Parametric Identification Method for an Absorption Air Conditioning Parabolic Trough Collector Solar Plant

In this work is established a parametric identification method for an absorption air conditioning solar plant. A scaled thermal plant, consisting of a thermal capacitor and a flow line that acts as a capacitor and thermal energy radiator is used. As the mathematical model of the scaled plant is structurally identical to that of the solar plant the first is used to determine the methodology that can be used later for the identification of the PTC solar plant. Parametric identification is a necessary step that allows to determine the unknown parameters of the mathematical model of any solar/thermal plant. This model then can be used to analyze the plant characteristics and design an appropriate control algorithm. Although the system model is nonlinear it can be expressed in the form of a linear regressor in the parameters. This permits to use the least squares method as the identification method. The method is applied to the thermal plant to identify the useful form that the covariance matrix and excitation signals should have to ensure that when applied to the solar plant its unknown parameters can be properly estimated. Once the solar plant parameters are properly estimated model can be used to analyze and simulate the operation of the absorption air conditioning system.

BSA binding affinity, free radical scavenging capacity and antibacterial activity of new Silver(I) complexes with Schiff base ligands

In this work, four silver(I) complexes with Schiff bases derived from ninhydrin and selected amino acids (methionine, histidine, cysteine, and phenylalanine) were synthesized. The aim of this study is to determine the potential biological activity of these complexes. FTIR and UV/VIS spectroscopy were used for structural characterization of the products. Antioxidant activity was examined in vitro using DPPH method. Antimicrobial screening was performed by diffusion technique on reference bacterial strains from the ATCC collection. Interaction with bovine serum albumin (BSA) was examined using UV/VIS spectroscopy. Based on the obtained spectral data, it is assumed that all Schiff bases coordinate the Ag(I) ion as a tridentate ONO donor ligand. The antioxidant activity of the synthesized compounds is extremely high, with a range of IC50 values of 0.023-0.06 mg/mL. Antimicrobial screening determined the inhibitory ability of almost all complexes for concentrations of 1 and 2 mg/mL, with zones of inhibition in the range of 9-19 mm. Examination of the interaction of BSA with Ag(I) complexes revealed the same change in the absorption maximum (hyperchromic shift) in the region of about 205 nm, which indicates that the interaction of BSA and the complex results in conformational changes of BSA.

X-ray fluorescence spectrometric determination of heavy metals in selected rice samples sold on the Liberian market: a case study conducted in Paynesville City, Greater Monrovia

Background: Environmental pollution with toxic heavy metals can be lead to the possible contamination of rice. Rice is a staple food widely consumed in the urban and rural parts of Liberia daily. Rice is cultivated in approximately 113 countries and a fundamental source for energy and protein. Objective: The study assesses selected heavy metals (As, Pb, Cd, Se, and Cr) concentration in selected imported rice and traditionally grown rice and bulgur wheat in Liberia. Methods: Six grade of imported rice, Bulgar wheat, and traditionally grown rice were purchased from the Duport Road and Red-Light markets in Greater Monrovia and analyze using X-ray Fluorescence Spectrometer. All data were analyzed using XLSTAT, and data was used to calculate the risk factor of each rice sample. Results: The mean concentration of heavy metal found in the rice as follow: As, 1.31ppm; Cd, 9.42ppm; Cr. 12.3ppm; Se, 5.73ppm; and Pb, 1.75ppm. The estimated daily intakes (EDIs) were calculated in combination with the rice consumption data. The mean intakes of As, Cd, Cr, Se, and Pb through rice were estimated to be 1.32, 9.42. 12.4. 5.74, and 1.75 mg/kg BW/day. Chromium has the average estimated daily intake. The combined hazard index for the heavy metals in each sample and the total cancer risk for each sample contributed most significantly to a cancer risk of rice consumption during adult life expectancy.Conclusion: The selected heavy metal concentration from the rice sample was above the FAO/WHO reference Standard but was within the range of the contaminant level except for chromium, which is above the accepted range. However, the hazard index and the total cancer risk indicate a potential non-carcinogenic and carcinogenic risk.

