Kinetics and decomposition mechanisms of selected Nitrogen-containing species

This thesis calculates the rate of hydrogen abstraction reactions and the mechanisms of nitrogen oxides (NOx and N2O) reduction, especially those relevant to the oxidation and pyrolysis of nitrogen-rich fuels such as biomass. The dissertation firstly focuses on the interaction of hydrocarbons with the amidogen radical (NH2) and nitrogen dioxide (NO2), before analysing in detail the decomposition of ammonium nitrate (AN) both in gas and liquid media. In addition to this, the moderation of nitrous oxide (N2O) and nitrogen oxides (NOx) via their reaction with a biomass surrogate of catechol was also studied. The underlying aims of the study were to report the mechanisms and kinetic factors controlling the interaction of NH2 and NO2 radicals with a wide array of hydrocarbons, then to map out the prominent reaction pathways prevailing in the decomposition of ammonium nitrate (AN) and conversion of N2O into N2 via dissociative adsorption onto a catechol moiety. Accurate quantum-mechanical calculations probed the hydrogen abstraction reactions from small aliphatic and aromatic hydrocarbons by NH2 and NO2 radicals. Reaction and activation energies for all plausible hydrogen abstraction channels were executed with the accurate chemistry model of CBS-QB3. Reaction rate parameters were obtained based on conventional transition-state theory, accounting for a plausible contribution from tunnelling effects and treating internal rotations as hindered rotors. We established that a linear correlation existed between the strength of the C-H bonds (i.e., primary, secondary, vinylic, and benzylic) and the activation energies for H abstraction channels operated by NH2 and NO2 radicals. Moreover, the meta-hybrid Density Functional Theory (DFT) of M05-2X/6-311+G(d,p) levels elucidated viable systematic conversion routes of N2O into N2 via interaction with a catechol molecule. Two theoretical methodologies were applied to study thermal decomposition of AN in gas and liquid phases. A continuum solvation model density-polarisable continuum model (SMD-PCM) expounds the catalysing effect of water on AN thermal cracking. The solvation model systematically predicts lower activation energies when contrasted with analogous gas phase values. An important part of the thesis investigates the potential of biomass constituents for the so-called selective non-catalytic reduction of NOx into nitrogen molecules. The laboratory-scale rig offers a continuous supply of carrier and reaction gases which run through a tubular reactor coupled with FTIR spectroscopy, micro-GC and a chemiluminescence NOx analyser. The consumption of the biomass surrogate (catechol) is analysed using a triple quadruple mass spectrometer (QQQ-MS) at temperatures starting from 400 °C. Fine-tuning of experimental conditions encompasses residence time and inlet reactant mixing ratios. Above 800 °C, we report more than 80 % NOx reduction efficiency. In summary, our findings throughout the thesis present previously unreported data and new insights pertinent to the combustion chemistry of several selected N-species

Frequency of Source and Total Body Surface Area (TBSA) Burn Percentage with Outcome in Burn Patients

Objectives: To determine the frequency of source and total body surface area (TBSA) burn percentage with outcome in patients admitted in Pak Italian burn unit, Multan. Study design: retrospective study. Setting: Pak Italian burn unit, Multan. Study Duration: six months from January 2017 to June 2017. Material and Methods: Medical records of 260 patients admitted in Pak Italian burn unit, Multan from January 2017 June 2017 were collected and the required information was recorded on a pre designed questionnaire. Data was analyzed using SPSS version 20. Results: Mean age of patients presenting with burn was 32.18 with standard deviation of 8.57 years. Out of total 260 patients, the male victims were n= 151(58.1%) victims Flame burn (68.1%) being the most common cause followed by electric burn (16.2 %), scalds (10.4%) and acid burn. Most of the patients (35.4%) have TBSA burn 11-20%. A mortality rate of 16.2% was observed which has a significant relation with TBSA burn (p=0.00) but gender and source of burn was not significantly related with mortality. Conclusion: Flame burn  are the most common cause of burn injury followed by electric burn. Most of the victims are male. Keywords:Burn injury, total body surface area burn(TBSA), flame burn, scalds, acid burn

