The Synergistic Effects of Hybrid Micro and Nano Silica in Influencing the Mechanical Properties of Epoxy Composites-A New Model.

Epoxy nano composites containing micro and nano silica were prepared by varying the filler's weight loading as an attempt to investigate the effects of incorporating these fillers in influencing its mechanical properties. Mechanical properties characterizations include the evaluation of tensile. The mechanical properties of the epoxy composites were found to tremendously increase as both micro and nano silica were added together at a 1:1 wt.% ratio. For example, the highest values of Young's modulus were recorded to be 5.39 GPa for 25 wt.% loading (12.5 wt.% Micro + 12.5 wt.% nano), while Young's modulus values of 5.22 MPa and 5.32 MPa were recorded for micro and nano silica, respectively, at the same weight loading. The most outstanding results were observed at 25 wt.% hybrids (12.5 wt.% micro silica + 12.5 wt.% nano silica), where the values of Young's modulus were increased by 228% compared to the neat epoxy. This study successfully demonstrated synergistic effects demonstrated by combining micro and nano silica fillers, which created an interaction that significantly enhanced the Young's modulus of epoxy composites.

Immune stimulatory and anti-HIV-1 potential of extracts derived from marine brown algae Padina tetrastromatica.

Background Marine brown algae are biologically diverse and their medicinal value has been explored limited. We assessed whether Padina tetrastromatica Hauck will possess the immune stimulatory and human immunodeficiency virus (HIV-1) inhibitory activity. Materials and Methods Aqueous and methanolic extracts were tested for the Th1/Th2 cytokines using PBMC. Subsequently, leukotriene B4 (LTB4), nitric oxide (NO) and anti-oxidant effect were analyzed using RAW264.7 cells. In addition, Padina extracts were tested for the HIV-1 clade C & A by measuring the levels of viral p24 antigen in infected peripheral blood mononuclear cells (PBMCs) and against reverse transcriptase (RT). Results At 100 µg/mL, aqueous and methanolic extracts produced a significant amount of IL-10 and IFN-γ at 24 h and 72 h post-stimulation by PBMCs. It also produced a significant amount of LTB4, NO and had an antioxidant effect on RAW264.7 cell, suggesting the immune stimulating potential of P. tetrastromatica. Upon infection of PBMCs with 100 TCID50, aqueous and methanolic extracts of P. tetrastromatica inhibited HIV-1 C (>90%) and HIV-1 A (>50%) showed a significant reduction in HIV-1 p24 levels and HIV-1 RT inhibition (>50%). GC-MS study revealed a relative abundance of tetradecanoic and oleic acid in the methanolic extract of P. tetrastromatica, which might be responsible for immune stimulation and anti-HIV-1 activity. Conclusion At lower concentrations (100 mg/mL), the aqueous and methanolic extracts of P. tetrastromatica showed the strong immune stimulation and greatest anti-HIV-1 potential in vitro. This study demonstrates the therapeutic potential of these brown algae P. tetrastromatica for the benefit of mankind.

Tuning the Pseudospin Polarization of Graphene by a Pseudomagnetic Field.

One of the intriguing characteristics of honeycomb lattices is the appearance of a pseudomagnetic field as a result of mechanical deformation. In the case of graphene, the Landau quantization resulting from this pseudomagnetic field has been measured using scanning tunneling microscopy. Here we show that a signature of the pseudomagnetic field is a local sublattice symmetry breaking observable as a redistribution of the local density of states. This can be interpreted as a polarization of graphene's pseudospin due to a strain induced pseudomagnetic field, in analogy to the alignment of a real spin in a magnetic field. We reveal this sublattice symmetry breaking by tunably straining graphene using the tip of a scanning tunneling microscope. The tip locally lifts the graphene membrane from a SiO2 support, as visible by an increased slope of the I(z) curves. The amount of lifting is consistent with molecular dynamics calculations, which reveal a deformed graphene area under the tip in the shape of a Gaussian. The pseudomagnetic field induced by the deformation becomes visible as a sublattice symmetry breaking which scales with the lifting height of the strained deformation and therefore with the pseudomagnetic field strength. Its magnitude is quantitatively reproduced by analytic and tight-binding models, revealing fields of 1000 T. These results might be the starting point for an effective THz valley filter, as a basic element of valleytronics.

Analysis of Serum Th1/Th2 Cytokine Levels in Patients with Acute Mumps Infection.

BACKGROUND: The mumps virus is frequently the causative agent of parotitis. There has been no study on serum cytokine levels of acute mumps parotitis except for a few which document cytokine levels in cerebrospinal fluid of mumps meningitis. It is with this notion, our study aimed to find Th1/Th2 cytokine levels from patients with acute mumps parotitis. MATERIALS AND METHODS: Concentrations of mumps-specific IgM, mumps, measles, rubella-specific IgG antibody, and Th1/Th2 cytokines, namely interferon-γ (IFN-γ), interleukin-2 (IL-2), IL-4, and IL-10 were measured simultaneously in serum from 74 patients (42 pediatric and 32 adult cases), 40 healthy subjects (20 pediatric and 20 adults) and in the supernatant of peripheral blood mononuclear cells stimulated with mumps virus genotype C which served as the positive control. Statistical significance was analyzed between each group by means of Mann-Whitney U-test, Kruskal-Wallis test, and Spearman's rank correlation coefficient test. RESULTS: IgM positivity confirmed acute infection in all 74 patients and of these 67 were vaccinated cases; however, very few of them (10/67) were positive for mumps IgG. We found that IFN-γ, IL-2, and IL-10 showed a statistically significant increase in both pediatric and adult patients with acute mumps infection when compared to healthy controls and values were comparable to the positive control. CONCLUSION: The Th1 cells play important roles during the acute phase of mumps parotitis.

Absence of edge states in covalently bonded zigzag edges of graphene on Ir(111).

The zigzag edges of graphene on Ir(111) are studied by ab initio simulations and low-temperature scanning tunneling spectroscopy, providing information about their structural, electronic, and magnetic properties. No edge state is found to exist, which is explained in terms of the interplay between a strong geometrical relaxation at the edge and a hybridization of the d orbitals of Ir atoms with the graphene orbitals at the edge.

Designing hypothesis of substituted benzoxazinones as HIV-1 reverse transcriptase inhibitors: QSAR approach.

A linear quantitative structure activity relationship (QSAR) model is presented for predicting human immunodeficiency virus-1 (HIV-1) reverse transcriptase enzyme inhibition. The 2D QSAR and 3D-QSAR models were developed by stepwise multiple linear regression, partial least square (PLS) regression and k-nearest neighbor-molecular field analysis, PLS regression, respectively using a database consisting of 33 recently discovered benzoxazinones. The primary findings of this study is that the number of hydrogen atoms, number of (-NH2) group connected with solitary single bond alters the inhibition of HIV-1 reverse transcriptase. Further, presence of electrostatic, hydrophobic and steric field descriptors significantly affects the ability of benzoxazinone derivatives to inhibit HIV-1 reverse transcriptase. The selected descriptors could serve as a primer for the design of novel and potent antagonists of HIV-1 reverse transcriptase.