Anatomical, physiological, and chemical alterations in lichen (Parmotrema tinctorum (Nyl.) Hale) transplants due to air pollution in two cities of Brahmaputra Valley, India.

The lichen species Parmotrema tinctorum (Nyl.) Hale was transplanted in two cities-Tezpur (small) and Guwahati (large)-of the Brahmaputra Valley to assess the impact of air pollution on the anatomy and physiology, and accumulation of pollutants. Significant damage to the anatomy was observed in samples, and the degree of damage was found to be higher in the transplants of the larger city. In the lichen transplants from locations having high traffic density, the total chlorophyll content was found to fall; on the contrary, electrical conductivity was found to be higher. The exposed-to-control ratio showed severe accumulation of Cd in all the transplants. Elements such as Cd, Pb, and Zn were found to be enriched in all the lichen samples from both Guwahati as well as Tezpur city. Besides, Cr, Cu, K, and Ni were also realized to be enhanced to a moderate extent. The correlations of indicator metal species pairs showed that anthropogenic influence was quite clear.

Chitosan-cinnamaldehyde Schiff base: A bioinspired macromolecule as corrosion inhibitor for oil and gas industry.

A Schiff base of chitosan with cinnamaldehyde (Cinn-Cht) was synthesized in a single step using microwave irradiation and characterized using spectroscopic techniques. The synthesized Schiff base was used for the mitigation of carbon steel corrosion in 15% HCl. The corrosion evaluation was performed using weight loss tests, electrochemical impedance measurements, and polarization studies. The corrosion inhibition efficiency increased with inhibitor dosage and achieved a high value of 85.16% at 400 mgL-1. The inhibitor adsorption followed the Langmuir isotherm and displayed a mixed physical and chemical adsorption behavior. To further improve the corrosion inhibition efficiency, potassium iodide (KI) was incorporated in the corrosive solution, which increased the inhibition efficiency further to 92.45% at a concentration of 10 mM. Surface studies carried out via SEM analyses indicated the inhibitor adsorption and protective film formation on the steel surface. The computational studies carried out via DFT revealed that mainly the protonated form of inhibitor adsorbs on the metal surface. Monte Carlo simulation studies also showed that the protonated form of the inhibitor molecule exhibited higher adsorption energy than the neutral inhibitor.

Microwave-assisted synthesis of a new Piperonal-Chitosan Schiff base as a bio-inspired corrosion inhibitor for oil-well acidizing.

A new Schiff base of chitosan, namely Piperonal-chitosan (Pip-Cht), was synthesized for the first time, using a microwave irradiation method and characterized using spectroscopic techniques. The corrosion inhibition behavior of the new Schiff base was evaluated on carbon steel in 15% HCl medium via gravimetric and electrochemical techniques. This is the first work on the application of chemically functionalized chitosan as a corrosion inhibitor in the oil-well acidizing environment. The Pip-Cht inhibitor exhibited a high corrosion inhibition efficiency of 85.16% at a moderate dose of 600 mg L-1. Further, the addition of potassium iodide as a synergistic agent to the corrosive electrolyte produced a significant improvement in the inhibition efficiency to 91.15% at a low dosage of 10 mM of KI. At a higher temperature of 65 °C, the combination of both the inhibitor and KI yielded a high inhibition efficiency. The results of the gravimetric and electrochemical experiments were corroborated using AFM and SEM studies. The DFT calculations indicated that corrosion inhibition behavior of the Schiff base mainly occurs in the protonated form.

Biomonitoring by epiphytic lichen species-Pyxine cocoes (Sw.) Nyl.: understanding characteristics of trace metal in ambient air of different landuses in mid-Brahmaputra Valley.

This study presents a comparative assessment of the trace metal air pollutants of urban, peri-urban, and rural areas of the Brahmaputra Valley plain in the Eastern Himalayan region using biomonitoring of Pyxine cocoes. In situ collection of the thalli growing on Bombax sp. from representative locations was done, which was analyzed for Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, and Zn using ICP-OES. The metals, viz. Cd, Cr, Ni, Pb, and Zn, were highly enriched, indicating anthropogenic influences. The coefficients of variation (CV) of Co, Cr, and Ni were also high, pointing at their accumulation from local sources. Influence of local sources was also observed for Cd, Fe, and Mn in peri-urban and Cd in urban samples. Metals related to automobiles were accumulated in greater volume in samples of peri-urban locations, which implies the impact of the highway that runs through these locations and other associated human activities. The samples of urban areas were found to be enriched with metals originating from both vehicular emissions and road dust. Also, accumulations of Co, Cr, Cu, Fe, Mn, and Ni in the lichen thalli were found to be around tea gardens. Inter-species correlations were found to be positively significant for most of the elements. Principal component analysis (PCA) of the metal data revealed that vehicular emission and coal burning, street dust, and crustal dust were the major sources of trace metals in the ambient air of the region.

