Microreactor Technology as a Tool for the Synthesis of a Glitazone Drug Intermediate

One of the bottlenecks in the pharmaceutical industry is drug production scale‐up, which can be performed by microreactor technology. Such an approach was applied to the synthesis of (Z)‐5‐(4‐hydroxybenzylidene)thiazolidine‐2,4‐dione, a bioactive aromatic heterocyclic compound belonging to the class of glitazones. n‐Propanol was the best solvent and piperidine the best catalyst for the batch reaction, which was completed in only 5.5 h. In the microreactor, the productivity was almost independent of solvent. The microreactor behaved as a plug‐flow reactor and operated at a steady state for ten hours without efficiency loss. The results suggest that microreactors may replace batch reactors in scaling up drug production.     

Integration of microbial and chemical processing for a sustainable metallurgy

Bioprocessing for the recovery of metal from divergent resources using the microbial strategy has emerged as a green technology in metallurgical operations. The limitations to maintain the ideal condition for bacterial growth with slow kinetics, however, have been considered as major obstacles to bioprocessing being implemented more widely. This can be overcome by integrating the microbes with a chemical processing route. The available reports on recent developments in hybrid bio‐chemical processing of both primary and secondary resources have presented promising results, exhibiting the potential for use in large‐scale metallurgy. In this context, reviewing the factors of the hybrid process would benefit from knowledge acquired in fundamental studies. The present review focuses on bio‐chemical process integration using eco‐friendly design tools for treating the difficult to extract resources and complex spent materials as well. Furthermore, the potential of hybrid technology has been evaluated by establishing an economic model as a case study which encompasses features of economic development, environmental consideration and societal matters to achieve process sustainability. © 2017 Society of Chemical Industry     

Synthesis of a quaternary ammonium derivative of chito‐oligosaccharide as antimicrobial agent for cellulosic fibers

A derivative of chito‐oligosaccharide (COS), N‐(2‐hydroxyl)propyl‐3‐trimethyl ammonium chito‐oligosaccharide chloride (HTACC), was synthesized using a reaction of glycidyltrimethylammonium chloride (GTMAC) and COS prepared by depolymerization of a fully deacetylated chitosan. COS and HTACC were applied to the cotton fabrics with a pad‐dry‐cure process using the reaction between the hydroxyl group of cellulose and terminal aldehyde group in COS and HTACC. Their minimum inhibition concentration (MIC) was evaluated, and the antimicrobial activity and durability to laundering of cotton fabrics treated with them were compared. The complete substitution of NH₂ groups in COS with GTMAC was obtained at a 4 : 1 mol ratio of GTMAC to NH₂ in 18 h at 80°C under the presence of acetic acid. MIC values of the 1.04 DS of HTACC and COS were 50 and 400 μg/mL, respectively. A cotton fabric treated with 0.2% of HTACC and 1.8% of COS exhibited 100% reduction of bacteria. At the 50th laundering cycle, 0.3% of HTACC and 2.4% of COS indicated 100% bacterial reduction. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 2009–2015, 2000     

Design of a Pipe/Ring Type of Sparger for a Bubble Column Reactor

The sparger is an important accessory of bubble column reactors which governs the performance of the reactor. Specifically the sparger design becomes more important when the aspect ratio of the bubble column is low. The maldistribution and design of the sparger are of major concern and both these aspects are described in detail in the present work. Various methods for reducing maldistribution have been discussed and a simple method for its reduction is presented experimentally. Further a step‐wise design procedure for a pipe/ring type of sparger for bubble columns is presented together with a work example.     

Coconut water as a potential resource for cellulose acetate membrane preparation

BACKGROUND: Cellulose acetate membranes are frequently used for pressure‐driven membrane processes. The aim of this work was to prepare cellulose acetate membranes from nata‐de‐coco using coconut water as starting material. The use of this lignin‐free material will certainly minimize the use of chemicals usually needed in the traditional pulps and substitute for the use of wood, which helps prevent global warming and preserves nature as well. RESULTS: Coconut water was fermented by Acetobacter xylinum for 6 days to produce nata‐de‐coco, which was then acetylated to produce cellulose diacetate with an acetyl content of 39.6%. Fourier transform infrared analysis showed characteristic peaks for the acetyl group at 1748 and 1236 cm^?1. The resulting membranes made from the hydrolysis product showed a water flux of 210.5 L m^?2 h^?1 under an applied pressure of 2 kg cm^?2 while the rejection coefficients of dextran T‐500 and T‐2000 solutions were 78 and 93.7%, respectively. CONCLUSION: Coconut water has a potential to be used in the fabrication of membranes by converting it to nata‐de‐coco and then to cellulose diacetate which gives an added value to its original nature. It is also highly competitive compared to the traditional pulps, by which acetylation decreases the degree of crystallinity of nata‐de‐coco resulting in higher membrane permeability. Copyright © 2007 Society of Chemical Industry     

