Purification, molecular characterization of Lactocin 63 produced by Lactobacillus coryniformis FZU63 and its antimicrobial mode of action against Shewanella putrefaciens.

Bacteriocins derived from lactic acid bacteria (LAB) are well recognized as promising food preservative due to high safety and potent antibacterial activity against foodborne pathogens and spoilage bacteria. In this study, an antimicrobial agent-producing strain FZU63 from Chinese sauerkraut was identified as Lactobacillus coryniformis based on physio-biochemical characterization and 16S rDNA sequence analysis. In addition, a bacteriocin was purified from the culture supernatant of L. coryniformis FZU63, and its molecular mass was determined as 1493.709 Da. Moreover, the amino acid sequence of the bacteriocin was predicted to be RQQPMTLDYRW-NH2 using nanoliter/microliter liquid chromatography combined with triple quadrupole-linear ion trap tandem mass spectrometry and was named as Lactocin 63. Furthermore, Lactocin 63 displays potent antimicrobial activity against the tested Gram-positive and negative bacteria based on the results of determining MICs. Subsequently, the action mode of Lactocin 63 against Shewanella putrefaciens was investigated. The results demonstrated that Lactocin 63 targets and is adsorbed onto the bacterial cell wall and membrane and then disrupts cytoplasmic membrane, which is leading to leakage of cytoplasm according to the results of flow cytometry analysis and the observation of cellular ultra-structure using confocal laser microscopy and atomic force microscopy. Collectively, these results are helpful and providing the theoretical base for developing and applying LAB-derived bacteriocins as promising bio-preservatives to combat foodborne pathogens and spoilage bacteria in seafood industries.Key points• A bacteriocin-producing strain Lactobacillus coryniformis was isolated.• A novel bacteriocin produced by Lactobacillus coryniformis FZU63 was characterized.• Action mechanism of the bacteriocin against S. putrefaciens was elucidated in vitro.

Quantitative-profiling of neurotransmitter abnormalities in the disease progression of experimental diabetic encephalopathy rat.

Diabetic encephalopathy (DE) is one of the most prevalent chronic complications of diabetes mellitus (DM), with neither effective prevention nor proven therapeutic regimen. This study aims to uncover the potential dysregulation pattern of the neurotransmitters in a rat model of streptozotocin (STZ)-induced experimental DE. For that purpose, male Sprague-Dawley (SD) rats were treated with a single intraperitoneal injection of STZ. Cognitive performance was detected with the Morris water maze (MWM) test. Serum, cerebrospinal fluid (CSF), and brain tissues were collected to measure the levels of neurotransmitters. Compared with the control rats, the acetylcholine (ACh) levels in serum, CSF, hippocampus, and cortex were all significantly down-regulated as early as 6 weeks in the STZ treatment group. In contrast, the glutamate (Glu) levels were decreased in CSF and the hippocampus, but unaffected in the serum and cortex of STZ-treated rats. As for γ-aminobutyric acid (GABA), it was down-regulated in serum, but up-regulated in CSF, hippocampus, and the cortex in the STZ-treated group. The mRNA expressions of neurotransmitter-related rate limiting enzymes (including AChE, GAD1, and GAD2) and pro-inflammatory cytokines (including IL-1ß and TNF-α) were all increased in the DE rats. Our data suggest that DM induces isoform-dependent and tissue-specific neurotransmitter abnormalities, and that neuroinflammation may underlay the nervous system dysfunction observed in the progression of DE.

[Cloning, expression, directed evolution in vitro and structural simulation of ß-glycosidase from Bacillus subtilis].

