Aerobic bacteria in safe type chronic suppurative otitis media in Gezira State, Sudan

Chronic suppurative otitis media (CSOM) is a challenging disease with a high burden on society in developing countries. Information regarding CSOM in Sudanese patients is scarce. This study aimed to identify aerobic bacteria involved in CSOM and to determine their sensitivity towards commonly prescribed antibiotics. A multi-center prospective cross sectional study was conducted between June 2012 and October 2013 in private and public ENT clinics in Gezira State, Sudan. The study included 217 CSOM patients most of whom were males or had unilateral disease. The most common isolates were Staphylococcus aureus (42.6%), Klebsiella pneumoniae (14.7%), Pseudomonas aeroginosa (12.5%) and Proteus mirabilis (10.2%). The sensitivity of all isolates was highest towards gentamicin and ciprofloxacin while multiple drug resistance was prominent towards amoxyclav, cotrimoxazole, cefuroxime, cefaclor and ceftriaxone. Ciprofloxacin and gentamicin appear to be the best choices for empiric therapy in patients with CSOM. In contrast, the use of amoxyclav, cotrimoxazole, cefuroxime, cefaclor and ceftriaxone should be discouraged.Keywords: Aerobic bacteria, Chronic suppurative otitis media, Gezira State, Sudan

Factors Affecting Activity of Cellulose Enzymes Produced By Three Fungi

Three fungi (Trichoderma viride, Asperigillus niger and Penicillium digitatum) were used in the present study for the production of the cellulase enzymes (carboxymethylcellulase and cellobiase). The effects of different metal ions on the activities of these enzymes were , caused a ++and Mn+ , K++, Ba++using the reducing group method. The addition of Ca investigatedsignificantly higher increase in the activity of the carboxymethylcellulase enzyme of the three . However, the addition ++and Zn++ e a less increase was found by the addition of Mgfungi, whilactivity. The activity of the is enzyme caused a decrease in th ++, and Fe++, Cu++, Cd+, Ag+of Naand +ence of Hg, but it was decreased in the pres+and K ++cellobiase was increased with Caat the was occurred A. nigerenzyme produced by cellobiasehe higher activity of the T.++Cd, however, ++Ca and ++900 ppm for Mn –500 , while it occurred at+900 ppm of K –200 of range P. and T. viride ase of bothobiFor the cell 900 ppm. –800 of at the range it occurred ,++Ba for . ++, no significant different was noticed with different concentrations of Cadigitatumfungi at all th ase enzyme of boobigave a lower activity for the cell ++On the other hand, Ba concentrations. The optimum temperature for the carboxymethylcellulase enzyme activity was at . P. digitatum and T. viride bothfor C 050 –C 0it was between 40 , whileA. niger50°C for C.0However, the optimum temperature for the cellobiase activity of the three fungi was at 40 The optimum activity of the carboxymethylcellulase enzyme produced by A. niger was at pH 4, and for that of T. viride was at pH 6. Two peaks were detected for the same enzyme produced by P. digitatum, at pH 6 and pH 7. However, the optimum pH value for the cellobiase enzymes produced by the three fungi was at pH 4.0only

Production and characterization of Pectic enzymes from three fungi

Pectins are compounds  that  are resistant   to  enzymatic  cleavage  in most  organisms  and  plants, Studies  were  therefore  made towards finding methods for hydrolyzing these compounds. One such approach  is enzymatic hydrolysis.  Three fungi   (Trichoderma   viride,    Asperigillus     niger   and penicillum   digitatum)  are   used   for  production   of   pectinase  enzymes, Two  methods (reducing  sugar and viscometary)  were  used  for  measuring enzymes activities. Pectin and sodium polypectate compounds were used  as substrates. The  production of  pectinases by the three fungi was investigated in culture media. T. viride and P. digitatum  gave  maximum   production  of pectinase  enzymes  after  two  week  and  A. niger  gave  it  after  one week. Purification   by   ammonium    sulphate   precipitation,     showed   that   the maximum  pectinase  activity  was  at   80%   concentration for both fungi A niger and P. digitatum. By using  gel  electrophoresis, five bands were found to   give   pectinase  enzymes   activities. The   present   study   showed    the importance   of   fungi   as   sources  of  enzymes and recommends that more studies  must   be   done   in   the  field of  biotechnology to produce glucose  from natural products by  using fungi. &nbsp

Nanomechanical and Morphological Characterization of Tungsten Trioxide (WO3) Thin Films Grown by Atomic Layer Deposition

