Air-Impingement Drying of Tortilla Chips

Tortilla pieces were prepared from nixtamalized masa flour, and dried under impinging hot air. The effect of different drying conditions on the drying rate, texture, shrinkage profile and microstructure was analyzed. The results indicated that drying rate was mostly affected by the air temperature; texture was crispier at higher air temperatures: shrinkage of the piece was higher at lower convective heat transfer coeffieient; and microstructure looked smoother at higher air temperature.     

Effect of Loading Position and Storage Duration on the Textural Properties of Eggplant

Eggplant has a very limited shelf life and, like other vegetables, is susceptible to different types of damage during and after harvest operations. Besides, eggplant is inhomogeneous considering its inner construction point of view. It is therefore important to specify how storage might affect their mechanical properties and how they vary in morphology. In this work, eggplants were divided into three portions along the longitudinal axis and their textural properties were separately investigated using different types of test over a 10-day period of storage. The results showed that the tension strength, rupture force and Young’s modulus of skin tissue decreased with increasing the length of storage period, and they were generally different in the different portions of the fruit that were sampled. The values of Young’s modulus and rupture force of pulp tissue taken from compression tests decreased from 1.466 to 0.821 MPa and 20.70 to 17.66 N for upper section, 0.637 to 0.536 MPa and 15.33 to 13.13 N for middle section and 0.518 to 0.422 MPa and 14.19 to 12.19 N for bottom section, respectively, with the increase in storage period. Similarly, as the samples were stored longer, the Young’s modulus and rupture force of their combined skin and pulp tissues, obtained from penetration tests, decreased from 3.01 to 2.02 MPa and 31.21 to 24.95 N for upper section, 2.59 to 1.66 MPa and 28.64 to 21.66 N for middle section and 1.91 to 1.15 MPa and 23.18 to 17.37 N for bottom section, respectively.     

酶水解苦味肽对大黄鱼白细胞与溶菌酶活性的影响

目的探究酶水解苦味肽对大黄鱼白细胞与溶菌酶活性的影响。方法分别利用木瓜蛋白酶、胰蛋白酶、胃蛋白酶,碱性蛋白酶和风味蛋白酶酶解鮸鱼鱼肉制备苦味最高的苦味肽。以幼大黄鱼为实验对象,分别设置4个不同的组(对照组、低剂量组、中剂量组、高剂量组),对其进行腹腔注射苦味肽,观察8周后采血检测,以白细胞/总血细胞的平均比率和溶菌酶活性为指标评价苦味肽对大黄鱼先天免疫系统的作用效果。结果胃蛋白酶水解产生的苦味肽苦味最高。对照组的白细胞/总血细胞的平均比率为14.6%,低剂量组(0.6 mg/鱼)为28.86%,中剂量组(1.2 mg/鱼)为35%,高剂量组(2.4 mg/鱼)为29.3%。在白细胞对乳胶颗粒的体外吞噬作用实验中,对照组与测试组的吞噬指数分别为1.15(0mg/L),1.88(0.4mg/L),3.84(0.8mg/L),5.94(1.2mg/L)。溶菌酶在60min内的相对裂解活性分别为0.17、0.101、0.307和0.198。与对照组相比苦味肽可以提高大黄鱼的免疫力,当注射剂量为1.2mg时,吞噬与溶菌酶活性都显著升高,可初步确定最佳注射剂量为1.2mg。结论苦味肽可以通过多途径有效地提高天然免疫的作用,可以降低大黄鱼疾病的发生,值得进一步研究。     

Solid State Bioconversion of Oil Palm Empty Fruit Bunches for Production of Citric Acid by Wild Strains of Aspergillus Niger

This study investigated the potential of Aspergillus niger strains for the production of citric acid from oil palm empty fruit bunches (EFB) through solid state bioconversion (SSB). Twenty six wild strains of Aspergillus niger isolated from lemon, orange, and sewage treatment plant sludge were evaluated. Factors considered in the study were citric acid production, sugar consumption, and protein content as growth indicator. Two strains of Aspergillus niger (IBO-103MNB) and (IBO-114MNB) were found to have good potential with citric acid production of 128.43 ± 6.3 and 140.50 ± 1 g kg^-1 of dry EFB with bioconversion time of 4 and 8 d, respectively. The productivity of citric acid by these strains was found to be 32 and 17.5 g kg^–1d^–1, respectively.     

Tension behavior of unidirectional glass/epoxy composites under different strain rates

By considering wide applications of composite materials, having a proper knowledge of them under dynamic loading is necessary. In order to study the effects of strain rates on the behavior of the materials, special testing machines are needed. Most of the research in this field is focused on applying real loading and gripping boundary conditions on the testing specimens. In this study, behavior of unidirectional glass fiber reinforced polymeric composites under uni-axial loading is determined at quasi-static and intermediate strain rates of 0.001–100 s⁻¹. The tests were performed using a servo-hydraulic testing apparatus equipped with a strain rate increase mechanism. For performing the tests, a jig and a fixture are designed and manufactured. The performance of the test jig was evaluated and found to be adequate for testing of composites. Dynamic tests results are compared with the results of static tensile tests carried out on specimens with identical geometry. Experimental results show a significant increase of the tensile strength by increasing the strain rate. The tensile modulus and strain to failure are also observed to increase slightly by increasing the strain rate.     

CMOS photodetector systems for low-level light applications

Electron beam induced second harmonic generation (SHG) is studied in Er³⁺ doped PbO–GeO₂ glasses containing silver nanoparticles with concentrations that are controlled by the heat-treatment of the samples. The SHG is observed at T = 4.2 K using a p-polarized laser beam at 1064 nm. Enhancement of the SHG is observed in the samples that are submitted to electron beam incidence. The highest value of the nonlinear susceptibility, 2.08 pm/V, is achieved for the sample heat-treated during 72 h and submitted to an electron beam current of 15 nA. The samples that were not exposed to the electron beam present a susceptibility of ≈0.5 pm/V.     

Numerical modelling of masonry joints degradation in built tunnels

Old tunnels are generally supported by masonry structure. Nowadays, these constructions present many instability problems (cracks, collapses, convergence, etc.) due to aging phenomena on both blocks and mortars. After the analysis of blocks mechanical behaviour over time [Idris, J., Verdel, T., Al-Heib, M., 2008a. Numerical modelling and mechanical behaviour analysis of ancient tunnel masonry structures. Tunnelling and Underground Space Technology 23, 251–263.], we try in this paper to simulate the evolution of masonry joints mechanical behaviour in built tunnels and to quantify the influence of their mechanical proprieties on the tunnel behaviour by the help of the experimental design method and distinct elements numerical modelling.     

Synthesis of Unsymmetrical Diorganyl Chalcogenides under Greener Conditions: Use of an Iodine/DMSO System,Solvent‐ and Metal‐Free Approach

Herein, we report a greener iodine‐catalyzed protocol to access different types of unsymmetrical diorganyl chalcogenides. This new approach works in the absence of solvent and metal. The desired products were obtained in good to excellent yields using one equivalent of arylboronic acids, half an equivalent of various diorganyl dichalcogenides, iodine (10 mol%) as a catalyst and 2 equivalents of dimethyl sulfoxide (DMSO; as oxidant), with a reaction time of 10 min under microwave irradiation.