OBJECTIVE: To further study physiological functions and structure of ß-glycosidase, we cloned the bglC gene of Bacillus subtilis and expressed it in E. coli BL21 (DE3), followed by the characterization and structural simulation of the enzyme. METHODS: We amplified the bglC gene and transferred it into E. coli BL21 (DE3), then we obtained a mutant with higher hydrolytic activity by directed evolution. After purifying the enzymes through a nickel-nitrilotriacetic acid agarose column, we characterized the wild-type and mutant enzymes. By means of CD spectrum, Native-PAGE and protein 3-D structure modeling, we analyzed the higher structure of the ß-glycosidase. RESULTS: We got one mutant enzyme BS-GLY_M1 (A242T/T385A/S425L) with improved hydrolytic activity by directed evolution and screening. The specific activity of wild-type enzyme was 9.7 U/mg, with optimum temperature at 60 degrees C and optimum pH at 7.0. The specific activity of BS-GLY_M1 was 17. 1U/mg, with optimum temperature at 55 degrees C and optimum pH at 7.0. Moreover, the half-life time of the mutant enzyme at 55 degrees C was 3.5 h, 2 h longer than that of wild-type enzyme. Furthermore, the catalytic efficiency (K(m)/K(cat)) of BS-GLY_M1 on the substrates 4-nitrophenyl-ß-galactoside, lactose, and arbutin improved obviously. The polymer forms of the enzyme under the native conditions were of dimer and tetramer, but the dimer was the most probable functional unit. Result of structural simulation also showed slight changes occurred in the tertiary structure of the mutant enzyme, which may be the main reason for the enhanced thermal stability and catalytic efficiency of BS-GLY _M1. [ CONCLUSION: ß-glycosidase from Bacillus subtilis could be expressed in E. coli BL21 (DE3), meanwhile its hydrolysis efficiency could be further improved by directed evolution.

New-Generation Ferroelectric AlScN Materials.

Ferroelectrics have great potential in the field of nonvolatile memory due to programmable polarization states by external electric field in nonvolatile manner. However, complementary metal oxide semiconductor compatibility and uniformity of ferroelectric performance after size scaling have always been two thorny issues hindering practical application of ferroelectric memory devices. The emerging ferroelectricity of wurtzite structure nitride offers opportunities to circumvent the dilemma. This review covers the mechanism of ferroelectricity and domain dynamics in ferroelectric AlScN films. The performance optimization of AlScN films grown by different techniques is summarized and their applications for memories and emerging in-memory computing are illustrated. Finally, the challenges and perspectives regarding the commercial avenue of ferroelectric AlScN are discussed.

A ferroelectric fin diode for robust non-volatile memory.

Among today's nonvolatile memories, ferroelectric-based capacitors, tunnel junctions and field-effect transistors (FET) are already industrially integrated and/or intensively investigated to improve their performances. Concurrently, because of the tremendous development of artificial intelligence and big-data issues, there is an urgent need to realize high-density crossbar arrays, a prerequisite for the future of memories and emerging computing algorithms. Here, a two-terminal ferroelectric fin diode (FFD) in which a ferroelectric capacitor and a fin-like semiconductor channel are combined to share both top and bottom electrodes is designed. Such a device not only shows both digital and analog memory functionalities but is also robust and universal as it works using two very different ferroelectric materials. When compared to all current nonvolatile memories, it cumulatively demonstrates an endurance up to 1010 cycles, an ON/OFF ratio of ~102, a feature size of 30 nm, an operating energy of ~20 fJ and an operation speed of 100 ns. Beyond these superior performances, the simple two-terminal structure and their self-rectifying ratio of ~ 104 permit to consider them as new electronic building blocks for designing passive crossbar arrays which are crucial for the future in-memory computing.

Green preparation of graphene oxide nanosheets as adsorbent.

