Novel Biodegradable Cast Film from Carbon Dioxide Based Copolymer and Poly(Lactic Acid)

Poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC) blends with different levels of chain extender were prepared and cast into films. The effect of chain extender on the mechanical, thermal and barrier properties of the films were investigated. With the inclusion of the chain extender, the compatibility and interfacial adhesion between the two polymer phases were significantly improved by a mean of forming a PLA–chain extender–PPC copolymer. Reactions between the chain extender, PLA and PPC were observed through FTIR study. SEM study also confirmed the improved compatibility and interfacial adhesion. The elongation at break of the compatibilized film with optimal amount of chain extender showed dramatic increase by up to 1940 %. DSC studies revealed that chain extender hindered the crystallization of the film which explained the decrease in both water and oxygen barrier when adding chain extender. PLA was found to be able to enhance both oxygen and water barrier of the blend as compared to neat PPC, while in the case of the blend with chain extender, oxygen and water barrier properties exhibited reduction at the beginning. However, when increasing chain extender concentration, these two barrier performance exhibited an upward trend. It was found that PLA/PPC blend showed much better oxygen barrier property than both parent polymers, which can be ascribed to the acceleration effect of PPC on the crystallization of PLA.     

Aerosol optical and physical properties during winter monsoon pollution transport in an urban environment

We analysed aerosol optical and physical properties in an urban environment (Kolkata) during winter monsoon pollution transport from nearby and far-off regions. Prevailing meteorological conditions, viz. low temperature and wind speed, and a strong downdraft of air mass, indicated weak dispersion and inhibition of vertical mixing of aerosols. Spectral features of WinMon aerosol optical depth (AOD) showed larger variability (0.68–1.13) in monthly mean AOD at short-wavelength (SW) channels (0.34–0.5 μm) compared to that (0.28–0.37) at long-wavelength (LW) channels (0.87–1.02 μm), thereby indicating sensitivity of WinMon AOD to fine aerosol constituents and the predominant contribution from fine aerosol constituents to WinMon AOD. WinMon AOD at 0.5 μm (AOD _{0. 5}) and Angstrom parameter ( α) were 0.68–0.82 and 1.14–1.32, respectively, with their highest value in December. Consistent with inference from spectral features of AOD, surface aerosol loading was primarily constituted of fine aerosols (size 0.23–3 μm) which was 60–70 % of aerosol 10- μm (size 0.23–10 μm) concentration. Three distinct modes of aerosol distribution were obtained, with the highest WinMon concentration at a mass median diameter (MMD) of 0.3 μm during December, thereby indicating characteristics of primary contribution related to anthropogenic pollutants that were inferred to be mostly due to contribution from air mass originating in nearby region having predominant emissions from biofuel and fossil fuel combustion. A relatively higher contribution from aerosols in the upper atmospheric layers than at the surface to WinMon AOD was inferred during February compared to other months and was attributed to predominant contribution from open burning emissions arising from nearby and far-off regions. A comparison of ground-based measurements with Moderate Resolution Imaging Spectroradiometer (MODIS) data showed an underestimation of MODIS AOD and α values for most of the days. Discrepancy in relative distribution of fine and coarse mode of MODIS AOD was also inferred.     

Catalase and ascorbate peroxidase—representative H<Subscript>2</Subscript>O<Subscript>2</Subscript>-detoxifying heme enzymes in plants

Plants have to counteract unavoidable stress-caused anomalies such as oxidative stress to sustain their lives and serve heterotrophic organisms including humans. Among major enzymatic antioxidants, catalase (CAT; EC 1.11.1.6) and ascorbate peroxidase (APX; EC 1.11.1.11) are representative heme enzymes meant for metabolizing stress-provoked reactive oxygen species (ROS; such as H₂O₂) and controlling their potential impacts on cellular metabolism and functions. CAT mainly occurs in peroxisomes and catalyzes the dismutation reaction without requiring any reductant; whereas, APX has a higher affinity for H₂O₂ and utilizes ascorbate (AsA) as specific electron donor for the reduction of H₂O₂ into H₂O in organelles including chloroplasts, cytosol, mitochondria, and peroxisomes. Literature is extensive on the glutathione-associated H₂O₂-metabolizing systems in plants. However, discussion is meager or scattered in the literature available on the biochemical and genomic characterization as well as techniques for the assays of CAT and APX and their modulation in plants under abiotic stresses. This paper aims (a) to introduce oxidative stress-causative factors and highlights their relationship with abiotic stresses in plants; (b) to overview structure, occurrence, and significance of CAT and APX in plants; (c) to summarize the principles of current technologies used to assay CAT and APX in plants; (d) to appraise available literature on the modulation of CAT and APX in plants under major abiotic stresses; and finally, (e) to consider a brief cross-talk on the CAT and APX, and this also highlights the aspects unexplored so far.     