Rapid test methods for analyzing degradable polyolefins with a pro‐oxidant system

Chemiluminescence, size exclusion chromatography, differential scanning calorimetry, thermogravimetry, and Fourier transform infrared spectroscopy were used to assess differences in oxidation rate between two different pro‐oxidant systems in degradable low‐density polyethylene. The pro‐oxidant formulation used consisted of manganese stearate and natural rubber or manganese stearate and a synthetic, styrene‐butadiene copolymer rubber. The low‐density polyethylene containing the pro‐oxidant with natural rubber showed the highest degradation rate. Chemiluminescence and thermogravimetry were found to be the most effective techniques for establishing the differences between different pro‐oxidant systems. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2309–2316, 2001     

Design of a Flexible Pilot Plant Reactor for the Steam Cracking Process

A design technique for a pilot plant reactor of single diameter is presented to scale up or down steam cracking coils of different configurations like mono‐tubular, classical, and reversed splits. Using dimensional analysis, two criteria are selected in establishing partial similarity between different scales, the mean residence time, and the axial pressure profile in the reactor, in addition to preserving the flow pattern within the turbulent region. The sensitivity and accuracy of the proposed method is compared to another conceivable alternative that focuses on the lateral gradients. The pilot reactor coil is adapted for any large‐scale reactor by the adjustment of feed flow rate and the effective length exposed to the firebox heat flux. Simulation results for naphtha cracking in a commercial split coil and also the equivalent pilot plant reactors are used for verification and validation of this method.     

Development of a Design Methodology Against Fast Cook‐Off Threat for Insensitive Munitions

This work provides a design methodology for a typical energetic system to get Type V insensitive munition (IM) response against fast cook‐off threat. Experimental and numerical results for a generic test item filled with PBXN‐109 explosive are presented. Two key aspects of IM design against fast cook‐off threat are investigated, which are “time‐to‐reaction” and “critical ventilation area”. By dividing the problem to pre‐ignition and post‐ignition, the complexity of the problem is reduced. The first part of the study covers two‐dimensional and three‐dimensional simulations of the problem, where the generic test item is modelled using commercial CFD software (ANSYS – Fluent). The second part of the study reveals low pressure (2–10 MPa) burning characteristics of a PBXN‐109 by strand burner tests. After obtaining the pressure dependent burning rate, a conservation of mass equation is used to determine the chamber pressure using MATLAB Simulink software. Calculations are in reasonable agreement with the experimental results. Calculations are compared with the tests performed. The results are in reasonable agreement with some discrepancies of 8.9 % for time to reaction prediction and of 10.9 % for ventilation characteristics analyses. Possible reasons of these differences are discussed.     

A reduced‐order model for chemical species transport in a tube with a constant wall concentration

A two‐dimensional advection‐diffusion model accompanied with a parabolic velocity profile of Poiseuille flow is considered for the chemical species transport in a tube with a constant wall concentration. The Reynolds decomposition technique is applied to reduce it to an equivalent one‐dimensional model for advective‐dispersive transport in a tube through which the effective advection coefficient, the dispersion coefficient, and the effective Sherwood number are developed for the problem under study. The derived and the classical Taylor models are also compared in order to find the difference between the two arrangements. The reduced‐order model for the transport equation shows that the effective advection coefficient increases, whereas the dispersion coefficient in the tube decreases as compared to the classical Taylor equation. The effective Sherwood number for the steady state form of the developed model is found to be only a function of the Peclet number, which varies in the range of 3.215 ≤ Sh ≤ 4. These results find application in design of experiments and improve our understanding of mass transfer in microfluidic devices.     

Empirical Likelihood for a Long Range Dependent Process Subordinated to a Gaussian Process

This article develops empirical likelihood methodology for a class of long range dependent processes driven by a stationary Gaussian process. We consider population parameters that are defined by estimating equations in the time domain. It is shown that the standard block empirical likelihood (BEL) method, with a suitable scaling, has a non‐standard limit distribution based on a multiple Wiener–Itô integral. Unlike the short memory time series case, the scaling constant involves unknown population quantities that may be difficult to estimate. Alternative versions of the empirical likelihood method, involving the expansive BEL (EBEL) methods are considered. It is shown that the EBEL renditions do not require an explicit scaling and, therefore, remove this undesirable feature of the standard BEL. However, the limit law involves the long memory parameter, which may be estimated from the data. Results from a moderately large simulation study on finite sample properties of tests and confidence intervals based on different empirical likelihood methods are also reported.     

