A Comparative Analysis of Hydrogen Storage Characteristics in AZ31 Magnesium Alloy with the Addition of Graphene and Carbon Nanotubes via Ball Milling Process

In the present investigation, an examination was conducted on the hydrogen storage performance of industrial waste grade AZ31 magnesium alloy when combined with either Carbon Nanotubes or Graphene. This study aims to understand the enhancement of hydrogen storage properties reinforced with polymer materials, such as Graphene or Carbon Nanotubes. The experimental samples, composed of AZ31 Magnesium Alloy combined with either Carbon Nanotubes or Graphene, were crafted through gravity casting. Thereafter, a high-energy ball milling process was employed to further refine the hydrogen storage material powders. The micrographic structures of all the sample powders were analyzed by x-ray diffraction (XRD), and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). Additionally, the average particle size distributions of the sample powders were quantified for comprehensive characterization. The absorbed and desorbed hydrogen capacity and kinetics was calculated by a Sievert's type apparatus. Overall, the performance of the sample powder AZ31-0.1G showed the highest absorption and desorption at a rate of 0.0036 wt%/s and 0.0084 wt%/s. Moreover, the hydrogen capacity of AZ31-0.1G reached the highest value at 5.32 wt%. The acquired data unveils that with the adding of either Graphene or Carbon Nanotubes as additives significantly improved the hydrogen storage capacity of AZ31 magnesium alloy

Mechanical Properties Enhancement of AZ91 Magnesium Alloy Reinforced with Various Ratios of Titanium Particles and Processed by ECAP

This study utilized AZ91 magnesium-aluminum alloy as the matrix for magnesium-based composites, reinforced with micron-sized titanium (Ti). Gravity casting and mechanical stirring were employed to fabricate specimens with 0 wt.%, 0.3 wt.%, and 0.5 wt.% Ti reinforcement. Heat-treated samples underwent Equal Channel Angular Pressing (ECAP), and microstructures were analyzed via SEM and XRD. The experimental results demonstrate that the addition of micron-sized titanium improves the yield strength, ultimate tensile strength, and hardness. The inclusion of 0.5 wt.% titanium powder resulted in a 17.5% increase in ultimate tensile strength and a 37% increase in yield strength. After secondary processing with ECAP, the ultimate tensile strength showed an additional 25% increase, while the yield strength increased by 13.5%. Vickers hardness test results reveal a significant 13.7% strength improvement with the addition of 0.5 wt.% titanium powder, and after ECAP secondary processing, there was a marginal additional increase of 0.8%

Enhancing Hydrogen Storage in AZ31 Alloy through Pd/G Composite

In this research, we investigated the catalytic effects of Palladium/Graphene(Pd/G) on AZ31 alloy for hydrogen storage. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (SEM-EDS) were employed to confirm the homogeneous distribution of AZ31 and observe phase changes after mechanical alloying with the catalysts. The hydrogen storage properties of AZ31 with catalysts were systematically examined, and the time of maximum reaction rate for nucleation was determined using Avarami Plot. The results of the study show that the incorporation of 2% Pd/G resulted in the fastest hydrogen absorption and desorption time, taking 200 seconds to achieve 90% hydrogen storage with a maximum of 6.04 wt%. The corresponding maximum hydrogen desorption occurred in 694 seconds, reaching 6.03 wt%. Consequently, the introduction of 2% Pd/G catalyst proved to be effective in significantly enhancing the hydrogen ab/desorption rates of AZ31 alloy

Magnesium Metal Matrix Composites and Their Applications

Magnesium is one of the lightest structural metals have the capability to replace the conventional alloys for mass saving applications and provides higher strength and stiffness. Additionally, it also has the ability to absorb the hydrogen in the form of hydrides and can be used as a future source of energy carrier. The theoretical hydrogen capacity of 7.6 wt% makes it more suitable for future energy sources but needs to reduce the working sorption temperature. Moreover, magnesium is the primary source of the body and has strength equal to the bone, making it more suitable for biomedical applications and higher biocompatibility. Some challenges of magnesium-based metal matrix composites are still encountering structural applications, hydrogen energy storage, and biomedical applications due to manufacturing methodologies and proper materials selection to get required results

A Bayesian measurement error model for two-channel cell-based RNAi data with replicates

RNA interference (RNAi) is an endogenous cellular process in which small double-stranded RNAs lead to the destruction of mRNAs with complementary nucleoside sequence. With the production of RNAi libraries, large-scale RNAi screening in human cells can be conducted to identify unknown genes involved in a biological pathway. One challenge researchers face is how to deal with the multiple testing issue and the related false positive rate (FDR) and false negative rate (FNR). This paper proposes a Bayesian hierarchical measurement error model for the analysis of data from a two-channel RNAi high-throughput experiment with replicates, in which both the activity of a particular biological pathway and cell viability are monitored and the goal is to identify short hair-pin RNAs (shRNAs) that affect the pathway activity without affecting cell activity. Simulation studies demonstrate the flexibility and robustness of the Bayesian method and the benefits of having replicates in the experiment. This method is illustrated through analyzing the data from a RNAi high-throughput screening that searches for cellular factors affecting HCV replication without affecting cell viability; comparisons of the results from this HCV study and some of those reported in the literature are included.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS496 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Dynamics of HBV cccDNA expression and transcription in different cell growth phase