Physarum-Inspired Bicycle Lane Network Design in a Congested Megacity

Improvement of mobility, especially environment-friendly green mobility, is challenging in existing megacities due to road network complexity and space constraints. Endorsing the bicycle lane network (BLN) in congested megacities is a promising option to foster green mobility. This research presents a novel bioinspired network design method that considers various constraints and preferences related to the megacity for designing an optimal BLN. The proposed method is inspired by natural Physarum polycephalum, a brainless, multi-headed single-celled organism, which is capable of developing a reticulated network of complex foraging behaviors in pursuit of food. The mathematical model of Physarum foraging behavior is adapted to maneuver various BLN constraints in megacity contexts in designing the optimal BLN. The Physarum-inspired BLN method is applied to two case studies on the megacity Dhaka for designing BLNs: the first one covers congested central city area, and the second one covers a broader area that includes major locations of the city. The obtained BLNs were evaluated comparing their available routes between different locations with the existing vehicle routes of the city in terms of distance and required travel times in different time periods, and the BLN routes were found to be suitable alternatives for avoiding congested main roads. The expected travel time using BLNs is shorter than other transport (e.g., car and public bus); additionally, at glance, the average travel speed on BLNs is almost double that of public buses in peak hours. Finally, the designed BLNs are promising for environment-friendly and healthy mobility

Leaf area estimation by linear regression modles for pigenonpea (Cajanus Cajan (L.) Millsp.)

Leaflet length (L) and breadth (B), fresh (LFwt) and dry weights (LDwt) of leaves of 50 samples (500 leaves, 10 in each sample) were used in the prediction model to estimate the leaf area (LA) in pigeonpea (Cajanus cajan cajan (L.) Millsp.). Two of the fifteen linear regression models, appeared more suitable for ease of measurement. These were LA = -17.784 + 6.823 L (Model-1) and LA = 0.5855 + 67.583 LFwt (Model-10). These regression models showed linear relationship when actual leaf area was plotted against predicted one in another 30 leaf samples (300 leaves, 10 in each sample). Moreover, models’ selection indices had high predictive ability represented by high R2 value with minimum error (low means square error and smaller percentage deviation). The selected models appeared unsophisticated but accurate, easy and rapid which can be used for estimation of leaf area of pigeonpea (Morphotype ‘Bogra’)

COMBINING ABILITY STUDIES OF GRAIN YIELD AND RELATED TRAITS IN PEARL MILLET

The present study was undertaken to explore the genetic architecture of pearl millet through combining ability analysis in a 5X5 diallel fashion. Both GCA and SCA mean squares were significant in grain yield, plant height, panicle length and days to flowering. However, these were non-significant for number of productive tillers and panicle girth. General combining ability estimates revealed that genotype MGP-322 was good general combiner for all the traits under study except for days to flowering for which MGP-335 and 13RBS-01 were good general combiners but these were poor general combiners for all other traits under study. The crosses MGP-322XMGP-328, MGP-322XMGP-335, MGP-328X13RBS-13, 13RBS-01X13RBS-13 and MGP-322X13RBS-01 were best specific combiners for grain yield and some other attributes respectively. All these crosses involved at least one good general combiner except MGP-328X13RBS-13. This suggested that good general combiners are the best tool in improving the crop yield by manipulating the genetic architecture. Combining ability variances revealed that although both GCA and SCA variances were important, however, SCA variances were higher than GCA variances suggesting that non additive type of gene action was more prominent in the inheritance of characters under study

Photodecomposition properties of brominated flame retardants (BFRs)

This study investigates the geometric and electronic properties of selected BFRs in their ground (S0) and first singlet excited (S1) states deploying methods of the density functional theory (DFT) and the time-dependent density functional theory (TDDFT). We estimate the effect of the S0 → S1 transition on the elongations of the C–Br bond, identify the frontier molecular orbitals involved in the excitation process and compute partial atomic charges for the most photoreactive bromine atoms. The bromine atom attached to an ortho position in HBB (with regard to C–C bond; 2,2ʹ,4,4ʹ,6,6ʹ-hexabromobiphenyl), TBBA (with respect to the hydroxyl group; 2,2ʹ,6,6ʹ-tetrabromobisphenol A), HBDE and BTBPE (in reference to C–O linkage; 2,2ʹ,4,4ʹ,6,6ʹ-hexabromodiphenylether and 1,2-bis(2,4,6-tribromophenoxy)ethane, respectively) bears the highest positive atomic charge. This suggests that, these positions undergo reductive debromination reactions to produce lower brominated molecules. Debromination reactions ensue primarily in the aromatic compounds substituted with the highest number of bromine atoms owing to the largest stretching of the C–Br bond in the first excited state. The analysis of the frontier molecular orbitals indicates that, excitations of BFRs proceed via π→π*, or π→σ* or n→σ* electronic transitions. The orbital analysis reveals that, the HOMO-LUMO energy gap (EH−L) for all investigated bromine-substituted aromatic molecules falls lower (1.85–4.91 eV) than for their non-brominated analogues (3.39–8.07 eV), in both aqueous and gaseous media. The excitation energies correlate with the EH−L values. The excitation energies and EH−L values display a linear negative correlation with the number of bromine atoms attached to the molecule. Spectral analysis of the gaseous-phase systems reveals that, the highly brominated aromatics endure lower excitation energies and exhibit red shifts of their absorption bands in comparison to their lower brominated congeners. We attained a satisfactory agreement between the experimentally measured absorption peak (λmax) and the theoretically predicted oscillator strength (λmax) for the UV–Vis spectra. This study further confirms that, halogenated aromatics only absorb light in the UV spectral region and that effective photodegradation of these pollutants requires the presence of photocatalysts.This study has been supported by the Australian Research Council (ARC), and grants of computing time from the National Computational Infrastructure (NCI), Australia as well as the Pawsey Supercomputing Centre. A.S. and K.S. thanks Murdoch University, Australia, for a postgraduate research scholarship

