Exopolymer produced by Pseudomonas aeruginosa: A super sorbent for ruthenium

Pseudomonas aeruginosa exopolymer was found to have a sorption capacity of 196.3 mg/g at 100 µg/mL of ruthenium, pH 2.8, and 30 min, which is 5–10 times higher compared to the earlier reports. Uptake mechanism was deduced using sorption studies and energy-dispersive X-ray fluorescence, proton-induced X-ray emission, scanning electron microscopy, and Fourier transform infrared spectroscopy techniques. Shrinking and volume change were observed in the morphology of the exopolymer upon ruthenium uptake. During biosorption, occurrence of ion exchange and involvement of carboxyl, ether, and alcoholic functional groups were noted. Biopolymer was found to be a potential sorbent for soluble radionuclide removal during nuclear fuel reprocessing and hazardous waste disposal.     

Study of thermal,flammability and mechanical properties of intumescent flame retardant PP/kenaf nanocomposites

Detrimental physical and mechanical properties are common problems for composites when their flame retardancy is improved through filler additions. An increased interest of the synergistic nanoparticle addition to improve the flame retardancy of natural fiber composites is the aim of this work. The paper investigates the synergistic effect of two different nanoparticles (halloysite nanotubes (HNTs) and montmorillonite (MMT) nanoclay) on the flame and mechanical properties in an intumescent ammonium polyphosphate (APP)-based polypropylene (PP)/kenaf composite system. First, the nature of nanoparticle dispersion in PP through X-ray diffraction (XRD) and transmission electron microscopy (TEM) reveals that under twin screw compounding process, the partial exfoliation and intercalation have taken place within the nanocomposites. An increase in the decomposition temperature was observed under thermogravimetric analysis (TGA), with the presence of HNT. However, MMT tends to lower the maximum decomposition temperature under inert atmosphere. The flammability analysis in an intumescent flame retardant (IFR) system shows that the suitable amount of high aspect ratio nanoparticles with their exfoliation characteristics effectively helps to reduce the sustained combustion. Even though, improved stiffness properties can be observed with the presence of increased filler content, particle agglomeration tends to reduce the mechanical strengths of these composites due to low compatibilization and crack propagation.     

Enhanced mechanical properties of acrylate based shape memory polymer using grafted hydroxyapatite

In the present study, the effect of grafted and ungrafted hydroxyapatite (HAp) filler on the mechanical properties of acrylate based shape memory polymer (SMP) composite is reported. HAp is grafted with polyethylene glycol methacrylate (PEGMA) monomer to avoid agglomeration and the same is embedded as reinforcement in tBA – PEGDMA matrix (70 wt% tBA: tert-butyl acrylate +30 wt% PEGDMA: polyethylene glycol dimethacrylate). The grafting process improved the interfacial interactions of the particles, dispersed in the polymer system and subsequently enhanced the mechanical properties of the shape memory polymer composites. The morphology of HAp particles is investigated by field emission scanning electron microscopy. The mechanical properties of SMP composites are evaluated at room temperature and above glass transition temperature (Tg) with grafted and ungrafted HAp particles. The addition of grafted HAp significantly improved the tensile strength (40%) and shape recovery rate (25%) of the SMP composite when compared to the SMP composite containing ungrafted HAp. SMP composite containing grafted HAp exhibited higher cell viability compared to the neat SMP and the SMP composite containing ungrafted HAp.     

Contrast sensitivity with presbyopic contact lenses

The purpose of the work was to assess the contrast sensitivity function of individuals wearing gas permeable (GP) multifocal contact lenses, soft bifocal contact lenses, and GP monovision lenses. Twenty-six females and six males between the ages of 42 and 65 participated in this study. The study included subjects wearing monovision (N?=?8), the Acuvue Bifocal (Johnson & Johnson) (N?=?8), Essential GP Multifocal (Blanchard) lenses (N?=?8) and progressive addition spectacle lenses (PAL) (N?=?8), with PAL wearers forming the control group. Measurements of binocular contrast sensitivity were obtained using the VISTECH 6500 system. Thresholds for each spatial frequency were fit to the equation CS(k)?=?ak?exp(?bk) [1?+?c exp(bk)]^?1/2, to describe the human contrast sensitivity function. The area under the contrast sensitivity function (CSF) curve was calculated for all four groups and compared. An index of performance was obtained, which was defined as the ratio of CSF with the contact lens correction to the CSF with spectacles. Of the contact lens wearing groups, GP multifocal contact lens wearers had the highest contrast sensitivity at all the spatial frequencies. Soft bifocal contact lens wearers exhibited higher contrast sensitivity than monovision wearers at all spatial frequencies. Subjects wearing GP multifocals had the largest area under the CSF; followed by those wearing soft bifocals, with monovision wearers having the smallest area. GP multifocals have the best visual function at 0.98, soft bifocals have an index of 0.65 and monovision has an index of 0.59. This study quantifies the visual performance of the three lens systems by measuring the area under the CSF curve. In addition, it provides indices of visual function with the contact lenses that will be helpful for analyses and comparisons in future studies.     

