Probing Coherent Vibrations of Organic Phosphonate Radical Cations with Femtosecond Time-Resolved Mass Spectrometry

Organic phosphates and phosphonates are present in a number of cellular components that can be damaged by exposure to ionizing radiation. This work reports femtosecond time-resolved mass spectrometry (FTRMS) studies of three organic phosphonate radical cations that model the DNA sugar-phosphate backbone: dimethyl methylphosphonate (DMMP), diethyl methylphosphonate (DEMP), and diisopropyl methylphosphonate (DIMP). Upon ionization, each molecular radical cation exhibits unique oscillatory dynamics in its ion yields resulting from coherent vibrational excitation. DMMP has particularly well-resolved 45 fs (732 ± 28 cm−1) oscillations with a weak feature at 610–650 cm−1, while DIMP exhibits bimodal oscillations with a period of ∼55 fs and two frequency features at 554 ± 28 and 670–720 cm−1. In contrast, the oscillations in DEMP decay too rapidly for effective resolution. The low- and high-frequency oscillations in DMMP and DIMP are assigned to coherent excitation of the symmetric O–P–O bend and P–C stretch, respectively. The observation of the same ionization-induced coherently excited vibrations in related molecules suggests a possible common excitation pathway in ionized organophosphorus compounds of biological relevance, while the distinct oscillatory dynamics in each molecule points to the potential use of FTRMS to distinguish among fragment ions produced by related molecules

Probing Coherent Vibrations of Organic Phosphonate Radical Cations with Femtosecond Time-Resolved Mass Spectrometry

Organic phosphates and phosphonates are present in a number of cellular components that can be damaged by exposure to ionizing radiation. This work reports femtosecond time-resolved mass spectrometry (FTRMS) studies of three organic phosphonate radical cations that model the DNA sugar-phosphate backbone: dimethyl methylphosphonate (DMMP), diethyl methylphosphonate (DEMP), and diisopropyl methylphosphonate (DIMP). Upon ionization, each molecular radical cation exhibits unique oscillatory dynamics in its ion yields resulting from coherent vibrational excitation. DMMP has particularly well-resolved 45 fs (732 ± 28 cm−1) oscillations with a weak feature at 610–650 cm−1, while DIMP exhibits bimodal oscillations with a period of ∼55 fs and two frequency features at 554 ± 28 and 670–720 cm−1. In contrast, the oscillations in DEMP decay too rapidly for effective resolution. The low- and high-frequency oscillations in DMMP and DIMP are assigned to coherent excitation of the symmetric O–P–O bend and P–C stretch, respectively. The observation of the same ionization-induced coherently excited vibrations in related molecules suggests a possible common excitation pathway in ionized organophosphorus compounds of biological relevance, while the distinct oscillatory dynamics in each molecule points to the potential use of FTRMS to distinguish among fragment ions produced by related molecules

Conserved Vibrational Coherence in the Ultrafast Rearrangement of 2-Nitrotoluene Radical Cation

2-Nitrotoluene (2-NT) is a good model for both photolabile protecting groups for organic synthesis and the military explosive 2,4,6-trinitrotoluene (TNT). In addition to the direct C−NO2 bond-cleavage reaction that initiates detonation in TNT, 2-NT undergoes an H atom attack reaction common to the photolabile 2-nitrobenzyl group, which forms the aci-nitro tautomer. In this work, femtosecond pump−probe measure- ments with mass spectrometric detection and density functional theory (DFT) calculations demonstrate that the initially prepared vibrational coherence in the 2-NT radical cation (2- NT+) is preserved following H atom attack. Strong-field adiabatic ionization is used to prepare 2-NT+, which can overcome a modest 0.76 eV energy barrier to H atom attack to form the aci-nitro tautomer as soon as ∼20−60 fs after ionization. Once formed, the aci-nitro tautomer spontaneously loses −OH to form C7H6NO+, which exhibits distinctly faster oscillations in its ion yield (290 fs period) as compared to the 2-NT+ ion (380 fs period). The fast oscillations are attributed to the coherent torsional motion of the aci-nitro tautomer, which has a significantly faster computed torsional frequency (86.9 cm−1) than the 2- NT+ ion (47.9 cm−1). Additional DFT calculations identify reaction pathways leading to the formation of the dissociation products C7H6NO+, C7H7+, and C6H6N+. Collectively, these results reveal a rich picture of coherently and incoherently driven dissociation pathways in 2-NT+