Processability and Biodegradability Evaluation of Composites from Poly(butylene succinate) (PBS) Bioplastic and Biofuel Co-products from Ontario

This study investigates the processability and biodegradability of composite bioplastic materials. Biocomposites were processed using twin-screw compounding of the bioplastic poly(butylene succinate) (PBS) with bio-based fillers derived from co-products of biofuel production. An extensive biodegradability evaluation was conducted on each biocomposite material, as well as the base materials, using respirometric testing to analyze the conversion of organic carbon into carbon dioxide. This evaluation revealed that the presence of meal-based fillers in the biocomposites increased the rate of biodegradation of the matrix polymer, degrading at a faster pace than both the pure PBS polymer and the switchgrass (SG) composite. This degradation was further confirmed using FT-IR and thermal analysis of the material structure before and after biodegradation. The increased biodegradation rate is attributed to the high concentration of proteins in the meal-based composites, which enhanced the hydrolytic biodegradation of the material and facilitated micro-organism growth. The SG-based composite degraded slower than the pure polymer due to its lignin content, which degrades via a different mechanism than the polymer, and slowed the biodegradation process.     

Environmental impact of leaching of trace elements from fly ash dumps on aquatic ecosystems

Ten sampling points were selected in Kanhan River, situated near the ash dump sites of Koradi Thermal Power Plant, Nagpur. The leaching of trace elements from fly ash dumps was experimentally determined by acid digestion, batch leaching and toxicity characteristic leaching procedure tests. Elemental concentrations in river water, sediment, plankton and five commonly prevailing fish species (Catla catla, Labeo bata, Cyprinus carpio, Cirrhinus reba, Puntius ticto) were determined using a Flame Atomic Absorption Spectrophotometer during the pre-monsoon and post-monsoon seasons. Metal concentrations (Cr, Mn, Zn, Cu, Fe, Ni, Cu and Pb) in river water were higher during the pre-monsoon season compared to the post-monsoon season. Zn (30.65?mg/kg) was observed to be the most predominant metal in plankton during the pre-monsoon season while, during the post-monsoon season, Fe (21.19?mg/kg) showed the maximum concentration. Muscles of C. catla had metal concentrations (Cr, Mn, Zn, Fe, Cu and Pb) above the permissible limits of Food and Agricultural Organization (FAO 1983) during the pre-monsoon season. Bioaccumulation factor (BAF) was found highest for Cr (37.5) in muscles of C. catla during the pre-monsoon season, while BAF was observed to be maximum in L. bata for Cu (28.09), which may be detrimental for human consumption.     

Lung subcellular fractions and surfactant lipid metabolism of rats exposed with DDT or endosulfan intratracheally

Abstract

The effect of intracheally administered DDT (5 mg/100 g body weight) or endosulfan (1 mg/100 g body weight) for three cosecutive days have been studied on lipid metabolism of rat lung subcellular fractions. Both the insecticides did not affect the lung weight and the protein contents of microsomes, lamellar bodies and surfactant but significantly increased the phospholipid contents of microsomal and surfactant system. Most of the neutral lipid components of lung subcellular fractions were also increased by DDT or endosulfan treatments, except that of surfactant triglycerides which were decreased by DDT treatment. DDT or endosulfan both increased the incorporation of radioactive [methyl‐³H]choline into microsomal phosphatidylcholine (PC) and surfactant dipalmitoylphosphatidylcholine (DPPC) without affecting the incorporation of radioactive [methyl‐¹⁴C]methionine, showing the increased synthesis of PC via CDPcholine pathway. The results presented in this communication showed that DDT and endosulfan, the two different chloroinsecticides have similar effects on microsomal lipid metabolism but produce different biochemical manifestations on the secretion of surfactant phospholipids.     

Minimizing changing climate impact on buildings using easily and economically feasible earth to air heat exchanger technique

The biggest challenge of the 21st century is to satisfy the escalating demand of energy and minimize the globally changing climate impact. Earth to air heat exchanger (EAHE) system can effectively reduce heating affects on buildings. An experimental study was carried out by designing EAHE system using low cost building materials like Bamboo (Bambuseae) and hydraform (cement and soil plaster) to reduce the energy consumption of buildings and minimize the impact of climate change. This system utilizes earth’s constant subterranean temperature for naturally heating or cooling the inlet air. This study was carried out in the North Eastern part of India. An open loop EAHE system was developed to predict the heating and cooling potential of the system. Within the system locally available bamboos were used for constructing the tunnel pipes and soil-cement mixture plaster was used to enhance the conductivity of the bamboo pipes. Soil-cement mixtures are capable of decreasing the humidity by 30 to 40 %. Majority of the North Eastern region of India, have humid climatic conditions through out the year. Experiment was performed continuously for 7 days and the result shows that irrespective to the inlet air temperature (ranges from 35 °C to 42 °C), outlet air temperature was recorded between 25 °C and 26 °C, which shows the effectiveness of the system. After a series of experimental analysis the study reveals that underground tunnel based fresh air delivery system is one of the easily feasible and economically feasible techniques which can drastically reduce the energy consumption of the buildings and help in addressing the continuously escalating demand of power and minimizing the impact of changing climatic conditions on buildings.     

