Microstructure evolution under different austenitizing temperatures and its effect on mechanical properties and mechanisms in a newly high aluminum bearing steel

A new type of lightweight high aluminum bearing steel had been developed based on the widely used high carbon chromium bearing steel. Via multi-scale experimental characterizations and theoretical calculations, here we mainly focused on the evolution of microstructure including precipitates under different quenching temperatures. Accordingly, the mechanical properties, mechanisms and fracture features of the new high-Al steel after tempering were characterized in detail. As austenitizing temperature rose, matrix of steel varied from multiphase structure of martensite, retained austenite (RA) and ferrite to the full martensite and RA. RA was found in all four samples with the austenitizing temperature from 850 °C to 1000 °C. In terms of precipitates, a transformation from M3C to M7C3 were observed. As a phase newly introduced by Al, AlFe3C (κ carbides) would dissolve into matrix at 900 °C. Eventually, the yield strength of the researched steel could reach 1430 MPa with an unnotched impact energy of 35 J. Theoretical results showed that high strength of researched steel was mainly caused by solid solution effect of carbon and high density of dislocation. In terms of toughness and fracture observation, high impact energy was attributed to the highest density of grain boundary, and also, κ carbides were found at the origin of secondary crack. This study highlighted the significant effect of Al addition and quenching process based on the traditional bearing steel, which showed a novel method and idea to reduce significantly the weight of bearings

Use of Complementary and Alternative Medicine by Cancer Patients at Zhejiang University Teaching Hospital Zhuji Hospital, China

Complementary and alternative medicine (CAM) is garnering increasing interest and acceptance among the general population throughout the world. The use of CAM by cancer patients is very common in China. The referenced English literature has no rural community-based study from China on this subject. This study was conducted to define the prevalence, pattern of use, and reasons for using CAM by cancer patients at Zhejiang University Teaching Hospital Zhuji Hospital (ZUTH-ZJH), China. Face-to-face interviews using a structured questionnaire were used to determine the use of CAM by cancer patients. All consenting cancer patients were interviewed as they presented at the Department of Surgical Oncology of ZUTH-ZJH, from September 2009 to February 2010. One hundred and twenty one patients were interviewed; 64 (52.9%) were males and 57 (47.1%) were females. One hundred and thirteen patients (93.4%) have used CAM at some time during their current cancer illness, fifty two (46.0%) are female and sixty one (54.0%) are male patients; 8 (6.6%) patients have not used any form of CAM. Chinese medicine (73.5.0%) was the most commonly reported CAM modality. Over 71.7% of those who used CAM were satisfied, only 28.3% were disappointed. Twenty eight users (24.8%) did not see any benefit from the CAM, but eighty one patients (71.7%) could describe some specific benefits. Only one patient will use orthodox medicine instead of CAM in the future, almost all patients will continue to use CAM in the future. CAM use is very common among cancer patients in local area of China. Most users obtain the expected benefits, and adverse events are uncommon. It is imperative that oncologists should explore the use of CAM with their cancer patients and work towards an integrated model of health-care provision. This knowledge will enable oncologists to better counsel the patients

Anisotropic and asymmetric deformation mechanisms of nanolaminated graphene/Cu composites

We conducted molecular dynamics (MD) simulations of tension and compression along the direction and MD simulations of compression along the and directions on nanolaminated graphene/Cu (NGCu) composites to investigate the effects of the incorporated graphene and the deformation mechanisms related to the loading direction. The deformation behavior and the defect structures were found to be strongly dependent on the loading conditions. An asymmetric tension-compression deformation behavior was thus found in graphene/Cu nanolaminates under the loading, which was dominated by stacking faults and deformation twins formed by dislocation slide under tension and compression, respectively. High density and ordered nanotwins were formed at the graphene/Cu interfaces. Two different formation mechanisms of the twins were found under the compression, and the nucleated twins were easy to be thickened with the assistance of the graphene wrinkles. Multiple twins were formed under the compression by the dislocation cross-slip. This study provides a way to introduce graphene reinforcement and twin boundary to Cu matrix composites and design nanotwinned graphene/Cu composites with excellent mechanical performance

