The congener-specific biota-sediment accumulation factors (BSAFs) model for hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) was evaluated for four different freshwater fish species (Orienus plagiostomus, Tor putitora, Glyptothorax punjabensis, and Cyprinus carpio) in in situ riverine conditions of Kabul River, Pakistan.
Materials and methods
The congeners of HCH and DDT were quantified using gas chromatograph (GC-ECD). The BSAF for each congener (HCHs and DDTs) was calculated from paired observation of congener’s measured concentrations in fish and sediment taken at the same site. Pearson’s correlation and linear regression analyses were performed to determine the influence of sediment organic carbon fraction (fsoc) and organism lipid fraction (flipid) on BSAF, and the relationship between BSAFs and logarithm of octanol-water partition coefficients (log Kows) of HCH and DDT congeners, respectively.
Results and discussion
The BSAFs for total HCH (t-HCH) and total DDT (t-DDT) ranged from 0.6 to 1.5 and from 0.2 to 1.6, respectively. The model was significantly influenced by both fish (p = 0.004) and chemical types (p = 0.002) at 95 % confidence level. The sediment organic carbon fraction (fsoc) and fish lipid fraction (flipid) had not-too-weak effects on BSAF values for all fish species. The BSAF values were linearly fitted with logarithmic octanol-water partition coefficients (log Kows) of HCH and DDT congeners, despite the different chemical structures, and different compound class significant negative correlations between log Kows and BSAF values were found, indicating that hydrophobicity is one of the key factors influencing the bioaccumulation potential of the investigated compounds.
Conclusions
The present study confirmed the applicability of the BSAF model as a screening tool for predicting bioaccumulation of sediment-associated HCH and DDT congeners in investigated fish species under small-scale in situ riverine conditions of Kabul River and suite the model for benthic fish (G. punjabensis) on the basis of the 25th and 75th percentiles of congener-specific BSAF values.
The high-molecular weight (HMW) glutenin subunits of bread wheat are major determinants of end-use quality. The objective of this study was to determine the 1Dx and 1Dy subunits present in 43 synthetic hexaploid wheat (SHW) lines derived by crossing durum ‘Langdon’ to 43 Aegilops tauschii accessions. Protein samples were initially electrophoresed multiple times on SDS-PAGE gels to arrange subunits into similar groups and then were electrophoresed on urea/SDS-PAGE gels. Initial results with SDS-PAGE gels indicated that there were six 1Dx and six 1Dy subunits in these SHW lines. However, results of the urea/SDS-PAGE indicated that some of the subunit groups could be further differentiated into additional subunits. A total of eleven 1Dx and eight 1Dy subunits including the newly designated subunits 1Dx2t-1, 1Dx2t-2, 1Dx2t-3, 1Dx1.5t-1, 1Dx2.1t-1, 1Dy10t-1, and 1Dy12t-1 were identified, and they composed 17 1Dx and 1Dy combinations in the SHW lines. Eight of the combinations included at least one novel subunit and hence they were novel Glu-D1 alleles. Our results indicated that urea/SDS-PAGE can be very useful in identifying new HMW glutenin subunits. Quality testing of the SHW lines will determine if any of the alleles are useful in improving wheat-baking quality. 相似文献
In the present investigation position of mandibular foramen of the mandible in relation to other landmarks were studied. Panoramic x-ray of 103 females and 94 males who come to above mentioned clinic selected by available sampling. All samples were Iranian with the age above 18 years old. X-ray machine and method were same for all samples. Special landmarks in right side of mandible were identified and their distance from mandibular foramen were recorded by millimetric ruler. The measured landmarks were as follow: Mandibular angle, Coronoid process, Mandibular notch, Head of mandible, Posterior border of ramus of mandible, Anterior border of the ramus, External oblique line, Mylohyoid line, Occlusal plane: mandibular angle were measured by protractor. Results between male and female were compared by Mann Whitney U test. The average of both sexes ages were 34.7 years. Difference between distance of mandibular foramen from following landmarks between male and females were significant: (1) Mandibular angle, (2) Head of mandible, (3) Posterior border of ramus, (4) Mylohyoid and (5) Occlusal plane. Present investigation revealed position variation of M.F. in relation to other landmarks and differences between male and female, we suggest kind of investigation individual under 18 years old. 相似文献
