Bioerosion in the middle Eocene larger foraminifer Nummulites in the Fayum depression,Egypt

The present paper focuses for the first time on the trace fossils present in carbonate tests of the famous Egyptian middle Eocene larger foraminifer Nummulites gizehensis group. Bioerosion is represented by a unique diversified assemblage of seven ichnospecies belonging to four ichnogenera. Diagnostic drilling holes of the ichnogenus Oichnus are represented by the three ichnospecies O. simplex, O. paraboloides and O. asperus. Rare spiral galleries of Trypanites helicus and sinuous tunnels of Maeandropolydora sulcans were identified. Simple U-shaped borings of Caulostrepsis taeniola and Caulostrepsis isp. were also recognized within the studied nummulites. The reported drilling holes are attributed essentially to the predation of gastropods, whereas the other recognized galleries are assigned mainly to boring activities of the polychaete worms. Well-preserved tests with rare bioerosion and encrustation indicate deposition under a high rate of sedimentation and no prolonged transportation. Conversely, taphonomic characteristics of the bioeroded and encrusted nummulites can be used as good palaeoecological indictors of a deposition under low to fair rate of sedimentation. Coexistence of non-bioeroded and bioeroded/encrusted tests, common thick-bedded nummulite wackestone and packestone, predominated larger and flat Nummulites spp., and non-preferred imbrications are taken altogether with the reported ichnological assemblage to suggest that the nummulites were accumulated in situ and/or under weak influence of physical processes (storm and waves) in a shallow-marine environment, possibly middle to inner carbonate ramps.     

Comparison of Satellite Altimetric Gravity and Global Geopotential Models with Shipborne Gravity in the Red Sea

The determination of high-resolution geoid for marine regions requires the integration of gravity data provided by different sources, e.g. global geopotential models, satellite altimetry, and shipborne gravimetric observations. Shipborne gravity data, acquired over a long time, comprises the short-wavelengths gravitation signal. This paper aims to produce a consistent gravity field over the Red Sea region to be used for geoid modelling. Both, the leave-one-out cross-validation and Kriging prediction techniques were chosen to ensure that the observed shipborne gravity data are consistent as well as free of gross-errors. A confidence level equivalent to 95.4% was decided to filter the observed shipborne data, while the cross-validation algorithm was repeatedly applied until the standard deviation of the residuals between the observed and estimated values are less than 1.5 mGal, which led to the elimination of about 17.7% of the shipborne gravity dataset. A comparison between the shipborne gravity data with DTU13 and SSv23.1 satellite altimetry-derived gravity models is done and reported. The corresponding results revealed that altimetry models almost have identical data content when compared one another, where the DTU13 gave better results with a mean and standard deviation of ?2.40 and 8.71 mGal, respectively. A statistical comparison has been made between different global geopotential models (GGMs) and shipborne gravity data. The Spectral Enhancement Method was applied to overcome the existing spectral gap between the GGMs and shipborne gravity data. EGM2008 manifested the best results with differences characterised with a mean of 1.35 mGal and a standard deviation of 11.11 mGal. Finally, the least-squares collocation (LSC) was implemented to combine the shipborne gravity data with DTU13 in order to create a unique and consistent gravity field over the Red Sea with no data voids. The combined data were independently tested using a total number of 95 randomly chosen shipborne gravity stations. The comparison between the extracted shipborne gravity data and DTU13 altimetry anomalies before and after applying the LSC revealed that a significant improvement is procurable from the combined dataset, in which the mean and standard deviation of the differences dropped from ?3.60 and 9.31 mGal to ?0.39 and 2.04 mGal, respectively.     

Characterization of bioflocculants produced by bacteria isolated from crude petroleum oil

The aim of this study was to look for high efficient bioflocculant-producing microorganisms. Among 36 bacterial colonies isolated from a crude petroleum oil sample, three of them as Bacillus subtilis and Pseudomonas spp. exhibited flocculation activity exceeding 90 % after 3 days of cultivation. They were identified by 16 S rDNA sequence analysis as Bacillus subtilis and Pseudomonas sp. Spectroscopic analysis of the polymers by nuclear magnetic resonance and fourier-transform infrared revealed that the polymers were glycoproteins. These polymers were soluble in water and insoluble in any organic solvents tested. The effects of bioflocculant dosage, temperature and pH on the flocculation activity were evaluated. The maximum bioflocculation activities were observed at an optimum bioflocculant dosage of 3.5 mg/L (strains Bacillus subtilis and Pseudomonas) and 5.0 mg/L (strain CPO14), respectively. In addition, these biopolymers were able to flocculate kaolin suspension (5 g/L) over a wide range of pH (pH 3–9) and temperature (5–50 °C) tested in the presence of CaCl₂. The highest flocculation activities of strains CPO8, CPO13 and CPO14 were 96.03 %, 92.17 % and 97.59 %, respectively in the early stationary phase (at 24 h), while the cell production reached its maximum in the stationary phase (at 72 h). Their efficient flocculation capabilities suggest potential applications in industries.     