Ultratough reduced graphene oxide composite films synergistically toughened and reinforced by polydopamine wrapped carbon nanotubes

Nacre like graphene based composite films (GCFs) have been developed over the last decade. Although the progress in ultrastrong GCFs is remarkable, fabricating GCFs with excellent integrated properties of strength, flexibility, and toughness still remains a challenge. Here, a ternary GCF of reduced graphene oxide (rGO), polydopamine (PDA) and multi-walled carbon nanotubes (MWCNTs) was developed. The MWCNTs were modified by PDA to form PDA@MWCNTs which were then compounded with GO to fabricate the rGO-PDA@MWCNT films by evaporation-induced assembly and chemical reduction. The preparation was simple, cheap and environmentally-friendly. The PDA increased the dispersion of MWCNTs in the rGO-PDA@MWCNT films, crosslinked the rGO sheets, and enhanced the entanglement of MWCNTs and the interactions between MWCNTs and rGO sheets. Benefiting from the synergistic effect of PDA and MWCNTs, the rGO-PDA@MWCNT films exhibited excellent integrated properties by increasing strength, tensile fracture strain and toughness to 579 ± 35 MPa, 12.03 ± 0.56%, and 34.03 ± 1.60 MJ/m3, which were 2.26, 2.02 and 4.94 times that of pure rGO films, respectively. The rGO-PDA@MWCNT films also exhibited a high conductivity of 612 ± 68 S/cm and excellent structural stability under extreme environments. These excellent integrated properties of the rGO-PDA@MWCNT films will promote their applications in aerospace engineering, flexible electrical devices and artificial muscle.</p

Surface/structural characteristics and band alignments of thin Ga2O3 films grown on sapphire by pulse laser deposition

Comprehensive structural, electrical and optical studies are performed on a series of gallium oxide (Ga2O3) ultrathin films grown on sapphire with different growth temperatures (400–1000 °C) by pulsed laser deposition, via X-ray absorption spectroscopy (XAS), Raman scattering (RS) and X-ray photoelectron spectroscopy (XPS). For samples grown at different temperatures, the XAS results showed the coordination numbers of the materials varying, while their bond lengths remained nearly similar value. The RS revealed a low frequency vibration translation tetrahedral-octahedral mode (202 cm−1) of GaO4 and a mid-frequency deformation octahedral mode (346 cm−1) of GaO6 for films grown at higher temperatures. XPS analyses suggested the surface of samples composed of Gasingle bondO bonds with binding energy decreasing as the growth temperature increased. The β-Ga2O3/sapphire heterojunction is identified with the staggered-gap (type II) structure, and the valence-band offset (VBO) is found between (−0.52)–(−0.74) eV while conduction-band offset (CBO) from (−2.32)–(−3.32) eV. The band gap of the β-Ga2O3 was deduced from the energy loss signals for O 1s photoelectrons. With the increase of the growth temperature, the band gap increases and both the VBO and CBO decrease. The identification of band alignment for heterojunction may facilitate interests in designing advanced opto-electronic devices

Graphene/Graphitized Polydopamine/Carbon Nanotube All-Carbon Ternary Composite Films with Improved Mechanical Properties and Through-Plane Thermal Conductivity

