Enhancing Microstructural and Mechanical Properties of Ferrous Medium-Entropy Alloy through Cu Addition and Post-Weld Heat Treatment in Gas Tungsten Arc Welding.

This study investigates the impact of a high-entropy alloy filler metal coated with copper (Cu) and post-weld heat treatment (PWHT) on the weldability of a ferrous medium-entropy alloy (MEA) in gas tungsten arc welding. The addition of 1-at% Cu had an insignificant effect on the microstructural behaviour, despite a positive mixing enthalpy with other elements. It was observed that a small amount of Cu was insufficient to induce phase separation into the Cu-rich phase and refine the microstructure of the as-welded specimen. However, with an increase in the PWHT temperature, the tensile strength remained mostly consistent, while the elongation significantly increased (elongation of as welded, PWHT700, PWHT800, and PWHT 900 were 19, 43, 55 and 68%, respectively). Notably, the PWHT temperature of 900 °C yielded the most desirable results by shifting the fracture location from the coarse-grained heat-affected zone (CGHAZ) to base metal (BM). This was due to significant recrystallisation and homogenised hardness of the cold-rolled BM during PWHT. However, the CGHAZ with coarse grains induced by the welding heat input remained invariant during the PWHT. This study proposes a viable PHWT temperature (900 °C) for enhancing the weldability of cold-rolled ferrous MEA without additional process.

Graphene Encapsulated Al Particles for Improvement of Thermal Conductivity in Composites.

Graphene reinforced aluminum matrix composites (GRAMCs) with improved thermal conductivity were prepared via a pH-controlled self-assembly process that involved adjusting the concentration of dispersed graphene oxide (GO) solutions. Uniform dispersion was achieved using GO coating on the aluminum (Al) surfaces. Graphene encapsulated Al powders (Al/GO) were sintered through spark plasma sintering (SPS) to prepare bulk composites, these were then analyzed to determine the thermal and mechanical properties. The density of the Al/GO composites was determined to be 99% or more compared to the theoretical density of pure Al. The Vicker's hardness and thermal conductivity increased by about 47% and 15% more than the pristine Al bulks. These processes can improve properties of the thermal interface between GO and Al, enabling uniform coating without a crosslinking agent. An Al/GO composite, fabricated through the pH-controlled self-assembly process, should be useful for various applications requiring to high thermal conductivity.

Bioactives in cactus (Opuntia ficus-indica) stems possess potent antioxidant and pro-apoptotic activities through COX-2 involvement.

BACKGROUND: Bioactives extracted from cactus (Opuntia ficus-indica) stems were investigated for their chemopreventive activities using human cancer cells in vitro. The bioactives present in crude extracts were detected and quantified using high-performance liquid chromatography. RESULTS: Among all the extracts, such as hexane, ethyl acetate (EtOAc), acetone, methanol (MeOH), and MeOH:water (80:20), the MeOH extract had the highest amount of polyphenolic compounds and the acetone extract exhibited the most potent effect at scavenging the 2,2,-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS(•+) ) radical. In addition, most of the extracts, with the exception of hexane, exhibited significant cytotoxicity in human SW480 colon and MCF7 breast cancer cells. Overall, the SW480 cells were more sensitive than the MCF7 cells to the cytotoxic effect of the O. ficus-indica extracts (OFEs). Cell death by OFE treatment caused significant inhibition of cyclooxygenase-2 and increased the Bax/Bcl2 ratio in both SW480 and MCF7 cell lines. However, degradation of poly (ADP-ribose) polymerase was significantly increased by OFE only in the MCF7 cells, thereby inducing apoptosis. CONCLUSION: These findings demonstrate the health-benefit roles, including anti-oxidative and anti-proliferative activities as well as pro-apoptotic effects, of bioactive compounds in OFEs, suggesting a chemopreventive role in human cancer cells.

Preparation and Properties of Polysulfone-poly(ethylene glycol) graft copolymer membrane.

In this study, Graft copolymers composed of PSf backbones and PEG side chains were synthesized to prepare gas separation membranes with enhancing permeability and selectivity on carbon dioxide separation. PSf-g-PEG copolymers were synthesized by two steps, chloromethylation and graft reactions. Grafted PEG segment of PSf was controlled by molecular weight of PEG. Thermal properties of prepared mebrane were studied by TGA and DSC. T(g) of the copolymers was decreased with increasing of molecular weight of PEG. Hydrophilicity of PSf-g-PEG copolymer membrane was measured using contact angle method, and PEG grafted polymers showed lower contact angles due to higher hydrophilicity. Gas permeation properties of CO2 and N2 gases through the membranes were measured using time-lag method. The permeability of CO2 was enhanced with PEG moiety contents and increasing of number of PEG segment. The selectivity of CO2/N2 was increased with introducing of PEG due to higher solubility with CO2 gas.

Characterization of sulfonated silica nanocomposite electrolyte membranes for fuel cell.

