Effect of surface treatment of jute fibers on the interfacial adhesion in poly(lactic acid)/jute fiber biocomposites

Jute fibers have immense potential to be used as natural fillers in polymeric matrices to prepare biocomposites. In the present study jute fibers were surface treated using two methods: i) alkali (NaOH) and ii) alkali followed by silane (NaOH+Silane) separately. Effects of surface treatments on jute fibers surface were characterized using fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) analyses. Further, the effects of surface treatments on jute fibers properties such as crystallinity index, thermal stability, and tensile properties were analyzed by X-ray diffraction method (XRD), thermo gravimetric analysis (TGA), and single fiber tensile test respectively. The effects of surface treatment of jute fibers on interphase adhesion between of poly(lactic acid) (PLA) and jute fibers were analyzed by performing single fiber pull-out test and was examined in terms of interfacial shear strength (IFSS) and critical fiber length.     

Influence of calcium carbide formulations on growth,yield and nitrogen uptake of wheat under field conditions

Field experiments were conducted in 2006–2007 and 2007–2008 to evaluate the effects of three calcium carbide (CaC₂) based formulations (slow release sources of acetylene and ethylene) - matrix-1 [(M-1)(21% CaC₂, 58% polyethylene and 21% plaster of paris)], matrix-2 [(M-2)(42% CaC₂, 48% polyethylene and 10% plaster of paris)] and paint coated [(PC)(35% CaC₂, 44% paint and 21% plaster of paris)] - on nitrification inhibition; growth, yield and nitrogen (N)-uptake of wheat. All the three CaC₂ formulations (CCF,s) inhibited nitrification, reduced plant height, and improved N-uptake, spike bearing tillers, 1000-grains weight and yield of Inqulab-91 and Bhakhar-02 wheat cultivars. Increase in grain yield was found maximum (22% over the control) with M-1 applied at 30 kg CaC₂ ha^?1; followed by M-2 and PC. Furthermore, CaC₂ significantly reduced lodging in Bhakhar-02 plots. It is concluded that grain yield of wheat can be enhanced by the application of CaC₂ formulations particularly M-1 along with NPK fertilizers.     

Investigation formaize inbred lines resistance to <Emphasis Type="Italic">Maize Rough Dwarf Virus</Emphasis>(MRDV)

Maize rough dwarf virus (MRDV) is the most important disease affecting maize growth in Iran. In the present study, the putative resistance capacity of 35 maize inbred lines against the causal agents of MRDVwas studied under natural field infection in 2010 and 2011. The viral transmitter was a plant hopper known as Laodelphax steriatellus. Early sowing provided suitable temperatures for vector propagation and transmission and therefore natural infection under field conditions. Sowing single rows of SC704 as vector spreader between every five rows of inbred lines caused adequate vector propagation and viral transmission. This shows that viral infection was sufficient and possible resistance was linked to viral resistance, not failure, in vector transmission. In principal component biplot, plant height vector had wide angles with the vectors for disease severity index and MRDV incidence that showed the negative association of plant height with MRDV disease. The percentage of natural infection to MRDV in susceptible control(SC704) was about 64%. The genotypes A679, K3547/3, K3545/6, K3653/2, and B84 were more susceptible to MRDV. Only the line K3640/3 had low disease incidence and severity and it can be considered as resistant for possible use in genetic studies. Results showed that an early sowing of maize in temperate regions increases the chance of transmitting viruses via their vector.     

