We report on large-scale nonequilibrium molecular dynamics simulations of shock wave compression in tantalum single crystals. Two new embedded atom method interatomic potentials of Ta have been ...developed and optimized by fitting to experimental and density functional theory data. The potentials reproduce the isothermal equation of state of Ta up to 300 GPa. We examined the nature of the plastic deformation and elastic limits as functions of crystal orientation. Shock waves along (100), (110), and (111) exhibit elastic-plastic two-wave structures. Plastic deformation in shock compression along (110) is due primarily to the formation of twins that nucleate at the shock front. The strain-rate dependence of the flow stress is found to be orientation dependent, with (110) shocks exhibiting the weaker dependence. Premelting at a temperature much below that of thermodynamic melting at the shock front is observed in all three directions for shock pressures above about 180 GPa.
The human oral cavity is host to a diverse microbiota. Much of what is known about the behaviour of oral microbes derives from studies of individual or several cultivated species, situations which do ...not totally reflect the function of organisms within more complex microbiota or multispecies biofilms. The number of validated models that allow examination of the role that biofilms play during oral cavity colonization is also limited. The CDC biofilm reactor is a standard method that has been deployed to study interactions between members of human microbiotas allowing studies to be completed during an extended period under conditions where nutrient availability, and washout of waste products are controlled. The objective of this work was to develop a robust in vitro biofilm‐model system from a pooled saliva inoculum to study the development, reproducibility and stability of the oral microbiota. By employing deep sequencing of the variable regions of the 16S rRNA gene, we found that the CDC biofilm reactor could be used to efficiently cultivate microbiota containing all six major phyla previously identified as the core saliva microbiota. After an acclimatisation period, communities in each reactor stabilised. Replicate reactors were predominately populated by a shared core microbiota; variation between replicate reactors was primarily driven by shifts in abundance of shared operational taxonomic units. We conclude that the CDC biofilm reactor can be used to cultivate communities that replicate key features of the human oral cavity and is a useful tool to facilitate studies of the dynamics of these communities.
Significance and Impact of the Study: The CDC biofilm reactor is a continuous‐flow culture model that has been deployed to study complex interactions between members of human microbiotas. In this study, we used the CDC biofilm reactor to efficiently grow and maintain diverse oral microbiota. This robust model could be used to both study the safety of antimicrobial‐containing oral care products and examine novel approaches to modify plaque composition using pre‐ or probiotics.
Since the 1980s, vacuum hot rolling has been developed to fabricate the stainless steel clad plates by the Iron and Steel Institute of Japan. Herein, hot rolling is a widely used solid-state bonding ...process to join the carbon steel substrate and stainless steel cladding. In this paper, we provide a brief overview of the vacuum hot rolling process and effective parameters on the interface characteristics and shear strength of stainless steel clad plate. The effects of surface preparation condition, atmosphere condition, vacuum degree, rolling temperature, rolling reduction ratio, interlayer, heat treatment on the microstructure, interface characteristics and mechanical properties of stainless steel clad plate have been analyzed in detail. It is shown that the interface transition zone is formed due to the carbon diffusion, and the strong interface bonding is attributed to the sufficient alloy elements diffusion of Fe, Cr and Ni. Moreover, the interface shear strength and toughness are also affected by interfacial precipitation phase and multiple oxides. Finally, the present work concluded the bonding mechanism of hot-rolled stainless steel clad based on the oxide film theory, diffusion theory, recrystallization theory and three stage theory.
OBJECTIVETo observe the therapeutic effect of metformin on pathological pain in mice with radiation dermatitis and explore the underlying mechanism.METHODSThirty-two male adult ICR mice were ...randomized into normal control group, radiation dermatitis model group, metformin treatment (200 mg/kg) group and gabapentin (100 mg/kg) group (n=8).In the latter two groups, metformin treatment was administered after modeling via intraperitoneal injection and gabapentin by gavage on a daily basis for 16 days; the mice in the control group and model group received intraperitoneal injection of normal saline.After the last administration, radiation dermatitis was graded in each group.Mechanical withdraw threshold (MWT) and thermal withdrawal latency (TWL) of the mice were tested one day before and at 1, 4, 8, 12 and 16 days after modeling.Western blotting was used to measure the protein expression levels of p38MAPK, p-p38MAPK, NF-κB p65 and p-NF-κB p65 in the L4-L6 spinal cord, and the concentrations of IL-1β, IL-6 and TNF-
To examine algino-oligosaccharide production by alginase from newly isolated Flavobacterium sp. LXA and its elicitor and antibacterial activity. Algino-oligosaccharide production from alginate was ...carried out using alginase obtained from a newly isolated Flavobacterium sp. LXA. When alginase was partially purified by dual ammonium sulfate precipitation and used for alginate degradation, the viscosity loss correlated well with the release of reducing terminals. The optimal temperature and pH for alginate degradation was 40°C and pH 7·0, respectively. When alginate was added at an initial concentration of more than 0·8%, the maximal degradation rate of alginate was obtained. Under these optimal reaction conditions and with partially purified alginase, the average degrees of polymerization (DP) of alginate-degraded products was about 6·0, which favoured algino-oligosaccharide production. The algino-oligosaccharides showed an elicitor activity stimulating the accumulation of phytoalexin and inducing phenylalanine ammonia lyase in soybean cotyledon, and antimicrobial activity on Pseudomonas aeruginosa. Algino-oligosaccharide could be degraded from alginate by the partially purified alginase and its maximal bioactivity occurred on the oligosaccharide with average DP 6·8. Algino-oligosaccharide was first reported to have elicitor and antibacterial activity and have potential as a biological agent for protection against plant or human disease.
