Hyperbaric laser chemical vapor deposition of high-strength aluminum- silicon-carbide nanocomposite fibers for aerospace and transportation applications

For over 25 years, hyperbaric pressure laser chemical vapor deposition (HP-LCVD) has been studied by various authors as a mean for growing three-dimensional structures and fibers [1-2]. Novel normally-immiscible materials (NIMs) [3], amorphous/glassy ceramics [4], and high-strength fibers have been grown [5]. However, the highest experimental pressures to date have only reached beyond the critical point of certain alkanes (\u3c60 bar) [6]. Our group has found it useful to synthesize materials from high pressure fluids, where the ensuing cooling rates after deposition can exceed 106 K/s. This has enabled the growth of (metastable) amorphous and nanostructured materials, including diamond-like carbon and boron carbides [7-8]. For this work, freestanding nanocomposite fibers were grown from mixtures of Bis(trimethylsilyl)methane and various organometallic and halide aluminum precursors. A chopped, cw fiber laser at 1064nm and diode lasers at 808nm were used for this work. The 1/e2 laser beam waists were approximately 10-15 microns across. The resulting Al-Si-C fibers could be grown continuously—and were nanostructured due to the precursor pressures and laser powers employed. A variety of phases were found to be present, including aluminum carbide, silicon carbide, carbon, and silicon-rich phases. Scanning electron microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) were used to characterize the composition and structure of the resulting materials. A map of the ternary phase diagram under these non-equilibrium conditions will be provided and discussed in detail. These fibers will find utility in reinforcements for ceramic- and metal-matrix composites for aerospace and transportation applications. References: [1]F. T. Wallenberger, P. C. Nordine, M. Boman, Composites Science and Technology, 1994, 51, 192. [2]J. L. Maxwell, US Patent #5,786,023, 1996. [3]J. L. Maxwell, M. R. Black, C. A. Chavez, K. R. Maskaly, M. Espinoza, M. Boman, Applied Physics A-Materials Science and Engineering, 2008, 91, 507. [4]F. T. Wallenberger, P. C. Nordine, Journal of Materials Research, 1994, 9, 527. [5]M. Boman, D. Bauerle, Journal of the Chinese Chemical Society, 1995, 42, 405. [6] J. Maxwell, Unpublished Results. [7]J. Maxwell, M. Boman, W. Springer, J. Narayan, S. Gnanavelu, Journal of the American Chemical Society, 2006, 128, 4405. [8]J. Maxwell, C. Chavez, W. Springer, K. Maskaly, D. Goodin, Diamond and Related Materials, 2007, 16, 1557

Effect of graphene addition on the transport critical current density of bulk (Tl0.85Cr0.15) Sr2CaCu2O7-δ superconductor

In this work, the effect of graphene addition on the transport critical current density of (Tl0.85Cr0.15) Sr2CaCu2O7-δ (Tl-1212) superconductor was investigated. Thallium-based high temperature superconductor (HTS) with nominal starting composition (Tl0.85Cr0.15) Sr2CaCu2O7-δ was prepared using high purity oxide powders via solid state reaction method. 0.001 – 0.005 wt.% of graphene were added into Tl-1212 superconductors. The characteristic of the samples were determined by powder X-ray diffraction method, scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDX), electrical resistance measurements and transport critical current density measurements. The zero-resistance temperature, Tc-zero was found to decrease from 95 K to 84 K with the increase of graphene. The temperature dependence transport critical current density (Jc) of the pure and graphene added bulk samples were investigated. Jc of the non-added bulk sample was 1320 mA/cm2 at 30 K while the Jc of sample with 0.001 wt.% graphene was 3660 mA/cm2 at 30 K. Results showed that the Jc of the Tl-1212 samples decreased with increasing graphene addition. Graphene acted as impurity which is believed to perform the flux pinning effect to Tl-1212. Thus, the Jc of Tl-1212 superconductors was enhanced. The phase formation and morphology of samples Tl-1212 were also discussed in this paper

Sifat magnet, mikrostruktur dan morfologi komposit getah asli termoplastik berpengisi Ferit NiZn/MwNT

Ferit NiZn dan nanotiub karbon diadunkan ke dalam getah asli termoplastik mengikut nisbah campuran 1:1. Kesan penambahan pengisi ke atas sifat magnet, struktur dan morfologi nanokomposit dikaji. Dua parameter magnet, iaitu pemagnetan tepuan dan daya koersif nanokomposit didapati bergantung kepada penambahan pengisi dalam matriks. Interaksi antara kedua-dua pengisi dalam matriks TPNR juga mempengaruh sifat magnet. Pengisi hibrid (ferit NiZn dan nanotiub karbon) bertabur sekata dalam matriks termoplastik getah asli. Kehabluran semi-amorfus fasa polipropilena didapati berlawanan dengan peningkatan kehabluran pengisi apabila kandungan pengisi bertambah

Protein kinases modulate store-operated channels in pulmonary artery smooth muscle cells

