Sol-Gel Derived Single Layer Zeolite-MgF2 Composite Antireflective Coatings with Improved Mechanical Properties on Polycarbonate

Single layer antireflective coatings with good optical and mechanical properties are difficult to be obtained on temperature sensitive substrates like plastics. This challenge has been taken up in the present study. Single layer MgF2 and for the first time, zeolite 4Å… and zeolite 4Å… - MgF2 composite antireflective coatings were generated by a wet chemical route on flat polycarbonate sheets and characterized for their reflectance, surface roughness, thickness, porosity, surface morphology and scratch hardness by haze measurement. Autoclaving and boiling water treatment under microwave irradiation were used in case of MgF2 sols and zeolite/zeolite-MgF2 coatings respectively. Pure MgF2 coatings deposited after autoclaving of the MgF2 sol yielded a low refractive index of 1.28 and an average reflectance of 1.9% vis-Å -vis 9.7% reflectance for an uncoated polycarbonate substrate over the wavelength range of 400-1100 nm. Single layer zeolite coatings after a brief treatment in boiling water under microwave irradiation yielded a reflectance of 5.1%. A composite zeolite-MgF2 coating exhibited a reflectance of 2.8% and the percentage change in haze after crockmeter testing in case of the composite coating was lower than that of a pure MgF2 coating. This implied that the composite layer had improved mechanical properties combined with good optical properties and could be suitable for practical applications

SYNTHESIS OF SILVER NANOPARTICLES FROM ANDROGRAPHIS PANICULATA AND EVALUATION OF THEIR ANTIBACTERIAL ACTIVITY

AbstractAim:  Andrographis paniculata is one of the most important antibacterial effects. The result proved Andrographis paniculata have antibacterial activity. The objective of this study to synthesis of silver nanoparticles from  Andrographis paniculata  and evaluate antibacterial method.Methods: Synthesis of silver nanoparticles from Andrographis paniculata leaves was done by using 1mM AgNO3 solution and incubates 24hr at room temperature.  Characterization of synthesized nanoparticles was done by        UV–Vis absorption spectroscopy, FTIR analysis, SEM analysis and  antibacterial activity.Results: In this result synthesized AgNPs from leaf extract of Andrographis paniculata showed potential antibacterial activity with various human pathogenic bacteria. Antibacterial activity of the silver nanoparticles was performed by a disk diffusion method. The highest antibacterial activity of AgNPs synthesized by Androraphis paniculata  leaf  was found against Salmonella typhi (30 mm). The AgNPs synthesized in this process were found to have efficient antibacterial activity against human pathogenic bacteria.Conclusion: In totality, the AgNPs prepared are safe to be discharged in the environment and possibly utilized in processes of pollution remediation.  AgNPs may also be efficiently utilized in agricultural research to obtain better health of crop plants as shown by our study. The study concluded that the AgNPs from Andrographis paniculata leaf extract have potential antibacterial activity

Sol–gel derived Ba/SrTiO3–MgF2 solar control coating stack on glass for architectural and automobile applications

Fully dielectric solar control coatings based on alternating layers of Ba (or Sr) TiO3 and MgF2 were deposited on soda lime glass substrates. Three-layered stacks BaTiO3/MgF2/BaTiO3 and SrTiO3/MgF2/SrTiO3 were generated using BaTiO3, SrTiO3 and MgF2 sols deposited on glass using dip coating technique. The multi-layered coating stack was fired at 450oC with different heating rates using a conventional muffle furnace and a conveyorized belt furnace, by which two methods of heat treatment were investigated. Heat treatment after deposition of each layer and a consolidated firing of the three-layered stack with intermediate drying between the layers were carried out and optical properties of the coatings compared. The heat treated coatings were characterized for their UV–Vis–NIR transmittance, microstructure, phase purity, thickness and refractive indices. The coating stack based on BaTiO3 as the high refractive index material in conjunction with MgF2 exhibited better solar control properties than SrTiO3 as the high refractive index material. Moreover, a fast firing of the BaTiO3/MgF2/BaTiO3 stack in a conveyorized belt furnace yielded good NIR blocking and solar control properties, whereas slow firing in a muffle furnace exhibited ~ 80% visible light transmittance with an NIR transmittance of ~ 75%

Optical properties of multilayer BaTiO3/SiO2 film structures formed by the sol–gel method