Chronic arsenicosis in cattle with special reference to its metabolism in arsenic endemic village of Nadia district West Bengal India

Thirty Milch cattle were selected randomly from a village of Nadia district of West Bengal, India containing high arsenic in water and soil samples. Milk, feces and hair samples were collected to analyze arsenic status in animals. Water and straw samples were also estimated for arsenic. Milk products prepared from milk of cattle rearing in arsenic prone village were also collected to quantify total arsenic and speciation of arsenic in milk and feces samples were also carried out. It was observed that high amount of arsenic was present in milk, feces, hair of cattle and water and straw samples in arsenic prone village. Milk product also contained significant amount of arsenic than that of milk product of control village. Speciation study revealed arsenite fraction was mainly eliminated through milk, whereas organoarsenic species were mainly excreted through feces.     

Synthesis,Characterization and Properties of New Semifluorinated Poly(arylene ether phosphine oxide)s

Bis(4‐fluoro‐3‐trifluoromethylphenyl)phenylphosphine oxide is synthesized and six new poly(arylene ether)s are prepared by nucleophilic displacement of the fluorine atom on the benzene ring by several diphenols under basic conditions. The products show very high glass transition temperatures of up to 252 °C and very good thermal stabilities of up to 490 °C for 5% weight loss. The polymers display very low heat release rates in the microscale combustion calorimeter test, suggesting good flame retardance. All polymers are soluble in a wide range of organic solvents. Transparent thin films cast from dichloromethane exhibit tensile strengths up to 54 MPa, a modulus of elasticity up to 0.97 GPa and elongation at break up to 47% depending on their exact repeating unit structures.

     

Effect of Feedstock Powders on the Microstructural and Electrical Characteristics of 8 mol% Yttria-Stabilized Zirconia Plasma-Sprayed Coatings

Plasma-sprayed coatings of 8 mol% yttria-stabilized zirconia (YSZ) were fabricated using the feedstock powders obtained from co-precipitation (PPT) and spray-drying (SD) processes. Particle size and the specific mass (SM) of the feedstock powder were found to be the critical parameters that influence the microstructural and electrical properties of the coatings. While dense and larger particle-sized PPT powder resulted in a porous microstructure, dense coatings were obtained for SD powders with relatively lower SM. Electrical conductivity values of SD-coatings were found to be 30% higher than that of PPT-coatings. Electrical conductivity values of plasma-sprayed PPT-coatings improved significantly on decreasing the particles size. However, the size effect was only subtle in the case of SD coatings. PPT-coatings fabricated from smaller particle-sized powders had the necessary electrical conductivities appropriate for solid oxide fuel cell electrolyte applications.     

Highly stable,protein capped gold nanoparticles as effective drug delivery vehicles for amino-glycosidic antibiotics

A method for the production of highly stable gold nanoparticles (Au NP) was optimized using sodium borohydride as reducing agent and bovine serum albumin as capping agent. The synthesized nanoparticles were characterized using UV–visible spectroscopy, transmission electron microscopy, X‐ray diffraction (XRD) and dynamic light scattering techniques. The formation of gold nanoparticles was confirmed from the appearance of pink colour and an absorption maximum at 532 nm. These protein capped nanoparticles exhibited excellent stability towards pH modification and electrolyte addition. The produced nanoparticles were found to be spherical in shape, nearly monodispersed and with an average particle size of 7.8 ± 1.7 nm. Crystalline nature of the nanoparticles in face centered cubic structure is confirmed from the selected‐area electron diffraction and XRD patterns. The nanoparticles were functionalized with various amino-glycosidic antibiotics for utilizing them as drug delivery vehicles. Using Fourier transform infrared spectroscopy, the possible functional groups of antibiotics bound to the nanoparticle surface have been examined. These drug loaded nanoparticle solutions were tested for their antibacterial activity against Gram-negative and Gram-positive bacterial strains, by well diffusion assay. The antibiotic conjugated Au NP exhibited enhanced antibacterial activity, compared to pure antibiotic at the same concentration. Being protein capped and highly stable, these gold nanoparticles can act as effective carriers for drugs and might have considerable applications in the field of infection prevention and therapeutics.     

Visualizing the complex 3D geometry of the perfusion border zone in isolated rabbit heart

Myocardial infarction, caused by a major blockage of a coronary artery, creates a border zone (BZ) between perfused and nonperfused tissue, which is believed to be the origin of fatal cardiac arrhythmias. We used a combination of optical clearing and polarization-sensitive optical coherence tomography to visualize a three-dimensional organization of the BZ in isolated rabbit hearts (n=5) at the microscopic level with a high spatial resolution. We found that the BZ has a complex three-dimensional structure with nonperfused areas penetrating into perfused tissue with finger-like projections. These "fingers" may play an important role in the initiation and maintenance of ventricular arrhythmias.