From rose petal to bone scaffolds: Using nature to fabricate osteon-like scaffolds for bone tissue engineering applications

In this study, rose petal was used to fabricate osteon-like scaffolds for bone tissue engineering applications. Rose petal was coupled with nanocrystalline forsterite colloid to mimic the lamellar structure of porous osteons. The microstructures on the surface of the petals were utilized as template for pores and lacuna spaces which are suitable for cell attachment. On the other hand, rolling the petals allowed us to form the osteon structure with haversian canal and lacuna spaces on the body of the samples. After trying different temperatures, the results showed that samples annealed at 1100 °C closely mimicked the lacuna spaces, haversian canal, and lamellar structures of osteons. These scaffolds had the pore diameter in the range of about 13–20 μm and presented good bioactivity and biocompatibility. It was found that red rose petal is a good candidate to be used as a template for designing scaffolds for bone tissue engineering applications.     

Thermodynamic and Electrochemical Investigations of Poly(Methyl Methacrylate–Maleic Anhydride) as Corrosion Inhibitors for Mild Steel in 0.5 M HCl

Protection of Metals and Physical Chemistry of Surfaces - In this research, poly(methyl methacrylate-maleic anhydride)P(MMA-MAH)s with different percentages methyl methacrylate and maleic anhydride...     

Energy Efficient Reservation-Based Cluster Head Selection in WSNs

Due to the type of applications, wireless sensor nodes must always be inexpensive and small. Hence, the presence of constraints such as the limitation of energy resource is inevitable. So far, several studies have been carried out in order to present solutions for the reduction of energy consumption. In the meantime, clustering is given prime significance as an efficient method, which means partitioning network into distinct areas and is a way for managing nodes communication. In clustering algorithms, although the continuous execution of clustering phase and dynamic cluster head selection lead to energy consumption parity, they cause considerable energy dissipation due to the need for message transmitting to set new clusters and cluster heads. In this paper, the effect of using reservation to reduce message transmitting and energy dissipation has been studied. Reservation is the mechanism by the aid of which the number of communicated messages for the regular execution of clustering phase and cluster head selection can be reduced. The results of analysis and simulation show that the proposed method has significant impact on energy dissipation reduction.     

Measuring chemical emissions from wet products--development of a new measurement technique

A new approach for estimating chemical emissions from wet products has been developed. The concept of such approach is that emission rates can be estimated from the amount of target chemicals in the product as a function of evaporation time. Samples were placed under a laboratory fume hood under controlled conditions (surface air velocity and temperature). Weight losses of the product were monitored and residuals at different time intervals were chemically analyzed. Emission factors of the target chemicals were then calculated based on the weight losses and residual levels of the chemicals. To demonstrate the applicability of this approach, two wet products with very different physical characteristics, one liquid and one paste-like viscous fluid, were chosen. Emissions of two principle chemicals in the products, decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) were measured. The influences of initial sample weight, surface air velocity, and temperature were investigated. The calculated emission profiles were compared with those obtained from the chamber method. The described approach could be used as an alternative screening method for emission tests of wet products, especially for compounds with low vapour pressure when sink effect poses serious challenge in traditional chamber-based emission tests.     

Flexibility in service parts supply chain: a study on emergency resupply in aviation MRO

Recent trends in the commercial aviation industry have resulted in rapidly increasing complexity and decentralisation in service parts logistics systems. As a consequence, MRO service providers tend to adopt more flexible strategies, such as service parts sourcing and demand fulfilment for customers with different service-level requirements. The MRO service providers often enter into cooperative agreements with other service providers to pool inventories, enabling them to increase their flexibility in delivering services to multiple airlines with different contractual terms. Although using cooperative strategies, such as emergency resupply, is useful to increase flexibility, the inherent complexity of optimal mechanism is a critical issue that needs to be further investigated. To this aim, we consider a repairable service parts inventory system with multi-customer classes and develop an optimal emergency resupply policy. Following this, to overcome the intractability issue of finding the optimal policy, an efficient approximation method is proposed. Numerical results indicate that the proposed approximation method is highly accurate, and leads to a significant costs reduction. This paper sheds light on the effectiveness of emergency resupply policy that improves MRO service providers’ flexibility and enables them to ensure responsive service parts inventory.     

