactivated due to the chemical reactions between enzyme molecules and support, resulting in a decrease in the enzymes’ catalytic activity (Liu et al., 2018a). The objective of the current study was to construct a nanostructured lipase via Mg-amino-clay as a carrier and improve the catalytic activity and stability of lipase by immobilization. Lipase produced by Aspergillus oryzaewas immobilized on aminopropyl functionalized magnesium phyllosilicate (a 2:1 trioctahedral talc-like silicate Mg-amino-clay) via a 1-(3-Dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride (EDC) coupling agent. The physical and chemical properties of the Mg-amino-clay and Mg-amino-clay-based nanostructured biocatalyst (Mg-clay-lipase) were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy. Optimal immobilization conditions were determined by taking into account the following variables: amount of initial lipase, EDC concentration, and reaction time. The results revealed that the optimum temperature, pH, and thermal stability of Mg-clay-lipase were greater than equivalent values for free lipase under optimal conditions (described below – Process for Immobilization of Lipase on Mg-amino-clay). The Michaelis-Menten constant (Km) values were 5.25 mM and 7.42 mM while the maximum reaction rates (vmax) were 30.58 mM/(L·min) and 55.87 mM/(L·min) for free lipase and Mg-clay-lipase, respectively. The present study provided a new nanostructured biocatalyst and demonstrated that the enzyme activity and stability of Mg-clay-lipase were superior to those of free lipase due to the mechanism of 'interface activation'.

Maintaining drinking water security is a global issue, and phosphorus is a limiting factor affecting drinking water quality. Hence, this study took Fushi Reservoir as a test area, and set up field runoff observation plots around the reservoir catchment, which is covered by moso bamboo stands. Through field observation, the vertical variation of phosphorus loss in different stands of moso bamboo was initially studied. The results showed that: (1) For the vertical dimensions (atmospheric rainfall, stemflow, throughfall, surface runoff) from high to low, the loss of total phosphorus (TP) increased, and the proportion of dissolved phosphorus increased from 29.29% (atmospheric rainfall) to 62.76% (surface runoff). (2) Different rainfall factors had various impacts on phosphorus loss at the different vertical levels. The accumulation of rainfall had the greatest impact on surface runoff TP loss, with the correlation coefficient reaching 0.994 (P < 0.01), while surface runoff particulate phosphorus loss was mostly affected by the average rainfall intensity. (3) Modifying the forest structure in water source areas can reduce the loss of TP via stemflow and throughfall, but the effect on surface runoff TP loss is variable. Thus, it is expected that this novel study can serve as a reference for improving the environmental quality of water source areas, and help in reducing phosphorus loss and controlling non-point source pollution.

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Heterogeneity in the acquired genetic cause of osimertinib resistance leads to difficulties in understanding and addressing molecular mechanisms of resistance in clinical practice. Recent studies and clinical cases established that altered BRAFcould drive osimertinib resistance in an EGFR-independent manner. Herein, we present a case in which an EGFR-positive, MET-amplified nonsmall cell lung cancer (NSCLC) patient acquired BRAFp.D594N mutation on third-line osimertinib plus crizotinib and responded to seventh-line treatment with osimertinib plus MEK inhibitor trametinib. Disease control was maintained for 6 months. BRAFp.D594N is a kinase impaired mutation but leads to increased MEK/ERK signaling, which could activate the downstream signaling of EGFR and induce drug resistance. There has been preclinical evidence supporting dual inhibition of MEK and EGFR for overcoming this resistance. To the best of our knowledge, our case is the first to provide clinical evidence that trametinib plus osimertinib was effective for EGFR-mutant NSCLC patients with acquired BRAFp.D594N mutation. More supporting data and systematic validation studies are needed for comprehensive understanding of this therapy strategy and future applications.

In recent years, nanozymes have become promising alternatives to natural enzymes owing to their high catalytic efficiency, substrate specificity, and mild reaction conditions. The catalytic performance of nanozymes can be further improved by doping heterogeneous metals to provide high redox potentials. However, nanozymes for the degradation of endocrine-disrupting chemicals (EDCs) have been scarcely studied, and the degradation mechanisms remain unclear. Herein, a series of aminoclays (ACs) containing various metal dopants were prepared and employed for the degradation of phenolic compounds. The as-synthesized ACs with a Cu-Mn molar ratio of 1:7 (CuMnAC-1–7) showed excellent stability and superior activity for oxidizing bisphenol A (BPA) than natural laccases owing to the electron transport between Cu2+/Cu+and Mn4+/Mn3+in the nanozyme. The catalytic oxidation process of BPA consists of a non-free radical pathway mediated by Mn3+, as well as a free radical pathway facilitated by superoxide radicals (O2·-) and singlet oxygen (1O2). Specifically, Mn3+deprived the electrons of the BPA benzene ring to form phenolic hydroxyl radicals, which were then polymerized to BPA dimers. Cu+in the structure reduced Mn4+to Mn3+, accelerating the electron deprivation of BPA and promoting the polymerization reaction. Finally, the high-charge-density region on the dimeric benzene ring tended to lose electrons and form free radicals, facilitating the polymerization into trimers and tetramers. The CuMnAC-1–7 could remove 95% of BPA at a concentration of 200 mg/L within 1 h under acidic conditions. This study provides a new strategy to design high-performance laccase nanozymes for EDCs degradation.