This study investigates the nanomechanical properties and surface morphology of tungsten oxide WO3thin films deposited on p-type Si(100) substrates using atomic layer deposition (ALD) technology with 2000 ALD deposition cycles at a growth temperature of 300°C and annealed at different temperatures. The samples were further furnace annealed at 500, 600 and 700°C for 60 min. The influence of the deposition process on the structure and properties of the WO3 films is discussed, presented and correlated to the characteristic features of the ALD technique. The results depict significant difference in the hardness and modulus measurements between the as deposited sample and the annealed ones. The hardness and modulus drop from 14 and 170 GPa for the as deposited sample to 10 and 140 GPa for the annealed ones respectively. Surface roughness was observed to increase with annealing temperature and the initially amorphous as deposited sample reached complete recrystallization and transformed into polycrystalline films as indicated by XRD

Repeated Load Relaxation Testing of Pure Polycrystalline Nickel at Room Temperature Using Nanoindentation

We present the results of repeated relaxation tests using nanoindentation to derive the activation volume of the dislocation velocity and the ratios of the dislocation density and dislocation velocity. An experimental technique, based on classical uniaxial relaxation experiments, was developed to establish a constant strain during repeated load relaxation transients and then to calculate the stiffness of unloading, and therefore the hardness, across the transients with acceptable results. We found that the activation volume of the dislocation velocity from our nanoindentation methodology was in good agreement when compared to the same reported for uniaxial experiments. © 2014 AIP Publishing LLC

Correlation of CsK2Sb Photocathode Lifetime With Antimony Thickness

CsK2Sb photocathodes with quantum efficiency on the order of 10% at 532 nm, and lifetime greater than 90 days at low voltage, were successfully manufactured via co-deposition of alkali species emanating from an effusion source. Photocathodes were characterized as a function of antimony layer thickness and alkali consumption, inside a vacuum chamber that was initially baked, but frequently vented without re-baking. Photocathode lifetime measured at low voltage is correlated with the antimony layer thickness. Photocathodes manufactured with comparatively thick antimony layers exhibited the best lifetime. We speculate that the antimony layer serves as a reservoir, or sponge, for the alkali

Numerical Simulation of the Donor-Assisted Stir Material for Friction Stir Welding of Aluminum Alloys and Carbon Steel

In this research effort, we explore the use of a donor material to help heat workpieces without wearing the tool or adding more heat than necessary to the system. The donor material would typically be a small piece (or pieces) of material, presumably of lower strength than the workpiece but with a comparable melting point. The donor, a sandwich material, is positioned between the tool head and the material to be welded, where the tool initially plunges and heats up in the same manner as the parent material that is intended for welding. The donor material heats up subsequent to tool penetration due to friction and as a result heats up the material beneath it. This preheating technique softens the harder parent material, which helps to minimize tool wear and produce better weld performance. The goal is to investigate the use of the donor material as a preheating technique that minimizes wear and tear on the tool head without negatively impacting the structural properties of the weld. To demonstrate the donor material concept, a combination of Cu-Al, Cu-1045 Carbon steel (CS), and Al-1045 CS sets of donor and parent materials were used in the simulation, in addition to control samples Al-Al and CS-CS. We simulated two thicknesses of donor material 25 and 50% of the parent material thickness, respectively. The simulation suggests that the donor material concept generates phenomenal results by reducing the temperature and axial forces for the friction stir welding of aluminum AA6061 and carbon steel 1045. It also assists downstream during welding, resulting from frictional mechanical work which is converted into stored heat

Evaluation of the Mechanical Properties of Germanium-on-Insulator (GeOI) Films by Raman Spectroscopy and Nanoindentation

Germanium-on-insulator (GeOI) films fabricated using the Smart Cut™ wafer bonding and film exfoliation technology were investigated for the mechanical properties and induced phase transformations by using nanoindentation and Raman spectroscopy experiments. The hardness and modulus results of the GeOI films are significantly different from the literature published Silicon-on-Insulator and bulk germanium results. The GeOI films are softer and more flexible as compared to bulk Ge hardness and stiffness properties. The Raman spectroscopy of the spherical indents indicates bands of metastable Ge phases @ 220 cm−1, 195 cm−1, and 184 cm−1 wavenumbers. Our results demonstrate that a spherical indenter impacted a wider area of contact and produced GeOI indented surfaces free of cracks and fracture. The spherical indenter tip kept the Ge top layer intact when compared to the Berkovich indenter tip during penetration. In contrast, the Berkovich indenter tip developed excessive fracture that resulted in displacing the Ge top layer sideways and exposed the Si substrate underneath revealing Raman spectra bands of metastable Si phases @ 350 cm−1, 399 cm−1, and 430 cm−1