Improving the existing roadway tunnels capacity by adding new tunnels—a structural approach

The roadway tunnel is considered a good solution for the success of modern roadway networks. It can help to overcome possible traffic congestion and considerably reduce journey time. The continuous growth of traffic volumes leads to increase congestion and decrease safety. This leads to the need for extra tunnel space. The extra tunnel space can be achieved either by the widening of the existing tunnel or by adding a new one. The choice of the suitable method is dependent on many factors like tunnels alignment, site conditions, construction method, tunnel operation, risk assessment…etc. The current research investigates the second alternative through a specific case study as an example. The method comprises adding two new tunnels to an existing twin roadway tunnels. The investigated problem considers the new tunnels to be added vertically or horizontally. The influence of the new tunnel construction on the existing tunnels is investigated considering both the variation of relative position and spacing distance in a parametric study context. Several numerical models are employed to check the construction sequence and the tunnelling safety. These models are used to evaluate the induced stresses in surrounding ground for two different soil types, straining actions in tunnels’ liner and deformations of both ground and liner. The result demonstration shows how to find out the minimum practical and safe spacing distance between the driven new tunnels and the existing ones without the need for the relatively expensive soil strengthening techniques.     

Isolation and molecular characterization of some copper biosorped strains

The biosorption of copper (II) from aqueous solution using different bacterial strains was studied. Copper-biosorbing bacteria were isolated from tannery effluent collected from Borg Al-Arab, Alexandria, Egypt. These isolates displayed different degrees of copper biosorption under aerobic conditions. Based on 16S rDNA gene sequence analysis, three of them (S2, S5 and S7) were identified as Chryseobacterium sp., Enterobacter sp. and Stenotrophomonas sp., respectively. Initial copper (II) ion concentrations from 25–250 mg/L at constant temperature 30 °C were studied. The residual copper (II) concentration and its toxicity effect in solution were determined using atomic absorption spectrophotometer and bioluminescent bioreporter. The bioluminescence inhibition of strain (S5) reached to 91.4 % as compared with the strain (S7) reached to 83.3 % at 225 mg/L of copper ion where the maximum biosorption efficiency for S5 and S7 were 71 % and 70.1 % correspondingly using atomic absorption. The bioluminescent bioreporter was proved to be fast and accurate technique for measurement the toxicity effect of residual copper (II) in solution.     

Biosynthesis of biodegradable polyhydroxyalkanotes biopolymers in genetically modified yeasts

In the recent decade, biosynthesis of the degradable biopolymers polyhydroxyalkanotes in transgenic yeasts became an important research task. Most research strategies depend on either metabolic engineering or molecular approaches. In the present work, research compared PHA biosynthesis in two types of yeasts; Saccharomyces cerevisiae and a non-convenient Kloeckera spp. Yeast strains were equipped in their cytoplasm with the phaABC_Re operon containing genes phbA, phbB and phbC of the PHA biosynthetic pathway of Ralstonia eutropha, which encode β-ketothiolase, NADPH-linked acetoacetyl-CoA reductase and PHA synthase, respectively. The transgenic strains Saccharomyces cerevisiae and Kloeckera sp. were able to produce PHA. The maximum content of the polymer detected in the recombinant strain INVSc1/PHA1 was 2.68 % and only poly-3-hydroxybutyrate (PHB) accumulated. However, the non-conventional transgenic strain KY1/PHA was able to accumulate as maximum of 7.06 % of the copolymer poly-(3-hydroxybutyrate-co-poly-3-hydroxyvalerate) (PHV). Western blot analysis confirmed expression of the phaABC_Re operon in the transgenic yeast strains. The nature of the PHA thus produced by all tested strains was analyzed by ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy.     

Geometric Dependence of the Scalar Transfer Efficiency over Rough Surfaces

We performed a series of wind-tunnel experiments under neutral conditions in order to create a comprehensive database of scalar transfer coefficients for street surfaces using regular block arrays representing an urban environment. The objective is to clarify the geometric dependence of scalar transfer phenomena on rough surfaces. In addition, the datasets we have obtained are necessary to improve the modelling of scalar transfer used for computational simulations of urban environments; further, we can validate the results obtained by numerical simulations. We estimated the scalar transfer coefficients using the salinity method. The various configurations of the block arrays were designed to be similar to those used in a previous experiment to determine the total drag force acting on arrays. Our results are summarized as follows: first, the results for cubical arrays showed that the transfer coefficients for staggered and square layouts varied with the roughness packing density. The results for the staggered layout showed the possibility that the mixing effect of air can be enhanced for the mid-range values of the packing density. Secondly, the transfer coefficients for arrays with blocks of non-uniform heights were smaller than those for arrays with blocks of uniform height under conditions of low packing density; however, as the packing density increased, the opposite tendency was observed. Thirdly, the randomness of rotation angles of the blocks in the array led to increasing values of the transfer coefficients under sparse packing density conditions when compared with those for cubical arrays.