Negative ion FAB mass spectroscopy of some ribose alkylated 5'-UMP derivatives

Characteristic fragment ions obtained in Fast atom bombardment (FAB) mass spectroscopy of ribose alkylated Uridine 5'-monophosphate (5'-UMP) derivatives in negative ion mode are described. All the compounds examined exhibited either [M]- or quasimolecular ion [M - H]- the fragmentations can be used to characterize these nucleotides.     

The electrodeposition of indium onto vitreous carbon from acidic chloride media

Cyclic voltammetry and potential step techniques have been used to study the electrodeposition of indium metal from 1 mol dm^?3 potassium chloride, pH 2–4.5, onto a vitreous carbon electrode. It is confirmed that the In/In³⁺ couple is fast in chloride media and the nucleation and growth of the indium phase is discussed. It is shown that instantaneous nucleation occurs at an overpotential of only a few mV and that the growth of the nuclei is three dimensional.     

Physiological and Immunological Changes Associated with Oral Microbiota When Using a Thermoplastic Retainer

Background: The study examined the oral microbiota, physiological and immunological changes in patients using thermoplastic retainers during three months of use. Methods: The study included several steps. Firstly, 10 swabs were collected from the buccal and palatal surfaces of the teeth of the patients, approximately 2 mL of saliva was collected from the same patients and 2 mL of saliva was collected from 10 healthy people to measure the pH and secretory IgA level. This was followed by the isolation and identfication of the bacterial isolates in the patient samples. Then, isolate susceptibility toward chlorhexidine (CHX) and their adhesion ability to thermoplastic retainer surfaces was measured. In addition to that the study estimated the numbers of Lactobacillus and Streptooccus mutans colonies during three months and finally, a comparsion of pH acidity and IgA level between the patients and healthy people was performed. The results showed the predominant bacteria during the three months were Lactobacillus spp. and Streptococcus spp. followed by different rates of other bacteria. Raoultella ornithinolytica showed more resistance to CHX while Lactobacillus spp. showed more sensitivity. Streptococcus mutans colony levels were higher than Lactobacillus spp. colonies during the three months, also S. mutans had the highest value in adherence to retainer thermoplastic. Finally, pH acidity showed a highly significant difference (p ≤ 0.05) in the third month, like IgA levels (p ≤ 0.05). Conclusions: According to the results obtained from the current study, the researchers noted that the thermoplastic retainers helped change the oral cavity environment.     

A multi-beam ion/electron spectra-microscope design

This paper presents the design of a multi-beam charged particle instrument that simultaneously focuses electrons, gallium, oxygen and cesium ions onto the same sample. In addition, the instrument has provision to capture the spectra of both secondary electrons and ions in parallel. The mass spectrometer part of the instrument is expected to detect and identify secondary ion species across the entire range of the periodic table, and also record a portion of their emitted energy spectrum. The electron energy spectrometer part of the instrument is designed to acquire the entire range of scattered electrons, from the low-energy secondary electrons through to the elastic backscattered electrons.     

A sequential sampling rule for selecting the most probable multinomial event

Summary A sequential sampling rule is given for selecting the most probable event from a multinomial distribution withk cells. A random number of observations is taken from the given multinomial distribution at each stage of sampling, where the number is distributed according to a Poisson distribution with mean λ. The sampling is stopped when the count in any cell is greater than or equal to a given positive integerN. The cell with the highest count is selected for the most probable event. The mathematical analysis of the problem is simplified as a result of the statistical independence of the cell frequencies due to the randomization of the sample number. The expected value of the stage when the sampling terminates is decreasing in λ. The sequential sampling scheme in which one observation is taken at a time until the highest cell count is equal toN, corresponds to λ→0. A table is given showing some properties of the given selection procedure.     

Mesophilic Digestion Kinetics of Manure Slurry

Anaerobic digestion kinetics study of cow manure was performed at 35°C in bench-scale gas-lift digesters (3.78 l working volume) at eight different volatile solids (VS) loading rates in the range of 1.11–5.87 g l⁻¹ day⁻¹. The digesters produced methane at the rates of 0.44–1.18 l l⁻¹ day⁻¹, and the methane content of the biogas was found to increase with longer hydraulic retention time (HRT). Based on the experimental observations, the ultimate methane yield and the specific methane productivity were estimated to be 0.42 l CH₄ (g VS loaded)^–1 and 0.45 l CH₄ (g VS consumed)^–1, respectively. Total and dissolved chemical oxygen demand (COD) consumptions were calculated to be 59–17% and 78–43% at 24.4–4.6 days HRTs, respectively. Maximum concentration of volatile fatty acids in the effluent was observed as 0.7 g l^–1 at 4.6 days HRT, while it was below detection limit at HRTs longer than 11 days. The observed methane production rate did not compare well with the predictions of Chen and Hashimoto’s [1] and Hill’s [2] models using their recommended kinetic parameters. However, under the studied experimental conditions, the predictions of Chen and Hashimoto’s [1] model compared better to the observed data than that of Hill’s [2] model. The nonlinear regression analysis of the experimental data was performed using a derived methane production rate model, for a completely mixed anaerobic digester, involving Contois kinetics [3] with endogenous decay. The best fit values for the maximum specific growth rate (μ _m) and dimensionless kinetic parameter (K) were estimated as 0.43 day^–1 and 0.89, respectively. The experimental data were found to be within 95% confidence interval of the prediction of the derived methane production rate model with the sum of residual squared error as 0.02.     

Thermal,magnetic and spectral studies of metal-quinone complexes. Part II. Media effect on Coligation of Aqua Ligands

Syntheses of phthiocol complexes with Cu(II) in inert media resulted in anhydrous monomer Cu-4: [Cu(NQ)₂] and dimer Cu-5: [Cu(NQ)(NSQ)]₂, however synthesis in air generates polymeric hydrated Cu-6: [Cu(NQ)₂(H₂O)₂]_n. Media and colligation give rise to charge transfers in coordination compounds and lead to different redox ligations of 3-methyl-2-hydroxy-1,4-naphthoquinone. These redox forms are determined from quantitization of activation energies (E _a) of different pyrolytic steps in TG using the rising temperature expression of Coats and Redfern. 'Tyrosinase'-type mechanism is discussed for the redox-type ligation. Characteristic six-line EPR signals of dimeric Cu-5 lead to zero field splitting parameters D=0.01608 cm^-1and E=0.01576 cm^-1. Cu-6 shows molecular association through hydrogen bonding. Variable temperature magnetic measurement data of Cu-6 from 6 to 300 K is fitted to the polymeric expression of Bonner and Fisher model. The best fit was obtained with antiferrromagnetic exchange coupling constantJ=-2 cm^-1, g=2.2 having R=4.2·10^-4. This revised version was published online in July 2006 with corrections to the Cover Date.     

On multiindices and multivariables presentation of the Voigt functions

This paper aims at presenting multiindices and multivariables study of the unified (or generalized) Voigt functions which play an important rôle in the several diverse field of physics such as astrophysical spectroscopy and the theory of neutron reactions. Some expressions (representations) of these functions are given in terms of familiar special functions of multivariables. Further representations and series expansions involving multidimensional classical polynomials (Laguerre and Hermite) of mathematical physics are established.