Multi-layer film structures BaTiO3/SiO2 with a thickness of ~1 μm containing up to 14 pairs of layers were synthesized by the sol–gel method with sequential heat treatment. It is shown that the synthesized structures are X-ray amorphous. The formation of bands in the transmission and reflection spectra caused by interference effects is demonstrated. A more regular structure exhibits a photon band gap (opacity band) in the visible range with main minimum at 636 nm and corresponding maximum in the reflection spectra. Dispersion characteristics of barium titanate films with different concentrations of initial sols were studied and an increase in the refractive index with an increase in the concentration of sol was demonstrated. For a sol with a concentration of 60 mg/ml, the refractive index in the spectral range of 390–1600 nm is 1.88–1.81. The prospects of sol–gel technology for the formation of BaTiO3/SiO2 structures for nanophotonics and solar radiation converters are discussed

Association between autophagy and KRAS mutation with clinicopathological variables in colorectal cancer patients

Autophagy is a host defensive mechanism responsible for eliminating harmful cellular components through lysosomal degradation. Autophagy has been known to either promote or suppress various cancers including colorectal cancer (CRC). KRAS mutation serves as an important predictive marker for epidermal growth factor receptor (EGFR)-targeted therapies in CRC. However, the relationship between autophagy and KRAS mutation in CRC is not well-studied. In this single-centre study, 92 formalin-fixed paraffin-embedded (FFPE) tissues of CRC patients (42 Malaysian Chinese and 50 Indonesian) were collected and KRAS mutational status was determined by quantitative PCR (qPCR) (n=92) while the expression of autophagy effector (p62, LC3A and LC3B) was examined by immunohistochemistry (IHC) (n=48). The outcomes of each were then associated with the clinicopathological variables (n=48). Our findings demonstrated that the female CRC patients have a higher tendency in developing KRAS mutation in the Malaysian Chinese population (p<0.05). Expression of autophagy effector LC3A was highly associated with the tumour grade in CRC (p<0.001) but not with other clinicopathological parameters. Lastly, the survival analysis did not yield a statistically significant outcome. Overall, this small cohort study concluded that KRAS mutation and autophagy effectors are not good prognostic markers for CRC patients

Upconversion emission from erbium doped sol-gel derived ВаТiOз powders and coatings

Upconversion is a process where light can be emitted with photon energies higher than those of the light generating the excitation (www.rp-photonics.com/upconversion). Diverse inorganic matrices doped with trivalent lanthanides - erbium and holmium exhibit upconversion, transferring infrared light into visible. Thus the effect attracts attention for detection and visualization of infrared radiation. Recently we reported that sol-gel derived barium titanate possessing refractive index about 1.9 in amorphous state can be used as component of optical interference filter in combination with low refractive index films as silica or magnesium fluoride. At the same time room-temperature luminescence of lanthanides in sol-gel derived barium titanate makes the material and method promising for light conversion. In this work we investigate erbium upconversion emission from sol-gel derived BaTiO3 films and powders

Photoactive Properties of Transport Sol-Gel Layers Based on Strontium Titanate for Perovskite Solar Cells

In this work, we have investigated the photocurrent and spectral sensitivity of the silicon/SrTiO3:xNb/perovskite structures. The sol–gel method carried out the deposition of undoped SrTiO3 layers as well as niobium-doped (SrTiO3:Nb) layers at atomic concentrations of 3 and 6% Nb. The perovskite layer, CH3NH3PbI3_xClx, has been deposited by the vacuum co-evaporation technique. The layers have been characterized by scanning electron microscopy and X-ray diffraction measurements. The volt–ampere characteristics and spectral sensitivity of the fabricated samples have been measured under illumination with selective wavelengths of 405, 450, 520, 660, 780, 808, 905, 980, and 1064 nm of laser diodes. We have shown that for different configurations of applied voltage between silicon, SrTiO3:xNb, and CH3NH3PbI3_xClx, the structures are photosensitive ones with a variation of photocurrent from microamperes to milliamperes depending on Nb concentration in SrTiO3, and the highest photocurrent and spectral sensitivity values are observed when a SrTiO3:Nb layer with 3 at.% of Nb is used. A possible application of the proposed structure with a SrTiO3:Nb layer for perovskite solar cells and photodetectors is being discussed