Congestion-Aware Routing (CAR):Vehicular Traffic Routing Based on Real-Time Road Occupancy Estimates

This work addresses the problem of routing vehicular traffic on road networks. Fair routing is effected using real-time data acquired from a sensor network superimposed on road networks. Routing information is in the form of which route provides the fastest set of interlinked road segments between any departure-destination pair of nodes. The work adopts Dijkstra’s Shortest Path First (SPF) routing algorithm and derives a suitable routing metric from road occupancy data as a major contribution of this work that makes the SPF algorithm applicable to vehicular traffic routing on road networks. Also, a hypothetical road network and a corresponding Mobile App is used to illustrate our novel vehicular traffic routing algorithm. It is shown in this work that the method is more practical and easier to realize than a method in literature — Spatial and Traffic Aware Vehicular Routing (STAR)

Poultry manure effect on growth and yield of maize

The effect of poultry manure application on maize (Zea mays) growth and yields was studied on a Ferric Acrisol in the semi-deciduous rain forest zone of Ghana. Eight treatments of 0, 2, 4, 6, 8 tons of poultry manure (pm) per hectare, 60-40-40 kg NPK/ha, 2 × 2 t pm/ha and 2 t pm + 30-20-20 kg NPK/ha were used in a randomized complete block design (RCBD) with five replications. The study showed that poultry manure is a valuable fertilizer and can serve as a suitable alternative to chemical fertilizer in the forest zone of Ghana. Poultry manure treatments produced higher values for height, leaf area index and biomass. The 4 t pm/ha rate produced maize grain yield of 2.07 t/ha which was statistically not different from that of the chemical fertilizer rate (2.29 t/ha) and 6 t pm/ha (2.60 t/ha), while the 6 t pm/ha was not statistically different from the 8 t pm/ha rate. Split application of 4 t pm/ha (i.e. 2 × 2 t pm/ha) and 2 t pm/ha + 30-20-20 kg NPK/ha gave similar biomass and grain yields as the 4 t pm/ha. Poultry manure application registered over 53% increases of N levels in the soil, from 0.09% to 0.14%. Exchangeable cations increased with manure application. The study recommends an application rate of 4 t pm/ha for maize on this type of soil in this agro-ecolog

Growth, carcass and meat characteristics of local breed of rabbits fed diets containing soaked and dried mango (Mangifera indica) seed kernel meal

This study was conducted to find substitutes for dietary maize in rabbit rations, to minimize competition between humans and livestock over the commodity. Mango seed kernel meal (MSKM) was used to substitute up to 20% of maize in rabbit rations, to assess its effects on growth, carcass and meat characteristics. Fresh mango seeds were obtained, husks were removed and seeds soaked in fresh potable water for 48 hours. The seeds were then dried to a moisture content of about 15 %, and then milled for use. Three experimental diets were formulated, where T1 (control, had no MSKM), T2 (10% of maize was replaced with MSKM) and T3 (20% of maize was replaced with MSKM). A total of 48 six-week old rabbits of indeterminate breeds (24 males and 24 females) were assigned to the three dietary treatments (16 rabbits per treatment), and were fed ad-libitumfor 6 weeks, to determine feed intake and growth rates of the rabbits. Water was however provided ad-libitum. At the end of the feeding trial, 24 rabbits were randomly selected (8 from each treatment, equal number of males and females) and were slaughtered humanely after a 12-hour feed withdrawal, for carcass and proximate analyses of the meat. Results from the study indicate that, feed intake and growth rates of the animals reduced significantly (p<0.05) when dietary maize replacement with MSKM increased beyond 10% inclusions. However, crude protein, phosphorus,potassium and zinc contents of the meat increased significantly (p<0.05) as MSKM inclusions increased. That notwithstanding, carcass parameters and organ weights were not affected by substituting up to 20% of maize with MSKM (p>0.05). It can be concluded that MSKM can efficiently be used to substitute up to 20% of maize in rabbit rations, for reduced feed cost, improved crude protein, phosphorus, potassium, and zinc contents of the meat

