Qualitative and Quantitative Changes in the Essential Oil of Lemon Verbena (Lippia citriodora) as Affected by Drying Condition

The objective of this study was to evaluate the effect of drying air temperature and air flow rate on the quantity and quality of the essential oil of lemon verbena. A completely randomized design was applied with a factorial arrangement of two factors: temperature (30, 40, and 50°C) and air flow rate (0.5, 1, and 1.5 m/s). The leaves were harvested in full blooming stage and placed in the drying machine at different temperatures and air flow rates. The essential oil of leaves was extracted by hydrodistillation in a Clevenger apparatus and analyzed by gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS). The results showed that the interaction between different temperatures under various air flow rates had a significant effect on the content and chemical composition of the essential oil. Seventeen compounds were identified in essential oil of lemon verbena, of which geranial, neral, and limonene were the major components. The maximum oil content and majority compounds of essential oil were obtained at 50°C and a 0.5 m/s air flow. Finally, seven mathematical models of thin-layer drying such as correlation coefficient (R ²), sum of square errors (SSE), and root mean square error (RMSE) were evaluated and the modified Page model was found to be the best drying model for lemon verbena.     

Article length and citation outcomes

Scientometrics - We examine the relationship between article length and citation counts. Focusing on articles published between 2010 and 2014 in the top five economics journals and their citation...     

A study of the potential of using the Earth to air heat exchanger for cooling and heating of residential buildings in Iraq

The Earth to air heat exchanger (EAHE) is an effective passive cooling and heating system for buildings. This paper studied numerically the potential for reduction in energy consumption for cooling and heating loads for a residence equipped with an EAHE system in the climate of Nasiriya city, which is located in southern Iraq and at 31.7°N and 45.8°E, latitude and longitude, respectively. Also, this paper presents a study about the thermal performance of three types of EAHE systems, system 1, consisting of one layer of EAHE and buried at an available area of house garden with 3‐m depth, system 2, at the same site of system 1, but with two layers of EAHE at two depths, 3 and 4 m, and finally, system 3, buried along the area of the house at a depth of 3 m. First, the built numerical model was validated against experimental results, and the results of the comparison showed good agreement. The electricity consumption for cooling and heating of the house is calculated with and without the EAHE system. The results showed that with using EAHE, there is a considerable saving in energy and saving in the cost of electricity consumption, which reached 376 329 IQD ($301.11) over 1 year for system 2.     

Novel fabrication of extremely high aspect ratio and straight nanogap and array nanogap electrodes

Microsystem Technologies - We reported a reproducible, simple and novel method for fabricating electrodes with high aspect ratio and highly straight nanometer size gap. The gap size could be...     

Nature of the Pseudogap in High-Tc Cuprates: Analysis?of?the?Bulk Magnetic Susceptibility of?La2?xSrxCu1?yZnyO4

The nature of the pseudogap in the quasiparticle spectral density in high-T _c cuprates is a matter of intense debate. In this study we have investigated the effects of Zn substitution on the uniform (q=0\boldsymbol{q}=0, where q\boldsymbol{q} is the wave vector) magnetic susceptibility, χ(T), of La_2−x Sr _x Cu_1−y Zn _y O₄ sintered samples with different hole concentrations, p(≡x), over a wide range of Zn contents (y). Non-magnetic Zn suppressed T _c most effectively and enhanced χ(T) systematically at low temperatures. We have extracted the characteristic pseudogap energy scale, ε _g, from the analysis of χ(T) data. Unlike T _c,ε _g was found to be fairly insensitive to the level of Zn substitution, even when T _c was completely suppressed by Zn. The Zn-induced Curie-like enhancement of the χ(T) was also found to be closely related to the PG energy scale. We discuss the possible implications of these findings in this paper.     

Surface analytical approach to TiCl3-based Ziegler-Natta catalysts combined with microstructure analysis of polymer

In the field of Ziegler-Natta catalysis (ZNC), most of the previous works have been focused on the characterization of either catalyst surface or polymer microstructure but the combined studies of these two aspects are still limited. A clearer understanding concerning the isospecific nature of active sites on the donor-free TiCl₃ - based catalyst has been presented in this work in terms of both surface characteristics of the catalyst and microstructure of polypropylene (PP) produced. Ti- and Al-species existing in the catalyst surface have been identified by high resolution X-ray photoelectron spectroscopic (XPS) and solid-state magic angle spinning nuclear magnetic resonance (²⁷Al MAS NMR) techniques, respectively. Moreover, grinding effect on catalyst performance has been carried out to investigate the nature of active sites by particle size distribution (PSD) method. Microstructures of PPs produced using the surface characterized catalysts have been investigated by temperature rising elution fractionation (TREF), ¹³C NMR and GPC methods. It can be demonstrated that the surface structure of catalyst is dominantly affected by the type of Al-alkyl cocatalyst used as well as the preparation method of catalyst whilst it precisely determine the nature of isospecificity of active sites and its distribution. Two different types of surface Ti⁺³-species have been identified on the catalyst surface depending on the different vacant coordination states of surface titanium species. On the other hand, ²⁷Al MAS NMR experiments have shown the presence of surface aluminum in four (Al^IV), five (Al^V) and six (Al^VI) coordination number of multiple environments. The states of surface Al-species are sensitive to coordination number and symmetry of the local environment around the aluminum nuclei. Higher isospecificity of active sites is seen to be related to the higher fulfilled coordinated states of surface Ti- and Al-species.     

Particle formation and agglomeration of an alumina-zirconia powder synthesized an supercritical CO2 method

Alumina - 20 vol% zirconia doped with 2 mol% yttria composites were prepared by a supercritical CO₂ method. The powder characteristics were examined through control of the supercritical conditions; temperature and pressure. The agglomeration degrees (N) for powders were changed from 1.2 and 5.4. As the value N become smaller or close to unity, powder agglomerates tend to approach their primary powder size. The sintered sample had hardness of 12.5 GPa. SEM and TEM characterization were used to characterize the microstructure and morphology of the prepared powders.     

An efficient algorithm for multi-objective optimal operation management of distribution network considering fuel cell power plants

This paper presents an interactive fuzzy satisfying method based on Hybrid Modified Honey Bee Mating Optimization (HMHBMO). Its purpose is to solve the Multi-objective Optimal Operation Management (MOOM) problem which can be affected by Fuel cell power plants (FCPPs). Minimizing total electrical energy losses, total electrical energy cost, total pollutant emission produced by sources and deviation of bus voltages are the objective functions in this method. A new interactive fuzzy satisfying method is presented to solve the multi-objective problem by assuming that the decision-maker (DM) has fuzzy targets for each of the objective functions. Through the interaction with the DM, the fuzzy goals are quantified by eliciting the corresponding membership functions. Considering the current solution, the DM updates the reference membership values until the best solution can be obtain. The MOOM problem is modeled as a mixed integer nonlinear programming problem. Therefore, evolutionary methods can be used to solve this problem since they are independence of objective function’s type and constraints. Recently researchers have presented a new evolutionary method called Honey Bee Mating Optimizations (HBMO) algorithm. Original HBMO often converges to local optima and this is a disadvantage of this method. In order to avoid this shortcoming we propose a new method. This method improves the mating process and also combines the modified HBMO with a Chaotic Local Search (CLS). Numerical results on a distribution test system have been presented to illustrate the performance and applicability of the proposed method.