New Highly Effective Phosphite‐Phosphoramidite Ligands for Palladium‐Catalysed Asymmetric Allylic Alkylation Reactions

We have designed a new family of readily available highly‐modular phosphite‐phosphoramidite ligands for asymmetric allylic alkylation reactions. The introduction of a phosphoramidite moiety in the ligand design is highly advantageous in the product outcome. Thus, this ligand series affords high reaction rates and enantioselectivities and, at the same time, shows a broad scope for disubstituted hindered and unhindered substrate types.     

Oxidative Stability of Conventional and High-Oleic Vegetable Oils with Added Antioxidants

The oxidative stability of conventional and high-oleic varieties of commercial vegetable oils, with and without added antioxidants, was evaluated using the oil stability index (OSI). Oil varieties studied were soybean (SOY), partially-hydrogenated soybean (PHSOY), corn (CORN), sunflower (SUN), canola (CAN), high-oleic canola (HOCAN), very high-oleic canola (VHOCAN), oleic safflower (SAF) and high-oleic sunflower (HOSUN). One or more commercial antioxidants were added to the four most stable oils at supplier-recommended levels: rosemary extract (RM; 1,000 ppm), ascorbyl palmitate (AP; 1,000 ppm), tert-butylhydroquinone (TBHQ; 200 ppm), and mixed tocopherols (TOC; 200 ppm). OSI in hours (h) at 110 °C of the conventional oils were 5.2, 7.6, 8.4, 9.8, 10.9 and 14.3 h for SUN, SOY, CAN, CORN, PHSOY and SAF, respectively. OSI of high-oleic variants were 12.9, 16.5 and 18.5 h for HOCAN, HOSUN and VHOCAN, respectively. Maximum OSI values for the four most stable oils when treated with antioxidants, were 40.9, 48.5, 48.8 and 55.7 h for HOCAN, VHOCAN, SAF and HOSUN, respectively. Addition of TBHQ, alone and in combination with other antioxidants, resulted in the greatest increase in oxidative stability of SAF and other high-oleic oils evaluated. AP had a positive synergistic effect when used with TBHQ, while RM decreased TBHQ effectiveness.     

Blood glucose prediction using multi-objective grammatical evolution: analysis of the “agnostic” and “what-if” scenarios

Genetic Programming and Evolvable Machines - In this paper we investigate the benefits of applying a multi-objective approach for solving a symbolic regression problem by means of Grammatical...     

Polygeneration Study of Low-to-Medium Enthalpy Geothermal Reservoirs in Mexico

This study combines the thermodynamic analysis of a polygeneration system along with the numerical modelling of the thermal behavior of geothermal reservoirs in...     

Purification and properties of a lipase from Penicillium chrysogenum isolated from industrial wastes

A fungal lipase was isolated from the wastes of industrial cultures of Penicillium chrysogenum employed in antibiotics production. Lipase activity was only detected in solid aggregates present in the protein concentrates. To extract the lipase, Triton X‐100 was the most suitable surfactant. The lipase was further purified by hydrophobic interaction and anion exchange chromatography. A molecular mass of approx 40 kDa and a pI of approx 3.8 were estimated. Optimum pH and temperature were 7.9–8.1 and 45 °C respectively. Although its activity in the hydrolysis of lipids and esters is not very high, the lipase from P chrysogenum proved to be notably efficient in several synthetic reactions in non‐aqueous media. © 2000 Society of Chemical Industry     

THE NYQUIST ROBUST STABILITY MARGIN—A NEW METRIC FOR THE STABILITY OF UNCERTAIN SYSTEMS

The Nyquist robust stability margin k_N is proposed as a new tool for analysing the robustness of uncertain systems. The analysis is done using Nyquist arguments involving eigenvalues instead of singular values, and yields exact necessary and sufficient conditions for robust stability. The concept of a critical line on the Nyquist plane is defined and used to calculate a critical perturbation radius which in turn is used to produce k_N. The new approach gives alternatives to computing exact stability margins in some cases of highly directional uncertainty templates where other models are not applicable. © 1997 by John Wiley & Sons, Ltd.     

Surimi gels from striped mullet (Mugil cephalus) employing microbial transglutaminase

Striped mullet (Mugil cephalus) is an abundant marine coastal fish of tropical waters and has a low commercial value. This work deals with the assessment of striped mullet as a resource for surimi gels. To improve the gels obtained, the addition of microbial transglutaminase was evaluated. Optimal conditions for setting were determined using mathematical models. Concentration of microbial transglutaminase (MTGase), temperature and time were studied to improve the mechanical properties of surimi gels from striped mullet. Shear stress was strongly affected by the variables studied while shear strain was moderately affected. Maximum shear stress (156 kPa) was obtained by employing the following setting conditions: a concentration of MTGase of 9.3 g/kg of surimi, a temperature of 37°C and a time of 3.9 h. Under these conditions the shear strain was 1.34. Maximum shear strain (1.57) was obtained by employing the following conditions: a concentration of MTGase of 5 g/kg of surimi, a temperature of 34.5°C and a time of 1 h. Under these conditions the shear stress was 123 kPa.     

双引擎勇士

历史总是让我们在"喷火"、"野马"、"零"式战斗机和令人恐惧的德国Bf-109等著名飞机上见识到二战的空中神话,它们都是一些单引擎战斗机.事实上我们忘记了,很多同样或类似的任务是由双引擎战机执行的.和它们的单引擎兄弟一样,双引擎飞机也在历史上赢得了一席之地,铸就不少空中传奇. 我们将在本期的杂志中向那些似乎总是被遗忘的...