Photolytic Hazes in the Atmosphere of 51 Eri b

We use a 1D model to address photochemistry and possible haze formation in the irradiated warm Jupiter, 51 Eridani b. The intended focus was to be carbon, but sulfur photochemistry turns out to be important. The case for organic photochemical hazes is intriguing but falls short of being compelling. If organic hazes form, they are likeliest to do so if vertical mixing in 51 Eri b is weaker than in Jupiter, and they would be found below the altitudes where methane and water are photolyzed. The more novel result is that photochemistry turns H$_2$S into elemental sulfur, here treated as S$_8$. In the cooler models, S$_8$ is predicted to condense in optically thick clouds of solid sulfur particles, whilst in the warmer models S$_8$ remains a vapor along with several other sulfur allotropes that are both visually striking and potentially observable. For 51 Eri b, the division between models with and without condensed sulfur is at an effective temperature of 700 K, which is within error its actual effective temperature; the local temperature where sulfur condenses is between 280 and 320 K. The sulfur photochemistry we have discussed is quite general and ought to be found in a wide variety of worlds over a broad temperature range, both colder and hotter than the 650-750 K range studied here, and we show that products of sulfur photochemistry will be nearly as abundant on planets where the UV irradiation is orders of magnitude weaker than it is on 51 Eri b.Comment: 24 pages including 11 figures and a tabl

Production and characterization of titanium carbide particulate reinforced AA6061 aluminum alloy composites using stir casting

Abstract: Stir casting is an economical method to produce aluminum matrix composites. In the present work, composites of aluminum alloy AA6061 reinforced with various amounts (0, 5, 10 and 15wt. %) of TiC particles were prepared by stir casting technique. X-ray diffraction patterns of the prepared composites clearly revealed the incorporation of TiC particles without the presence of any other compounds. The microstructures of the composites were studied using optical and scanning electron microscopy. It was observed that the TiC particles distributed all over the composite and properly bonded to the matrix alloy. Local clusters of TiC particle were also seen in a few places. The result shows that the reinforcement of TiC particles enhances the microhardness, ultimate tensile strength and wear resistance of the composite. The details of fracture morphology, worn surface and wear debris are also presented in this paper

Predicting the influence of process parameters on tensile strength of AA6061/TiC aluminum matrix composites produced using stir casting

Abstract: Stir casting is an economical method to produce aluminum matrix composites (AMCs). In this work, stir casting was used to produce AA6061/15wt. % TiC AMCs. An empirical relationship was developed to predict the effect of stir casting parameters on the ultimate tensile strength (UTS) of AA6061/TiC AMCs. A central composite rotatable design consisting of four factors and five levels was used to minimize the number of experiments i.e. castings. The factors considered were stirrer speed, stirring time, blade angle and casting temperature. The effect of those factors on the UTS of AA6061/TiC AMCs was derived using the developed empirical relationship and elucidated using microstructural characterization. Each factor significantly influenced the UTS. A higher or lower values of those factors resulted in poor tensile strength. The variation in the UTS was attributed to porosity content, cluster formation, segregation of TiC particles at the grain boundaries and 2 homogenous distribution in the aluminum matrix. The UTS was high when the porosity content was low and the distribution was homogenous. The present work concludes that a careful selection and control of stir casting parameters are necessary to reduce porosity content and obtain uniform distribution to improve the load bearing capacity of the AA6061/TiC AMCs

Commissioning of the electron injector for the AWAKE experiment

The advanced wakefield experiment (AWAKE) at CERN is the first proton beam-driven plasma wakefield acceleration experiment. The main goal of AWAKE RUN 1 was to demonstrate seeded self-modulation (SSM) of the proton beam and electron witness beam acceleration in the plasma wakefield. For the AWAKE experiment, a 10-meter-long Rubidium-vapor cell together with a high-power laser for ionization was used to generate the plasma. The plasma wakefield is driven by a 400 GeV/c proton beam extracted from the super proton synchrotron (SPS), which undergoes a seeded self-modulation process in the plasma. The electron witness beam used to probe the wakefields is generated from an S-band RF photo-cathode gun and then accelerated by a booster structure up to energies between 16 and 20 MeV. The first run of the AWAKE experiment revealed that the maximum energy gain after the plasma cell is 2 GeV, and the SSM mechanism of the proton beam was verified. In this paper, we will present the details of the AWAKE electron injector. A comparison of the measured electron beam parameters, such as beam size, energy, and normalized emittance, with the simulation results was performed