This research involved an environmental strain of Stenotrophomonas maltophilia which has been reported to produce serological cross-reactivity with Shigella dysenteriae type 8 specific antisera. Since clinical diagnosis of shigellosis is largely based on culture and serology, the investigation was aimed at in vivo and in vitro virulence comparison between the culturally similar environmental S. maltophilia isolate and the reference S. dysenteriae strains. The findings of this study revealed the absence of virulent genes of Shigella sp. like ipaH, virA and stx1 and characteristic invasive large plasmid in the test isolate. The Western blot analysis revealed that serological cross-reactivity of Stenotrophomonas maltophilia was due to certain protein component(s) in its outer membrane. The isolate was capable of producing extracellular protease, exhibited alpha hemolysis and was negative for hemagglutinating assay. The isolate gave negative reaction with rabbit ileal loop and Sereny tests. The S. maltophilia isolate did not possess any enterotoxic or invasive property as that of virulent S. dysenteriae strains. Further characterizations and adequate genetic manipulations of this environmental isolate may contribute to the development of a potential vaccine candidate for shigellosis. 相似文献
One of the key requirements for developing multiphase polymer products is the ability to predict the fracture and tensile
strength of these materials when subjected to static and dynamic loading. The existence of wave instability at the interface
of multilayer polymer products is well known. The experimental studies have shown that interfacial wave instability of two-layer
Poiseuille flow play an important role in polymer processing operation. This article is designed mainly to provide guidelines
for the development of experimental techniques for the improvement of the two-layer polymer extrudate in the polymer processing
industry. This is done by performing a series of tensile tests on two-layer polymer extrudate in order to get insight into
the relation between interfacial wave and mechanical properties of high density polyethylene (HDPE) and polypropylene (PP)
systems. Observed variations of the mechanical properties have been related to the conformation of the interfacial wave so
that a relationship between interface morphology corresponding to extrusion instabilities and mechanical characteristics of
the interfacial strength for this polymer system (PP/HDPE) are established. 相似文献
Jute fabrics (hessian cloth) reinforced polypropylene (PP) matrix composites (45 wt% fiber) were fabricated by compression
molding. Jute fabrics were treated with 2-hydroxyethyl methacrylate (HEMA) using ultraviolet radiation in order to improve
the mechanical properties of the composites. Concentration of HEMA, soaking time and radiation dose were optimized. It was
found that 15% HEMA in methanol along with photoinitiator Darocur-1173 (2 %), 10 min soaking time and 20th pass of radiation
rendered better performance. Urea of different concentrations (0.5–2 %) was incorporated with 15 % HEMA to monitor its effect
on the properties and 1 % urea revealed the best results. For the improvement of the properties, jute fabrics were treated
with potassium permanganate (KMnO4) solution in acetone of different concentrations (0.02, 0.03, 0.05, and 0.5 %) at different soaking times (1, 2, 3, and 5
min) before the composite fabrication. Optimized jute fabrics (jute fabrics treated with 0.03 % KMnO4) were again treated with HEMA (15 %) solution along with urea (1 %) and promising improvement of mechanical properties of
the composites was observed. Scanning electron microscopy, water uptake, soil degradation and thermal aging of the treated
and untreated composites were also performed. 相似文献
Jute yarns were cured with acrylic acid (AA) and phosphoric acid (PA) using UV radiation in order to prepare selective ion
adsorbent. A series of formulations were prepared in methanol containing varying percentages of (10–70 %) of AA and 2 % photo-initiator
(PI) (Darocur-4043). jute yarns were soaked in this formulation for various soaking times (10–30 min) and cured under UV radiation
of different intensities (20–50 UV passes). Concentration of AA, soaking time and intensity of UV radiation were optimized
based on polymer loading (PL). The maximum PL (21 %) was observed for 50 % AA solution for 20 min soaking time at 40 UV passes.
Various formulations were prepared using 5–15 % (w/w) of phosphoric acid, 50 % AA and 2 % PI in methanol. Then jute yarns
were soaked in this solution for 20 min and irradiated at 40th UV pass. The concentration of PA was again optimized for maximum
PL. It was found that the formulation containing 10 % PA, 50 % AA, 38 % methanol and 2 % PI showed 70.95 % of PL. To investigate
the adsorbent behavior, a 10 ppm CuSO4 solution was prepared and then grafted yarns were soaked in the solutions for 30–300 min at different conditions. After withdrawing
the yarns, the remaining copper in the solution were measured by atomic absorption spectrophotometer (AAS). It was revealed
that copper was successfully removed by using the grafted jute yarns. 相似文献
This review article is based on different aspects of wheat breeding for drought tolerance. Drought is regarded as one of the
most serious threats to agriculture in Pakistan. Therefore, breeding for drought tolerance must be given top priority. Here,
we try to study various options available to wheat breeders exploring the underlying mechanisms of drought tolerance. The
progress made in conventional and non-conventional (molecular) based approaches with potential findings and constraints are
reviewed in this article. Equipped with such information, it will be possible for breeders to further explore the mysteries
of drought tolerance and to select genotypes with an improved yield under water-deficit conditions. 相似文献