Proximate chemical composition of sea grapes Caulerpa racemosa (J. Agardh, 1873) collected from a sub-tropical coast

Background: Nutritional fact study has prime importance to make the species edible and commercially viable to the consumers. Proximate chemical composition and amino acid profile were investigated to understand the nutritional value and protein quality of an edible algae Caulerpa racemosa. Methods: Samples were collected randomly by hand from the intertidal zone of the sub-tropical coastal Island St. Martin’s Island from February 2013 to May 2014. Samples were preserved using standard methods for chemical analysis. Proximate composition was determined using standard methods, Kjeldahl method for protein, Soxhlet method for crude lipid, H2SO4 (0.3 N) and NaOH (0.5 N) for dietary fibre, muffle furnace method for moisture content, ion-exchange chromatography for amino acid and statistical package used for validating the data. Results: The result of the study reveals that C. racemosa contains higher amount of proteins (19.72±0.77%), crude lipid (7.65±1.19%) and fibre (11.51±1.32%) compared to other green and brown algae. The higher concentration of aspartic acid (12.7±0.2%) and glutamic acid (9.2±0.7%) were observed in C. racemosa, while histidine (2.6±0.7%), methionine (1.4±0.4%) and tyrosine (3.8±0.2%) were the limiting amino acids. Lysine (6.6±0.2%), leusine (6.9±0.6%), glycine (6.5±0.4%), arginine (6.4±0.3%), alanine (7.6±0.6%) and threonine (6.2±0.5%) were obtained at a higher percentage of total amino acids. Conclusion: This study suggests that C. racemosa could be potentially used as a nutritious and functional food item for human consumption. Further studies on this edible species should be focused on fatty acid composition, vitamins, non-starch polysaccharide constituents, trace elements and sensory perceptions in order to depict safer and versatile utilization

Length–weight relationships of three fish species from a tropical mangrove estuary of Sarawak, Malaysia

Length–weight relationships for three mangrove fish species, Setipinna melanochir (Bleeker, 1849), Ilisha elongata (Anonymous [Bennett], 1830), and Nibea soldado (Lacépède, 1802) were determined. Samplings were conducted in a tropical mangrove estuary, Sarawak, Malaysia (3°59′25.76′′N; 113°43′51.6′′E) at the peak of three different seasons using gillnets (100 × 2.5 m, mesh sizes 1, 2 and 4 inches) during 2014–2015. No information regarding length–weight relationships of these species was reported previously in FishBase

Mortality and pulmonary complications in patients undergoing surgery with perioperative sars-cov-2 infection: An international cohort study

Background The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (740%) had emergency surgery and 280 (248%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (261%) patients. 30-day mortality was 238% (268 of 1128). Pulmonary complications occurred in 577 (512%) of 1128 patients; 30-day mortality in these patients was 380% (219 of 577), accounting for 817% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 175 [95% CI 128-240], p<00001), age 70 years or older versus younger than 70 years (230 [165-322], p<00001), American Society of Anesthesiologists grades 3-5 versus grades 1-2 (235 [157-353], p<00001), malignant versus benign or obstetric diagnosis (155 [101-239], p=0046), emergency versus elective surgery (167 [106-263], p=0026), and major versus minor surgery (152 [101-231], p=0047). Interpretation Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely