The influence of gallium on the magnetocaloric properties of Gd5Si2Ge2

Gd₅Si₂Ge₂ was alloyed with varying amounts of Ga to study its influence on the giant magnetocaloric effect. Investigations on Gd₅(Si_2−xGe_2−x)Ga_2x with 2x = 0.03, 0.05 and 0.13 were carried out using X-ray powder diffraction, temperature and magnetic field dependent magnetization measurements, and differential scanning calorimetry. We observe that as the Ga content increases, the temperature stability range of the monoclinic phase narrows, and the orthorhombic structure gains stability. This is expected to be related to the decrease in the (Si/Ge)(Si/Ge) bond distance in the monoclinic phase. The maximum entropy change for the parent compound at 270 K was found to be 9.8 J kg⁻¹ K⁻¹ in an applied field of 5 T. For 2x = 0.03, this value reduces to 8.5 J kg⁻¹ K⁻¹, and the temperature corresponding to the maximum entropy change shifts marginally to 278 K. For other 2x values, the maximum entropy change further decreases.     

Production of structured lipids containing conjugated linolenic acid: optimisation by response surface methodology

Structured lipids containing conjugated linolenic acid (CLNA) were produced separately by enzymatic acidolysis reaction of corn and canola oils (CAO) with bitter gourd (Momordica charantia L) seed oil fatty acids [bitter gourd seed oil fatty acids (BGFA)]. Reactions were conducted using a commercial immobilised sn‐1,3‐specific lipase from Thermomyces lanuginosa (Lipozyme TL IM) in hexane. The effects of reaction time, substrate molar ratio, temperature and enzyme amount on incorporation yield of CLNA were investigated and optimised by response surface methodology with three‐level, two‐factor face‐centred cube design. When reactions were conducted using 10% enzyme for 3 h, the optimum reaction conditions were found for corn oil (CO) as 53.5 °C and 5.9:1 BGFA/CO molar ratio. At these conditions, the incorporation of CLNA into CO was determined as 41.4%. However, CLNA incorporation into CAO was resulted as 37% at optimum conditions which were 54.2 °C and 6.8:1 BGFA/CAO molar ratio.     

Prediction of building energy needs in early stage of design by using ANFIS

Studies performed on the prediction of building energy consumption are increasingly important for selecting the best control strategies against the excessive energy consumptions. This paper presents Adaptive Network Based Inference System (ANFIS) model to forecast building energy consumption in a cold region. The objective of this paper is to examine the feasibility and applicability of ANFIS in building energy load forecasting area. Different combinations of building samples formed by using three different form factors (FF 1/2, FF 1/1 and FF 2/1), nine azimuth angles varied 0^o–80^o, three transparency ratios of 15%, 20%, 25% and five insulation thicknesses of 0, 2.5, 5, 10 and 15 cm. Finally, it is observed that ANFIS can be a strong tool with the 96.5 and 83.8% for heating and cooling energy prediction in pre-design stage of energy efficient buildings for choosing the best combinations.     

Open cell lead foams: processing, microstructure, and mechanical properties

Open cell lead foams with the porosities between 48 and 74 % were prepared by means of powder metallurgical and casting routes, using ammonium bicarbonate particles, silica beads, and sodium chloride salt particles as space holder. The resulting foam samples structure closely resembled open cell foam structure: each cell had few interconnections with neighboring cells. Small-sized lead (II) fluoride precipitates were microscopically observed in the interior of cells in the foam samples prepared using silica beads as space holder, resulting from the reaction between silica and hydrofluoric acid in the space holder dissolution step. The compression stress–strain curve of foam samples prepared by powder metallurgical route showed brittle deformation behavior following the initial elastic deformation region, while the foam samples prepared by casting route showed characteristic foam deformation behavior: cell edge crushing on the bent cell walls, and cell wall tearing. The collapse stresses, densification strains, and elastic moduli of the prepared foams were further fitted with scaling relations.     

Preparation of Novel Sensors Based on Polyimide Membrane for Sensitive and Selective Determination of Dopamine

Polyimides as dopamine selective membrane were prepared from 4,4′-diaminodicyclohexylmethane and different dianhydrides. The chemical structure and thermal properties of these polyimides were examined. For the voltammetric sensor applications, polyimides exhibited suitable glass transition temperature (T_g), high thermal stability, and good adhesive properties. Moreover, polyimides were coated onto Pt electrode surface for the preparation of dopamine selective electrodes. Electrochemically dopamine responses of polyimide-coated electrodes were examined by differential pulse voltammetry. The sensor characteristics such as sensitivity, linearity, selectivity, response time, and stability of the prepared sensors have been determined. Prepared polyimide-coated electrodes can be used for selective and sensitive dopamine detection.     

