Dentrification potential of different landuse types in an agricultural watershed, lower Mississippi valley.

Expansion of agricultural land and excessive nitrogen (N) fertilizer use in the Mississippi River watershed has resulted in a three-fold increase in the nitrate load of the river since the early 1950s. One way to reduce this nitrate load is to restore wetlands at suitable locations between croplands and receiving waters to remove run-off nitrate through previous termdenitrification.next term This research investigated previous termdenitrificationnext term potential (DP) of different land uses and its controlling factors in an agricultural watershed in the lower Mississippi valley (previous termLMV)next term to help identify sites with high DP for reducing run-off nitrate. Soil samples collected from seven land-use types of an agricultural watershed during spring, summer, fall and winter were incubated in the laboratory for DP determination. Low-elevation clay soils in wetlands exhibited 6.3 and 2.5 times greater DP compared to high-elevation silt loam and low-elevation clay soils in croplands, respectively. DP of vegetated-ditches was 1.3 and 4.2 times that of un-vegetated ditches and cultivated soils, respectively. Soil carbon and nitrogen availability, bulk density, and soil moisture significantly affected DP. These factors were significantly influenced in turn by landscape position and land-use type of the watershed. It is evident from these results that low-elevation, fine-textured soils under natural wetlands are the best locations for mediating nitrate loss from agricultural watersheds in the previous termLMV.next term Landscape position and land-use types can be used as indices for the assessment/modeling of previous termdenitrificationnext term potential and identification of sites for restoration for nitrate removal in agricultural watersheds

Nitrous oxide consumption potentials of well-drained forest soils in Southern Québec, Canada.

To establish the major controls on N2O consumption by forest soils, we conducted laboratory incubations of 16 samples from four soil types, two organic and two mineral, varying in overlying forest vegetation (sugar maple, American beech and eastern hemlock). The fastest potential consumption of N2O occurred under anoxic conditionswith little soil nitrate and under elevated headspaceN2O concentration. Potential N2O consumption rates were fastest in organic soils under hemlock and beech trees (111 and 75 ng N2O-Ng−1 d−1, respectively) compared to mineral soils under beech and maple trees (45 and 41 ng N2O-N g−1 d−1). Organic soils showed faster N2O consumption rates than mineral soils, possibly due to larger organic C levels and higher C:N ratios. Acetylene treatment confirmed that denitrification was the process underlyingN2Oconsumption. These results suggest that soils regularly consume N2O with varying magnitude, most likely in anoxic microsites throughout the soil profile and that the potential for N2O consumption is larger in organic than in mineral forest soils

SYNTHESIS, CHARACHTERIZATION AND EVALUATION OF EXPANDABLE GRAPHITE BASED INTUMESCENT FIRE RETARDANT COATING FOR STEEL STRUCTURES

Structural steel is an integral part of any construction such as bridges, buildings, ships, cars and off shore structures. The integrity of structural steel has pivotal role in safety of structures and human. In the case of fire, the steel starts losing its load bearing ability above 500oC and in the case of fire, the temperature of unprotected steel rises to 800oC within 10 minutes. Intumescent fire retarding coatings are designed to insulate the structural steel under the action of heat, flames or fire thus protecting their integrity. The main objectives of this research project are to synthesis and characterization of an expandable graphite (EG) based intumescent coating formulation (ICF). An intumescent coating with considerable char expansion and flaky morphology can provide good heat shielding to the steel structures. A high residual weight of intumescent coating on exposure to fire forms a protective passive layer of char which can minimize the flow of heat to steel substrate. A range of formulations were synthesized by varying the concentration of intumescent ingredients. One formulation containing 8.5wt% expandable graphite was identified with char expansion 13.4 times. The performance of the ICF was optimized using a various particle size of EG. An ICF with 300m particle size improved char expansion, morphology, residual weight and reduced steel substrate temperature to 367oC after 60 minutes fire test. IFC formulation containing 300m was further studied for reinforcing inorganic fillers, Multi-walled carbon nanotubes (MWCNTs), Kaolin clay (KC) and Zirconium silicate (ZS). One formulation containing 5wt% ZS showed 24 times char expansion and residual weight was increased to 38% with respect to IF5-BA-Mel. The substrate temperature was reduced to 213°C and char was hard and adherent with substrate. Carbolite furnace was used to study the char expansion of intumescent coating formulations at 500oC and 800oC. Heat shielding test was performed according to ASTM E119 standard test. The test was conducted for 60 minutes and the temperature of the steel substrate was recorded at an interval of one minute. Scanning Electron Microscopy (SEM) and Field Emission Scanning Electron Microscopy (FESEM) were used to study the char morphology. Thermal stability of IFCs was analysed using Thermogravimetric analysis (TGA) and Differential thermal analysis (DTA). The chemical composition of residual char was determined using X-Ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-Ray Photoelectron spectroscopy (XPS). The weather resistance of IFCs was measured using Q-Sun Xenon Test Chambers. The gaseous products during burning of coating samples were analyzed by Pyrolysis Gas Chromatography (Py-GC). The examination of char morphology showed that flaky and multiporous type of char is most suitable to reduce the flow of heat to steel substrate. It was also noted that addition of ZS 5wt% in ICF modified the char morphology from flaky to multiporous and this was very helpful to minimize substrate temperature. XRD analysis of char of IFCs showed that the presence of high temperature boron based compounds i.e. borophosphate, boron oxide and borophosphate oxide which are stable at high temperature and helped to reduce the flow of heat to substrate. The presence of these compounds in the char was also confirmed by functional groups analysis using FTIR. The elemental analysis and carbon contents of selected ICFs showed high carbon contents compared to oxygen. This type of char is suitable for formation of carboneous layer on the substrate surface. TGA analysis showed a considerable increase in residual weight of IF5-BA-Mel reinforced with inorganic fillers. Py-GC analysis of gaseous products released during burning of selected ICFs showed less concentration compared to IF5-BA-Mel formulation. The weathering test of selected ICFs showed approximately 2% decrease in char expansion, however no change in char morphology was observed. Based on the results it was concluded that a ICF containing 5wt% ZS is more suitable for long term application due to high char expansion, lower substrate temperature, high residual weight and environment friendly properties

Frequency of Predisposing Factor of Nausea and Vomiting After Chest Surgery Under General Anaesthesia

Background: Postoperative nausea and vomiting are common and distressing postsurgical symptoms. These symptoms are of particular concern in outpatient surgery because they may require additional direct resources, such as supplies and antiemetic drugs, and may delay discharge. The objective of this study was to measure the frequency of factors which can cause nausea and vomiting under general anaesthesia after chest surgery. Methodology: This descriptive case series evaluated frequency of predisposing factor of nausea and vomiting in patients of anaesthesia department of Gulab Devi Hospital Lahore. Questionnaire is made and patients were asked about their age, fever, previous surgery, NPO status, smoking history and hospital stay. This study included 140 patients with post-operative nausea and vomiting. Results: In this study, 140 patients were taken in which  65 (46.43%) were female and 75 (53.57%) were male. In 140 patient 134 (95.7%) were NPO and 6 (4.3%) were not  NPO, 25 (17.9%) were obese and 115 (82.1%) were not obese, 88 (62.9%) patients were suffering fever and 52 (37.1%) were not suffering fever, 80 (57.1%) were infected and 59 (42.1%) were not infected, 53 (37.9%) patients had previous surgery and 87 (62.1%) had no previous surgery, 94 (67.1%) patients had received nitrous oxide and 46 (32.9%) didn\u27t, 97 (69.3%) received volatile gases and 43 (30.7%) not received, 29 (20.7%) received ketamine and 111 (79.3%) not received, 87 (62.1%) received suxamethonium and 53 (37.9%) not received, 119 (85.0%) received propofol and 21 (15.0%) not received, 110 (78.6%) received naluphine and 28 (20.0%) not received. Out of 140 patients, there were 122 (87.1%) who were suffering from pain and 18 (12.9%) were not. 91 (65.0%) patients had gastric distention and 49 (35.0%) patients didn\u27t. Opioids were given to 34 (24.3%) patients and not given to 106 (75.7%) patient. Conclusion: It is concluded that the nausea and vomiting after surgey under genral anesthesia is due to patient related factors in which most frequent is NPO. Drug related factors include propofol and nalbupin administration. Post operative factors include pain. In whole study of 140 patients, the  most frequent is patient related factor (NPO) other than drug related factors and post-operative factors

Pharmacokinetic-pharmacodynamic modeling of antibacterial agents in tissues and body fluids

The aim of this thesis was to assess the pharmacokinetic / pharmacodynamics (PK/PD) of anti-bacterial agents in tissues and body fluids through non-linear mixed effects (NLME) modeling. In the first project, a population pharmacokinetic (PopPK) model of telavancin was developed to describe its total concentrations in plasma and its unbound concentrations in plasma, muscle and subcutaneous tissue in 8 healthy volunteers measured by microdialysis. Monte Carlo simulations (MCS) based on the model suggested that the proposed pharmacodynamic targets to successfully treat relevant bacterial infections are achieved in plasma and muscle tissue with the current dosing (10 mg/kg daily). Secondly, a PopPK model was developed for piperacillin (an anti-pseudomonal penicillin) based on its concentrations in extracellular fluid (ECF) of the brain measured by microdialysis after single and multiple doses in 10 acute hemorrhagic stroke patients. MCS suggested that the concentrations achieved in brain are far too low to provide efficacy against important bacteria such as pseudomonas aeruginosa. Interestingly, changing the rate of infusion had only minimal effect on brain exposure of piperacillin. The last project aimed at improving the treatment of bacterial infections of critically ill patients. While the kidney is a frequent target of disease in such patients, assessment of their renal function is not trivial mainly because it is not stable. Therefore, conventional equations to predict creatinine clearance (CrCL) such as Cockcroft-Gault cannot be used as they assume a steady state condition. While measured CrCL (mCrCL) is generally considered a gold standard method, it requires urine collection which is highly error-prone. As an alternate procedure, a one-compartment NLME model for creatinine was developed based on serum and urine concentrations, with zero-order generation rate (CGR) and first order elimination. A novel auto-regressive approach was used to describe inter-occasion variability in creatinine clearance. The creatinine model was then used as a covariate to explain the pharmacokinetic variability in clearance of cefepime and meropenem. In this respect, the creatinine model performed better than the conventional approaches. In conclusion, all models developed provided valuable information for the assessment and improvement of antibacterial treatment