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Articles by S. Ahmad
Total Records ( 13 ) for S. Ahmad
  M. K. Hasan , J. Sulaiman , S. Ahmad , M. Othman and S. A.A. Karim
  Problem statement: Development of mathematical models based on set of observed data plays a crucial role to describe and predict any phenomena in science, engineering and economics. Therefore, the main purpose of this study was to compare the efficiency of Arithmetic Mean (AM), Geometric Mean (GM) and Explicit Group (EG) iterative methods to solve system of linear equations via estimation of unknown parameters in linear models. Approach: The system of linear equations for linear models generated by using least square method based on (m+1) set of observed data for number of Gauss-Seidel iteration from various grid sizes. Actually there were two types of linear models considered such as piece-wise linear polynomial and piece-wise Redlich-Kister polynomial. All unknown parameters of these models estimated and calculated by using three proposed iterative methods. Results: Thorough several implementations of numerical experiments, the accuracy for formulations of two proposed models had shown that the use of the third-order Redlich-Kister polynomial has high accuracy compared to linear polynomial case. Conclusion: The efficiency of AM and GM iterative methods based on the Redlich-Kister polynomial is superior as compared to EG iterative method.
  M.Z. Karim , M.N. Amin , M.A.K. Azad , F. Begum , M.M. Rahman , S. Ahmad and R. Alam
  Effects of sucrose, agar and pH on in vitro shoot multiplication of Chrysanthemum were studied. Nodal explant from the ex vitro grown plant was used as the test material. For optimum shoot induction and multiplication in MS medium containing BAP+ sucrose 30 gm l-1, agar 6 gm l-1 and pH 5.5-6.0 proved more effective. The media having 30 gm l-1 sucrose showed the highest percentage of explant responded to shoot proliferation and that was 100%. This sucrose concentration also showed the optimum result for number of usable shoots per culture, number of node shoot-1 and average length of shoots and the values were 5.4±0.6, 5.1±0.8 and 5.6±0.4 cm. The highest proliferation response of the explant was observed on MS medium having 6 gm l-1 of agar and the frequency was 100%. Among different level of pH, the highest percentage of explant showing proliferation was observed on the media adjusted to pH 5.5 and 6.0. The results presented here proved to be suitable for the in vitro shoot multiplication of Chrysanthemum morifolium.
  R. J Kossmann , A Gonzales , R Callan and S. Ahmad

Background and objectives: A bicarbonate dialysate acidified with citrate (CD) has been reported to have local anticoagulant effect. This study examines the effect of CD on dialysis efficiency, measured as eKt/Vurea, and predialysis concentrations of BUN, creatinine, phosphate, and β-2 microglobulin in chronic dialysis units.

Design, settings, participants, & measurements: Three outpatient chronic hemodialysis units with 142 patients were switched to CD for 6 mo. Using each patient's prior 6 mo on regular bicarbonate dialysate acidified by acetate (AD) as control, eKt/Vurea was compared with that of CD. Follow-up data for 7 mo after the study were collected from about one-half of the participants remaining on CD and the others returned to AD.

Results: eKt/Vurea, increased (P < 0.0001) from pre-CD value of 1.51 ± 0.01 to 1.57 ± 0.01 with CD. During CD use β-2 microglobulin levels declined (P = 0.0001) from 28.1 ± 10.0 to 25.9 ± 10.0. Similarly, the concentrations of BUN, creatinine, and phosphate also decreased on CD (P < 0.008). In the poststudy period, eKt/Vurea for the patients staying on CD remained unchanged at 1.60 ± 0.17 versus 1.59 ± 0.18 (P = NS), whereas in those returning to AD the eKt/Vurea decreased from 1.55 ± 0.20 to 1.52 ± 0.17 (P < 0.0001).

Conclusions: Data suggest that CD use is associated with increased solute removal.

