A semi-blind HVS based image watermarking scheme using elliptic curve cryptography

In the present paper, an advanced encryption technique commonly known as Elliptic Curve Cryptography (ECC) is used to embed a binary image as a watermark in five grayscale host images in a semi-blind manner. The ECC algorithm is a fast encryption technique which successfully encrypts the subject with significantly less number of bits as compared to other popular encryption algorithms such as Rivest-Shamir-Adleman (RSA) and Direct Selling Association (DSA). In the proposed watermarking scheme, embedding in the grayscale host images is carried out in DWT-SVD domain. First, entropy based Human Visual System (HVS) parameters are computed block wise to identify the most appropriate blocks in spatial domain. First level DWT is computed for these selected blocks and watermark embedding is carried out by using the calculated Singular Value Decomposition (SVD) parameters. Preliminary results of this work show that proposed scheme outperforms the other similar schemes carried out in DCT-SVD domain without using any encryption method. It is concluded that the use of DWT-SVD hybrid architecture along with the fast encryption technique ECC is responsible for better performance in present case. In the second part of this simulation, an established HVS model working in DCT domain is implemented and compared with the entropy based HVS model implemented in transform domain to embed the ECC encrypted binary watermark in images. In this case also, proposed scheme performs better both in terms of visual imperceptibility and robustness as compared to other scheme. It is concluded that HVS parameters – Luminance, Contrast and Edge Sensitivity are better placed in comparison to entropy parameters to examine image features and characteristics for watermarking purpose.     

Clustering effects in solution‐based nanoparticle/template hybrid coatings

Abstract— Templating processes with monodisperse polystyrene particles are being explored for a number of application areas, especially in microelectronics and optics. Classically, these depend on rather slow‐drying steps that allow for the polystyrene particles to gradually situate themselves into ordered arrays and patterns. On the other hand, many manufacturing processes are designed to operate much more rapidly (spin‐coating, roll‐coating, spray‐coating, etc.). The present work investigates the behavior of nanoparticle(titania)‐microparticle (polystyrene) hybrid solutions when processed with these rapid techniques. Very thin coatings were examined where the larger‐template particle‐particle interactions can be quantifiably observed and measured. This gives us insight into the conditions when structural order might be achievable in materials systems using these rapid, industrially important, coating techniques. The specific system that was investigated involves nanoscale titanium dioxide particles combined with monodisperse micron‐scale polystyrene template particles aimed at building flexible dye‐sensitized solar cells. For this application, the formation of strong physical networks of titanium dioxide nanoparticles with percolating interparticle channels for the electrolyte phase to reach all surfaces where dye molecules will reside is required.     

Bio-Synthesized Nanoparticles in Developing Plant Abiotic Stress Resilience: A New Boon for Sustainable Approach

Agriculture crop development and production may be hampered in the modern era because of the increasing prevalence of ecological problems around the world. In the last few centuries, plant and agrarian scientific experts have shown significant progress in promoting efficient and eco-friendly approaches for the green synthesis of nanoparticles (NPs), which are noteworthy due to their unique physio-biochemical features as well as their possible role and applications. They are thought to be powerful sensing molecules that regulate a wide range of significant physiological and biochemical processes in plants, from germination to senescence, as well as unique strategies for coping with changing environmental circumstances. This review highlights current knowledge on the plant extract-mediated synthesis of NPs, as well as their significance in reprogramming plant traits and ameliorating abiotic stresses. Nano particles-mediated modulation of phytohormone content in response to abiotic stress is also displayed. Additionally, the applications and limitations of green synthesized NPs in various scientific regimes have also been highlighted.     

Methods for determining microcystins (peptide hepatotoxins) and microcystin-producing cyanobacteria

Episodes of cyanobacterial toxic blooms and fatalities to animals and humans due to cyanobacterial toxins (CBT) are known worldwide. The hepatotoxins and neurotoxins (cyanotoxins) produced by bloom-forming cyanobacteria have been the cause of human and animal health hazards and even death. Prevailing concentration of cell bound endotoxin, exotoxin and the toxin variants depend on developmental stages of the bloom and the cyanobacterial (CB) species involved. Toxic and non-toxic strains do not show any predictable morphological difference. The current instrumental, immunological and molecular methods applied for determining microcystins (peptide hepatotoxins) and microcystin-producing cyanobacteria are reviewed.     

Structure and microwave dielectric properties of ALn4(MoO4)7 (A = Ba,Sr, Ca,Ln = La,Pr, Nd,and Sm) ceramics

ALn₄(MoO₄)₇ (A = Ba, Sr, Ca, Ln = La, Pr, Nd, Sm) ceramics are prepared by solid state ceramic route and the structural properties have been studied using powder X-ray diffraction and laser Raman spectroscopy. All the ceramics under study are phase pure except BaLn₄(MoO₄)₇ (Ln = Pr, Nd, Sm). Scanning electron micrographs of the sintered ceramics show closely packed microstructure with phase homogeneity. BaLa₄(MoO₄)₇ ceramic has a maximum density of 4.5 g/cm³ at 710°C together with ԑ_r = 11.8, Q_u x f = 39 300 GHz, and τ_f = −68 ppm/^oC. SrLa₄(MoO₄)₇ ceramic exhibited a maximum density of 4.4 g/cm³, ԑ_r = 11.7, Q_u x f = 44 200 GHz, and τ_f = −83 ppm/^°C at 740°C whereas CaLa₄(MoO₄)₇ ceramic possess a maximum density of 4.2 g/cm³, ԑ_r = 11.4, Q_u x f = 30 200 GHz and τ_f = −90 ppm/^oC at 750°C at microwave frequencies. The chemical compatibility of the BaLa₄(MoO₄)₇, SrLa₄(MoO₄)₇ and CaLa₄(MoO₄)₇ ceramics with silver electrode have been studied using powder X-ray diffraction of the co-fired samples and is further examined with energy dispersive X-ray spectroscopy.     

Novel agar–stearyl alcohol oleogel-based bigels as structured delivery vehicles

The present study describes the synthesis of novel bigels as delivery matrices for controlled delivery applications. The bigels were prepared by mixing agar hydrogel and stearyl alcohol oleogel in different proportions. The microscopic analysis of the bigels suggested the formation of biphasic bigels at lower proportions of oleogel and bicontinuous bigel at higher proportions. Stress relaxation study was used to analyze the mechanical properties. The viscoelastic property of the bigels was estimated by modeling the relaxation profile using Weichert model of viscoelasticity. The analysis of the electrical property of the bigels showed an increase in the impedance values as the oleogel content was increased. Further, a corresponding decrease in the electrical stability of the bigels was observed with an increase in the oleogel proportion. The analysis was prepared using (RQ)Q equivalent electrical circuit model. The ciprofloxacin hydrochloride release from the bigels was predominantly diffusion-mediated as analyzed by Korsmeyer–Pappas and Peppas–Sahlin models.     

Surface engineered magnetic nanoparticles for removal of toxic metal ions and bacterial pathogens

Surface engineered magnetic nanoparticles (Fe₃O₄) were synthesized by facile soft-chemical approaches. XRD and TEM analyses reveal the formation of single-phase Fe₃O₄ inverse spinel nanostructures. The functionalization of Fe₃O₄ nanoparticles with carboxyl (succinic acid), amine (ethylenediamine) and thiol (2,3-dimercaptosuccinic acid) were evident from FTIR spectra, elemental analysis and zeta-potential measurements. From TEM micrographs, it has been observed that nanoparticles of average sizes about 10 and 6 nm are formed in carboxyl and thiol functionalized Fe₃O₄, respectively. However, each amine functionalized Fe₃O₄ is of size ∼40 nm comprising numerous nanoparticles of average diameter 6 nm. These nanoparticles show superparamagnetic behavior at room temperature with strong field dependent magnetic responsivity. We have explored the efficiency of these nanoparticles for removal of toxic metal ions (Cr³⁺, Co²⁺, Ni²⁺, Cu²⁺, Cd²⁺, Pb²⁺ and As³⁺) and bacterial pathogens (Escherichia coli) from water. Depending upon the surface functionality (COOH, NH₂ or SH), magnetic nanoadsorbents capture metal ions either by forming chelate complexes or ion exchange process or electrostatic interaction. It has been observed that the capture efficiency of bacteria is strongly dependent on the concentration of nanoadsorbents and their inoculation time. Furthermore, these nanoadsorbents can be used as highly efficient separable and reusable materials for removal of toxic metal ions.     

Extraction and applications of lignin from bamboo: a critical review

European Journal of Wood and Wood Products - Bamboo, commonly known as green gold, has various advantages like its quick proliferation, requires no irrigation, replanting is not necessary, can be...     

Preparation of mechanically strong poly (ether block amide)/Mercaptoethanol breathable membranes for biomedical applications

Poly (ether block amide) (PEBA) was modified with Mercaptoethanol (ME) to introduce crosslinks in its polymeric structure and emphasis was laid on obtaining non-porous breathable membranes with improved mechanical properties which can be used for various biomedical applications. Pebax MH 1657 (mentioned as PEBA throughout the text) was cast polymerized with ME and the effect of ME on the properties of the membranes (such as water absorption, permeability, tensile strength, elongation & tear strength) was studied. Fourier Transform Infrared Spectroscopy- Attenuated Total Reflectance (FTIR-ATR), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Differential Thermogravimetry (DTG) techniques were used to characterize the membranes. Different amount of ME (10 to 40% w/w) was added to PEBA and 30% of ME was found to be most effective in increasing the mechanical properties of the membrane. Sulfhydryl group played an important role in enhancing mechanical strength of the membranes. PEBA/ME based non porous breathable membrane with excellent mechanical strength is a novel material that can be used for various biomedical applications.     

Structure and properties of short fibre reinforced silica matrix composite foams

Glass (GFC) and silica (SFC) fibre reinforced silica matrix composite foams with 84–90% porosity content have been developed through slurry-based processing, involving random dispersion of 10 wt.% fibres with aspect ratios of >1000 in hydrophobized silica-based suspensions, and direct foaming for air entrapment. Fibre entanglement has not been found either in the suspensions or in the sintered composite foams. Microstructural and mercury porosimetry studies of the composite foams have shown a trimodal size distribution with small (4–8 μm), medium (40–200 μm), and large (1 mm or more) pores. The pores appear spherical and interconnected, with the fibres embedded in cell-walls or struts. The dynamic Young's modulus of the silica-coated GFCs is found to be 3.5 and 5.2 times that of the coated and uncoated monolithic silica foams, respectively, confirming that both fibre-reinforcement and the presence of surface coating are beneficial for increase in stiffness of the composite foams.