As a basic building block of graphene-based materials, graphene oxide (GO) plays an important role in scientific research and industrial applications. At present, numerous methods have been employed to synthesize GO, there are still some issues that need to be solved, thus it is of importance to develop a green, safe and low-cost GO preparation method. Herein, a green, safe and fast method was designed to prepare GO, namely, graphite powder was firstly oxidized in a dilute sulfuric acid solution (H2SO4, 6 mol/L) with hydrogen peroxide (H2O2, 30 wt%) as oxidant, and then exfoliated to GO by ultrasonic treatment in water. In this process, H2O2 was the only oxidant, and no other oxidants were used, thus the explosive nature of GO preparation reaction in the conventional methods could be completely eliminated. This method has other advantages such as green, fast, low-cost and no Mn-based residues. The experimental results confirm that obtained GO with oxygen-containing groups has better adsorption property compared to the graphite powder. As adsorbent, GO can remove methylene blue (50 mg/L) and Cd2+ (56.2 mg/L) from water with removal capacity of 23.8 mg/g and 24.7 mg/g, respectively. It provides a green, fast and low-cost method to prepare GO for some applications such as adsorbent.

The natural occurrence, toxicity mechanisms and management strategies of Fumonisin B1：A review.

Fumonisin B1 (FB1) contaminates various crops, causing huge losses to agriculture and livestock worldwide. This review summarizes the occurrence regularity, toxicity, toxic mechanisms and management strategies of FB1. Specifically, FB1 contamination is particularly serious in developing countries, humid and hot regions. FB1 exposure can produce different toxic effects on the nervous system, respiratory system, digestive system and reproductive system. Furthermore, FB1 can also cause systemic immunotoxicity. The mechanism of toxic effects of FB1 is to interfere with the normal pathway of sphingolipid de novo biosynthesis by acting as a competitive inhibitor of ceramide synthase. Meanwhile, the toxic products of sphingolipid metabolic disorders can cause oxidative stress and apoptosis. FB1 also often causes feed contamination by mixing with other mycotoxins, and then exerts combined toxicity. For detection, lateral flow dipstick technology and enzyme linked immunosorbent assay are widely used in the detection of FB1 in commercial feeds, while mainstream detection methods such as high performance liquid chromatography and liquid chromatography-mass spectrometry are widely used in the laboratory theoretical study of FB1. For purification means of FB1, some natural plant extracts (such as Zingiber officinale and Litsea Cubeba essential oil) and their active compounds have been proved to inhibit the toxic effects of FB1 and protect livestock due to their antifungal and antioxidant effects. Natural plant extract has the advantages of high efficiency, low cost and no contamination residue. This review can provide information for comprehensive understanding of FB1, and provide reference for formulating reasonable treatment and management strategies in livestock production.

Lycopene Alleviates Chronic Stress-Induced Hippocampal Microglial Pyroptosis by Inhibiting the Cathepsin B/NLRP3 Signaling Pathway.

Lycopene (LYC) exerts a strong neuroprotective and antipyroptotic effects. This study explored the effects and mechanisms of LYC on chronic stress-induced hippocampal microglial damage and depression-like behaviors. The caspase-1 inhibitor VX-765 attenuated chronic restrain stress (CRS)-induced hippocampal microglial pyroptosis and depression-like behaviors. Moreover, the alleviation of CRS-induced hippocampal microglial pyroptosis and depression-like behaviors by LYC was associated with the cathepsin B/NLRP3 pathway. In vitro, the caspase-1 inhibitor Z-YVAD-FMK alleviated pyroptosis in highly aggressively proliferating immortalized (HAPI) cells. Additionally, the alleviation of corticosterone-induced HAPI cell damage and pyroptosis by LYC was associated with the cathepsin B/NLRP3 pathway. Furthermore, the cathepsin B agonist pazopanib promoted HAPI cell pyroptosis, whereas LYC inhibited pazopanib-induced pyroptosis via the cathepsin B/NLRP3 pathway. Similarly, Z-YVAD-FMK inhibited pazopanib-induced HAPI cell pyroptosis. These results suggest that LYC alleviates chronic stress-induced hippocampal microglial pyroptosis via the cathepsin B/NLRP3 pathway inhibition. This study provides a new strategy for treating chronic stress encephalopathy.

Ultralow-power in-memory computing based on ferroelectric memcapacitor network.