Sulfonated poly(arylene ether sulfone) (SPAES) and sulfonated silica (silica-SO3H) prepared via sol-gel reaction are used as an organic polymer matrix and inorganic nanoparticles. The contents of the silica-SO3H particles in the composite membranes are controlled at 0.5, 1, 2, 3 and 5 wt.% in order to evaluate the appropriate content for high proton conductivity. Randomly dispersed silica particles are obtained from all composite membranes as a result of the hydrophilic domains in the polymer and silica-SO3H. In this study, the optimum silica-SO3H content for high proton conductivity is 3 wt.% in fully hydrated conditions and 0.5 wt.% in low humidity conditions.

Glucosinolate biosynthesis in hairy root cultures of broccoli (Brassica oleracea var. italica).

Here we present previously unreported glucosinolate production by hairy root cultures of broccoli (B. oleracea var. italica). Growth media greatly influenced the growth and glucosinolate content of hairy root cultures of broccoli. Seven glucosinolates, glucoraphanin, gluconapin, glucoerucin, glucobrassicin, 4-methoxyglucobrassicin, gluconasturtiin, and neoglucobrassicin, were identified by analysis of the broccoli hairy root cultures. Both half and full strength B5 and SH media enabled the highest accumulation of glucosinolates. In most cases, the levels of glucosinolates were higher in SH and BS media. Among the 7 glucosinolates, the accumulation of neoglucobrassicin was very high, irrespective of growth medium. The neoglucobrassicin content was 7.4-fold higher in SH medium than 1/2 MS, in which its level was the lowest. The 1/2 B5 medium supported the production of the highest amounts of glucobrassicin and 4-methoxyglucobrassicin, the levels for which were 36.2- and 7.9- fold higher, respectively, than their lowest content in 1/2 MS medium. The 1/2 SH medium enabled the highest accumulation of glucoraphanin and gluconapin in the broccoli hairy root cultures, whose levels were 1.8- and 4.6-fold higher, respectively, than their lowest content in 1/2 MS medium. Our results suggest that hairy root cultures of broccoli could be a valuable alternative approach for the production of glucosinolate compounds.

Chemopreventive effect of cactus (Opuntia humifusa) extracts: radical scavenging activity, pro-apoptosis, and anti-inflammatory effect in human colon (SW480) and breast cancer (MCF7) cells.

Cactus (Opuntia spp) is widely cultivated as a vegetable, fruit, and forage crop and has been used in traditional medicine in American Indian, Mexican, and Korean cultures. Accumulative evidence from both in vitro and in vivo studies using cacti suggests their biological and pharmacological activities, such as their anti-cancer and anti-inflammatory roles in different cancer cells. In this study, the Opuntia humifusa stem (OHS) was extracted with different solvents and screened for radical scavenging activity using 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS˙(+)) and 1,1-diphenyl-2-picryl hydrazyl (DPPH). In addition, the total phenolic and flavonoid contents of each extract were analyzed using the Folin-Ciocalteu method and high performance liquid chromatography, respectively. Further, the cacti's bioactive fractions were evaluated for cell cytotoxicity and to understand their mechanism of action on human colon cancer (SW480) and breast cancer (MCF7) cells. An ethyl acetate (EtOAc) extract exhibited the highest cytotoxicity and resulted in an up-regulated expression of the pro-apoptotic protein Bax (bcl-2 associated X protein) and a down-regulated expression of the anti-apoptotic protein Bcl2 in both SW480 and MCF7 cells. The apoptosis was mediated through activation of caspase 8, 9, and 3/7 activities as well as PARP cleavage in SW480 cells, while the same extract activated only a caspase 9 activity in MCF7 cells. Furthermore, incubation of cells with the EtOAc extract down-regulated the expression of inflammatory molecules such as cyclooxygenase-2 (COX2) and inducible nitric oxide synthase (iNOS) in SW480 cells but not in MCF7 cells. Taken together, these results suggest that SW480 colon cancer cells are more susceptible to bioactive compounds present in OHS and may have potential in the prevention of cancer through modulation of apoptosis markers and inhibition of inflammatory pathways.

5-Geranyloxy-7-methoxycoumarin inhibits colon cancer (SW480) cells growth by inducing apoptosis.

For the first time, three coumarins were isolated from the hexane extract of limes (Citrus aurantifolia) and purified by flash chromatography. The structures were identified by NMR (1D, 2D) and mass spectral analyses as 5-geranyloxy-7-methoxycoumarin, limettin, and isopimpinellin. These compounds inhibited human colon cancer (SW-480) cell proliferation, with 5-geranyloxy-7-methoxycoumarin showing the highest inhibition activity (67 %) at 25 µM. Suppression of SW480 cell proliferation by 5-geranyloxy-7-methoxycoumarin was associated with induction of apoptosis, as evidenced by annexin V staining and DNA fragmentation. In addition, 5-geranyloxy-7-methoxycoumarin arrested cells at the G0/G1 phase, and induction of apoptosis was demonstrated through the activation of tumour suppressor gene p53, caspase8/3, regulation of Bcl2, and inhibition of p38 MAPK phosphorylation. These findings suggest that 5-geranyloxy-7-methoxycoumarin has potential as a cancer preventive agent.