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Fabrication of Nanocomposite Scaffolds Including Metal Nanoparticles for Tissue Engineering Applications
Get PDFThis study presents the findings of a research on fabricating composite nanofibrous mats including silver and copper nanoparticles for tissue engineering applications. For this purpose, two different types of silver nanoparticles (soluble starch capped silver nanoparticles, sodium alginate capped silver nanoparticles) and two different types of copper nanoparticles (soluble starch capped copper nanoparticles, sodium alginate capped copper nanoparticles) were successfully incorporated into polyvinyl alcohol (PVA) fibers through electrospinning process. Characterization studies with x-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR), inductively coupled plasma spectrometer (ICP) were conducted to determine physical and structural properties of the obtained nanofiber mats. According to SEM analysis it was observed that interconnected and randomly-oriented nanofibers were successfully generated. Additionally, XRD and FTIR studies proved the existence of silver nanoparticles and hydroxapatite on the nanofiber mats immersed in simulated body fluid (SBF) for 7 days. The results indicated that long term silver ion release was achieved. Overall results showed that these nanofibrous mats can be good candidates as multifunctional scaffolds for tissue engineering applications
Synthesis and Surface Activities of a Silicone Based Ester Quaternary Amine and Optimization of Synthesis Conditions by Response Surface Method
Get PDF A novel silicone based ester quaternary ammonium salt (Si-QAS) was synthesized by conjugation of γ-chloropropyl methyl dimethoxysilane and distearic ester of methyldiethanolamine. The chemical structure of the Si-QAS was characterized by using FTIR and 1H NMR. Physicochemical properties of the compound were further investigated and the results showed that the critical micelle concentration of the esterquat was 2.36×10-4 mol.L-1, the corresponding surface tension γCMC was 24.25 mN.m-1, and the standard Gibbs free energy of formation for micellization and adsorption were -30.64 kJ.mol-1 and -56.87 kJ.mol-1, respectively. A mathematical model based on the method of response surface was also established to optimize the conditions of the synthesis process. Microwave power was found to have the strongest effect on synthesis progress and the optimal synthesis conditions were microwave power at 600 W for 20.89 min with a solvent amount of 9.24 g
Sustainability Risks of Coastal Cities from Climate Change
Get PDF Issues influencing the sustainability of coastal cities are assessed, reflecting the combination of impending sea level rise and storm surges, and increasing growth in populations in coastal cities. Geologic-time scales are utilized to draw parallels to characterize relevant historical occurrences that help to understand the context of projections of impending sea level rise issue to year 2100. Given that Antarctica holds sufficient water to raise global sea levels by 58 m if the ice were to melt, this indicates that even a small percentage of melting of the polar ice caps, should this occur, will have enormous implications to the sustainability of coastal cities which are projected to hold 12.4 percent of the world’s population by 2060. The result is the combination of predicted sea level rise and associated storm surges indicate that drastic measures must be promoted to improve the sustainability of coastal cities
On Traces of n-Additive Mappings on Semiprime Ring
Get PDF Let R be a ring with centre Z(R). In this paper we prove that a nonzero Lie ideal L of a semiprime ring R of characteristic different from (2n-2) is central if it satisfies one of the following: (i)f(xy)∓[x,y]∈Z(R), (ii)f(xy)∓[y,x]∈Z(R), (iii)f(xy)∓xy∈Z(R), (iv)f(xy)∓yx∈Z(R), (v)f([x,y] )∓[x,y]∈Z(R), (vi)f([x,y] )∓[y,x]∈Z(R), (vii)f([x,y] )∓xy∈Z(R),(viii)f([x,y] )∓yx∈Z(R),(ix)f(xy)∓f(x)∓[x,y]∈Z(R),(x)f(xy)∓f(y)∓[x,y]∈Z(R),(xi)f([x,y] )∓f(x)∓[y,x] ∈ Z(R), (xii)f([x,y] )∓f(x)∓[y,x]∈Z(R), (xiii)f([x,y] )∓f(y)∓[x,y]∈Z(R), (xiv)f([x,y] )∓f(y)∓[y,x]∈Z(R), (xv)f([x,y] )∓f(xy)∓[x,y]∈Z(R), (xvi)f([x,y] )∓f(xy)∓[y,x]∈Z(R), (xvii)f(x)f(y)∓[x,y]∈Z(R), (xviii)f(x)f(y)∓[y,x]∈Z(R), (xix)f(x)f(y)∓xy∈Z(R), (xx)f(x)f(y)∓yx∈Z(R) for all x,y∈L, where f stands for the trace of an n-additive ma