<p>Abstract</p> <p>Background</p> <p>This study investigates whether protein kinase G (PKG), protein kinase A (PKA) and protein kinase C (PKC) are involved in the regulatory mechanisms of store-operated channel (SOC) in pulmonary arteries.</p> <p>Methods</p> <p>Pulmonary artery smooth muscle cells (PASMCs) were enzymatically dissociated from rat intralobar pulmonary arteries. Whole cell, cell-attached and inside-out patch-clamp electrophysiology were used to monitor SOCs in isolated PASMCs.</p> <p>Results</p> <p>Initially the Ca²⁺-ATPase inhibitor cyclopiazonic acid (CPA, 10 μM) initiated a whole cell current that was reduced by the SOC blocker SKF-96365 (10 μM). Subsequent work using both cell-attached and whole cell configurations revealed that the PKG and PKA inhibitors, KT5823 (3 μM) and H-89 (10 μM), also stimulated SOC activity; this augmentation was attenuated by the SOC blockers SKF-96365 (10 μM) and Ni²⁺(0.1 mM). Finally using the inside-out configuration, the PKC activator phorbol 12-myristate 13-acetate (PMA, 10 μM) was confirmed to modestly stimulate SOC activity although this augmentation appeared to be more substantial following the application of 10 μM inositol 1,4,5-triphosphate (Ins(1,4,5)P₃).</p> <p>Conclusions</p> <p>SOC activity in PASMCs was stimulated by the inhibition of PKG and PKA and the activation of PKC. Our findings suggest that the SOC could be a substrate of these protein kinases, which therefore would regulate the intracellular concentration of calcium and pulmonary arteriopathy via SOC.</p

Crystal structure of bis[μ2-(N-(2-hydroxyethyl)-N-methylcarbamodithioato-κS:κS,κS′)]-bis(triethylphosphine-P)-di-silver(I), C20H46Ag2N2O2P2S4

C20H46Ag2N2O2P2S4, triclinic, P1̄ (no. 2), a = 9.3895(1) Å, b = 13.1597(2) Å, c = 13.1803(2) Å, α = 88.119(1)°, β = 86.601(1)°, γ = 70.173(1)°, V = 1529.22(4) Å3, Z = 2, R gt(F) = 0.0162, wR ref(F 2) = 0.0406, T = 100(2) K

What is at stake in a war? A prospective evaluation of the Ukraine and Russia conflict for business and society

War produces devastating impacts on humankind, especially in terms of lives and livelihoods. While war is a widely studied topic in history, it remains relatively understudied in business. To address this gap, this article explores the impact of war for business and society. To do so, this article undertakes a prospective evaluation of the Ukraine and Russia conflict as a recent case of war. In doing so, this article reveals that a war can impact society within (e.g., limit access to basic necessities and monetary resources, increase unemployment and reduce purchasing power, and increase asylum seekers and refugees) and outside (e.g., supply shortage and inflation and threat of false information) as well as business within(e.g., threat of cyberattacks, threat to digital and sustainable growth, and short-term and long-term sanctions and support) and outside (e.g., test of business ethics and moral obligations and test of brand management) war-torn countries. The article concludes with an agenda for future research involving war, business, and society

In Vitro and In Vivo Cytotoxicity of Boron Nitride Nanotubes: A Systematic Review

Boron nitride nanotubes (BNNTs) are an exciting class of nanomaterials due to their unique chemical and physical characteristics. In recent decades, BNNTs have gained huge attention in research and development for various applications, including as nano-fillers for composites, semiconductor devices, hydrogen storage, and as an emerging material in biomedical and tissue engineering applications. However, the toxicity of BNNTs is not clear, and the biocompatibility is not proven yet. In this review, the role of BNNTs in biocompatibility studies is assessed in terms of their characteristics: cell viability, proliferation, therapeutic outcomes, and genotoxicity, which are vital elements for their prospective use in biomedical applications. A systematic review was conducted utilising the databases Scopus and Web of Science (WOS) (2008&ndash;2022). Additional findings were discovered manually by snowballing the reference lists of appropriate reviews. Only English-language articles were included. Finally, the significant analysis and discussion of the chosen articles are presented

Extrusion-Based Bioprinted Boron Nitride Nanotubes Reinforced Alginate Scaffolds: Mechanical, Printability and Cell Viability Evaluation

Alginate (Alg) hydrogels are commonly used as bioinks in 3D bioprinting. However, one of the significant drawbacks of using Alg hydrogels is their unstable mechanical properties. In this study, a novel hydrogel-based ink composed of Alg reinforced with functionalised boron nitride nanotubes (f-BNNTs) was developed and systematic quantitative characterisation was conducted to validate its printability, physiochemical properties and biocompatibility. The printability, contact angle and mechanical test results indicated good structural stability of the scaffolds. The thermal stability of the scaffolds increased with the incorporation of f-BNNTs into Alg. Human embryonic kidney cells (HEK 293T) were seeded on the scaffolds and the cell viability was recorded for 24, 48 and 72 h. Quantitative studies showed a slight effect on toxicity with a higher concentration of BNNTs in scaffolds. The results suggest that the 3D printable f-BNNTs reinforced Alg could be used as bioink for tissue engineering applications with further studies on biocompatibility

Behaviour of soil nailed retaining structures

Laboratory tank-scale model tests and large scale trench tests were carried out to study the behavior of nailed soil retaining walls. The influence of nail length, nail inclination, facing stiffness and method of nail installation on the behavior of soil nailed walls was investigated.RP 48/9