  S. Andleeb , N. Atiq , M. I. Ali , F. Ur-Rehman , A. Hameed and S. Ahmad
  Biodegradation and decolorization of Drimarene blue K2-RL (anthraquinone) dye by a fungal isolate Aspergillus niger SA1 was studied in self designed lab scale bioreactor system with different solid supports. Aspergillus niger SA1, was efficiently immobilized on sand and sodium alginate beads. The immobilized cells were used in the form of fluidized bed reactor for textile dye (Drimarene blue) removal. Both the reactors were operated at room temperature and pH=5.0 in continuous flow mode with increasing concentrations of dye in simulated textile effluent. The reactors were run on fill and draw mode, with hydraulic retention times of 24-72 h. The fluidized bed bioreactor with sand as immobilizing support (FBR1) showed overall better performance as compared to fluidized bed bioreactor with sodium alginate as immobilizing support (FBR2). The average overall color, BOD and COD removal in the FBR1 system were up to 78.29, 70.81 and 83.07% respectively, with 50 ppm initial dye concentration and HRT of 24 h. While 72.19%, 86.63% and 74.74% removal of color, BOD and COD were observed, respectively, in FBR2 with the same conditions. Reductions in BOD and COD levels along with color removal proved that decolorization and biodegradation occurred simultaneously.
  S. Ahmad , M. Hair-Bejo , Z. Zunita and S. Khairani-Bejo
  Salmonella enteritidis (SE) has always been related to subclinical infection in the chickens infected after 2 weeks of hatching. However, few pathogenic phage types were proven for their ability to manifest systemic infection and cause the organism to be shed into the surrounding environment. It was the objective of the study to determine the pathogenicity of SE Phage Type (PT) 1 in Specific-Pathogen-Free (SPF) chickens. About 93, 21 day old SPF chickens where divided into 3 groups namely the Control, SE and Mortality groups. The chickens were raised separately in caging system and given free access to antibiotic-free ration and water. The SE and Mortality groups were inoculated orally (1.0 mL) with SE PT 1 (1x108 cfu mL-1). The chickens in the SE and Control groups were sacrificed at various intervals throughout the trial. Samples were collected for bacterial isolation and histological examination. The mortality percentage of the chickens in the Mortality group was recorded. The study showed that no mortality was recorded throughout the trial in the mortality as well as the SE group. Body weight was lower in the SE group when compared to the Control group throughout the trial except at days 2, 3 and 5 post inoculation (pi) reaching its peak at day 14 pi when the SE group body weight was 26% lower than the controls. Clinical signs observed in the SE and Mortality group were represented by diarrhoea, inappetance, ruffled feather and stunted chickens while no abnormal clinical signs where recorded in the Control group. Grossly mild airsacculitis, mild peritonitis and hepatic congestion where recorded in the SE group at day 2 pi until day 5 pi while no gross lesions where recorded in the Control group. SE was first isolated in the caecum (66%) at 12 h pi. At day 1 pi SE was isolated from the caecum and spleen (33%) whilst at day 2, SE was isolated from the caecum (100%) and caecal tonsil (66%). No SE was isolated from the cloacal swabs throughout the trial. The villi height was generally lower in the SE group when compared to the Controls, however it was significantly lower (p<0.05) in the duodenum at 12 h, days 1, 3, 5, 10, 14 and 21 pi; in the jejunum at 6 h, days 2, 14 and 21 pi while in the ileum at days 1, 3 and 5 pi. The crypts depth measurement was fluctuating however it ended up by being higher in the SE group, nevertheless it was significantly lower (p<0.05) in the SE group when compared to the Control group in the duodenum at 6 h and day 14 pi in the jejunum at day 10 pi; in the ileum at 12 h pi. Histopathological changes recorded included hepatitis, congestion and focal areas of necrosis; splenitis, congestion and oedema in the adenoid sheathed arteries; congestion and areas of necrosis in the lymphoi follicles of the bursa of Fabricius; enteritis, congestion and sloughing of necrotic enterocytes in the intestinal villi with presence of bacterial clusters in the villi surface and intestinal lumen. SE rods present in the caecal tonsils were seen to be engulfed by macrophages at days 1 and 2 pi, necrosis of the enterocytes on the villi surface and infiltration of the bacteria was recorded at day 2 pi while at days 5 pi the bacteria multiplication were seen and often located upon the M-like M cells however, no actual engulfment was recorded.
