High-performance optical wavelength-selective switches based on double ring resonators

In order to improve the performance of optical wavelength-selective switches based on double micro-ring resonators, an asymmetric intra-step-barrier coupled double strained quantum wells (AICD-SQWs) structure is utilized as the active light guiding medium. The AICD-SQW active layer has advantages, such as large change range in absorption coefficient, high extinction ratio, large Stark shift and very low insertion. For predicting the switching characteristics of double ring resonators structure, the absorption coefficient and real refractive index changes of the AICD-SQW active layer are calculated for different applied electric fields for TE input light polarization. Simulation results show that switching characteristics strongly depend on changes in absorption coefficient and real refractive index of active layer. In addition, isolations of 37.44 dB and 26.84 dB are realized between drop and through ports, when drop and through ports are ON and OFF, respectively, and vice versa.     

A synthesis of fluid and thermal transport models for metal foam heat exchangers

Metal foam heat exchangers have considerable advantages in thermal management and heat recovery over several commercially available heat exchangers. In this work, the effects of micro structural metal foam properties, such as porosity, pore and fiber diameters, tortuosity, pore density, and relative density, on the heat exchanger performance are discussed. The pertinent correlations in the literature for flow and thermal transport in metal foam heat exchangers are categorized and investigated. Three main categories are synthesized. In the first category, the correlations for pressure drop and heat transfer coefficient based on the microstructural properties of the metal foam are given. In the second category, the correlations are specialized for metal foam tube heat exchangers. In the third category, correlations are specialized for metal foam channel heat exchangers. To investigate the performance of the foam filled heat exchangers in comparison with the plain ones, the required pumping power to overcome the pressure drop and heat transfer rate of foam filled and plain heat exchangers are studied and compared. A performance factor is introduced which includes the effects of both heat transfer rate and pressure drop after inclusion of the metal foam. The results indicate that the performance will be improved substantially when a metal foam is inserted in the tube/channel.     

The episodal associative memory: Managing manufacturing information on the basis of similarity and associativity

In this paper we report on continuing research on the organization and functionalities of a certain type of computer-implemented associative memory. The associative memory in question is being created to serve as part of a feature-based design system, at present to be used primarily in support of the design, fabrication planning, or inspection planning of discrete mechanical machine parts. This present effort is consonant with prior related work in the realm of case-based reasoning, especially as related to the role of memory in design. Our associative memory innovations are in the use of fuzzy sets and neural net computing in the representation, storage and retrieval of design, fabrication, inspection and materials knowledge. We have designed and implemented a considerable portion of the associative memory and have demonstrated retrieval of previous designs on the basis of qualitative geometry. We have also demonstrated ability to explore materials composition with the objective of meeting critical materials properties constraints.     

Activated carbon from sugar cane bagasse by carbonization in the presence of inorganic acids

Dried ground bagasse, impregnated with 50% inorganic acids and carbonized at 500°C, showed the sequence H₃PO₄ > H₂SO₄ > HCl > HNO₃, with respect to the efficiency of activation. Treatment with phosphoric acid of various concentrations (30–50 wt%) was followed by carbonization at 300–500°C for 3 h. Pore structure parameters were determined from the low-temperature adsorption of nitrogen, by applying the BET and α_s methods. Activated carbons obtained at low temperatures are essentially microporous with a low degree of mesoporosity. At higher temperatures products of higher surface area and total pore volume with developed mesoporosity and low microporosity are formed. An increase in the period of carbonization leads to a small decrease in both surface area and pore volume. Activated carbons with surface areas > 1000 m² g^?1 and mean pore dimensions around 2·0 nm, suitable for various purposes, are thus obtained.     

Pan-heating of low-linolenic acid and partially hydrogenated soybean oils

Genetically modified low-linolenic acid soybean oil (LL-SBO) was compared to partially hydrogenated soybean oil (PH-SBO). Samples were heated on a Teflon pan at ∼180°C until a selected end point of ≥20% polymer content was reached. High-performance size-exclusion chromatography analysis indicated the PH-SBO contained >20% polymer after 20 min of heating, whereas the LL-SBO sample contained >20% polymer after 10 min. Supercritical fluid chromatography analysis indicated degradation rates of 0.161±0.011 min⁻¹ for LL-SBO and 0.086±0.004 min⁻¹ for PH-SBO. The volatile compounds were identified and quantitated with static head-space-GC-MS. 1-Heptene (239.9 ppm) and hexanal (1486.1 ppm) were present at the greates concentration among the volatile compounds in LL-SBO. The volatile compounds present in the greatest concentrations in heated PH-SBO were hexanal (376.9 ppm) and pentane (82.1 ppm). After 10 min of heating, the LL-SBO oil FFA value (2.66%), p-anisidine value (386.5 abs/g oil), Food Oil Sensor reading (18.75), and color intensity (Y=4.0, R=1.0) were significantly greater than those of PH-SBO after 14 min of heating (4.28%, 298.5 abs/g oil, 16.08, Y=1.0, R=0.1, respectively). There was a significant difference in the degradation rates between LL-SBO and PH-SBO (P<0.05). The PH-SBO was more stable than the LL-SBO.     

