Effects of Na2Cr2O7 Inhibitor on the Corrosion Potential Response of Steel Reinforced Concrete in Saline Medium

Electrochemical monitoring method of the open circuit potential was used to investigate the effect of the concentrations of Na2Cr2O7 on the corrosion potential response of steel reinforced concrete in sodium chloride medium. In the study, five different concentrations of Na2Cr2O7 admixtures were employed in a system of replicated samples of steel-reinforced concrete specimens partially immersed in 3.5% NaCl to simulate marine and saline environments. Forty days measured responses from these were subjected to the statistical analyses of the Normal and the Weibull distribution functions and tested using the Kolmogorov-Smirnov goodness of fit criteria. Results obtained from the analyses identified 4 g Na2Cr2O7 with optimal averaged potential response inhibition performance by the Normal model which showed better agreements in its models of Na2Cr2O7 potential test data than that obtained from the Weibull model of the same data. These bear pertinent implications on the need for suitability studies of appropriate statistical distribution for studying performance of corrosion inhibitors even as suggestions were proffered for addressing results conflicts among replicates of steel reinforced concrete samples employed

Fan blade protection system

In one type of aircraft propulsion system, propeller blades are mounted on a ring which surrounds a turbine. An annular space exists between the turbine and the ring. If a propeller blade should break free, the unbalanced centrifugal load tends to deform the ring. The invention reduces the deformation, as by locating spacers between the turbine and the ring

The Role of Prior Sales Experience of Buyers and Duration in Buyer-Seller Relationships

This paper examines the impact that a buyer’s prior sales experience and the duration of the buyer-salesperson relationship has on the satisfaction and commitment linkages established within the literature. First, two key facets of satisfaction (social and economic) are linked to buyer’s commitment to the salesperson. Next, buyer-salesperson relationship duration is examined as an influencer between the satisfaction and commitment linkages. Following this, the study shifts its focus to examine if and how buyers with prior sales experience view the buyer-salesperson relationship different than buyers without prior sales experience. Findings of the study highlight the importance of developing our understanding of buyer-salesperson relationships with regards to multi-faceted satisfaction, buyer background, and relationship length

Pollen dimorphism and dioecy in Vitis aestivalis

Problems of low production and sterile pollen in varieties of Vitis vinifera may be tracable to their ancestral relations with dioecious wild grapes.Like V. riparia, the wild summer grape V. aestivalis has dimorphic male and female flowers; but unlike V. riparia it also has dimorphic pollen grains with the pollen from the female flower being significantly smaller.It seems fairly certain that V. aestivalis is truly dioecious

Effect of Coarse Aggregate Size and Gradation on Workability and Compressive Strength of Plain Concrete

In this study effect of coarse aggregate size and gradation on workability and compressive strength of concrete was investigated. A mix ratio of 1:2:4 with a target strength of 20/25MPa, was adopted with a water-cement ratio of 0.6. Concrete cubes were produced with uniform coarse aggregate size of 4.75, 6.7, 9.5, 13.2 and 19mm respectively, with another set of samples produced with all the coarse aggregate sizes. Slump tests were carried out for all mixes and all sets of samples were tested for compressive strength after, 7, 14 and 28 days of curing. It was observed that workability was similar for all mixes with no well-defined pattern of relationship with size of coarse aggregate used. Compressive strength was observed to increase with increase in coarse aggregate size. Authors attributed this to the less quantity of water absorbed by larger size coarse aggregate during mixing which results in lesser quantity of capillary pores after curing. Maximum compressive strength was recorded for samples with 9.5mm coarse aggregate size. These show that quality concrete can still be produced with single-sized coarse aggregate as long as the optimum size can be determined for the particular mix.&nbsp

The integrability of Lie-invariant geometric objects generated by ideals in the Grassmann algebra

We investigate closed ideals in the Grassmann algebra serving as bases of Lie-invariant geometric objects studied before by E. Cartan. Especially, the E. Cartan theory is enlarged for Lax integrable nonlinear dynamical systems to be treated in the frame work of the Wahlquist Estabrook prolongation structures on jet-manifolds and Cartan-Ehresmann connection theory on fibered spaces. General structure of integrable one-forms augmenting the two-forms associated with a closed ideal in the Grassmann algebra is studied in great detail. An effective Maurer-Cartan one-forms construction is suggested that is very useful for applications. As an example of application the developed Lie-invariant geometric object theory for the Burgers nonlinear dynamical system is considered having given rise to finding an explicit form of the associated Lax type representation

A decade study of the incidence and clinical analysis of ectopic pregnancy at a tertiary hospital in Eastern Nigeria

Background: Ectopic pregnancy (EP), a condition where a fertilized egg grows outside a woman’s uterus, is a fertility- and life-threatening gynecological condition. This study aimed at determining the incidence of EP, clinical presentation, gestational age at presentation, risk factors and treatment modalities.Methods: This study was conducted at St. Charles Borromeo specialist hospital, Onitsha, Nigeria (January 2009 to December 2018). Information were obtained from the hospital’s medical records as retrieved from various wards. Data were analyzed using IBM SPSS, version 23, then presented as percentage in tables and figure.Results: Out of 13,402 pregnancies recorded in this study, 119 were EPs giving an incidence of 0.89%. 105 case notes were included in this study since they met the inclusion criteria. Majority of the women belonged to the age group of 26-30 years. Patients with EP presented more between 7-8 weeks of gestational age (40%), though 7.6% were unsure of their last menstrual period. 80 EP cases (76.2%) were ruptured while 25 (23.8%) were unruptured. The ectopic gestation occurred most at the ampulla (51.4%) and more at the right side (66.6%) than the left (33.4%). Pelvic inflammatory disease (30.4%) followed by prior abortion (20.0%) were major predisposing risk factors. The most common clinical presentations were abdominal pain (92.38%), amenorrhea (57.14%) and vaginal bleeding (51.42%). 85.7% had salpingectomy, 9.5% were medically managed.Conclusions: EP remains a major gynecological emergency. Diagnosis before rupture could offer an opportunity for a successful medical management, thereby; minimizing morbidity and mortality