Studies on diarrhea prevalence in selected communities in greater Monrovia, Liberia

Diarrhea is an epidemic that threatens the livelihood of children less than five years in developing countries. Control and mitigation pose a severe challenge in these countries. The subjective of the study is to assess the prevalence of and factors associated with diarrhea among families in Greater Monrovia. The study recruited 257 families from three communities and geographically and randomly assigned to the two groups (A & B). Socio-demographic survey and knowledge and behavior questionnaires on diarrhea prevalence were used to collect data. Reports from the study indicate that family in Group A (93%) and Group B (83.6%) have significant knowledge associating contaminated drinking water and contaminated food with diarrhea; X2 =11.2, p = 0.001. The family behavior shows that Group A (33%) and Group B (51%) do not treat their drinking water before consumption. The findings from this study recommend an education and awareness intervention on diarrheal and related illnesses to increase family knowledge and improvement of the behavior community public health improvement process.

CONTRIBUTION TO THE IMPROVEMENT OF BITUMINOUS ENROBES: APPLICATION TO THE DEVELOPMENT WORKS OF THE YAOUNDE-DOUALA MOTORWAY IN CAMEROON

The frequent closure of roads for the sake of maintenance and refurbishment is an increasing problem for the road administrators and users, because of induced high costs, restrictions and influence they impose, traffic jam, and the many other disruptions such interventions have on traffic. In these circumstances, carriageways with long life span, with adapted tar, have much to offer, especially if they can exhibit optimum performances without requiring major repairs for over 30 years. On high traffic roads, research have shown that binders with elevated modules are a reliable and credible alternative to render their life span more sustainable and durable. In this context, the advantages presented by the absence of important repairs and refurbishing can be enough to justify the initial high costs of these advanced carriage way coatings. Studies on the different binders to be used were done, which have permitted in accordance with the performance of the layers, the required tests and the different study levels. Also, this has permitted us to analyze the obtained results and conclude that due to the expected needs, the LA and MDE tests, the PSV tests are the criteria that determine the selection of aggregates; The complexes modular methods, fatigue resistance (level IV), seem to be necessary for the forecasting of the mechanical behavior of bituminous materials.

Assessment of Perceived Service Quality Using SERVQUAL Mod-el: A case study of Pakistan International Airline (PIA) In-Flight Hospitality

Service industry is rapidly growing worldwide with latest and sophisticated tools and strategies for satisfaction of their ultimate customers. Provision of an exceptional service is the lifeblood of airline survival, with the airline’s mid-flight operations being the most crucial fragment of the whole service encounter. This study hence quantifies and weighs the perceived service quality against the desired service quality expected by the customers of Pakistan International Airlines in their in-flight operations, through the 5 main dimensions of SERVQUAL exemplified by the 30 service attributes. The main objective of this study is to find out gap between perceived service quality and expected service quality.This research is quantitative in nature, Factor Analysis and one sample T-Test were used for analysis of data and close-ended questionnaires were used to collect the data from sample of 120 passengers who travelled through PIA at least once is last 12 months. According to the results shown by the Factor Analysis, 8 components were retained or extracted out of 30 variables; all the variables have high correlation with components as overall correlation measured by Factor Analysis is 0.804 which is excellent in the practice. According to KMO and Bartlett’s test, the sampling accuracy remained .857 which is quite good measurement. In addition to that, one sample T- test shows that variable Assurance scores 2.88 average mean perception out of 3.0 average mean expectation touches the expectations but not up to desire level of quality. However, other variables like responsiveness, Empathy, Reliability and Tangibility score 2.78, 2.67, 2.67, and 2.64 respectively.Average Mean Difference Gap (P-E) shows variable Assurance reveals low level of gap -0.12. However, this does not fill the quality gap of minimum 3.0 of Average Mean Expectation. This study exhibits tremendous service gap in other variables as Responsiveness -0.22, Empathy -0.33, Reliability -0.33 and Tangibility possesses -0.35 in terms of Average Mean Difference Gap.The necessity of this research study was deeply felt as a thin of number of passengers prefers PIA services. The service quality of PIA is diminishing with poor service strategies, insufficient facilities and lack of inflight hospitality measures for passengers; therefore, this research will help the key decision makers to identify the areas to improve, and take necessary remedial actions

Investigation of the relationship of the morphometric measurements of the hands and fingers with the personality traits of leadership