Quantification of Condensed Tannins in Sainfoin Powder (Onobrychisviciifolia) by FT-NIR Spectroscopy
Get PDF Models based on FT-NIR spectroscopy and PLS-regressions were developed over three harvest years to determine the condensed tannins contents (CT, %(w/w)) in sainfoin powders. The three data sets corresponding to the three harvest years were used as calibration and then validation sets, successively. Finally, a global model gathering all the three years data sets has been developed. The developed models predict CT in a range of 2.06 to 11.28 %(w/w). The accuracy of the models depended on the range of CT-values of the calibration and validation sets. Finally, it was possible to predict the CT with a SEP-value lower than 0.5% (w/w) and R2-value higher than 0.9. In the present study, some of the PLS-parameters such as bias, slope and SEP have been statistically evaluated using the international standard ISO 12099:2017. The final global model was very promising since bias was not significantly different from 0, the slope was not significantly different from 1, and obtained SEP was 0.49% (w/w) while the calculated SEP-limit was 0.47% (w/w). The presently developed model was robust over the three years and the global model presented very interesting values. Such approach would be very useful to develop a new quantitative, rapid and low cost method to assess the CT of sainfoin powders. This method will allow us to free ourselves from the traditional chemical method that consumes time, money and chemicals
Transforming Sub-Saharan Africa’s Agriculture through Agribusiness Innovation
Get PDFAgribusiness offers promising opportunities to accelerate Africa’s agricultural sector development, increase food security, address poverty, youth employment and drive agriculture-led economic growth. This desk research offers a snapshot of the agribusiness activities in Africa with emphasis on the contribution of higher education institutions that are members of the Regional Universities Forum for Capacity Building in Agriculture (RUFORUM) and selected public universities in Ghana. Our review shows that agribusiness yet in its infancy is gaining traction and longer-term prospects are promising based on initial success and encouraging outcomes in some countries. Various initiatives are taking place in the region, including agribusiness incubation; capacity building, education, and agribusiness knowledge transfer programs at different levels. Partnerships among stakeholders such as government, international groups and private sectors are also growing to boost and encourage better value chain management for agriculture across the African continent. A few RUFORUM university members are setting up the pace in terms of investments to nurture agricultural entrepreneurs through curriculum enhancement; intellectual property and technology transfer policies, and technology commercialization models for conventional and modern technologies through business incubation parks and spin-off companies. Some of the successes and milestones in agribusiness development have yet to happen in many RUFORUM members and in public universities in Ghana. Drawing upon published reports, scholarly articles, and our primary analysis, we highlight several key actions and recommendations that can inform policy and practice to expand and sustain the growth trajectory of agribusiness as a new developmental platform for Afric
Development of Innovative Coating Methods for Metal Based Roof
Get PDF Metal panels are one of the most common roofs covering in Malaysian buildings. Nevertheless, the commercial metal roof is generally known as not being effective enough in reflecting sunlight and emitting thermal energy. Hence, innovative coating solutions were developed and analysed in terms of their thermal performance. Seashells and woodchips were used as the raw materials to develop the innovative coating. Thermocouple modules were integrated with Arduino to measure the surface temperatures of 3 roof prototype, Prototype A (commercial metal panel), Prototype B (with woodchips coating) and Prototype C (with seashells coating). Their temperature profiles were investigated, and their thermal performance was analysed, and from that, the overall heat transfer coefficient (U value) was calculated. It was found that temperature for Prototype C was the lowest in the range of 32 to 50ºC, while Prototype A were in the range of 32 to 60ºC, and there is no significant difference between prototype A and B. In addition, temperature difference for Prototype C are always in positive values, reaching as high as 6ºC in the afternoon. The other 2 prototypes fluctuated between the range of - 4ºC and 4ºC. These results were proved with the U-values calculated in which UA was 217 W/m2K, UB was 44 W/m2K and UC is 69.6 W/m2K. However, UB contradicts with the temperature profile results. Overall, Prototype C, with seashells coating shows promising results as material of innovative roof based coating