Analog storage through synaptic weights using conductance in resistive neuromorphic systems and devices inevitably generates harmful heat dissipation. This thermal issue not only limits the energy efficiency but also hampers the very-large-scale and highly complicated hardware integration as in the human brain. Here we demonstrate that the synaptic weights can be simulated by reconfigurable non-volatile capacitances of a ferroelectric-based memcapacitor with ultralow-power consumption. The as-designed metal/ferroelectric/metal/insulator/semiconductor memcapacitor shows distinct 3-bit capacitance states controlled by the ferroelectric domain dynamics. These robust memcapacitive states exhibit uniform maintenance of more than 104 s and well endurance of 109 cycles. In a wired memcapacitor crossbar network hardware, analog vector-matrix multiplication is successfully implemented to classify 9-pixel images by collecting the sum of displacement currents (I = C × dV/dt) in each column, which intrinsically consumes zero energy in memcapacitors themselves. Our work sheds light on an ultralow-power neural hardware based on ferroelectric memcapacitors.

Co-exposure of chronic stress and alumina nanoparticles aggravates hippocampal microglia pyroptosis by activating cathepsin B/NLRP3 signaling pathway.

Combined exposure of chronic stress and alumina nanoparticles (AlNPs) aggravates hippocampal injury, but the pathogenesis is unevaluated. This study aimed to investigate the effect and mechanism of co-exposure to chronic stress and AlNPs on hippocampal microglia pyroptosis. In this study, chronic restraint stress (CRS) alone caused NLRP3-mediated hippocampal microglia pyroptosis, but AlNPs did not. Moreover, co-exposure to CRS and AlNPs exacerbated hippocampal microglia pyroptosis, resulting in more severe hippocampal damage and behavioral deficits in rats. Protein-protein interaction network predicted that cathepsin B was a potential regulatory protein of NLRP3. CRS up-regulated cathepsin B expression which had a more pronounced increase in co-exposure group. Whereas, caspase-1 inhibitor VX-765 alleviated hippocampal microglia pyroptosis and behavioral deficits in rats. Consistent with in vivo results, co-exposure of corticosterone and AlNPs aggravated NLRP3-mediated pyroptosis and cathepsin B expression in HAPI cells. Nevertheless, the pyroptosis of HAPI cells was inhibited by cathepsin B inhibitor CA-074Me and NLRP3 knockout, respectively. NLRP3 agonist nigericin failed to promote the pyroptosis of HAPI cells in the presence of cathepsin B inhibition. These results demonstrated that co-exposure to chronic stress and AlNPs could aggravate hippocampal microglia pyroptosis by activating cathepsin B/NLRP3 signaling pathway, resulting in hippocampal damage and behavioral deficits.

Facile preparation of Ti3C2Tx sheets by selectively etching in a H2SO4/H2O2 mixture.

MXenes and MXene-based composite materials have potential applications in a wide range of areas due to their unique physical and chemical characteristics. At present, it is still a major challenge to develop a simple, safe, and efficient route to prepare MXenes without using fluorinated etchants. Herein, we design a facile method to prepare Ti3C2Tx MXene sheets by selectively etching Ti3AlC2 powders in an aqueous diluted H2SO4 solution with H2O2 as an oxidant. In a system of H2SO4 and H2O2, an aqueous H2SO4 solution with a concentration of 6 mol/L is a strongly acidic medium with no volatility, and 30% H2O2 acts as a strong green oxidizer without harmful by-products. The experimental process is safe and convenient to conduct in a beaker under a water bath of 40°C. The etching process can be completed in 1 h under the air atmosphere conditions. The experimental results confirmed that the etched Ti3AlC2 powders can be successfully separated into Ti3C2Tx nanosheets under ultrasound treatment without using any intercalation agent. The relevant etching mechanism is may be attributed to the synergy effect of H2SO4 and H2O2, which triggers sequential selective etching of Al layers from the Ti3AlC2 phase. It may provide a new green way to prepare MXene-based materials without using toxic HF or HF-containing etchants.

Ultralow-Power Machine Vision with Self-Powered Sensor Reservoir.