关中冬小麦叶片氮素含量高光谱遥感监测模型

为给黄土高原大范围的冬小麦氮素营养遥感监测提供理论依据,通过田间试验,研究了冬小麦叶片氮素含量遥感监测的最佳生育时期、最敏感波段及其他最优光谱参量。结果表明,灌浆期是利用高光谱遥感监测冬小麦叶片氮素营养状况的最佳生育时期;在拔节、抽穗和灌浆期680nm波段光谱反射率R680均能较好地反映冬小麦叶片氮素含量,基于光谱位置以及叶面积指数的光谱参量也能较好地反映冬小麦叶片氮素含量。拔节期、抽穗期和灌浆期分别以680nm波段光谱反射率R680、绿峰反射率Rg和植被指数(SDr-SDb)/(SDr+SDb)对小麦叶片氮素含量的拟合效果最佳,其回归方程分别为Y=27.54-280.247 X+1456.245 X2、Y=8.632 X-0.24和Y=25.83 X1.012。     

Identification of QTL for oil content,seed yield,and flowering time in oilseed rape (<Emphasis Type="Italic">Brassica napus</Emphasis>)

A genetic map was constructed with 353 sequence-related amplified polymorphism and 34 simple sequence repeat markers in oilseed rape (Brassica napus L.). The map consists of 19 linkage groups and covers 1,868 cM of the rapeseed genome. A recombinant doubled haploid (DH) population consisting of 150 lines segregating for oil content and other agronomic traits was produced using standard microspore culture techniques. The DH lines were phenotyped for days to flowering, oil content in the seed, and seed yield at three locations for 3 years, generating nine environments. Data from each of the environments were analyzed separately to detect quantitative trait loci (QTL) for these three phenotypic traits. For oil content, 27 QTL were identified on 14 linkage groups; individual QTL for oil content explained 4.20–30.20% of the total phenotypic variance. For seed yield, 18 QTL on 11 linkage groups were identified, and the phenotypic variance for seed yield, as explained by a single locus, ranged from 4.61 to 24.44%. Twenty-two QTL were also detected for days to flowering, and individual loci explained 4.41–48.28% of the total phenotypic variance.     

Tree species could have substantial consequences on topsoil fauna: a feedback of land degradation/restoration

The characteristics of the faunal community in the soil are closely related to soil quality and function. Land degradation, which reduces vegetation cover, may affect the soil surface-active fauna because both the above ground and below ground invertebrates depend on complex plant communities. In this study, we evaluated the effect of land degradation/restoration and factors affecting soil fauna in northern Iran. The studied land uses were virgin natural forest (VNF), Alnus subcordata C.A.M. plantation (ASP), Quercus castaneifolia C.A. Mey plantation (QCP), Cupressus sempervirens var. horizontalis plantation (CSP) and degraded natural forest (DNF). VNF and ASP enhanced soil earthworm density (2.43 and 2.12 ind. m^?2) and dry mass (27.44 and 23.39 mg m^?2) with more ratio of epigeic. The activities of acarina (91,851.37 and 85,810.43 ind. m^?2), collembola (83,009.50 and 74,996.18 ind. m^?2) and protozoa [921.25 and 851.81 (×?10² g soil)] were increased under VNF?≈?ASP, respectively. Nematode population (650 in 100 g soil) significantly improved under VNF. In general, good quality forest floor, alkaline soil and accumulation of macro-element nutrients improved biological activities under the VNF and ASP sites, while low-quality forest floor, acidic soil, less macro-elements nutrients decreased biological activities imposed by the QCP, CSP and DNF sites. More activities of the studied soil fauna were found in autumn and spring. The findings of this study support the importance of preserving natural forests. In addition, employing N₂-fixing and suitable native broadleaved species have been proposed in a bid to rehabilitate DNFs.     

Thermal degradation modeling for single-shear nailed connections

The load-carrying capacity of a timber structure is highly dependent on the strength of its connections. Very limited information exists on the thermal degradation, or the properties at elevated temperatures, of such connections. This insufficient information is one of the major impediments for modeling elevated temperature performance for wood-frame structures. The objective of this study was to characterize thermal degradation of yield load capacity of single-shear nailed connections between wood and oriented strand board (OSB) as a function of time and temperature. The mechanism of degradation was explained using first order kinetics. Using the principles of time–temperature superposition (TTS), predictive models for connection capacity degradation were developed. A total of 450 wood-to-OSB connections were tested laterally after exposure to nine different elevated temperature regimes. The degradation of yield load strength over time occurred at a constant linear rate. Temperature dependence of this rate was modeled using the Arrhenius activation energy theory. Using Arrhenius activation energy theory and principles of TTS, a master curve was developed to predict the performance of connections after exposure to a temperature of 150°C. The predictions matched well with independent experimental observations. The master curve developed using TTS provides predictive estimates of residual capacity in a connection as well as its failure times.     

