Mechanical Properties of Cashew Nut Under Compression Loading at Varied Moisture Contents
Abstract
In the present study, the moisture-dependent mechanical properties, i.e. rupture force, deformation and rupture energy along three different axes (i.e. L, B, T), of the cashew (Anacardium occidentale) varieties (Vengurle 1, Vengurle 3, Vengurle 4 and Vengurle 7) were studied at 17–85% db under compression loading. The rupture force decreases linearly (r2 ≥ 0.752) with the increase in moisture content from 17 to 85% db, for Vengurle 1 along length, width and thickness of 15,080–3467, 17,000–4275 and 21,014–3388 g; for Vengurle 3 along length, width and thickness of 25,090–4031, 26,000–3851, 31,256–3449 g; for Vengurle 4 along length, width and thickness of 22,000–3342, 21,000–3360, 27,000–3725 g; for Vengurle 7 along length, width and thickness of 20,900–5542, 25,080–5542 and 29,000–7009 g, respectively. The deformation at rupture increases linearly (r2 ≥ 0.671) with the increase in moisture content from 17 to 85% db, for Vengurle 1 along length, width and thickness of 2.1–2.98, 2.42–3.56 and 3.4–6.21 mm; for Vengurle 3 along length, width and thickness of 2.8–4.73, 2.65–4.3 and 4.21–6.16 mm; for Vengurle 4 along length, width and thickness of 4.2–6.89; 2.81–5.35 and 5.6–6.7 mm; for Vengurle 7 along length, width and thickness of 4.56–7.8, 3.2–5.56 and 6.2–7.27 mm, respectively. The rupture energy decreases linearly (r2 ≥ 0.720) with increase in moisture content from 17 to 85% db for Vengurle 1 along length, width and thickness of 143–36.58, 108–56 and 123–80.38 mJ; for Vengurle 3 along length, width and thickness of 271–59.54; 82.00–33.68 and 265–101 mJ; for Vengurle 4 along length, width and thickness of 136–80.96, 58.54–23.32 and 154–96.74 mJ; for Vengurle 7 along length, width and thickness of 273–98.26, 123–21.22 and 255–151 mJ, respectively. The rupture force was higher along thickness and decreases along width and length, and it was maximum for Vengurle 3 followed by Vengurle 7, Vengurle 4 and Vengurle 1. The deformation at rupture was higher along the thickness and decreases along width and thickness and was maximum at Vengurle 7 followed by Vengurle 4, Vengurle 3 and Vengurle 1, respectively. The rupture energy was higher at length for Vengurle 7 and decreases at Vengurle 3, followed by Vengurle 1 and Vengurle 4 along length of the cashew nut.
Physical properties of almond nut and kernel
Several physical properties of almond nut and kernel were evaluated as functions of moisture content. The average length, width, thickness, the geometric mean diameter, unit mass and volume of nuts were 25.49, 17.03, 13.12, 18.13 mm, 2.64 g and 2.61 cm 3 respectively. Corresponding values for kernel were 21.19, 14.34, 6.38, 11.42 mm, 0.69 g and 0.71 cm 3 respectively. In the moisture range from 2.77 to 24.97 db, studies on re-wetted almond nut showed that the bulk density decreased from 655 to 525 kg/m 3 , true density increased from 1015 to 1115 kg/m 3 , porosity increased from 35.32% to 53.21%, projected area increased from 3.74 to 3.9 cm 2 , and terminal velocity increased from 5.62 to 7.98 m/s. For the kernel, the corresponding values changed from 595 to 475 kg/m 3 , 900 to 995 kg/m 3 , 34.23% to 50.29%, 1.68 to 2.39 cm 2 and from 5.62 to 7.2 m/s respectively. The rupture strength of almond nut and kernel decreased with increasing moisture content. The highest rupture strength occurred when loaded along the X -axis. In the same moisture range 2.77–24.97 db the static coefficient of friction varied from 0.28 to 0.83for almond nut and from 0.53to 0.78 for kernel over different material surfaces. 2003Elsevier Ltd. All rights reserved.
An Ultrasensitive Analytical Method Based on Chemiluminescence Sensing Electrochemical Parallel Catalytic Reaction Event
An ultrasensitive electrochemiluminescence (ECL) method on the combination of electrochemical parallel catalytic reaction and chemiluminesence signal sensing was proposed for improving ECL analytical characteristics using vanadate(V) as a representative. Vanadate(V) could be electrochemically reduced to generate vanadate(II) which could be chemically oxidized by potassium periodate to regenerate vanadate(V) and give parallel catalytic wave effect. Then, the reduced product of potassium periodate could react with butyl-rhodamine B to emit a sensitive chemiluminescence signal. The chemiluminescence intensity was correlative with vanadate(V) concentration. The investigation on the electrochemical reaction rate constant (k0) confirmed that the speed of electrochemical reaction was faster than that of the subsequent chemiluminescence reaction. The possibility of the combination of electrochemical parallel catalytic reaction with chemiluminescence signal sensing was proved. The similar ECL behaviors could be observed at zirconia nanowires-Nafion modified electrode. Because of the separation and enrichment effect of the modified electrode on vanadate(V), the selectivity and sensitivity was further improved greatly. Based on these findings, a new concept on the combination of electrochemical parallel catalytic reaction and chemiluminesence signal sensing was proposed and an ultrasensitive ECL method for the determination of vanadate(V) was developed at zirconia nanowires-Nafion modified electrode. Under the optimum experimental conditions, the ECL intensity was linear with the concentration of vanadate(V) in the range of 2.0×10−12 mol/L–2.0×10−10 mol/L. The detection limit was 8.0×10−13 mol/L, which was more than 6 orders of magnitude lower than that observed by electrochemical current transduction for electrochemical parallel catalytic reaction at zirconia nanowires-Nafion modified electrode.