ANALYSIS OF PUBLIC AND PRIVATE - SECTORS PARTNERSHIP (PPP) IN HOUSING DELIVERY IN, NIGER STATE. NIGERIA

Abstract: One of the greatest challenge confronting both rural and urban residents in Niger State is the need to provide adequate shelter. This study examined the individual significant contribution of the public and private sector in public-private partnerships (PPP) in housing contracts in Niger State, Nigeria. The study review that PPP has so far achieved little success in providing decent and unaffordable housing accommodation to Nigerlites. Accordingly to Niger State housing corporation 2 bedrooms flat worth N3,500,000.00 and 3 bedrooms flat worth N4,500,000.00 so it’s clear that the houses are unaffordable to low and medium incomes earners. The researcher finding that the private sector in Niger State can be said to have contributed very little to the development of an urban project in the state, however, even this insignificant level of participation has been serious challenges by poor funding and lack of policy framework to regulate it activities. Therefore, it is paramount importance that the state should develop a regulatory framework and partner with the private sector in this regard so as to ensure that the resident of Niger State has access to this important component of the human environment. Researcher concluded that to ensure the effective participation of the private sector in housing delivery in Niger State in general and Minna in particular, the following recommendation has been put forward (1) Aside from providing enabling environment for the private sector to develop real estate, government should also invest more in provision of site and services scheme this will hasten the development of estate sector.  (2) The establishment a power federal mortgage bank (FMB) and  urban development bank would guarantee investors access to loan and other facilities needed for mass housing development.(3) strengthening the activities of the Niger State Ministry of land and housing in order to ensure that both the formal and informal neighborhood save provided with sanction and neighborhood facilities and (4) The establishment of a PPP steering committee in the Niger State that would be responsible for the general oversight of state’s PPP arrangement. (5) Finally, the study recommends that to ensure the success of public and private partnership in housing delivering, all tiers of government must strive to complement the weakness of the public sector with the strength of the private sector.

Temperature dependence of the interlayer magnetoresistance of quasi-one-dimensional Fermi liquids at the magic angles

The interlayer magnetoresistance of a quasi-one-dimensional Fermi liquid is considered for the case of a magnetic field that is rotated within the plane perpendicular to the most-conducting direction. Within semi-classical transport theory dips in the magnetoresistance occur at integer amgic angles only when the electronic dispersion parallel to the chains is nonlinear. If the field direction is fixed at one of the magic angles and the temperature is varied the resulting variation of the scattering rate can lead to a non-monotonic variation of the interlayer magnetoresistance with temperature. Although the model considered here gives a good description of some of the properties of the Bechgaard salts, (TMTSF)2PF6 for pressures less than 8kbar and (TMTSF)2ClO4 it gives a poor description of their properties when the field is parallel to the layers and of the intralayer transport.Comment: 10pages, RevTeX + epsf, 3 figure

Detection and phenotypic characterization of methicillin-resistant Staphylococcus aureus from clinical and community samples in Abakaliki, Ebonyi State, Nigeria

Objective: The objective of this study was to isolate and phenotypically characterize methicillin-resistant Staphylococcus aureus (MRSA)from clinical and community samples in Abakaliki, Nigeria.Methods: A total of 709 clinical (303) and community samples (406) samples were obtained for this study. MRSA isolates were detected using Kirby-Bauer disc diffusion method with the inclusion of 1 μg oxacillin and cefoxitin antibiotic disc. The isolates were screened for the β-lactamase production using nitrocefin sticks.Results: A total of 44 MRSA isolates were obtained from the samples with prevalence frequency of 22.6 % and 20.8 % from clinical and community samples respectively. The clinical isolates were completely resistant (100 %) to ceftazidime, tetracycline and penicillin. Gentamicin and ciprofloxacin were the most effective antibiotics against the clinical and community isolates respectively with a susceptibility frequency of 63.2 % and 80 %. Exactly 38.1 % and 24.2 % of the clinical and community S. aureus isolates were positive for beta-lactamase production respectively. The HA-MRSA and CA-MRSA isolates had MARI valueswithin the range of 0.3 to 1.0.Conclusion: This present findings of multi-drug resistance MRSA is very worrisome as it further highlights the pressing need to keep a strict watch on MRSA emerging from this study area.Keywords: MRSA, beta-lactamase, antibiotics, multidrug resistance, clinical samples, community samples

Mid-Infrared Spectroscopy of Uranus from the Spitzer Infrared Spectrometer: 2. Determination of the Mean Composition of the Upper Troposphere and Stratosphere

Mid-infrared spectral observations Uranus acquired with the Infrared Spectrometer (IRS) on the Spitzer Space Telescope are used to determine the abundances of C2H2, C2H6, CH3C2H, C4H2, CO2, and tentatively CH3 on Uranus at the time of the 2007 equinox. For vertically uniform eddy diffusion coefficients in the range 2200-2600 cm2 s-1, photochemical models that reproduce the observed methane emission also predict C2H6 profiles that compare well with emission in the 11.6-12.5 micron wavelength region, where the nu9 band of C2H6 is prominent. Our nominal model with a uniform eddy diffusion coefficient Kzz = 2430 cm2 sec-1 and a CH4 tropopause mole fraction of 1.6x10-5 provides a good fit to other hydrocarbon emission features, such as those of C2H2 and C4H2, but the model profile for CH3C2H must be scaled by a factor of 0.43, suggesting that improvements are needed in the chemical reaction mechanism for C3Hx species. The nominal model is consistent with a CH3D/CH4 ratio of 3.0+-0.2x10-4. From the best-fit scaling of these photochemical-model profiles, we derive column abundances above the 10-mbar level of 4.5+01.1/-0.8 x 10+19 molecule-cm-2 for CH4, 6.2 +- 1.0 x 10+16 molecule-cm-2 for C2H2 (with a value 24% higher from a different longitudinal sampling), 3.1 +- 0.3 x 10+16 molecule-cm-2 for C2H6, 8.6 +- 2.6 x 10+13 molecule-cm-2 for CH3C2H, 1.8 +- 0.3 x 10+13 molecule-cm-2 for C4H2, and 1.7 +- 0.4 x 10+13 molecule-cm-2 for CO2 on Uranus. Our results have implications with respect to the influx rate of exogenic oxygen species and the production rate of stratospheric hazes on Uranus, as well as the C4H2 vapor pressure over C4H2 ice at low temperatures