Prediction of Water Level using Monthly Lagged Data in Lake Urmia,Iran

Water Resources Management - Prediction of water level fluctuations in lakes is a necessary task in hydrological and limnological studies. Lake Urmia, a hyper-saline lake in the North Western part...     

Ultrasonic characterization of lactose crystallization in gelatin gels

Ultrasonic velocity and attenuation measurements (2.25 MHz center frequency) were used to follow bulk crystallization of lactose (43% and 46%) from gelatin (1.5% and 3%) gels at 25 °C, and compared to turbidity (500 nm) and isothermal calorimetric measurements. Ultrasonic velocity decreased slightly (approximately 0.5%) during crystallization while ultrasonic attenuation was low in the absence of lactose crystals and increased progressively during crystallization. The lag time before the onset of crystallization decreased and the maximum rate of increase in attenuation during crystallization increased with increasing lactose supersaturation but was not affected by gelatin concentration (P < 0.05). Similar results were seen in turbidity and isothermal calorimetric measurements. Ultrasonic attenuation measurements have the potential to measure crystallization kinetics in complex food matrices and to be applied on-line. Practical Application: Many foods contain crystals that affect their taste and texture (for example, lactose crystals can give a grainy defect in ice cream). The formation of crystals is often hard to predict so methods to measure the development of crystals inside real foods are useful. In this study, we show that as lactose crystallizes in a gelatin gel the ultrasonic attenuation--capacity to absorb sound--increases and can be related to the amount of crystals present. Ultrasound is easier to apply in real food processing than the existing methodologies.     

Improvement of polyvinyl alcohol/casein blend film properties by adding cellulose nanocrystals

This study aims to prepare and examine the properties of poly(vinyl alcohol)/casein (PVA/CAS) based films reinforced with cellulose nanocrystals (NC), which can be presented as an alternative to petroleum-based polymer packaging materials. PVA/CAS and 0.5–1–3–5 wt% NC containing PVA/CAS biocomposite films were prepared by solution casting method. Afterward, the 1NC film, which exhibited the best mechanical properties, was crosslinked with various amounts of glyoxal. Structural, morphological (polarized optical microscope), mechanical (tensile), thermal (differential scanning calorimetry, thermogravimetric analysis), contact angle, and water vapor transmission rate (WVTR) properties of the samples were investigated. The 1NC film exhibited the highest tensile strength (TS) and elongation values in PVA/CAS/NC films, and its mechanical properties decreased due to agglomeration with increasing NC amount. As expected, crosslinking improved the TS. The thermal stability of the PVA/CAS film was generally improved with the addition of NC and crosslinking. The high WVTR value of the PVA/CAS film decreased with the addition of NC and the 1NC film presented the lowest value. Thanks to the complex structure formed as a result of crosslinking and the reduced free volume, the WVTR of the 1NC film has reduced. The results showed that PVA/CAS-based films with good mechanical properties and water vapor barrier are promising as packaging materials.     

Identification of Turkish extra virgin olive oils produced in different regions by using NMR (1H and 13C) and IRMS (13C/12C)

Isotope ratio mass spectroscopy (IRMS) and nuclear magnetic resonance (NMR) spectroscopy techniques are two of the analytical methods that are used to characterize food products. The aim of this study is to classify extra virgin olive oil (EVOO) samples collected from different regions of Turkey based on ¹H and ¹³C NMR spectra along with IRMS δ¹³C carbon isotope ratio data by using chemometrics multivariate data analysis methods. A total of 175 EVOO samples were analyzed in 2014/15 and 2015/16 harvest seasons. Multivariate classification and clustering models were used to identify geographical and botanical origins of the EVOOs. IRMS results showed that there was no significant difference in terms of δ¹³C values between the years in terms of harvest year (p > 0.05), only extraction phase and variety were statistically significant factors (p < 0.05). The interactions of the factors showed that the harvest year × variety interaction is important. The outcomes of this research clearly indicated that considering the partial least squares discriminant analysis result with NMR spectra, the percent success of the model in the South Marmara, North Aegean, and South Aegean region samples were 95%, 95.7%, and 96.4% in the model set, respectively. The results showed that by using classification and clustering models, geographic marking and labeling of these oils can be carried out regardless of differences in year and production systems (2 and 3 phase extraction system) according the NMR analysis.