Gas phase toluene hydrogenation is investigated over Pt/Al2O3 catalyst with temperature ranging from 75 to 125 °C and at atmospheric pressure. Strong activity variations are observed during long duration experiments. These variations are thoroughly investigated and a mechanistic model is proposed with dynamic adsorption activity of the reactants, used to explain the decrease in catalyst activity. This model considers competitive adsorption behaviour of the reactants and dissociative adsorption of hydrogen. Such a model can also be used to explain the strong metal-support interaction (SMSI) effect induced by the catalyst support. The decrease in activity after temperature maxima as previously observed can also be addressed by the approach presented. A comparison of activity variation at different residence times i.e. 20–50 kgcat·s·mol−1 and different hydrogen and toluene partial pressures is also simulated.
Authors:Sobiya Shafique, Shazia Shafique and Aqeel Ahmad
Pakistan holds the position of top chilies producers. So Capsicum annuum L. production in Pakistan should be promoted by combating against diseases. The only solution is to cultivate resistant varieties. Presently six chili varieties were treated with Fusarium oxysporum Schlecht. and screened for the most resistant and the most susceptible varieties. Representative varieties were evaluated for their biochemical and transcriptional profiles to discover the bases of antifungal-resistance. Results concluded that the most resistant variety was “Dandicut” and the most susceptible was “Ghotki”. Tannins, coumarins, flavonoids, phenolics, Riboflavins and saponins were observed in higher quantities in Dandicut as compared to Ghotki. Defense related enzymes i.e. polyphenol oxidase, phenyl ammonia lyase and peroxidase were found in elevated amounts in Dandicut than in Ghotki. Transcriptional results showed that defense related genes i.e. PR2a, acidic glucanase; Chitinase 3, acidic; Osmotin-like PR5 and Metallothionein 2b-like had higher expressional rates in Dandicut. Pearson’s correlation coefficient revealed stronger direct interaction in signal transduction and salicylic acid pathway. Resistance of chili varieties is salicylic acid based. Results obtained from this study not only help to improve chili production in Pakistan but also facilitate variety development operations. Moreover, it also constructed a scale to evaluate innate resistance among varieties.
Authors:N. Naz, M. Hameed, M. Sajid Aqeel Ahmad, M. Ashraf and M. Arshad
Five distinct habitats along salinity gradient were explored for plant ecological attributes including soil plant interaction, vegetation composition and species distribution in the Cholistan desert. Higher saline sites supported
Aeluropus lagopoides, Cymbopogonjwarancusa, Ochthochloa compressa, Haloxylon recurvum
, whereas moderately saline habitats supported predominantly
Fagonia indica, C. jwarancusa
. The community structure and composition of each habitat type were very specific, the most dominant component being
. Each species has very specific relation to different environmental variables, and this reflects the habitat status, ecological adaptations and stress tolerance degree of the individual species. On the whole, it can be concluded that salinity alone was not responsible for the distribution of species at salt affected habitats.
Authors:Jahangir Khan, Zoobia Bashir, Aqeel Ahmad, Wajeeha Tariq, Anam Yousaf and Madiha Gohar
This study mathematically correlates incidence of cotton leaf curl virus (CLCuV), environmental factors (i.e., rainfall, humidity and temperature), and silverleaf whitefly population in agricultural system of Pakistan. It has been concluded that the disease is directly linked with rainfall and humidity. The third most influential factor in defining CLCuV incidence is the vector population, which is also strictly dependent upon monthly mean temperature of Pakistan. Developed mathematical interrelation is capable of predicting disease incidence of future months. Therefore, it will help agriculturists to control disease in agricultural areas of Pakistan. It is strongly advised on the basis of current research that vector population controlling practices should be immediately applied after detecting small elevations in mean monthly temperature.
Hypersensitive response/reaction is a form of the cellular demise frequently linked alongside plant resistance against pathogen infection. Main transducers for this reaction are the intermediates of reactive oxygen and ion fluxes which are plausibly needed for hypersensitive response (Hpr Sen Rsp). An immediate and enormous energy production and its intra-cellular biochemical conduction are imperative for an Hpr Sen Rsp to be occurred. A number of studies proved that there are such diverse types of factors involved in triggering of Hpr Sen Rsp that morphologies of dead cells have become a vast topic of study. Hpr Sen Rsp could play a frolic role in plants as certain programmed cellular disintegrations in other organisms, to restrict pathogen growth. In fact, Hpr Sen Rsp can be involved in all types of tissues and most of the developmental stages.