A neuromorphic visual system integrating optoelectronic synapses to perform the in-sensor computing is triggering a revolution due to the reduction of latency and energy consumption. Here it is demonstrated that the dwell time of photon-generated carriers in the space-charge region can be effectively extended by embedding a potential well on the shoulder of Schottky energy barrier. It permits the nonlinear interaction of photocurrents stimulated by spatiotemporal optical signals, which is necessary for in-sensor reservoir computing (RC). The machine vision with the sensor reservoir constituted by designed self-powered Au/P(VDF-TrFE)/Cs2 AgBiBr6 /ITO devices is competent for both static and dynamic vision tasks. It shows an accuracy of 99.97% for face classification and 100% for dynamic vehicle flow recognition. The in-sensor RC system takes advantage of near-zero energy consumption in the reservoir, resulting in decades-time lower training costs than a conventional neural network. This work paves the way for ultralow-power machine vision using photonic devices.

Ultrathin nickel oxide film as a hole buffer layer to enhance the optoelectronic performance of a polymer light-emitting diode.

In order to promote a polymer LED (PLED), we fabricated and introduced an ultrathin nickel oxide (NiO) buffer layer (<10 nm) between the indium tin oxide (ITO) anode and the poly (3, 4-ethylenedioxythiophene) hole injection layer in the PLED. The NiO buffer layer was easily formed on the ITO anode by electron-beam deposition of a nickel (Ni) metal source and an oxygen plasma treatment process. As a result, the PLED device with the NiO buffer layer on its ITO anode had the same turn-on voltage as conventional PLED devices without the NiO buffer layer, and the luminance of the PLED device with the NiO buffer layer was doubled, compared with the conventional PLED devices without the NiO buffer layer. Improvement of the optoelectronic performance of the PLED can be attributed to the increase of the current driven into the diode, resulting from the NiO buffer layer, which can enhance the hole injection and balance the injection of the two types of carriers (holes and electrons). Thus it is an excellent choice to introduce the NiO buffer layer onto the ITO anode of the PLED devices in order to enhance the optoelectronic performance of PLED devices.

Synthesis of Tower-Like ZnO Nanostructures and Its Optical Properties.

A peculiar tower-like ZnO nanostructure was synthesized using an economical and facile hydrothermal method, with zinc acetate [ZAc, Zn(CH3COO)2 · 2H2O] and hexamethylenetetramine (HMTA, C6H12N4) as the source materials. The as-synthesized tower-like ZnO was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The characterization results indicated that the tower-like ZnO nanostructures are high-quality monocrystals. The as-synthesized ZnO nanostructures may have application in sensing area due to its high specific surface areas. The growth mechanism, as well as the optical properties of the as-synthesized tower-like ZnO nanostructures was also studied.

Plasmon-Enhanced Ultraviolet Photoluminescence from the Graphene/GaN Nanofilm.

The response of graphene surface plasmon (SP) in ultraviolet (UV) wavelength region and its functional applications on the short wavelength of graphene/semiconductorare both fascinating research areas. Herein, a hybrid structure of graphene/GaN nanofilm was designed and fabricated to investigate the photoluminescence (PL) performance and the coupling dynamics. It is demonstrated that the resonant coupling between graphene SPs and GaN exciton emission is responsible for the substantially enhanced PL from the structure of graphene/GaN nanofilm. The underlying mechanism of the improved PL performance was proposed based on theoretical simulation and experimental characterization. The results are helpful to design new types of optic and photoelectronic devices based on SP coupling in graphene/semiconductor hybrid structures.

3D Graphene Oxide Hydrogel Derived from Waste Toner as Adsorbent.

