Enhanced ZT of Ca3Co4O9 by nano-sized precursor

Ca3Co4O9 sample synthesized from nanometer of CaCO3 and Co2O3 sized precursor has been prepared by solid-state reaction and fast sintering by hot press method. The fast-sintering time can maintain the particle size of the nanometer. Their thermoelectric properties at high temperatures have been studied at 300 - 1000 K. When the usage of a nano-sized precursor leads to decrease electrical resistivity, increase power factor, and would lead to huge growth, respectively. The main effect is observed on thermal conductivity that is lower than sample synthesized with micrometer precursors powder from 0.67 W/mK which became 0.36 W/mK at 973 K. The best ZT value of Ca3Co4O9 reaches 0.51 at 973 K.

Evaluation of nuts morphology and composition of fatty acids in certain Iranian Pistacia vera L. (Anacardiaceae) cultivars

<p>Fruits of various Pistachio (<em>Pistacia vera</em> L.) cultivars are widely used in food industries for its inimitable color, taste and nutrient value.<strong> </strong>We elevated fruit morphology and kernel fatty acids composition of eleven Iranian cultivars of pistachio. Oils of kernels were extracted using cold press method, and composition of the oil fatty acids in the methyl ester form was detected using gas chromatography (GC). For morphological study, nine qualitative and quantitative traits were evaluated. The quantitative ones widely differed among the studied cultivars, and ANOVA test revealed the significant variations (<em>p</em> = 0.00) for all of them. Moreover, the qualitative traits varied among the cultivars. We characterized 11 fatty acid components representing about 99.56 to 100 % of the total oil composition. The principal fatty acids for all the cultivars were: oleic, linoleic and palmitic acids, while their amounts differed among the cultivars. In this regard, unsaturated fatty acids comprised the major oil part, 87.46 to 88.89 %. Oleic acid (53.11-70.99 %) and palmitic acid (9.09 to 10.55 %) were detected as the unsaturated and saturated fatty acids in all the evaluated cultivars. The quality index of oils were determined according to oleic/ linoleic acids ratio, which highly varied among the cultivars. According to UPGMA tree and PCO plot, we divided the investigated cultivars into four chemotypes, and each of them was characterized by the certain oil composition.</p>

Effect of Cr6+ on the Properties of Alkali-Activated Slag Cement

In order to investigate the effect of Cr6+ on the properties of alkali-activated slag cement (AAS), the effects of added dosage of Na2Cr2O4 on the setting time and compressive strength of AAS were measured. The leaching concentration of Cr6+ from AAS cement stone was measured using dual-beam UV-visible spectrophotometry. The effect of Na2Cr2O4 on the hydration kinetics of AAS cement was monitored by microcalorimetry and the corresponding kinetic parameters were analyzed. The pore solution from AAS was collected and analyzed using the high pressure press method. The effects of Na2Cr2O4 on the hydration products of AAS cement were observed and compared using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The experimental results showed that the AAS hydration process was markedly affected by Na2Cr2O4 dosage. The setting time of AAS pastes was increased and the compressive strength of cement stones was reduced with increasing dosage of Na2Cr2O4. With the development of AAS hydration, the leaching concentration of Na2Cr2O4 gradually decreased. Na2Cr2O4 did not affect the dissolution of slag particles, but impeded the formation of C-S-H gel. The Cr6+ was immobilized chemically in the form of needle-like CaCrO4 particles formed by the chemical reaction between Na2Cr2O4 and Ca2+ leaching from the slag.

Comparative Studies on Mechanical Performance of Epoxy and Polyester Hybrid Composites with Jute and Glass Layers

The natural fibers are the alternative to glass and other human-made fibers, because of their low cost and readily available from natural resources and acts as a reinforcing material for the polymer composites. Jute is the most widely used natural fibers among the various fibers due to its superior characteristics. Composite materials are made with different materials that are physically and chemically different alienated by interfaces. In this work, epoxy and polyester hybrid composites reinforced with jute and glass fiber were fabricated by hydraulic press method and their tensile and impact properties were compared. The mechanical properties of jute/glass hybrid composites with different layers such as tensile strength, percentage of elongation and impact strength were evaluated using ASTM specifications. Tensile and Charpy impact test results indicated that jute/glass fiber reinforced epoxy composites have shown optimum properties than polyester composites.