Heavy metals in drinking water: Occurrences, implications, and future needs in developing countries.

Heavy metals in drinking water pose a threat to human health. Populations are exposed to heavy metals primarily through water consumption, but few heavy metals can bioaccumulate in the human body (e.g., in lipids and the gastrointestinal system) and may induce cancer and other risks. To date, few thousand publications have reported various aspects of heavy metals in drinking water, including the types and quantities of metals in drinking water, their sources, factors affecting their concentrations at exposure points, human exposure, potential risks, and their removal from drinking water. Many developing countries are faced with the challenge of reducing human exposure to heavy metals, mainly due to their limited economic capacities to use advanced technologies for heavy metal removal. This paper aims to review the state of research on heavy metals in drinking water in developing countries; understand their types and variability, sources, exposure, possible health effects, and removal; and analyze the factors contributing to heavy metals in drinking water. This study identifies the current challenges in developing countries, and future research needs to reduce the levels of heavy metals in drinking water.

Cell-adhesive thermogelling PNIPAAm/hyaluronic acid cell delivery hydrogels for potential application as minimally invasive retinal therapeutics.

Copolymers of N-isopropylacrylamide (NIPAAm) and acrylic acid N-hydroxysuccinimide (NAS) were synthesized via free radical polymerization and conjugated with amine-functionalized hyaluronic acid (HA) and cell adhesive RGDS peptides. These novel copolymers were designed to facilitate noninvasive delivery of a liquid suspension of cells into the delicate subretinal space for treatment of retinal degenerative diseases such as age-related macular degeneration (AMD) and diabetic retinopathy. The various synthesized copolymers all displayed subphysiological phase transition temperatures, thereby allowing temperature-induced scaffold formation and subsequent entrapment of transplanted cells within an adhesive support matrix. Successful grafting of HA and RGDS peptides were confirmed with Fourier Transform Infrared (FTIR) spectroscopy and quantified with (1)H Nuclear Magnetic Resonance (NMR) spectroscopy. All copolymers demonstrated excellent compatibility with retinal pigment epithelial (RPE) cells in culture and minimal host response was observed following subcutaneous implantation into hairless SKH1-E mice (strain code 447).

Core-cross-linked alginate microcapsules for cell encapsulation.

Self-cross-linkable polyelectrolyte pairs comprised of poly(methacrylic acid, sodium salt-co-2-[methacryloyloxy]ethyl acetoacetate) (70:30 mol ratio, A70) and poly-L-lysine are incorporated into CaAlg beads to form either a covalently cross-linked shell or a core-cross-linked bead. In both cases the reactive polyanion is added to a solution of sodium alginate that may contain live cells and dropped into a calcium chloride gelling bath. Subsequent exposure to poly-L-lysine (15-30 kDa) leads to formation of a cross-linked shell, while exposure to lower molecular weight poly-L-lysine (4-15 kDa) leads to formation of an interpenetrating matrix of covalently cross-linked synthetic polymer within the CaAlg template. The resulting spherical composites are resistant to chemical and mechanical stress yet remain cyto-compatible. This approach to cell-encapsulation may be useful for cell immuno-isolation in therapeutic cell transplants.

Self-cross-linking polyelectrolyte complexes for therapeutic cell encapsulation.

Self-cross-linking polyelectrolytes are used to strengthen the surface of calcium alginate beads for cell encapsulation. Poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride), containing 30 mol % 2-aminoethyl methacrylate, and poly(sodium methacrylate), containing 30 mol % 2-(methacryloyloxy)ethyl acetoacetate, were prepared by radical polymerization. Sequential deposition of these polyelectrolytes on calcium alginate films or beads led to a shell consisting of a covalently cross-linked polyelectrolyte complex that resisted osmotic pressure changes as well as challenges with citrate and high ionic strength. Confocal laser fluorescence microscopy revealed that both polyelectrolytes were concentrated in the outer 7-25 microm of the calcium alginate beads. The thickness of this cross-linked shell increased with exposure time. GPC studies of solutions permeating through analogous flat model membranes showed molecular weight cut-offs between 150 and 200 kg/mol for poly(ethylene glycol), suitable for cell encapsulation. C 2C 12 mouse cells were shown to be viable within calcium alginate capsules coated with the new polyelectrolytes, even though some of the capsules showed fibroid overcoats when implanted in mice due to an immune response.