Background: The hand is a functionally critical organ at the distal end of the upper extremity. Also, the creases in the hands and the digital flexion creases on the fingers are the important external anatomical landmarks.Objectives: There are no studies found in the literature, linking solely the leadership personality traits with the anthropometric measurements of the hand.Methods: This descriptive study was to investigate the relationship between the 44 anthropometric measurements about hand, and the leadership personality traits in young adults from both genders.Results: When the leadership frames were compared by the scores, human resource leadership scores were significantly higher in the females. The charismatic leadership frame scores positively correlated with the parameters in males; including the breadth of the right hand, the breadth of the left hand, the index finger length of the left hand, and the distal phalanx length of the index finger on the left hand. The transformational leadership score was positively correlated with the left hand width and with the distal phalanx of the index finger on the left hand. In females, it was found out that the frames of human leadership and charismatic leadership correlated negatively with the length of the right thumb.Conclusions: According to the results of our study, we concluded that the breadth of the hand and the measurements of the thumb and the index fingers can provide opinion on leadership personality traits.

Naphthoquinone impairs reproductive functions in plasmodium berghei berghei-infected male swiss mice

Background: Various antimalarial drugs adversely affect male reproductive functions. Naphtoquinones, a class of antimalarial drugs have been shown to effectively combat malaria parasites. However, the effects of naphtoquinone on reproductive functions remain elusive. The study determined the effects of naphthoquinone on reproductive functions of Plasmodium berghei berghei-infected male Swiss miceMethods: Thirty male Swiss mice were divided into 6 groups (n = 5) namely; Control, 1 mg/kg naphthoquinone, 2 mg/kg naphthoquinone, Plasmodium berghei berghei (Pbb)-infected, Pbb-infected+1 mg/kg naphthoquinone and Pbb-infected+2 mg/kg naphthoquinone. Parasitaemia was confirmed by microscopy. Naphthoquinone (i.p.) was administered for seven days following confirmation of parasitaemia. Thereafter, they were sacrificed. Serum levels of FSH, LH, testosterone and cortisol were assayed via ELISA. Sperm characteristics were evaluated by microscopy. Data were expressed as mean ± SEM and analysed using ANOVA at p<0.05.Results: Sperm motility reduced in the Pbb-infected compared with control. Sperm viability, motility and count reduced in naphthoquinone only groups and Pbb-infected+naphthoquinone groups compared with the control. Naphthoquinone groups and Pbb-infected alone decreased in LH and testosterone concentrations compared with the control.Conclusion: Naphthoquinone treatment impaired reproductive functions in Plasmodium berghei berghei-infected male Swiss mice.

Entomophagy in traditional healthcare practiced by indigenous communities: potential, implications and constraints

Several insect species including termites, honey bees, American cockroach, grasshoppers, stink bugs, aquatic bugs, silkworms and mopane caterpillars are popularly consumed by indigenous and tribal communities in South America, sub-Saharan Africa, South-east Asia and the Pacific. Different life stages of the insects were found effective in therapeutic treatment against health disorders and life-threatening diseases. In entomophagy (process of insect eating), allergy, content of anti-nutrients, contamination of micro-organisms, chemicals and biochemical compounds, and parasitic infection are major constraints for wide adoption of entomophagy. An urgent attention of policymakers, people’s organizations and researchers is therefore needed. This review is focused on worldwide utilization of selected edible insects for therapeutic treatment wherever modern medical facilities are not readily available or indigenous people prefer traditional healers. Certain practical safety measures against anticipated health risk are also elaborated.

Optimization conditions of alkaline protease production by Streptomyces sp.H1 isolated from red sea coastal region in submerged culture

A potent alkaline protease producing strain characterized and identified as Streptomyces sp. H1 was isolated from soil around red sea shore. The enzyme was produced extracellulary in submerged culture revealed maximum level during early stationary phase. Alkaline protease showed the highest activity at incubation time, pH and inoculum size of 3 days, 9 and 8% respectively. Among different carbon sources beet molasses gave a maximum production followed by starch, sucrose and fructose. High yield of protease production was noticed with casein followed by peptone, yeast extract and ammonium sulphate. Furthermore, it was optimized with 7g/l NaCl resulted in higher level of protease. Optimization of the process parameters resulted in about 3.4 fold increase in the alkaline protease. Partial purification of the crude enzyme was achieved by fractional precipitation using ammonium sulfate at 50% saturation. Due to the maximum production of protease in the presence of cheaper substrate as beet molasses, stability at alkaline pH 9 and temperature up to 70 oC besides salt tolerance make the strain and its enzyme useful in different industrial applications.