Sour Cherry (Cerasus vulgaris Miller) Kernel Oil as the Novel Functional Edible Oil: Sensory Evaluation and Antioxidant and Physicochemical Properties

This study aims to extract oil from fresh sour cherry kernel (Cerasus vulgaris Miller) using the cold press method. The oil content and moisture were obtained as 31.89% and 4%, respectively. The organoleptic assessment of the oil was acceptable and the free fatty acid value was obtained as 1.36 (mg KOH/g oil). In addition, peroxide value and anisidine index of sour cherry kernel oil were obtained as 0.99 meqO2/kg oil and 0.15, respectively. The predominant fatty acids were linoleic acid (42.34%), oleic acid (35.45%), α-eleostearic acid (9.34%), and palmitic acid (6.54%), respectively. The kernel oil contained nine major triacylglycerols consisting of OLL (20.44%), OOL (16.99%), LLL (8.20%), LLEl (7.28%), PLO (7.24%), OElO (5.03%), OOO (4.70%), ElLO (4.54%), PLL (4.35%), and POO (3%), respectively. The most abundant sterol compounds were β-sitosterol (83.55%), ∆5-avenasterol (6.8%), sitostanol (4.8%), campesterol (3.5%), and stigmasterol (0.53%), respectively. Also, antioxidant activity, total phenol content (TPC), total anthocyanin content (TAC), total flavonoid content (TFC), total tannin content (TTC), and total tocopherol content were obtained as 73.22%, 33.44 mg GA/g dry matter, 177.84 mg/L, 46.37 mg/g dry matter, and 1.21 mg GA/g dry matter, 832.5 mg/kg oil, respectively. The amount of amygdalin in the oil sample was not detectable.

Kenaf Fiber/Pet Yarn Reinforced Epoxy Hybrid Polymer Composites: Morphological, Tensile, and Flammability Properties

The application of natural fibers is rapidly growing in many sectors, such as construction, automobile, and furniture. Kenaf fiber (KF) is a natural fiber that is in demand owing to its eco-friendly and renewable nature. Nowadays, there are various new applications for kenaf, such as in absorbents and building materials. It also has commercial applications, such as in the automotive industry. Magnesium hydroxide (Mg(OH)2) is used as a fire retardant as it is low in cost and has good flame retardancy, while polyester yarn (PET) has high tensile strength. The aim of this study was to determine the horizontal burning rate, tensile strength, and surface morphology of kenaf fiber/PET yarn reinforced epoxy fire retardant composites. The composites were prepared by hybridized epoxy and Mg(OH)2 PET with different amounts of KF content (0%, 20%, 35%, and 50%) using the cold press method. The specimen with 35% KF (epoxy/PET/KF-35) displayed better flammability properties and had the lowest average burning rate of 14.55 mm/min, while epoxy/PET/KF-50 with 50% KF had the highest tensile strength of all the samples. This was due to fewer defects being detected on the surface morphology of epoxy/PET/KF-35 compared to the other samples, which influenced the mechanical properties of the composites.

Predictive Capacity of Rainfall Data to Estimate the Water Needs of Fruit Plants in Water Deficit Areas

This study investigated the usefulness of three methods: (1) Press, (2) Grabarczyk and Rzekanowski, and (3) Treder, in estimating the water needs of apple, pear, cherry and plum trees grown in central Poland, where particular water deficits are observed. The assessments were based on meteorological data for the growing seasons 1989–2020. Orchard irrigation requires a simple and accessible method of estimating plant water requirements. The average water needs assessed for apple ranged from 435 mm (Press) to 729 mm (Grabarczyk and Rzekanowski), for pear between 353–699 mm (Grabarczyk and Rzekanowski), for cherry between 315 mm (Press) and 660 mm (Grabarczyk and Rzekanowski), and plum ranged from 455 mm (Press) to 718 mm (Grabarczyk and Rzekanowski). Regardless of the method used, precipitation in the studied period did not cover the water needs of the fruit trees. Additionally, there was a tendency to increase the water requirements of the plants. In each method, water needs in the second and third decades were higher than in the first. The highest water needs of the fruit trees were calculated using the Treder method, and the lowest using the Press method. In practice, each of the methods can be used to forecast the water needs of fruit plants, but the Treder method seems to be the simplest and most accessible.