Domestic Rainwater Harvesting in a Water-Stressed Community and Variation in Rainwater Quality from Source to Storage

The quality of rainwater, which is the main source of domestic water in Dzodze, a community in the Volta Region of Ghana, was unknown. Therefore, the possible utilization of contaminated domestic water and occurrence of health hazards could not be underestimated due to prevailing poor hygiene and a great lack of standard maintenance and treatment systems in the community. In this study, we assessed the quality of rainwater in the Dzodze Community community and how it varies along the DRWH chain from free-fall to storage. Rain samples were collected at three points along the domestic rainwater harvesting (DRWH) chain. Specifically, the three points from were free-fall, roof-catchmentroof catchment, and storage tank, and the two systems were "described as poorly-maintained" and "well-maintained" systems. The physico-chemical and bacteriological patterns of rainwater samples were analyzed for physico-chemical and bacteriological parameters and results were compared with World Health Organization (and Ghana Standards Board guideline values. The harvested rainwater was found to be of good physico-chemical quality, but not bacteriological, quality but not bacteriological, calling for treatment before utilization. Also, irrespective of the type of DRWH system (poorly-maintained or well-maintained), there were substantial changes in rainwater quality upon interaction with roof catchment, with an increase noticed in all parameters

Nitrogen use efficiency of poultry manure by maize

Nitrogen use efficiency is a measure of the extent to which a crop transforms available N to economic yield. Poultry manure is often reported to have lower N use efficiency than mineral fertilizer in the first year of application. However, under certain conditions such as rate of application, N mineralization rate, type of soil and crop, the converse may be the case. Will a farmer be better off in applying poultry manure at a particular rate than mineral fertilizer? A study was conducted on a forest acrisol to determine the physiological and apparent N efficiencies of poultry manure (PM) applied at various rates and mineral fertilizer to maize. Poultry manure rates of 2, 4, 6, 8 and 2 x 2 t ha-1 (i.e. split application) showed higher physiological N use efficiencies than the mineral fertilizer rate of 60-40-40 kg NPK ha-1 and 2 t PM ha-1 + 30-20-20 kg NPK ha-1. However, the mineral fertilizers (including combined half rate plus 2 t poultry manure) had the highest apparent N use efficiencies of 58% and 40% respectively, but low physiological N use efficiency. Among the poultry manure treatments, 4 t ha-1 with the highest N content of 2.17% in the maize ear leaves and grain N content of 12.56 g kg-1, had the highest physiological N use efficiency of 60 kg ha-1 making it the most efficient rate in the transformation of N into grain yield. Journal of Science and Technology (Ghana) Vol. 27 (2) 2007: pp. 71-7

Emulsifier Effects on the Stability of Different Wax Emulsions

Wax emulsion has varied application in various industries. Wax and water are immiscible hence the choice of an effective emulsifier is key in formulating wax emulsions. This work focused on identifying an emulsifier as well as its adequate composition that would adequately give a stable wax emulsion. Paraffin wax emulsion was prepared by emulsifying different petroleum waxes (PW) in water using different emulsifiers namely Sorbitan monooleate (SPAN 80), Polyoxyethylene (20), Polysorbate 80 (TWEEN 80), Nonylphenol polyoxyethylene glycol ether (Rokafenol N6 and N22) together with ABS NaS. The relationship between the individual emulsifiers as well as a blend of two different emulsifiers and the multi – functional wax emulsion stability is established. Blends of SPAN 80/TWEEN 80 and Rokafenol N6/Rokafenol N22 are used. The two mixtures have a relatively similar effect on the stability of wax emulsion and hence the Rokafenol N6/Rokafenol N22 blend is further looked at. The most stable emulsion is formed from 2.5 wt% Rokafenol N6/Rokafenol N22 in a ratio of 80/20. Wax emulsion may be diluted with water to a ratio of 1:5 without loss of stability and changes in particle size. Keywords: Wax emulsion, emulsifiers, hydrophobicity, Rokafenol N6, Rokafenol N2