Photocatalysis is a green and sustainable technique for converting solar energy into energy-storage molecules. A novel type of metal-free photocatalyst consisting of polydopamine (PDA) surface-functionalized graphitic carbon nitride (g-C3N4) was fabricated to enable the highly efficient visible-light-driven photocatalytic production of reduced nicotinamide adenine dinucleotide (NADH) through the photomediated reduction of NAD+. The photocatalytic performance and kinetic processes were investigated to evaluate the efficiency of NADH regeneration by the PDA/g-C3N4photocatalysts. It was shown that the PDA layer thus formed could promote the charge carrier transfer of g-C3N4to increase the solar-to-chemical conversion efficiency under visible light irradiation. A photocurrent density three times higher than that of pristine g-C3N4was obtained. The photocatalytic activity of the PDA/g-C3N4photocatalysts appeared to be dependent on the pH, with an increase in the pH from 3.0 to 9.5 substantially enhanced the NADH yield. The 20 wt % PDA/g-C3N4exhibited remarkably improved photocatalytic NADH regeneration efficiency, achieving an NADH yield of 94.7% with an initial reaction rate of 2.4 mmol·h–1·g–1, which is approximately six times higher than that of pristine g-C3N4. Our study thus identifies a promising photocatalyst for enhancing the photocatalytic efficiency for nicotinamide cofactor regeneration.

Shoot branching, determining plant architecture and crop yield, is critically controlled by strigolactones (SLs). However, how SLs inhibit shoot branching after its perception by the receptor complex remains largely obscure. In this study, using the transcriptomic and genetic analyss as well as biochemical studies, we reveal the key role of BES1 in the SL-regulated shoot branching. We demonstrate that BES1 and D53-like SMXLs, the substrates of SL receptor complex D14–MAX2, interact with each other to inhibit BRC1expression, which specifically triggers the SL-regulated transcriptional network in shoot branching. BES1 directly binds the BRC1promoter and recruits SMXLs to inhibit BRC1expression. Interestingly, despite being the shared component by SL and brassinosteroid (BR) signaling, BES1 gains signal specificity through different mechanisms in response to BR and SL signals.

The network switches and routers require both high-speed and large-capacity packet buffers. However, existing packet buffer architectures have the problems of speed scaling and flow number scaling limitations. To address the two problems simultaneously, this paper proposes a parallel hybrid SRAM/DRAM architecture for per-flow buffering in high-speed switches and routers. Tail SRAM and head SRAM are used to apply per-flow buffering for packet aggregation, so that the middle DRAM is accessed in a larger granularity and the DRAM's bandwidth utilization is improved. To mitigate the flow number scaling limitation, a dynamic memory allocation with hard timeout (DMA-HT) memory management algorithm is designed. The key idea of DMA-HT is that the memory space is dynamically allocated for the newly arrived flows, and a hard timeout is assigned for each queue. After a specific period of time, the memory space is freed, so that the SRAM space is efficiently utilized by the most recently active flows. A queuing system is used to model the proposed method, and theoretical analysis is performed to optimize the timeout value. With the derived formulas, multiple performance parameters are quantitatively analyzed, and the optimal timeout can be obtained. Both numerical results and simulations show that the proposed architecture can and reduce packet loss rate and average delay significantly compared with previous solutions with the same SRAM capacity.

High temperature adversely affects plant growth and development. The steroid phytohormones brassinosteroids (BRs) are recognized to play important roles in plant heat stress responses and thermotolerance, but the underlying mechanisms remain obscure. Here, we demonstrate that the glycogen synthase kinase 3 (GSK3)-like kinase BRASSINOSTEROID INSENSITIVE2 (BIN2), a negative component in the BR signaling pathway, interacts with the master heat-responsive transcription factors CLASS A1 HEAT SHOCK TRANSCRIPTION FACTORS (HsfA1s). Furthermore, BIN2 phosphorylates HsfA1d on T263 and S56 to suppress its nuclear localization and inhibit its DNA-binding ability, respectively. BR signaling promotes plant thermotolerance by releasing the BIN2 suppression of HsfA1d to facilitate its nuclear localization and DNA binding. Our study provides insights into the molecular mechanisms by which BRs promote plant thermotolerance by strongly regulating HsfA1d through BIN2 and suggests potential ways to improve crop yield under extreme high temperatures.