Salinity stress on various physiological and biochemical attributes of two distinct maize (Zea mays L.) genotypes

Present study investigates the effect of salinity stress on physiological and biochemical characteristics of two maize genotypes cultivated under controlled growth conditions. The selected maize genotypes being salt-tolerant and salt-sensitive were respectively designated as Sahwal-2002 and Sadaf. The experiment was conducted in triplicates, two varieties, three priming treatments and two salinity levels, in the Government College University, Faisalabad. The antioxidants activity was measured by comparing the tolerance in response to acute and prolonged salinity treatment. The difference of genotype with salinity tolerance as well as seed priming with phenylalanine were not dependent on antioxidant activity when salt exposure was prolonged. The results show that an indirect relationship was present for PAL seed priming and oxidative damage due to salt. The antioxidant enzymes present in plant effectively reduced the oxidative damage of salt and thus, increased the overall crop yield.     

Transfer of Heavy Metals from Soils to Vegetables and Associated Human Health Risks at Selected Sites in Pakistan

Contamination of the food chain with heavy metals is considered as one of the major environmental pathways of human exposure to metals leading to potential health risks. This study aimed to investigate the concentrations of heavy metals such as copper (Cu), zinc (Zn), chromium (Cr), nickel (Ni), and manganese (Mn) in agricultural soils and food crops (fruit, leaf, and root vegetables), and their associated health risks to the local population in selected southern districts of Khyber Pakhtunkhwa Province, Pakistan. The concentrations of the selected metals in soil varied over a wide range, in the following decreasing order: Mn > Zn > Cr > Ni > Cu. The bioaccumulation of metals in vegetables was within the permissible risk limits, except for Cr which showed higher contamination in all the tested food crops. The trend of metal transfer factors for different vegetables was in the order of Cu > Ni > Cr > Mn > Zn, while the calculated daily intake of metals (DIM) in adults and children through consumption of food crops was in the decreasing order of Mn > Zn > Ni > Cr > Cu. The health risk index (HRI) values for the heavy metals for both adults and children were less than 1. Therefore, no significant health risk is anticipated for the local consumers through ingestion of these food crops.     

Geostatistical analysis of soil mechanical properties in Ardabil plain of Iran

This study was conducted to estimate the spatial distribution of penetration resistance (PR), Proctor maximum bulk density (MBD) and critical water content (CWC) as soil mechanical indices. Soil samples to determine sand, silt, clay, organic carbon (OC), CaCO₃, bulk and particle density, total porosity, field water content, MBD and CWC values were collected. Field measurements of PR at 0–10 cm depth were taken from 105 geo-referenced points with 3000 × 3000 m intervals in agricultural lands of Ardabil plain, Iran. Ordinary kriging (OK) and inverse distance weighting (IDW) methods were used to analyze spatial variability of PR, MBD and CWC. The strongest spatial dependences with the lowest ranges of influence were found for OC (7560 m) and MBD (8370 m). The models of fitted semivariograms were Gaussian for PR and MBD, and exponential for CWC. The moderate spatial dependences with the ranges of 13,300 and 40,100 m were found for CWC and PR, respectively. The best prediction according to Lin’s concordance correlation coefficient was obtained by OK for PR (0.48) and IDW for MBD (0.09) and CWC (0.03). These results can be applied in programming of optimum tillage operations for reducing soil compaction risk in the studied region.