Graphene films (GFs) are promising ultrathin thermally conductive materials for portable electronic devices because of their excellent thermally conductive property, light weight, high flexibility, and low cost. However, the application of GFs is limited due to their poor mechanical properties and through-plane thermal conductivity. Here, a graphene-(graphitized polydopamine)-(carbon nanotube) (G-gPDA-CNT) all-carbon ternary composite film was fabricated by chemical reduction, carbonization, graphitization, and mechanical compaction of the evaporation-assembled (graphene oxide)-PDA@CNT film. The G-gPDA-CNT film exhibited a uniform all-carbon composite structure in which the components of the graphene, gPDA layers, and CNTs were cross-linked by strong covalent bonds. This unique structure promoted the load transfer and energy dissipation between the components by which the mechanical properties of the G-gPDA-CNT film were substantially improved. Furthermore, electron and phonon transfers were also promoted, greatly improving the electrical and thermal conductivities, especially the through-plane thermal conductivity of the G-gPDA-CNT film. The G-gPDA-CNT film showed a tensile strength of 67.5 MPa, 15.1% ultimate tensile strain, toughness of 6.07 MJ/m3, electrical conductivity of 6.7 × 105 S·m-1, in-plane thermal conductivity of 1597 W·m-1·K-1, and through-plane thermal conductivity of 2.65 W·m-1·K-1, which were 2.24, 1.44, 3.16, 1.46, 1.15, and 3.90 times that of the pure GFs, respectively.</p

Surface/structural characteristics and band alignments of thin Ga 2 O 3 films grown on sapphire by pulse laser deposition

Comprehensive structural, electrical and optical studies are performed on a series of gallium oxide (Ga 2 O 3 ) ultrathin films grown on sapphire with different growth temperatures (400–1000 °C) by pulsed laser deposition, via X-ray absorption spectroscopy (XAS), Raman scattering (RS) and X-ray photoelectron spectroscopy (XPS). For samples grown at different temperatures, the XAS results showed the coordination numbers of the materials varying, while their bond lengths remained nearly similar value. The RS revealed a low frequency vibration translation tetrahedral-octahedral mode (202 cm −1 ) of GaO 4 and a mid-frequency deformation octahedral mode (346 cm −1 ) of GaO 6 for films grown at higher temperatures. XPS analyses suggested the surface of samples composed of Ga[sbnd]O bonds with binding energy decreasing as the growth temperature increased. The β-Ga 2 O 3 /sapphire heterojunction is identified with the staggered-gap (type II) structure, and the valence-band offset (VBO) is found between (−0.52)–(−0.74) eV while conduction-band offset (CBO) from (−2.32)–(−3.32) eV. The band gap of the β-Ga 2 O 3 was deduced from the energy loss signals for O 1s photoelectrons. With the increase of the growth temperature, the band gap increases and both the VBO and CBO decrease. The identification of band alignment for heterojunction may facilitate interests in designing advanced opto-electronic devices

Stimulation of tumoricidal immunity via bacteriotherapy inhibits glioblastoma relapse

Abstract Glioblastoma multiforme (GBM) is a highly aggressive brain tumor characterized by invasive behavior and a compromised immune response, presenting treatment challenges. Surgical debulking of GBM fails to address its highly infiltrative nature, leaving neoplastic satellites in an environment characterized by impaired immune surveillance, ultimately paving the way for tumor recurrence. Tracking and eradicating residual GBM cells by boosting antitumor immunity is critical for preventing postoperative relapse, but effective immunotherapeutic strategies remain elusive. Here, we report a cavity-injectable bacterium-hydrogel superstructure that targets GBM satellites around the cavity, triggers GBM pyroptosis, and initiates innate and adaptive immune responses, which prevent postoperative GBM relapse in male mice. The immunostimulatory Salmonella delivery vehicles (SDVs) engineered from attenuated Salmonella typhimurium (VNP20009) seek and attack GBM cells. Salmonella lysis-inducing nanocapsules (SLINs), designed to trigger autolysis, are tethered to the SDVs, eliciting antitumor immune response through the intracellular release of bacterial components. Furthermore, SDVs and SLINs administration via intracavitary injection of the ATP-responsive hydrogel can recruit phagocytes and promote antigen presentation, initiating an adaptive immune response. Therefore, our work offers a local bacteriotherapy for stimulating anti-GBM immunity, with potential applicability for patients facing malignancies at a high risk of recurrence