  K.R. Jamaludin , N. Muhamad , M.N. Ab. Rahman , S. Ahmad , M.H.I. Ibrahim , N.H. M. Nor , M.R. Harun and M.Y.M. Daud
  This study presents and demonstrates the effectiveness of optimizing multiple quality characteristics of the injection molding of the MIM green compacts via Taguchi method-based Grey analysis. The modified algorithm adopted here was successfully used for both detraining the optimum setting of the process parameters and for combining multiple quality characteristics into one integrated numerical value called Grey relational grade. The significant molding parameters were identified as (1) Injection Pressure (2) Injection Temperature (3) Powder Loading (4) Mold Temperature (5) Holding Pressure and (6) Injection Speed. In addition, the multiple quality characteristics required are: (1) less defects (2) strong and (3) denser compact. The result concluded that the powder loading (C) is very significant for the combination of the quality characteristics.
  Sandhya Bahuguna , Abhishek Bahuguna and S. Ahmad
  Importance of neem products as insecticide, pesticides and herbicides is well recognized recently use of these products is insecticide in vegetables is being increased rapidly. Studies on seasonal incidence and effect of some neem products on Hadda beetle (Henosepilachna vigintioctopunctata fabr.) infested on Brinjal (Solanum melongena L.) were conducted at Allahabad Agricultural Institute-Deemed University, Allahabad during Rabi season 2006. The treatments of some commercial neem products viz. Neem Raj, Neemoria, Neem bark, Garlic, Neem Gold, Neem Seed Kernel Extract (NSKE), Neem leaf, Achook and one insecticide, i.e., Endosulfan were applied. The observation pertaining to the population of Hadda beetle on brinjal were recorded one day before treatments; the observation on the population mortality were recorded at 1, 2 and 5 days after treatments. The beetle population appeared in the 1st week of March (10th standard week) with an average population level of 0.1 beetle/leaf. Hadda beetle population gradually increased and reached peak level of 3.64 per leaf upto 3rd week of April (16th standard week). However, the population declined with maturation of the crop. Endosulfan was the most effective treatment with 100% mortality. All the other treatments were also effective at 5 days after spraying and they were also statistically at par with each other. Declined of beetle population was not much dependent on weather parameters (temperature, wind velocity, rainfall and relative humidity) but was influenced by the maturation of crop. The present study recommends that Endosulfan (0.07%) as the most effective treatment to control Hadda beetle infestation in Brinjal.
  M. Aslam , I.A. Mahmood , T. Sultan and S. Ahmad
  In Pakistan the legumes are grown mostly in rain-fed areas of marginal lands where soil fertility and native rhizobial populations are low. The result is lower yield of legumes compared with other countries. The experiments carried out by the scientists of National Agricultural Research Centre (NARC), Islamabad and other research institutes, have shown significant yield increases of legumes by inoculation with appropriate rhizobium strains. In these experiments the highest yield increase was noted in case of soybean ranging 30-196 percent. Yield increase of chickpea and peas was generally in the range of 20-40 percent, whereas increase in case of other food legumes i.e., lentil, mung and mash was 10-20 percent. Although these yield increases are quite reasonable, the adoption of inoculant is almost negligible, not increasing beyond 20,000 ha per annum. The demand from farmers has not increased. The farmers and field workers are needed to be educated with the technology in order to enhance use of inoculants. The inoculant production in the country is far below than required but it could be easily increased many fold provided its demand is created. Also, field worker/farmers are not properly educated in their use. There is a strong need for the private sector to develop large-scale production facilities and supply of proper rhizobial inoculants for the various legumes grown in Pakistan.
  S. Ahmad , S.R. Saha , M. Nazim Uddin , S.S. Choudhury , M.A. Awal and M.A. Salam
  A comparative study of ten cauliflower cultivars was done at the Regional Agricultural Research Station of the Bangladesh Agricultural Research Institute, Hathazari, Chittagong during the period from September, 1995 to January, 1996. It appeared that the time needed for reaching the optimum harvesting stage varied from 95 days in case of cv. Kartika and Tropical 45 days and 110 days in case of cv. Shiroyama-65 from the date of sowing. Maximum and minimum curd yields were obtained from the cv. Shiroyama-65 and cv. Poushali which were 18.38 and 6.4 tons ha-1, respectively.