Core IdeasThe expansion properties of montmorillonites treated with PHA steeply decreased.A mixture of montmorillonites and PHA solution is not a colloidal system.Al13groups are the main intercalator and factor influencing swelling behavior.The treatment may be applied in expansive soil research. Studies concerning noncolloidally crosslinked montmorillonites (NCMs) are significant for the chemical treatment of expansive soil. In this study, NCMs with OH/Al molar ratios of 1.0, 1.5, 2.0, and 2.5 and Al/montmorillonite ratios of 0.1, 0.3, 0.5, 0.8, and 1.0 mmol g−1were prepared via AlCl3–NaOH reactions and subsequent Al13–montmorillonite interactions. The resulting NCMs exhibited the characteristics of silt as well as significant expansion and mechanical property changes. The expansion properties of the NCM samples, including the free swelling ratio, swelling force, free expansion ratio, and expansion ratio under 50 kPa all decreased significantly. According to the X‐ray diffraction data, the basal spacing of the NCM samples became relatively stable and slightly expanded after the drying and rewetting processes. Additionally, the cohesive force and shear strength of the NCM samples increased significantly after the crosslinking process. Furthermore, the X‐ray fluorescence spectrometry results confirmed that the Al oxide content of the NCMs increased as the swelling properties decreased, indicating that primarily the Al13groups influenced the swelling behavior of the NCMs.

Abstract: A sandwich beam model consisting of two face sheets and a foam core bonded by a viscoelastic adhesive layer is considered in order to investigate interfacial fracture behavior. Firstly, a cohesive zone model in conjunction with a Maxwell element in parallel, or with a Kelvin element in series, respectively, is employed to describe the characteristics of viscoelasticity for the adhesive layer. The models can be implemented into the implicit finite element code. Next, the parametric study shows that the influences of loading rates on the cohesive zone energy and strength are quite different for different models. Finally, a sandwich double cantilever beam model is adopted to simulate the interface crack growth between the face sheet and core. Numerical examples are presented for various loading rates to demonstrate the efficacy of the rate-dependent cohesive models.

Model I quasi-static nonlinear fracture of aluminum foams is analyzed by considering the effect of microscopic heterogeneity. Firstly, a continuum constitutive model is adopted to account for the plastic compressibility of the metallic foams. The yield strain modeled by a two-parameter Weibull-type function is adopted in the constitutive model. Then, a modified cohesive zone model is established to characterize the fracture behavior of aluminum foams with a cohesive zone ahead of the initial crack. The tensile traction versus local crack opening displacement relation is employed to describe the softening characteristics of the material. And a Weibull statistical model for peak bridging stress within the fracture process zone is used for considering microscopic heterogeneity of aluminum foams. Lastly, the influence of stochastic parameters on the curve of stress-strain is given. Numerical examples are given to illustrate the numerical model presented in this paper and the effects of Weibull parameters and material properties on J-integral are discussed.

Various enzymatic reactions or enzymatic cascade reactions occur efficiently in biological microsystems due to space constraints or orderly transfer of intermediate products. Inspired by this, the horseradish peroxidase (HRP)-like nanozyme (Fe-aminoclay) was in situsynthesized on the surface of alkali-activated halloysite nanotubes and the natural enzyme (glucose oxidase, GOx) was immobilized on it to construct a high-efficiency GOx-FeAC@AHNTs cascade nanoreactor. In which, FeAC@AHNTs can not only be used as a carrier for immobilized enzymes, but also help its catalytic activity to cooperate with glucose oxidase in a cascade reaction. The microcompartments and substrate channel effect of this enzyme-nanozyme microsystem exhibit a superior catalytic performance than that of natural enzyme system, and exhibits excellent long-term stability and recyclability. Subsequently, the GOx-FeAC@AHNTs cascade nanoreactor was employed as a glucose colorimetric platform, which displayed a low detection limit (0.47 μmol/L) in glucose detection. This enzyme-nanoenzyme nanoreactor provides a simple and effective example for constructing a multi-enzyme system with limited space, and lays the foundation for subsequent research in the fields of biological analysis and catalysis.

From prokaryotes to eukaryotes, the DNA condensation process by basic proteins is essential to store the genome in vivo. The surface charge inversion with a DNA/HCcp3 charge ratio of 0.7/1 indicates a role for HCcp3-mediated counter ion-driven mechanism in DNA condensation. The formation of the cholesteric liquid-crystalline phase of DNA–HCcp3 complexes occurred when DNA charges were neutralized. The results suggest that DNA condensation processes by HCcp3 can be divided into two distinctive binding stages: the first state, prior to condensation, involves an entropy-driven binding process of HCcp3 to the DNA, while the second state is an electrostatically driven condensing and assembling process.

In this article, a novel method has been developed for extracellular prepared of amorphous ring and chain cobalt nanostructures using Staphylococcus epidermidisin combination with PVP as template. The nanostructures consist of cobalt nanoparticles with the average particle size of 50 nm. The morphological difference between chain and ring nanostructures is determined by the interaction between PVP and bacteria. Extracellular prepation of nanostructures using bacteria as template opens up a new possibility to fabricate metal-based nanostructures in biological system.