Development of a pre‐purification process for homoharringtonine

A novel pre‐purification method was developed for producing homoharringtonine from Cephalotaxus koreana, giving high purity and yield. The simple, efficient procedure involved biomass extraction, liquid–liquid extraction, and synthetic adsorbent treatment, followed by low‐pressure chromatography. The use of active clay treatment and silica gel low‐pressure chromatography in the pre‐purification process allowed for the rapid, efficient separation of homoharringtonine from interfering compounds and, compared with alternative processes, increased the yield and purity of crude homoharringtonine for subsequent high‐performance liquid chromatography (HPLC) purification. Homoharringtonine of over 52% purity could be obtained simply with high yield from biomass using this pre‐purification method, while minimizing solvent use and the scale and complexity of HPLC operations for homoharringtonine purification. Copyright © 2005 Society of Chemical Industry     

Hybrid time slots sequencing model for a class of scheduling problems

This article presents a new model for the short‐term scheduling of multistage batch plants with a single unit per stage, mixed storage policies, and multiple shared resources for moving orders between stages. Automated wet‐etching stations for wafer fabrication in semiconductor plants provide the industrial context. The uncommon feature of the continuous‐time model is that it relies on time grids, as well as on global precedence sequencing variables, to find the optimal solution to the problem. Through the solution of a few test cases taken from the literature, we show that new model performs significantly better than a pure sequencing formulation and better than a closely related hybrid model with slightly different sequencing variables. We also propose a new efficient heuristic procedure for extending the range of problems that can effectively be solved, which essentially solves relaxed and constrained versions of the full‐space model. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Derivative‐free optimization for expensive constrained problems using a novel expected improvement objective function

In this work, an algorithm for the optimization of costly constrained systems is introduced. The proposed method combines advantages of global‐ and local‐search algorithms with new concepts of feasibility space mapping, within a framework that aims to find global solutions with minimum sampling. A global search is initially performed, during which kriging surrogate models of the objective and the feasible region are developed. A novel search criterion for locating feasibility boundaries is introduced, which does not require any assumptions regarding the convexity and nonlinearity of the feasible space. Finally, local search is performed starting from multiple locations identified by clustering of previously obtained samples. The performance of the proposed approach is evaluated through both benchmark examples and a case study from the pharmaceutical industry. A comparison of the method with commercially available software reveals that the proposed method has a competitive performance in terms of sampling requirements and quality of solution. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2462–2474, 2014     

Flow Manifold Optimization for a Uniform Velocity Distribution in a Laminated Microreactor with Micro‐Pin‐Fin Arrays

Velocity uniformity in reaction channels has a significant effect on the performance of laminated microreactors with micro‐pin‐fin arrays (MPFAR) for hydrogen production. The hydrogen production efficiency can be improved by optimizing the structure of flow manifolds. The relationship between the flow manifold structure and the velocity distribution in the reaction channel with MPFAR is established by an equivalent electrical resistance network model validated via simulation. The effects of the flow manifold structure on the velocity distribution are investigated. The results show that the velocity distribution can be improved by increasing the y‐direction coordinate Y_pi of the flow manifold inlet tube. The flow manifold structure is optimized for better velocity distribution in reaction channels with different MPFAR widths.     

Screening for Amidases: Isolation and Characterization of a Novel D‐Amidase from Variovorax paradoxus

Using racemic tert‐leucine amide as sole nitrogen source in minimal medium, 162 strains were isolated by enrichment techniques and shown to contain amidase activity. Among these isolates three D ‐amidase producers were found and identified as Variovorax paradoxus (two strains) and Klebsiella spec. The D ‐amidase from Variovorax paradoxus was purified to homogeneity by three chromatographic steps. With dl ‐Tle‐amide as substrate Michaelis Menten kinetics were observed with a K_M of 0.74 mM, a K_I of 640 mM and a V_max of 1.4 U/mg. The amidase has a broad pH‐optimum between 7 and 9.5 and a temperature optimum at 47–49 °C. The amidase hydrolyzed amino acid amides as well as carboxamides and 2‐hydroxy acid amides. The stereoselectivity of the reaction was variable, however. Hydrolyzing dl ‐Tle‐amide the enantiomeric ratio E was >200 resulting in D ‐Tle with an ee of >99% and up to 47% conversion. Similar results were obtained with dl ‐Leu‐amide and dl ‐Val‐amide while dl ‐Phe‐amide was hydrolyzed with an enantiomeric ratio E of only 5.