  J.J. Lee , S. Ahmad and H.A. Roslan
  Morinda citrifolia, is a valuable medicinal plant with a wide range of therapeutic properties and extensive transformation study on this plant has yet been known. Present study was conducted to establish a simple and reliable transformation protocol for M. citrifolia utilising Agrobacterium tumefaciens via direct seed exposure. In this study, the seeds were processed by tips clipping and dried and subsequently incubated in inoculation medium. Four different parameters during the incubation such as incubation period, bacterial density, temperature and binary vectors harbouring β-glucuronidase (GUS) gene (pBI121 and pGSA1131), were tested to examine its effect on transformation efficiency. The leaves from the treated and germinated seedlings were analysed via Polymerase Chain Reaction (PCR), histochemical assay of the GUS gene and reverse transcription-PCR (RT-PCR). Results of the study showed that Agrobacterium strain LBA4404 with optical density of 1.0 and 2 h incubation period were optimum for M. citrifolia transformation. It was found that various co-cultivation temperatures tested and type of vector used did not affect the transformation efficiency. The highest transformation efficiency for M. citrifolia direct seed transformation harbouring pBI121 and pGSA1131 was determined to be 96.8% with 2 h co-cultivation treatment and 80.4% when using bacterial density of 1.0, respectively. The transformation method can be applied for future characterization study of M. citrifolia.
  S. Ahmad , M. Yaseen and A. Saboor
  Rice genotypes differed significantly in their growth response. Growth response in terms of paddy yield was influenced by P application, genotype and their interaction. Relative reduction in paddy yield ranged from none to 13%. The genotypes K. Basmati, NIAB-6, IRRI-6, Kernal, Basmati-370 and KSK-282 showed positive response to P application. Mostly genotypes with high P concentration had low P uptake, low phosphorus use efficiency and hence low paddy yield. NIAB-6 had used phosphorus efficiently at control P level. Rice genotypes NIAB-6, IRRI-6 and K. BASMATI were P responsive and productive and hence could be regarded as P-efficient rice genotypes. Phosphorus efficient genotypes could be grown under native or little P fertilizer application conditions.
  G. Hassan Mir , L.S. Devi , S. Ahmad , V. Manoj Kumar and P. Williams
  Investigation was undertaken to screen the potential native isolate of Trichoderma viride for bio suppression of corm rot pathogen complex, as Trichoderma viride are the most successful and widely used biocontrol agents. Taking the advantage and constraints of Trichoderma viride into consideration, efforts were made to encourage the native isolate against corm rot pathogens. Nine isolates of Trichoderma viride namely TK1, TK3, TK4, TK6, TK8, TK9, TK10, TK11 and TK15 were isolated from soils of different orchard plantations of Kashmir valley on modified Trichoderma Specific Medium (TSM). The isolates were studied for their cultural, morphometric characters and antagonistic potential against six newly recorded major fungal pathogens of saffron viz. sterile Basidiomycetes fungus, Rhizoctonia solani, Phytophthora sp., Fusarium oxysporum f. sp. gladioli, F. oxysporum and F. solani individually on Potato Dextrose Agar, the culture morphology of all the isolates was found to be similar. The isolate TK1, TK3, TK4, TK8, TK9, TK11 and TK15, were found fully overgrown on all corm rot Pathogens of saffron, where as the isolates TK13 failed to inhibit the Phytophthora sp. Efforts are onto evaluate the performance of promising isolate in field by soil and seed application methods.
  Y Chen and S. Ahmad

When high-energy protons interact in beam delivery systems and are stopped in patients, a fraction of beam will undergo nuclear interactions that release secondary particles, in particular, neutrons of different energies. The GEANT4 Monte Carlo Code was used to simulate the interaction of 250 MeV proton beam in tissue and iron to calculate the energy and angular distributions of generated protons, neutrons and photons, and thus provide H* (10), the ambient dose equivalent. A modular physics list by utilising electromagnetic interactions and hadronic interactions was constructed. Three different GEANT4 models that include the low-energy parameterisation, binary cascade and pre-compound model with Bertini cascade for proton inelastic interactions were compared. The findings suggest that the models play critical roles in terms of secondary particle generation. Further benchmarks are necessary to select the best model predicting a realistic scenario.

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