Properties of Poly(Vinyl Alcohol)/Chitosan Nanocomposite Films Reinforced with Oil Palm Empty Fruit Bunch Amorphous Lignocellulose Nanofibers

The objective of this study was to investigate the properties of poly(vinyl alcohol)/chitosan nanocomposite films reinforced with different concentration of amorphous LCNFs. The properties analyzed were morphological, physical, chemical, thermal, biological, and mechanical characteristics. Oil palm empty fruit bunch LCNFs obtained from multi-mechanical stages were more dominated by amorphous region than crystalline part. Varied film thickness, swelling degree, and transparency of PVA/chitosan nanocomposite films reinforced with amorphous part were produced. Aggregated LCNFs, which reinforced PVA/chitosan polymer blends, resulted in irregular, rough, and uneven external surfaces as well as protrusions. Based on XRD analysis, there were two or three imperative peaks that indicated the presence of crystalline states. The increase in LCNFs concentration above 0.5% to PVA/chitosan polymer blends led to the decrease in crystallinity index of the films. A noticeable alteration of FTIR spectra, which included wavenumber and intensity, was obviously observed along with the inclusion of amorphous LCNFs. That indicated that a good miscibility between amorphous LCNFs and PVA/chitosan polymer blend generated chemical interaction of those polymers during physical blending. Reinforcement of PVA/chitosan polymer blends with amorphous LCNFs influenced the changes of T_g (glass transition temperature), T_m (melting point temperature), and T_max (maximum degradation temperature). Three thermal phases of PVA/chitosan/LCNFs nanocomposite films were also observed, including absorbed moisture evaporation, PVA and chitosan polymer backbone structural degradation and LCNFs pyrolysis, and by-products degradation of these polymers. The addition of LCNFs 0.5% had the highest tensile strength and the addition of LCNFs above 0.5% decreased the strength. The incorporation of OPEFB LCNFs did not show anti-microbial and anti-fungal properties of the films. The addition of amorphous LCNFs 0.5% into PVA/chitosan polymer blends resulted in regular and smooth external surfaces, enhanced tensile strength, increased crystallinity index, and enhanced thermal stability of the films.     

Assessment of the exposure of two fish species to metals pollution in the Ogun river catchments, Ketu, Lagos, Nigeria

The concentrations of metals (Ca, Cd, Fe, Mn, Pb and Zn) were determined by flame atomic absorption spectrophotometry in water, sediments and fish samples in the Ogun river catchments, Ketu, Lagos, which is an important bird nesting, fishing and drinking water source. The results show that the southern tip bothering the Lagos lagoon is where the highest metal concentrations are found in the fish species (Tilapia sp. and Chrysichthys sp.), whereas the Agboyi creek segment near the lagoon with higher surrounding human population density recorded higher levels of metals in sediments and water samples. The two fish species accumulated different amounts of metals. However, the differences were not statistically different at p < 0.05. There is a significant correlation (p < 0.05) for Cd concentration in water. The concentrations of Pb in sampling points 3 and 4 as well as Cd, Mn and Fe in all six sampling points exceeds the World Health Organization (WHO) limits for drinking water. Levels of metals obtained for sediments are within the range reported for Nigeria’s river sediments. Based on this study, the human risks for heavy metals in the harvested fish species from the Ogun river catchments, Ketu, are low for now as the concentrations were below the recommended Food and Agriculture Organization (FAO) maximum limits for Pb (0.5 mg/Kg), Cd (0.5 mg/Kg), and Zn (30 mg/Kg) in fish.     

Rotation effects of grain legumes and fallow on maize yield,microbial biomass and chemical properties of an Alfisol in the Nigerian savanna

Understanding changes in soil chemical and biological properties is important in explaining the mechanism involved in the yield increases of cereals following legumes in rotation. Field trials were conducted between 2003 and 2005 to compare the effect of six 2-year rotations involving two genotypes each of cowpea (IT 96D-724 and SAMPEA-7) and soybean (TGx 1448-2E and SAMSOY-2), a natural bush fallow and maize on soil microbial and chemical properties and yield of subsequent maize. Changes in soil pH, total nitrogen (N_tot), organic carbon (C_org), water soluble carbon (WSC), microbial biomass carbon (C_mic) and nitrogen (N_mic) were measured under different cropping systems. Cropping sequence has no significant (P > 0.05) effect on soil pH and C_org, while WSC increased significantly when maize followed IT 96D-724 (100%), SAMPEA-7 (95%), TGx 1448-2E (79%) and SAMSOY-2 (106%) compared with continuous maize. On average, legume rotation caused 23% increase in N_tot relative to continuous maize. The C_mic and N_mic values were significantly affected by cropping sequence. The highest values were found in legume–maize rotation and the lowest values were found in fallow–maize and continuous maize. On average, C_mic made up to 4.8% of C_org and N_mic accounted for 4.4% of N_tot under different cropping systems. Maize grain yield increased significantly following legumes and had strong positive correlation with C_mic and N_mic suggesting that they are associated with yield increases due to other rotation effects. Negative correlation of grain yield with C_mic:N_mic and C_org:N_tot indicate that high C:N ratios contribute to nitrogen immobilization in the soil and are detrimental to crop productivity. The results showed that integration of grain legumes will reverse this process and ensure maintenance of soil quality and maize crop yield, which on average, increased by 68% and 49% following soybean and cowpea, respectively compared to continuous maize.     

