A comprehensive study of the loss of enzyme activity in a continuous membrane reactor – application to starch hydrolysis

Loss of enzyme activity is a problem associated with enzymatic reactions in continuous recycled membrane reactors (CRMR). It may result from catalyst leakage and also enzyme denaturation due to the effects of pH, temperature, shear effects or adsorption/deposit on membrane. In this study, the relative importance of these various factors has been assessed in order to reduce their adverse effects on starch hydrolysis in a CRMR. The effects of temperature and denaturation by adsorption/deposit on membrane were the most limiting phenomena. Reducing the temperature to overcome thermal denaturation was not a practical solution since this increases viscosity and thereby decreases permeate flux and reactor performance. Insofar that adsorption/deposit of enzymes on the membrane is directly linked to membrane fouling, back‐flushing or regularly purging retentate should reduce this phenomenon by lowering accumulation of high molecular weight products. © 2001 Society of Chemical Industry     

Pinoresinol and 1-acetoxypinoresinol, two new phenolic compounds identified in olive oil

Polyphenols of olive oil show autoprotective, sensory, and nutritional-therapeutic effects. Two new phenolic compounds have been isolated from virgin olive oils by preparative high-performance liquid chromatography and their structures established on the basis of their mass spectra and nuclear magnetic resonance spectral data. The compounds identified are the lignans pinoresinol and 1-acetoxypinoresinol. Both have been found in all the commercial virgin olive oils analyzed. Pinoresinol concentration was rather similar in all the oils. In contrast, 1-acetoxypinoresinol concentration was higher in oils of the Arbequina and Empeltre cultivars than in Picual or Picudo cultivars. Pinoresinol and 1-acetoxypinoresinol may represent the major phenolic compounds in some Arbequina and Empeltre oils. Lignans possess biological and pharmacological properties and, therefore, the two new compounds identified in olive oils may contribute to the reported beneficial effects which are attributed to polyphenols on human health of a diet rich in olive oil.     

TP53 in Acute Myeloid Leukemia: Molecular Aspects and Patterns of Mutation

Mutation of the tumor suppressor gene, TP53, is associated with abysmal survival outcomes in acute myeloid leukemia (AML). Although it is the most commonly mutated gene in cancer, its occurrence is observed in only 5–10% of de novo AML, and in 30% of therapy related AML (t-AML). TP53 mutation serves as a prognostic marker of poor response to standard-of-care chemotherapy, particularly in t-AML and AML with complex cytogenetics. In light of a poor response to traditional chemotherapy and only a modest improvement in outcome with hypomethylation-based interventions, allogenic stem cell transplant is routinely recommended in these cases, albeit with a response that is often short lived. Despite being frequently mutated across the cancer spectrum, progress and enthusiasm for the development of p53 targeted therapeutic interventions is lacking and to date there is no approved drug that mitigates the effects of TP53 mutation. There is a mounting body of evidence indicating that p53 mutants differ in functionality and form from typical AML cases and subsequently display inconsistent responses to therapy at the cellular level. Understanding this pathobiological activity is imperative to the development of effective therapeutic strategies. This review aims to provide a comprehensive understanding of the effects of TP53 on the hematopoietic system, to describe its varying degree of functionality in tumor suppression, and to illustrate the need for the adoption of personalized therapeutic strategies to target distinct classes of the p53 mutation in AML management.     

LLDPE with Exclusively Ethyl Branches by Tandem Catalysis with Single-Site Zr(IV)/Co(II) Catalysts

Semicrystalline linear low density polyethylenes (LLDPEs) with exclusively ethyl branching (from 7 to 56 branches per 1,000 carbon atoms) were prepared from ethylene by homogeneous tandem catalytic systems comprising (imino)pyridine cobalt(II) dichlorides as oligomerization precursors, bis(cyclopentadienyl)zirconium(IV) dichloride as copolymerization precursor and methyaluminoxane as activator. The activity of the tandem systems was evaluated by varying either the molar fraction of the cobalt precursors or the ethylene pressure. The latter parameter was of crucial importance to control both the productivity and the extent of 1-butene incorporation. In particular, increasing the ethylene pressure from 2 bar to 4 bar changed the “comonomer effect” from positive to negative.     

