Radiative Hydromagnetic Flow of Jeffrey Nanofluid by an Exponentially Stretching Sheet

Two-dimensional hydromagnetic flow of an incompressible Jeffrey nanofluid over an exponentially stretching surface is examined in the present article. Heat and mass transfer analysis is performed in the presence of thermal radiation, viscous dissipation, and Brownian motion and thermophoresis effects. Mathematical modelling of considered flow problem is developed under boundary layer and Rosseland’s approximations. The governing nonlinear partial differential equations are converted into ordinary differential equations via transformations. Solution expressions of velocity, temperature and concentration are presented in the series forms. Impacts of physical parameters on the dimensionless temperature and concentration are shown and discussed. Skin-friction coefficients are analyzed numerically. A comparison in a limiting sense is provided to validate the present series solutions.     

On Three-Dimensional Flow and Heat Transfer over a Non-Linearly Stretching Sheet: Analytical and Numerical Solutions

This article studies the viscous flow and heat transfer over a plane horizontal surface stretched non-linearly in two lateral directions. Appropriate wall conditions characterizing the non-linear variation in the velocity and temperature of the sheet are employed for the first time. A new set of similarity variables is introduced to reduce the boundary layer equations into self-similar forms. The velocity and temperature distributions are determined by two methods, namely (i) optimal homotopy analysis method (OHAM) and (ii) fourth-fifth-order Runge-Kutta integration based shooting technique. The analytic and numerical solutions are compared and these are found in excellent agreement. Influences of embedded parameters on momentum and thermal boundary layers are sketched and discussed.     

Effect of cadmium on the growth and antioxidant enzymes in two varieties of Brassica juncea

Increasing contamination and higher enrichment ratio of non-essential heavy metal cadmium (Cd) induce various toxic responses in plants when accumulated above the threshold level. These effects and growth responses are genotype and Cd level dependent. An experiment was conducted to analyze the effect of Cd toxicity in Brassica juncea [L] Czern and Coss by selecting its two varieties Varuna and RH-30. Cadmium (0, 25, 50 or 100 mg CdCl₂ kg⁻¹ of soil) fed to soil decreased the values of growth characteristics, activity of nitrate reductase and leaf water potential, whereas activities of antioxidant enzymes and proline content increased with the increasing concentration of Cd, observed at 30 and 60 day stages of growth, in both the varieties. Moreover, Cd uptake by the roots was higher in RH-30 than Varuna. Also the activity of antioxidant enzymes and proline accumulation were higher in Varuna with increasing soil level of Cd. Out of the two varieties, Varuna was more tolerant than RH-30 to Cd stress.     

Purification, N-terminal amino acid sequence and characterization of pH 2.5 optimum acid phosphatase (E.C. 3.1.3.2) from Aspergillus ficuum

An acid phosphatase from crude culture filtrate of Aspergillus ficuum was purified to homogeneity using three ion exchange chromatographic steps. SDS-PAGE of the purified enzyme gave a single stained band at approximately 68-KDa. The mobility of the native enzyme in gel filtration chromatography, however, indicated that the molecular mass to be about 130-KDa implying the active form to be a dimer. On the basis of a molecular mass of 68-KDa, the molar extinction coefficient of the enzyme at 280 nm was estimated to be 3.4 x 10(5) M-1 cm-1. The isoelectric point of the enzyme, as judged by chromatofocusing, was about 4.0. The purified enzyme is highly stable at 0 degree C. Thermal inactivation studies have indicated that the enzyme is unstable at 70 degrees C. The enzyme, however, exhibited a broad temperature optima with a maximum catalytic activity at 63 degrees C. The Km of the enzyme for p-nitrophenylphosphate is about 270 microM with an estimated turnover number of 2550 per sec. The enzyme is a glycoprotein as evidenced by the positive PAS staining; the sugar composition suggests the presence of N-linked high mannose-oligosaccharides. A partial N-terminal amino acid sequence up to the twenty-third residue was obtained. The enzyme was inhibited competitively by inorganic orthophosphate (Ki = 185 microM) and non-competitively by phosphomycin (Ki = 600 microM).     

Phytochemical and toxicological investigations of crude methanolic extracts,subsequent fractions and crude saponins of Isodon rugosus

Background

Isodon rugosus is used traditionally in the management of hypertension, rheumatism, tooth-ache and pyrexia. Present study was arranged to investigate I. rugosus for phytoconstituents, phytotoxic and cytotoxic activities to explore its toxicological, pharmacological potentials and to rationalize its ethnomedicinal uses. Briefly, qualitative phytochemical analysis of the plant extracts were carried out for the existence of alkaloids, flavonoids, saponins, oils, glycosides, anthraquinones, terpenoids, sterols and tannins. Plant crude methanolic extract (Ir.Cr), its subsequent fractions; n-hexane (Ir.Hex), chloroform (Ir.Chf), ethyl acetate (Ir.EtAc), aqueous (Ir.Aq) and saponins (Ir.Sp) in different concentrations were tested for phytotoxic and cytotoxic activities using radish seeds and brine shrimps (Artemia salina) respectively. The phytotoxic activity was determined by percent root length inhibition (RLI) and percent seeds germination inhibition (SGI) while the cytotoxicity was obtained with percent lethality of the brine shrimps.