Predicting the type of pregnancy using artificial neural networks and multinomial logistic regression: a comparison study

Some medical and epidemiological surveys have been designed to predict a nominal response variable with several levels. With regard to the type of pregnancy there are four possible states: wanted, unwanted by wife, unwanted by husband and unwanted by couple. In this paper, we have predicted the type of pregnancy, as well as the factors influencing it using two different models and comparing them. Regarding the type of pregnancy with several levels, we developed a multinomial logistic regression and a neural network based on the data and compared their results using three statistical indices: sensitivity, specificity and kappa coefficient. Based on these three indices, neural network proved to be a better fit for prediction on data in comparison to multinomial logistic regression. When the relations among variables are complex, one can use neural networks instead of multinomial logistic regression to predict the nominal response variables with several levels in order to gain more accurate predictions.     

Ammoniothermal treatment of silica gel and simultaneous changes in surface area

A high surface area silica gel was structurally modified by autoclaving in ammonium hydroxide solutions with pH values of 9–12, at temperatures of 100–180°C, and for periods up to 5 h. Drastic variations in the texture of the xerogel took place leading to a considerable decrease in the specific surface, and to an accompanying increase in the mean particle diameter, pore radius, and number of OH groups per unit area. The extent of change depends generally on the temperature, duration of treatment, and pH of solution, although the last factor seems to be the most prominent. Such variation is ascribed to the enhanced dissolution of silica in the alkaline solution. Activation energies of hydrolysis of the siloxane bond were calculated as 17.2–19.0 kJ/mol, from a relationship correlating change in surface area with time.     

Comparison of a low-linolenic and a partially hydrogenated soybean oil using pan-fried hash browns

Hash browns (HB) were fried (Teflon-coated pan, ∼180°C) with low-linolenic acid (LL-SBO) and creamy partially hydrogenated soybean oils (PH-SBO). High-performance size-exclusion chromatography of the oil extracted before heating indicated a relatively low polymer content (LL-SBO, 3.8%; PH-SBO, 1.6%), although the oil remaining in the pan after frying had a much greater polymer content (38.8%, LL-SBO; 17.5%, PH-SBO). The percentage of altered TAG in the LL-SBO sample (extracted from HB) was 34.4% after frying, whereas the PH-SBO had 33.2% altered TAG (as determined by supercritical fluid chromatography). In the LL-SBO pan-fried HB samples (not the extracted oil), 2-pentanone, hexanal, 2-hexenal, trans-2-heptenal, 2-pentylfuran, and trans-2-octenal were found, whereas the major volatile compounds in the HB fried with PH-SBO included hexanal, trans-2-hexenal, and trans-2-heptenal. Hexanal was the most abundant volatile compound in both HB samples (LL-SBO, 2.7 ppm; PH-SBO, 0.3 ppm). There were significant differences in the polymer content, hexanal content, p-anisidine values, and Foodoil sensor readings between LL-SBO and PH-SBO (P<0.05). The PH-SBO sample was more stable than the LL-SBO sample. Moreover, the LL-SBO oil sample in the pan after frying had the greater increase in polymer content.     

Effect of whey protein supplementation on levels of endocannabinoids and some of metabolic risk factors in obese women on a weight-loss diet: a study protocol for a randomized controlled trial

Background

Besides the effects of dietary long chain PUFA on circulating endocannabinoids concentrations, the impact of other nutrients on these system is not known and, whether changes in plasma endocannabinoids levels correlated with changes in body composition and biochemical metabolic risk factors in obese individuals, however, still remains to be characterized.

Methods

We will conduct a 2 months’ open label, parallel-group, randomized controlled trial to determine the effect of whey protein supplementation on levels of endocannabinoids, glycemic and lipid profile, inflammatory factors, adipocytokines and body composition in 60 premenopausal obese women on a weight-loss diet.

Conclusion

Due to strong relationship between endocannabinoids level and insulin resistance and obesity, in this trial, we will illustrate the other benefits of weight loss diet on health and metabolic risk factors. Also for the first, the effects of simultaneous weight loss diet and whey protein supplementation on these variables will be determined.

Trial registration

Iranian Registry of Clinical Trials IRCT2017021410181N8.