Numerical estimation of photovoltaic–electrolyzer system performance on the basis of a weather database

We performed a numerical simulation to investigate the performance of a photovoltaic (PV)–electrolyzer on the basis of a simulated weather database during the summer solstice (SS), autumnal equinox (AE), and winter solstice (WS), and all year round. First, we selected a location in southern Taiwan (latitude: 22.65°N) to create a local weather simulation database that included daily solar radiation, wind speed, and ambient temperature. The I–V curves of a PV system and an electrolyzer were obtained numerically by using Simpson integration computation. Subsequently, the optimal configuration of a PV driving system comprising the electrolyzer and the PV panel was determined. The database of weather conditions was input into the numerical estimation model of the PV–electrolyzer system, and the hydrogen generation rates and hydrogen production volumes under both clear skies and changeable weather conditions were obtained.     

24-Epibrassinolide regulates photosynthesis, antioxidant enzyme activities and proline content of Cucumis sativus under salt and/or copper stress

Brassinosteroids have been extensively used to overcome various abiotic stresses. But its role in combined stress of salt and excess copper remains unexplored. Seeds of two cultivars (Rocket and Jumbo) of Cucumis sativus were grown in sand amended with copper (100 mg?kg^?1), and developed seedlings were exposed to salt stress in the form of NaCl (150 mM) at the 30-day stage of growth for 3 days. These seedlings were subsequently sprayed with 0 or 0.01 μM of 24-epibrassinolide (EBL) at the 35-day stage. The plants exposed to NaCl and Cu in combination exhibited a significant decline in fresh and dry mass of plant, chlorophyll content, activities of carbonic anhydrase, net photosynthetic rate and maximum quantum yield of the PSII primary photochemistry followed by NaCl and Cu stress alone, more severely in Jumbo than in Rocket. However, the follow-up treatment with EBL to the stressed and nonstressed plant improved growth, chlorophyll content, carbonic anhydrase activity and photosynthetic efficiency, and further enhanced the activity of various antioxidant enzymes viz. catalase, peroxidase and superoxide dismutase and content of proline at the 40-day stage of growth, and the response of the hormone was more effective in Rocket than in Jumbo. The elevated level of antioxidant enzymes as well as proline could have conferred tolerance to the NaCl- and/or Cu-stressed plants resulting in improved growth, water relations and photosynthetic attributes. Furthermore, antioxidant enzyme activity and proline content were more enhanced in Rocket than in Jumbo cultivar.     

Prediction of diffuse solar radiation using satellite data

In the project of the solar systems, the values of the solar radiation of a region must be known. The global solar radiation measurements are performed by the Turkish Meteorological Service in Turkey, while the diffuse solar radiation measurements are unavailable. In this study, some new models for predicting the monthly average daily diffuse solar radiation on a horizontal surface for Erzincan, Turkey are developed using satellite data. The evaluation of the models is carried out with the statistical analysis methods of mean bias error (MBE), root mean square error (RMSE) and correlation coefficient (r). The results are proved that the correlation equations obtained in here can be used to forecast diffuse solar radiation reasonably well.     

Salicylic acid minimizes nickel and/or salinity-induced toxicity in Indian mustard (Brassica juncea) through an improved antioxidant system

Introduction  

This study was hypothesized that salicylic acid elevates the level of antioxidant system that will protect plants from the stress generated by nickel and/or salinity.     

Acute nitrate poisoning in two cattle

Abstract

The rate and product composition during photooxidation of aromatic hydrocarbons (toluene, o‐, m‐, p‐xylene and cumene) dissolved in n‐hexane and spread as a liquid film on water is reported. The photo degradability of these chemicals is 10–20%. The products identified are oxygenated aromatic compounds. It is observed that the absorption bands of the compounds under investigation depend upon the partial pressure of dissolved oxygen and these bands extend up to 290 nm. The new absorption band around 290 nm is probably due to broadening of ¹L_b bands which is responsible for direct photolysis.

stream. We have been especially interested in investigating the rate of disappearance and distribution of main oxidation products in two phases. Besides that an attempt has been made to throw some light on the reaction mechanism.     

Association of urinary arsenic and sleep disorder in the US population: NHANES 2015–2016

Environmental Science and Pollution Research - Arsenic is a known carcinogen and neurotoxin and is found in the natural earth crust. Arsenic exposure can develop depression, memory dysfunction, and...