Results

Ir.Cr was tested positive for the presence of alkaloids, glycosides, flavonoids, oils, terpenoids, saponins, tannins and anthraquinones. Among different fractions Ir.Sp, Ir.Chf, Ir.EtAc, and Ir.Cr were most effective causing 93.55, 89.32, 81.32 and 58.68% inhibition of seeds in phytotoxicity assay, with IC₅₀ values of 0.1, 0.1, 0.1 and 52 μg/ml respectively. Similarly, among all the tested samples, Ir.Sp exhibited the highest phytotoxic effect causing 91.33% root length inhibition with IC₅₀ of 0.1 μg/ml. Ir.Sp and Ir.Chf were most effective against brine shrimps showing 92.23 and 76.67% lethality with LC₅₀ values of 10 and 12 μg/ml respectively.

Conclusions

It may be inferred from the current investigations that I. rugosus contains different secondary metabolites and is a potential source for the isolation of natural anticancer and herbicidal drug molecules. Different fractions exhibited phytotoxic and cytotoxic activities, thus providing pharmacological basis for ethnomedicinal uses of this plant.     

Serum organochlorine pesticides residues and risk of cancer: A case-control study

Organochlorine pesticides (OCPs) are frequently used worldwide as insecticides, fungicides, herbicides and termiticides and have been associated with a variety of cancers in animal and human studies. In the present study, we examined residues of fourteen OCPs in the serum samples of diagnosed cancer patients and healthy residents of Karachi, Pakistan. A random collection of fasting blood samples was carried out from the donors with informed consent. Serum was separated within 2?h of blood collection and was then subjected to extraction with organic solvents followed by purification with florisil column. The final organic extract of each serum sample was processed with Gas Chromatograph coupled with Electron Capture Detector (GC-ECD). OCPs were detected in 97.59% of the cancer cases and 93.75% of the healthy subjects. Mean concentrations of total OCPs (ΣOCPs) was found elevated in the cancer group (0.606?mg/kg) compared with the control group (0.322?mg/kg). Endosulfan was the highest prevalent OCP with a mean concentration of 0.214?mg/kg in the cancer group and 0.166?mg/kg in the control group. The second most prevalent OCP was 4,4-DDE with a mean concentration of 0.131?mg/kg in the cancer group and 0.019?mg/kg in the control group. Highest level of ΣOCPs was detected in the breast cancer cases (20.411?mg/kg) with a mean level of (2.041?mg/kg). In light of the obtained results and available literature on the subject, it has been concluded that OCPs are positively associated with the risk of various cancers in humans.     

Field estimates of fitness costs of the pace‐of‐life in an endangered damselfly

Theory predicts that within‐population differences in the pace‐of‐life can lead to cohort splitting and produce marked intraspecific variation in body size. Although many studies showed that body size is positively correlated with fitness, many argue that selection for the larger body is counterbalanced by opposing physiological and ecological selective mechanisms that favour smaller body. When a population split into cohorts with different paces of life (slow or fast cohort), one would expect to detect the fitness–size relationship among and within cohorts, that is, (a) slower‐developing cohort has larger body size and higher fitness than faster‐developing cohort, and (b) larger individuals within each cohort show higher fitness than smaller individuals. Here, we test these hypotheses in capture–mark–recapture field surveys that assess body size, lifespan, survival and lifetime mating success in two consecutive generations of a partially bivoltine aquatic insect, Coenagrion mercuriale, where the spring cohort is slower‐developing than the autumn cohort. As expected, body size was larger in the slow‐developing cohort, which is consistent with the temperature‐size rule and also with the duration of development. Body size seasonal variation was greater in slow‐developing cohort most likely because of the higher variation in age at maturity. Concordant with theory, survival probability, lifespan and lifetime mating success were higher in the slow‐developing cohort. Moreover, individual body size was positively correlated with survival and mating success in both cohorts. Our study confirms the fitness costs of fast pace‐of‐life and the benefits of larger body size to adult fitness.     

Impact of orientation and flexibility of peptide linkers on <Emphasis Type="Italic">T. maritima</Emphasis> lipase Tm1350 displayed on <Emphasis Type="Italic">Bacillus subtilis</Emphasis> spores surface using CotB as fusion partner

Fusion protein construction often requires peptide linkers for prolonged conformation, extended stability and enzyme activity. In this study a series of fusion between Thermotoga maritima lipase Tm1350 and Bacillus subtillis coat protein CotB, comprising of several peptide linkers, with different length, flexibility and orientations were constructed. Effects of temperature, pH and chemicals were examined, on the activity of displayed enzyme. The fusion protein with longer flexible linkers L9 [(GGGGS)₄] and L7 (GGGGS-GGGGS-EAAAK-EAAAK-GGGGS-GGGGS) possess 1.29 and 1.16-fold higher activity than the original, under optimum temperature and pH respectively. Moreover, spore surface displaying Tm1350 with L3 (EAAAK-GGGGS) and L9 ((GGGGS)₄) showed extended thermostably, maintaining 1.40 and 1.35-fold higher activity than the original respectively, at 80 °C after 5 h of incubation. The enzyme activity of linkers with different orientation, including L5, L6 and L7 was determined, where L7 maintained 1.05 and 1.27-fold higher activity than L5 and L6. Effect of 0.1% proteinase K, bromelain, 20% ethanol and 30% methanol was investigated. Linkers with appropriate Glycine residues (flexible) showed higher activity than Alanine residues (rigid). The activity of the displayed enzyme can be improved by maintaining orientation and flexibility of peptide linkers, to evaluate high activity and stability in industrial processes.