Highly Diastereo‐ and Enantioselective Catalytic Domino Thia‐Michael/Aldol Reactions: Synthesis of Benzothiopyrans with Three Contiguous Stereocenters

Highly enantioselective organocatalytic domino thia‐Michael/aldol reactions between 2‐mercaptoacetophenone and α,β‐unsaturated aldehydes are presented. The reactions proceed with excellent chemo‐, diastereo‐ and enantioselectivity to give the corresponding benzothiopyran derivatives in high yields with up to >15:1 dr and 96 to >99 % ee.     

An approach to integrate manufacturing process information in part design phases

Design for Manufacturing (DFM) is the integrated practice of designing components while considering their manufacture (O’Driscoll, M., 2002. Design for manufacture. Journal of Material Processing Technology, 122, 318–321). The benefits of this practice have been widely acknowledged in the industry. Several techniques fall under the umbrella of Design for Manufacturing, and their implementation depends heavily on the context in which they will be applied. How to enhance their use by designers is still an issue. The use of a formalized design process, in which a software application is used to bring manufacturing knowledge to the forefront, would improve DFM implementation. In such a context, a fundamental issue is to define the manufacturing information that should be presented to the designer.This work addresses the capture and documentation of essential DFM information to make design decisions. Essential manufacturing information is that which can affect the fulfilment of functional requirements and product constraints. The proposed approach combines DFM techniques and principles of Axiomatic Design (AD) theory. The manufacturing information is represented by the concepts of Process Property (PP) and process Execution Variable (EV). The ultimate aim of the approach is to define manufacturing knowledge structures and develop a knowledge-based application for DFM.The approach was applied to a case study in which a connecting rod was the part to de designed and manufactured. The manufacturing processes selected were forging and powder metallurgy. The DFM information about these manufacturing processes, related to the connecting rod, was identified and formalized in a table-based data structure.     

Transformation kinetics for nucleus clusters

A rigorous mathematical approach based on stochastic geometry concepts is presented to extend previous Johnson–Mehl, Avrami, Kolmogorov treatment of transformation kinetics to situations in which nuclei are not homogeneously located in space but are located in clusters. An exact analytical solution is presented here for the first time assuming that nucleation sites follow a Matérn cluster process. The influence of Matérn cluster process parameters on subsequent growth kinetics and the microstructural path are illustrated by means of numerical examples. Moreover, using the superposition principle, exact analytical solutions are also obtained when nucleation takes place by a combination of a Matérn cluster process and an inhomogeneous Poisson point process. The new solutions presented here significantly increase the number of exactly solvable cases available to formal kinetics.     

Transformation kinetics for inhomogeneous nucleation

A rigorous mathematical approach based on an inhomogeneous (marked) Poisson point process is presented to extend previously proposed treatment of transformation kinetics to situations in which nuclei are not homogeneously located in space. The potential of the proposed methodology is illustrated by applying it to the case of nucleus intensity varying along a single preferential direction. The exact analytical solutions presented here significantly broaden the range of analytical solutions available to formal kinetics regarding nuclei location deviating from the classical “randomly” located nuclei assumption.     

Characterization and carbonylic hydrogenation of methyl oleate over Ru-Sn/Al2O3: Effects of metal precursor and chlorine removal

Hydrogenation of methyl oleate to oleyl alcohol was evaluated over Ru-Sn/Al₂O₃ catalysts, prepared from different precursors, at 270 °C and 5.0 MPa. Two kinds of metal precursors were employed: chlorine-free precursors and inorganic chlorides. In addition, several methods for chlorine removal of metal-chloride-based catalysts were studied. Catalysts were characterized by EDX, XRF, DRX, BET and TPR analyses. Selectivity toward unsaturated alcohol was higher with the bimetallic catalyst based on chlorine-free precursors than with the catalyst based on metal chlorides, owing that chlorine avoids, at certain extent, an effective interaction between ruthenium and tin species. However, the most selective catalyst was the bimetallic one based on chloride precursors and reduced with NaBH₄, due to elimination of residual chlorine and higher dispersion of Ru-Sn species.