Climate change impact, mitigation and adaptation strategies for agricultural and water resources, in Ganga Plain (India)

Agriculture consumes more than two-thirds of global fresh water out of which 90 % is used by developing countries. Freshwater consumption worldwide is expected to rise another 25 %by 2030 due to increase in population from 6.6 billion currently to about 8 billion by 2030 and over 9 billion by 2050. Worldwide climate change and variability are affecting water resources and agricultural production and in India Ganga Plain region is one of them. Hydroclimatic changes are very prominent in all the regions of Ganga Plain. Climate change and variability impacts are further drying the semi-arid areas and may cause serious problem of water and food scarcity for about 250 million people of the area. About 80 million ha out of total 141 million ha net cultivated area of India is rainfed, which contributes approximately 44 % of total food production has been severely affected by climate change. Further changing climatic conditions are causing prominent hydrological variations like change in drainage density, river morphology (tectonic control) & geometry, water quality and precipitation. Majority of the river channels seen today in the Ganga Plain has migrated from their historic positions. Large scale changes in land use and land cover pattern, cropping pattern, drainage pattern and over exploitation of water resources are modifying the hydrological cycle in Ganga basin. The frequency of floods and drought and its intensity has increased manifold. Ganga Plain rivers has changed their course with time and the regional hydrological conditions shows full control over the rates and processes by which environments geomorphically evolve. Approximately 47 % of total irrigated area of the country is located in Ganga Plain, which is severely affected by changing climatic conditions. In long run climate change will affect the quantity and quality of the crops and the crop yield is going to be down. This will increase the already high food inflation in the country. The warmer atmospheric temperatures and drought conditions will increase soil salinization, desertification and drying-up of aquifer, while flooding conditions will escalate soil erosion, soil degradation and sedimentation. The aim of this study is to understand the impact of different hydrological changes due to climatic conditions and come up with easily and economically feasible solutions effective in addressing the problem of water and food scarcity in future.     

Development and Evaluation of a Continuous Coarse (PM10–PM25) Particle Monitor

ABSTRACT

In this paper, we describe the development and laboratory and field evaluation of a continuous coarse (2.5-10 um) particle mass (PM) monitor that can provide reliable measurements of the coarse mass (CM) concentrations in time intervals as short as 5-10 min. The operating principle of the monitor is based on enriching CM concentrations by a factor of ~25 by means of a 2.5-um cut point round nozzle virtual impactor while maintaining fine mass (FM)—that is, the mass of PM_{2 5} at ambient concentrations. The aerosol mixture is subsequently drawn through a standard tapered element oscillating microbalance (TEOM), the response of which is dominated by the contributions of the CM, due to concentration enrichment. Findings from the field study ascertain that a TEOM coupled with a PM₁₀ inlet followed by a 2.5-um cut point round nozzle virtual impactor can be used successfully for continuous CM concentration measurements. The average concentration-enriched CM concentrations measured by the TEOM were 26-27 times higher than those measured by the time-integrated PM₁₀ samplers [the micro-orifice uniform deposit     

Toxic metals and organochlorine pesticides residue in single herbal drugs used in important ayurvedic formulation – ‘Dashmoola’

Herbal formulations are getting popularity throughout the world and commercialized extensively for various medicinal properties. WHO has emphasized the need for quality assurance of herbal products, including testing of heavy metals and pesticides residues. 'Dashmoola', a popular herbal formulation, with immunomodulator and febrifugal properties, consists of ten single root drugs. In view of WHO guidelines, single herbal drugs used in 'Dashmoola', were collected from different places of India for testing heavy metals and persistent pesticides residue. Although use of roots in 'Dashmoola' is prescribed in original ayurvedic literature but now many pharmacies use stem in place of roots. Therefore, in the present study both roots and stems were selected for estimation of six heavy metals namely arsenic (As), mercury (Hg), lead (Pb), cadmium (Cd), chromium (Cr) and nickel (Ni). Apart from these, the organochlorine pesticides residue viz. different metabolites of DDT, DDE, isomers of HCH and alpha-endosulfan were checked in total 40 samples of single crude drugs. Heavy metals except Hg, were present in most of the samples. In few samples Pb and Cd concentration were beyond the WHO permissible limits. Although alpha-HCH and gamma-HCH were present in almost all the samples, but other pesticides were not detected in these samples. DDT and DDE were found only in two samples.