An inventory model for imperfect items under inflationary conditions with considering inspection errors

This paper represents a discounted cash-flow approach for an inventory model for imperfect items under inflationary conditions with considering inspection errors. The previous imperfect quality inventory studies, however, have mostly had the emphasis on developing cost-minimizing models that do not consider imperfect inspection processes and related defect sales return issues despite their practical significance. In this paper, we assume that some produced items might not be perfect and the first stage inspector of product quality control might make some inspection errors during the separation of defective and perfect items. Thus, this study proposes a profit maximizing inventory model with incorporating both imperfect production quality and two-way imperfect inspection, i.e., Type-one inspection error of falsely screening out a proportion of no defects and disposing of them like defects and Type-two inspection error of falsely not screening out a proportion of defects, thereby passing them on to customers, resulting in defect sales returns. In addition, this model includes one more stage of inspection that is after the rework process and there is no inspection error in this stage. The purpose of this model is to determine the important factors of an inventory system to optimize the present value of the total profit in the finite time horizon. Finally, a numerical example is provided to solve the presented inventory model using our proposed innovative approach, which is further clarified through a sensitivity analysis.     

Performance evaluation of UV reactor using optical diagnostic techniques

Conventionally, the performance of a UV reactor is evaluated using the concentration of photoreactive chemicals at the outlet vs. the inlet. This research presents a novel method for measuring the concentration distribution of a photoreactive chemical inside a photoreactor using a modified planar laser‐induced fluorescence method. The fluence distribution was measured for a pilot scale photoreactor under different operating conditions. The visualized result of the fluence distribution revealed significant information about the local/overall performance of the photoreactor. This method is a powerful diagnostic tool for the determination of the local performance inside a UV reactor, as well as for the evaluation of models simulating UV reactor behavior. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

A systematic procedure to study the influence of occupant behavior on building energy consumption

Efforts have been devoted to the identification of the impacts of occupant behavior on building energy consumption. Various factors influence building energy consumption at the same time, leading to the lack of precision when identifying the individual effects of occupant behavior. This paper reports the development of a new methodology for examining the influences of occupant behavior on building energy consumption; the method is based on a basic data mining technique (cluster analysis). To deal with data inconsistencies, min-max normalization is performed as a data preprocessing step before clustering. Grey relational grades, a measure of relevancy between two factors, are used as weighted coefficients of different attributes in cluster analysis. To demonstrate the applicability of the proposed method, the method was applied to a set of residential buildings’ measurement data. The results show that the method facilitates the evaluation of building energy-saving potential by improving the behavior of building occupants, and provides multifaceted insights into building energy end-use patterns associated with the occupant behavior. The results obtained could help prioritize efforts at modification of occupant behavior in order to reduce building energy consumption, and help improve modeling of occupant behavior in numerical simulation.     

Impact of non-uniform urban surface temperature on pollution dispersion in urban areas

Airflow pattern through street canyons has been widely studied to understand the nature of pollution dispersion in order to develop guidelines for urban planners. One of the major contributing parameters in pollution dispersion is thermal-induced flow caused by surface and air temperature difference. However, most of the previous studies assumed isothermal condition for street canyons. Those addressed the thermal-induced flow, have assumed a uniform wall surface temperature distribution. The external building wall surface temperature distribution is not uniform, and is influenced by many factors including the wall surface characteristics, and shading. The non-uniform temperature distribution significantly impacts on 3-dimensional airflow within street canyons. Moreover, effect of intersection is barely considered in the literature where L/H<3 (L and H are respectively length and height of street canyon). This Paper reports the development of a 3-dimensional model to study the effect of non-uniform wall surface temperature distribution on the pollution dispersion and flow pattern within the short street canyons (L/H<3). For this purpose, a computational fluid dynamics (CFD) model is developed to investigate these effects on pollution dispersion in various prevailing wind velocities and directions. Moreover, active and passive techniques to reduce the level of concentration are examined. The study clearly shows that thermal-induced flow dominates during fair-weather condition.     

Effect of aluminum on microstructural and magnetic properties of nanostructured (Fe85Ni15)97Al3 alloy produced via mechanical alloying

In the present study, mechanical alloying process was employed for preparation of the nanocrystalline (Fe₈₅Ni₁₅)₉₇Al₃ alloy through ball mill method. The structure, mechanical properties, and magnetic behavior of the alloy at various milling times of 0, 4, 16, 32 and 64 h were studied by X-ray analysis, vibrating sample magnetometer (VSM) and scanning electron microscopy (SEM) measurements. The bcc Fe(Ni) phase was successfully formed within 32 h ball-milling. It was found that an increment in the milling time leads to higher lattice parameter while it decreases the grain size from 172 to 16 nm. Also, the VSM test results indicated that by increasing the milling time to 32 h, the saturation magnetization (M_s) and coercivity (H_c) increased.