This paper presents the design and analysis of a low-pass spatial filter which has wideband absorption at high frequency using a 3D metamaterial rasorber (MR). The unit cell of the 3D MR is composed ...of several stacked layers of square patches with tapered dimensions, which are separated by thin lossy dielectric laminas. Every two adjacent layers’ metallic patches constitute a resonance cavity, and the inside lossy dielectric substrate results in absorption at the resonance frequency. The stacked metal–dielectric laminas construct a frustum pyramid. With the dimensions of the resonance cavities tapering from the bottom layer to the top layer, the pyramid absorbs over their resonance frequencies so that wideband absorption can be achieved. Besides, the incident wave at the frequencies below all these resonance frequencies can transmit through these cavities. Hence, the pyramid also constructs a low-pass spatial filter. The operation mechanism of this 3D MR structure is analyzed from several aspects by numerical simulation, and experimental measurement has also been executed to verify the design. The 3D metamaterial rasorber performs as an absorber in the Ku-band and a low-pass filter below the X-band. The absorption band with absorptivity higher than 80% spans from 12.3 GHz to 18.2 GHz, and the insertion loss at the frequency below 11.1 GHz is less than 0.9 dB.
We report the emergence of non-susceptibility to cefiderocol from a subpopulation of Pseudomonas aeruginosa recovered from a patient without history of cefiderocol exposure. Whole genome sequencing ...identified mutations in major iron transport pathways previously associated with cefiderocol uptake. Susceptibility testing should be performed before therapy with siderophore cephalosporins.
The effects and mechanisms of Paenibacillus polymyxa Sx3 on growth promotion and the suppression of bacterial leaf blight in rice were evaluated in this study. The results from a plate assay ...indicated that Sx3 inhibited the growth of 20 strains of Xanthomonas oryzae pv. oryzae (Xoo). Rice seedling experiments indicated that Sx3 promoted plant growth and suppressed bacterial leaf blight. In addition, bacteriological tests showed that Sx3 was able to fix nitrogen, solubilize phosphate and produce indole acetic acid, indicating that various mechanisms may be involved in the growth promotion by Sx3. The culture filtrate of P. polymyxa Sx3 reduced bacterial growth, biofilm formation and disrupted the cell morphology of Xoo strain GZ 0005, as indicated by the transmission and scanning electron microscopic observations. In addition, MALDI‐TOF MS analysis revealed that Sx3 could biosynthesize two types of secondary metabolites fusaricidins and polymyxin P. In summary, this study clearly indicated that P. polymyxa Sx3 has strong in vitro and in vivo antagonistic activity against Xoo, which may be at least partially attributed to its production of secondary metabolites.
Significance and Impact of the Study
Antagonistic bacteria can grow well in their originating environment. However, it is unclear whether antagonistic bacteria were able to survive in different ecological environments. This study revealed that Paenibacillus polymyxa Sx3 isolated from rhizosphere soil of cotton significantly promoted the plant growth and suppressed bacterial leaf blight in rice. Therefore, it could be inferred that P. polymyxa Sx3 has the potential to be used as biocontrol agents in plants grown in different ecological environments.
Significance and Impact of the Study: Antagonistic bacteria can grow well in their originating environment. However, it is unclear whether antagonistic bacteria were able to survive in different ecological environments. This study revealed that Paenibacillus polymyxa Sx3 isolated from rhizosphere soil of cotton significantly promoted the plant growth and suppressed bacterial leaf blight in rice. Therefore, it could be inferred that P. polymyxa Sx3 has the potential to be used as biocontrol agents in plants grown in different ecological environments.
We find that optical second-harmonic generation (SHG) in reflection from a chemical-vapor-deposition graphene monolayer transferred onto a SiO2/Si(001) substrate is enhanced about 3 times by the flow ...of direct current electric current in graphene. Measurements of rotational-anisotropy SHG revealed that the current-induced SHG from the current-biased graphene/SiO2/Si(001) structure undergoes a phase inversion as the measurement location on graphene is shifted laterally along the current flow direction. The enhancement is due to current-associated charge trapping at the graphene/SiO2 interface, which introduces a vertical electric field across the SiO2/Si interface that produces electric field-induced SHG. The phase inversion is due to the positive-to-negative polarity switch in the current direction of the trapped charges at the current-biased graphene/SiO2 interface.
We report tensile experiments on Ni80P20 metallic glass samples fabricated via a templated electroplating process and via focused ion beam milling, which differed only in their surface energy states: ...Ga-ion-irradiated and as-electroplated. Molecular dynamics simulations on similar Ni80Al20 systems corroborate the experimental results, which suggest that the transition from brittle to ductile behavior is driven by sample size, while the extent of ductility is driven by surface state.
PDF