Waste toner powders are considered as hazardous materials to human and living things, and should be properly recycled by many effective ways due to their fine particle sizes and complex components. In this paper, waste toner powders were used as raw materials to successfully synthesize three dimensions (3D) graphene oxide (GO) hydrogel by means of a one-pot chemical transformation based on the improved Hummers' method. The obtained 3D GO hydrogel has porous structure and abundant oxygen-containing functional groups because of the inherent 3D solid structure of waste toner powder and the strong oxidation process of the improved Hummers' method. Interestingly, the as-prepared 3D GO hydrogel with excellent adsorptive property could quickly remove Pb(II) ions (100 mg/L, removal efficiency of 96% and removal capacity of 144 mg/g) and methylene blue (50 mg/L, removal efficiency of 97% and removal capacity of 48 mg/g) from water, respectively. The preparation process of 3D GO hydrogel was simple and easy to operate, and the output can be moderately mass produced, thus it would provide a new and effective disposal way for the recycling and reusing of waste toner.

Surface plasmon interference on the surface of an aluminum-covered fiber core array for solgel fabrication of submicrometer gratings.

An interesting method to fabricate submicrometer gratings (SMGs) utilizing the interference of surface plasmon waves (SPWs) is presented. The stationary wave field off the aluminum (Al) layer surface of an Al-covered UV fiber core, formed by the interference of the induced SPWs, has been employed as a submicrometer photolithography tool to inscribe SMGs on the surface of a self-processing hybrid HfO(2)/SiO(2) solgel film. Using atomic force microscopy, the period of the fabricated SMGs was measured as 105 nm. The intensity distribution of the stationary wave field was measured by a near-field scanning optical microscope and anastomosed with theoretical values calculated by using FDTD simulations.

Characterization and Application of PVDF and Its Copolymer Films Prepared by Spin-Coating and Langmuir-Blodgett Method.

Poly(vinylidene fluoride) (PVDF) and its copolymers are key polymers, displaying properties such as flexibility and electroactive responses, including piezoelectricity, pyroelectricity, and ferroelectricity. In the past several years, they have been applied in numerous applications, such as memory, transducers, actuators, and energy harvesting and have shown thriving prospects in the ongoing research and commercialization process. The crystalline polymorphs of PVDF can present nonpolar α, ε phase and polar ß, γ, and δ phases with different processing methods. The copolymers, such as poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), can crystallize directly into a phase analogous to the ß phase of PVDF. Since the ß phase shows the highest dipole moment among polar phases, many reproducible and efficient methods producing ß-phase PVDF and its copolymer have been proposed. In this review, PVDF and its copolymer films prepared by spin-coating and Langmuir-Blodgett (LB) method are introduced, and relevant characterization techniques are highlighted. Finally, the development of memory, artificial synapses, and medical applications based on PVDF and its copolymers is elaborated.

Burstein-Moss Effect Behind Au Surface Plasmon Enhanced Intrinsic Emission of ZnO Microdisks.

In this paper, ZnO microdisks with sputtering of Au nanoparticles were prepared to explore their plasmon/exciton coupling effect. An obvious blue shift and enhanced excitonic emission intensity were observed in the PL spectra of as-grown and Au-sputtered ZnO samples at room temperature. The investigation on the absorption spectra and temperature-dependent PL spectra has been demonstrated the Burstein-Moss effect behind the optical phenomena. These results revealed the coupling dynamics between the metal localized surface plasmon and semiconductor exciton.

Plasmon-enhanced Electrically Light-emitting from ZnO Nanorod Arrays/p-GaN Heterostructure Devices.

Effective and bright light-emitting-diodes (LEDs) have attracted broad interests in fundamental research and industrial application, especially on short wavelength LEDs. In this paper, a well aligned ZnO nanorod arrays grown on the p-GaN substrate to form a heterostructured light-emitting diode and Al nanoparticles (NPs) were decorated to improve the electroluminescence performance. More than 30-folds enhancement of the electroluminescence intensity was obtained compared with the device without Al NPs decoration. The investigation on the stable and transient photoluminescence spectraof the ZnO nanorod arrays before and after Al NPs decoration demonstrated that the metal surface plasmon resonance coupling with excitons of ZnO leads to the enhancement of the internal quantum efficiency (IQE). Our results provide aneffective approach to design novel optoelectronic devices such as light-emitting diodes and plasmonic nanolasers.