<p>Abstract</p> <p>Background</p> <p>The covalently closed-circular DNA (cccDNA) of hepatitis B virus (HBV) is associated with viral persistence in HBV-infected hepatocytes. However, the regulation of cccDNA and its transcription in the host cells at different growth stages is not well understood.</p> <p>Methods</p> <p>We took advantages of a stably HBV-producing cell line, 1.3ES2, and examine the dynamic changes of HBV cccDNA, viral transcripts, and viral replication intermediates in different cellular growth stages.</p> <p>Results</p> <p>In this study, we showed that cccDNA increased suddenly in the initial proliferation phase of cell growth, probably attributable to its nuclear replenishment by intracellular nucleocapsids. The amount of cccDNA then decreased dramatically in the cells during their exponential proliferation similar to the loss of extrachromosomal plasmid DNA during cell division, after which it accumulated gradually while the host cells grew to confluency. We found that cccDNA was reduced in dividing cells and could be removed when proliferating cells were subjected to long term of lamivudine (3TC) treatment. The amounts of viral replicative intermediates were rapidly reduced in these proliferating cells and were significantly increased after cells reaching confluency. The expression levels of viral transcripts were increased in parallel with the elevated expression of hepatic transcription factors (HNF4α, CEBPα, PPARα, etc.) during cell growth confluency. The HBV transcripts were transcribed from both integrated viral genome and cccDNA, however the transcriptional abilities of cccDNA was less efficient then that from integrated viral genome in all cell growth stages. We also noted increases in the accumulation of intracellular viral particles and the secretion of mature virions as the cells reached confluency and ceased to grow.</p> <p>Conclusions</p> <p>Based on the dynamics of HBV replication, we propose that HBV replication is modulated differently in the different stages of cell growth, and can be divided into three phases (initial proliferation phase, exponential proliferation phase and growth confluency phase) according to the cell growth curve. The regulation of cccDNA in different cell growth phase and its importance regarding HBV replication are discussed.</p

Optimisation of electrophoretic deposition parameters for gas diffusion electrodes in high temperature polymer electrolyte membrane fuel cells

Electrophoretic deposition (EPD) method was used to fabricate gas diffusion electrodes (GDEs) for high temperature polymer electrolyte membrane fuel cells (HT PEMFC). Parameters related to the catalyst suspension and the EPD process were studied. Optimum suspension conditions are obtained when the catalyst particles are coated with Nafion® ionomer and the pH is adjusted to an alkaline range of about 8 e10. These suspensions yield good stability with sufficient conductivity to form highly porous catalyst layers on top of the gas diffusion layers (GDLs). GDEs were fabricated by applying various electric field strengths of which 100 V cm-1 yields the best membrane electrode assembly (MEA) performance. Compared to an MEA fabricated by the traditional hand sprayed (HS) method, the EPD MEA shows superior performance with a peak power increase of about 73% at similar platinum (Pt) loadings. Electrochemical Impedance Spectroscopy (EIS) analysis shows lower charge transfer resistance for the MEA fabricated via the EPD method compared to the HS MEA. The EPD GDE exhibits a greater total pore area (22.46 m2 g-1) compared to the HS GDE (13.43 m2 g-1) as well as better dispersion of the Pt particles within the catalyst layer (CL).Web of Scienc

Fusion rules and boundary conditions in the c=0 triplet model

The logarithmic triplet model W_2,3 at c=0 is studied. In particular, we determine the fusion rules of the irreducible representations from first principles, and show that there exists a finite set of representations, including all irreducible representations, that closes under fusion. With the help of these results we then investigate the possible boundary conditions of the W_2,3 theory. Unlike the familiar Cardy case where there is a consistent boundary condition for every representation of the chiral algebra, we find that for W_2,3 only a subset of representations gives rise to consistent boundary conditions. These then have boundary spectra with non-degenerate two-point correlators.Comment: 50 pages; v2: changed formulation in section 1.2.1 and corrected typos, version to appear in J. Phys.

Sustained proliferation in cancer: mechanisms and novel therapeutic targets

Proliferation is an important part of cancer development and progression. This is manifest by altered expression and/or activity of cell cycle related proteins. Constitutive activation of many signal transduction pathways also stimulates cell growth. Early steps in tumor development are associated with a fibrogenic response and the development of a hypoxic environment which favors the survival and proliferation of cancer stem cells. Part of the survival strategy of cancer stem cells may manifested by alterations in cell metabolism. Once tumors appear, growth and metastasis may be supported by overproduction of appropriate hormones (in hormonally dependent cancers), by promoting angiogenesis, by undergoing epithelial to mesenchymal transition, by triggering autophagy, and by taking cues from surrounding stromal cells. A number of natural compounds (e.g., curcumin, resveratrol, indole-3-carbinol, brassinin, sulforaphane, epigallocatechin-3-gallate, genistein, ellagitannins, lycopene and quercetin) have been found to inhibit one or more pathways that contribute to proliferation (e.g., hypoxia inducible factor 1, nuclear factor kappa B, phosphoinositide 3 kinase/Akt, insulin-like growth factor receptor 1, Wnt, cell cycle associated proteins, as well as androgen and estrogen receptor signaling). These data, in combination with bioinformatics analyses, will be very important for identifying signaling pathways and molecular targets that may provide early diagnostic markers and/or critical targets for the development of new drugs or drug combinations that block tumor formation and progression