23 research outputs found
Preface to the 30th anniversary volume: A brief history of the journal [Online First Articles]
No full textDevelopment of Ti microalloyed high strength steel plate by controlling thermo-mechanical control process schedule
No full text
Detecting the greedy spectrum occupancy threat in cognitive radio networks
No full textRecently, security of cognitive radio (CR) is becoming a severe issue. There is one kind of threat, which we call greedy spectrum occupancy threat (GSOT) in this paper, has long been ignored in previous work. In GSOT, a secondary user may selfishly occupy the spectrum for a long time, which makes other users suffer additional waiting time in queue to access the spectrum and leads to congestion or breakdown. In this paper, a queueing model is established to describe the system with greedy secondary user (GSU). Based on this model, the impacts of GSU on the system are evaluated. Numerical results indicate that the steady-state performance of the system is influenced not only by average occupancy time, but also by the number of users as well as number of channels. Since a sudden change in average occupancy time of GSU will produce dramatic performance degradation, the greedy second user prefers to increase its occupancy time in a gradual manner in case it is detected easily. Once it reaches its targeted occupancy time, the system will be in steady state, and the performance will be degraded. In order to detect such a cunning behavior as quickly as possible, we propose a wavelet based detection approach. Simulation results are presented to demonstrate the effectiveness and quickness of the proposed approach. ? 2014 IEEE.EI
Effects of Histone Deacetylase 2 onEpithelial-Mesenchymal Transition in PulmonaryFibrosis
No full textBackground: Pulmonary fibrosis (PF) is a chronic and progressive interstitial lung disease. Histone deacetylases (HDACs) play
a crucial role in the onset and development of PF. Changes in HDACs 1–10 expression levels occur during PF development, and
their specific roles remain unclear. Therefore, we elucidated changes in the gene and protein levels of HDACs 1–10. Furthermore,
we selectively knocked down HDAC2 to explore the molecular mechanism underlying the regulatory role of HDAC2 in epithelialmesenchymal transition (EMT) during the development of PF.
Methods: Lewis lung carcinoma (LLC) cells were stimulated with transforming growth factor-β1 (TGF-β1) (5 ng/mL) to establish
a lung fibrosis cell model. Additionally, C57BL/6 mice received bleomycin through single intratracheal instillation at a 3.5 mg/kg
volume, diluted in 0.7 mL saline. Furthermore, EMT-related gene and protein expression levels were assessed using quantitative
PCR (qPCR) and Western blotting, respectively.
Results: We observed that HDAC2 expression levels were significantly increased in both the in vitro and in vivo PF models.
HDAC2 knockdown significantly decreased the expression levels of fibrosis indicators such as collagen type I (Col-I) and collagen
type IV (Col-IV), and EMT indicator α-smooth muscle actin (α-SMA) was observed. Conversely, it increased the expression
of EMT indicator E-cadherin (E-cad). Hematoxylin and eosin (H&E) and Masso staining revealed that HDAC2 knockdown
substantially reduced the degree of pulmonary fibrosis. These findings suggest that lowering HDAC2 expression inhibits EMT
and reduces PF. Moreover, in a TGF-β1-induced lung fibrosis cell model, HDAC2 knockdown significantly reduced epithelial
growth factor receptor levels, which inhibited mitogen-activated protein kinases (MAPK) signaling and decreased the protein
expression of p38 and c-Jun N-terminal kinase (JNK).
Conclusions: HDAC2 knockdown effectively impedes EMT and diminishes PF severity, impacting the JNK/p38 MAPK signaling
pathway, which may serve an inhibitory function
Superior stress relaxation resistance of 2.2 GPa martensitic steels and the effect of vanadium
No full textFor ultra-high-strength steels subjected to sustained loading, stress relaxation resistance is a core indicator determining their long-term service reliability. This work investigates the stress relaxation behaviors of two 2.2 GPa-grade martensitic steels (with and without V addition). Both steels were fabricated by flash heating and tempering treatments and exhibited high density dislocations in ultrafine-grained microstructure. Stress-relaxation testing results across various temperatures demonstrate superior relaxation resistance for these two steels. The thermal activation energy (ΔG0) of dislocations at an extremely high stress of 1750 MPa of V-free and V-alloyed steel is 11.8 eV and 14.8 eV, respectively. The synergistic combination of high mechanical strength and stress relaxation resistance in the present martensitic steels is superior to that of other metallic materials reported in previous studies. Furthermore, the higher activation energy and relaxation resistance of V-alloyed steel is primarily associated with the increased density of dislocation obstacles from grain boundaries and nanoprecipitates
Application of Click Chemistry in the Fabrication of Cactus-Like Hierarchical Particulates for Sticky Superhydrophobic Surfaces
No full textIn this article, cactus-like hierarchical structures were fabricated via click chemistry of azide−alkyne 1,3-dipolar Huisgen cycloaddition reaction. It is convenient to control the size of hierarchical particulates and to tune their surface roughness by adjusting the cycles of the click reaction. Dual-sized surface roughness, which biomimics the surface topology of sticky superhydrophobic gecko feet, originates from well-defined silica-based cactus-like particulates that are covalently bonded to an alkynyl-treated substrate. After surface modification with fluorinated azobenzene, the resulting hairy hierarchical structure coatings show the static water contact angle as high as 151.6 ± 1.5°, high adhesion to water, and outstanding chemical stability. We believe that the densely packed nanoscale aggregates are the key contributors to the observed high adhesion, presumably by generating large van der Waals’ forces from the large surface area in very close contact with water
Rapid Heating-Driven Variant Selection and Martensitic Refinement for Superior Strength–Ductility Synergy
No full textThis study elucidates the influence of rapid heating (300 °C/s) on martensitic transformation pathways, crystallographic variant selection, and the resulting mechanical performance in a medium-carbon steel. Compared with conventional heating, rapid heating markedly refines the prior austenite grain (PAG) and martensitic substructures, reducing the mean PAG size from 16.08 μm to 5.06 μm and the martensitic block size from 4.24 μm to 2.41 μm. The accelerated austenitizing and quenching promote a higher density of high-angle grain boundaries (HAGBs) and favor variant selection dominated by the closely packed (CP) group. Σ3 twin boundaries are also found to assist variant nucleation and contribute to microstructural complexity. Despite a marginal decrease in tensile strength, rapid-heated steels exhibit significantly enhanced ductility and a 28.3% increase in the product of strength and elongation (PSE) compared to their conventionally treated counterparts. These findings demonstrate that rapid heating not only enables effective refinement of martensitic substructures but also offers a powerful means of controlling variant evolution, thereby achieving a superior strength–ductility synergy in martensitic steels