Reducing the Cooling Energy of Existing Commercial Buildings with Passive Thermal Mass
Get PDFA major part of sustainability theory and practice is to reuse existing building stock wherever possible and to refrain from demolition and rebuilding minimising the resources and associated energy used. Many buildings therefore have internal refurbishments during their lives, the scale of which can range from minor fit outs through major interior refurbishments to finally those which see the central services replaced also. The ability to greatly improve the efficiency of a building during only minor refurbishment is an attractive proposal which would provide an intermediate opportunity to building owners to reduce cooling energy and its associated cost and more importantly avoid disruption to the base building services. This study investigates the effect of exploiting inherent building thermal mass in a standard commercial building in the Australian cities of Adelaide and Brisbane, and demonstrates the energy savings that can be made in the order of 30%
Photothermoelectric Detection of Phase Transitions in Liquid Thermoelectrics
Get PDF The recently introduced photothermoelectric technique (PTE) was applied to detect first order phase transitions in some liquid thermoelectrics (LTE). The investigated samples were based on dodecanol mixed with tetradodecylammonium nitrate (TDAN) and tetrabutylammonium nitrate (TBAN). It was demonstrated that the Seebeck effect, produced by a LTE, is an useful tool for the detection of phase transitions in the very same material. Additional photopyroelectric (PPE) measurements suported the obtained results
Cement Stabilization/Solidification of Heavy Metal-Contaminated Sediments Aided by Coal Fly Ash
Get PDFDischarge of various wastewater containing heavy metals from metallurgical, chemical engineering industries, etc. into water body results in the accumulation of heavy metals in sediments of rivers and lakes, and further severe sediment contamination. When the severely contaminated sediments are dredged, they must be handled before disposal. In this paper, the dredged sediments were stabilized/solidified with cement aided by coal fly ash. The compressive strength of stabilization/solidification specimens decreased with the increase of sediment/binder ratio. All specimens showed a satisfactory compressive strength except that the compressive strength of the specimen with the high sediment/binder ration of 3.33 was lower than 0.35 MPa, the requirement of US EPA. Coal fly ash effectively acted as the binder, but the excessive addition of coal fly ash resulted in the reduction of specimen compressive strength. The pH of TCLP leachates for the specimens, which met the requirement of the compressive strength, was distributed between 11.07 and 12.50, and the heavy metal concentration of the TCLP leachates was lower than 0.029 mg/L. A similar trend of acid neutralization capacity of the stabilization/solidification specimens was observed as that of the compressive strength. Curing in a hermetically sealed plastic bag at ambient temperature and a longer curing period improved the stabilization/solidification effect. Humidity and temperature played an important role during curing period. Under an aggressive condition with a fixed leachate pH of 4, the stabilization/solidification technology increased the heavy metals fixed to 88.47%, 93.30% and 87.71% for zinc, lead and cadmium, respectively, and the concentration of zinc, lead and cadmium in the leachates was lower than the limits of the identification standards for hazardous wastes-identification for extraction toxicity (GB 5085.3-2007). So cement stabilization/solidification aided by coal fly ash can be an alternative disposal technology for dredged sediments contaminated by heavy metals