Detailed analysis of stability and bifurcation properties and of the dynamic behaviour of isothermal continuous mixed suspension, mixed product removal (CMSMPR) crystallizers is presented using the moment equation model. It is shown that isothermal CMSMPR crystallizers may exhibit not only limit cycle oscillations but, in the case of magma-dependent nucleation, also saddle point instabilities. Applying the Mikhailov stability criterion, two equivalent sets of necessary and sufficient conditions are derived for checking the stability of steady states.

Dr. Kletz is one the pioneers in the process safety area, known widely for his work on inherent safety design and loss prevention. He worked 38 years in Imperial Chemical Industries, and became a fulltime researcher only after his retirement. He published more than 200 papers and 15 books during his retirement. The intellectual basis analysis presented in this article shows that he frequently cited his books in his articles, indicating that his industrial experience was very influential to his scholarly contributions. Lawley, H.G. was one of the researchers whose work had most influence on Kletz's research. Among Dr. Kletz's publications, the article ‘What You Don't Have, Can't Leak’ has the highest impact, while his most influential book is ‘Process plants: A handbook for inherently safer design’. The references co-citation network is divided in two clearly connected components: his earlier work related to infra-red spectra, and his later work addressing process safety related topics, including inherent safety and hazard and accident analysis. Both his work and that of his followers is rooted in a similar intellectual basis within process safety research, in which particularly Dr. Kletz's earlier work forms an influential original body of knowledge rooted in his industrial experience. His career is a prime example of how process safety research has been strongly influenced by knowledge from industrial practice, illustrating that a continued strong connection between industry and academia can lead to very fruitful outcomes. It is hoped that the presented analysis can inspire especially young graduates with academic interests to first embark on an industrial career to gain industrial experience before aiming to contribute to academic process safety knowledge.

Health care professionals (HCPs) are crucial to physician-assisted death (PAD) provision.To quantitatively assess the favorability of justifications for or against PAD legalization among HCPs, the effect of the terms “suicide” and “euthanasia” on their views and their support for three forms of PAD.Our questionnaire presented three cases: physician-assisted suicide, euthanasia for a competent patient, and euthanasia for an incompetent patient with an advance directive for euthanasia. Respondents judged whether each case was ethical and should be legal and selected their justifications from commonly cited reasons. The sample included physician clinicians, researchers, nonphysician clinicians, and other nonclinical staff at a major academic medical center.Of 221 HCPs, the majority thought that each case was ethical and should be legal. In order of declining favorability, justifications supporting PAD legalization were relief of suffering, right to die, mercy, acceptance of death, nonabandonment, and saving money for the health care system; opposing justifications were the slippery slope argument, unnecessary due to palliative care, killing patients is wrong, religious views, and suicide is wrong. The use of suicide and euthanasia terminology did not affect responses. Participants preferred physician-assisted suicide to euthanasia for a competent patient (P < 0.0001) and euthanasia for an incompetent patient to euthanasia for a competent patient (P < 0.005).HCPs endorsed patient-centered justifications over other reasons, including role-specific duties. Suicide and euthanasia language did not bias HCPs against PAD, challenging claims that such value-laden terms hinder dialogue. More research is required to understand the significance of competency in shaping attitudes toward PAD.

Recent advances in dividing wall column (DWC) have led to renewed interest in the design or redesign of many industrial processes. For the distillation system of cumene production, the existing design alternatives have the potentials of energy savings and consequently the reduction of total annual cost (TAC) and energy consumption. In this paper, cumene production based on the real industrial process is simulated in a conventional process using commercial process simulator Aspen Plus, and two DWC distillation processes are introduced. Then optimization study for the proposed DWC distillation processes is performed based on the TAC calculation with sensitivity analysis to investigate the effects of operating parameters. The results indicate that the optimum DWC distillation process works well for the production of cumene, and the corresponding TAC is reduced significantly accompanied by substantial energy savings.

A range of N-phenethyl, N-phenacyl, and N-(1- and 2-naphthylmethyl) derivatives of 5,7-dibromoisatin 2 were prepared by N-alkylation reactions. Their activity against human monocyte-like histiocytic lymphoma (U937), leukemia (Jurkat), and breast carcinoma (MDA-MB-231) cell lines was assessed. The results allowed further development of structure–activity relationships. The compound 5,7-dibromo-N-(1-naphthylmethyl)-1H-indole-2,3-dione 5a was the most potent against U937 cells with an IC50 value of 0.19 μM.

A mathematical model incorporating many of the important processes at work in the crystallization of emulsions is presented. The model describes nucleation within the discontinuous domain of an emulsion, precipitation in the continuous domain, transport of monomers between the two domains, and formation and subsequent growth of crystals in both domains. The model is formulated as an autonomous system of nonlinear, coupled ordinary differential equations. The description of nucleation and precipitation is based upon the Becker-Doring equations of classical nucleation theory. A particular feature of the model is that the number of particles of all species present is explicitly conserved; this differs from work that employs Arrhenius descriptions of nucleation rate. Since the model includes many physical effects, it is analyzed in stages so that the role of each process may be understood. When precipitation occurs in the continuous domain, the concentration of monomers falls below the equilibrium concentration at the surface of the drops of the discontinuous domain. This leads to a transport of monomers from the drops into the continuous domain that are then incorporated into crystals and nuclei. Since the formation of crystals is irreversible and their subsequent growth inevitable, crystals forming in the continuous domain effectively act as a sink for monomers "sucking" monomers from the drops. In this case, numerical calculations are presented which are consistent with experimental observations. In the case in which critical crystal formation does not occur, the stationary solution is found and a linear stability analysis is performed. Bifurcation diagrams describing the loci of stationary solutions, which may be multiple, are numerically calculated.

The design and application of a novel plug flow crystalliser is described. Simultaneous collection of SAXS and WAXD during the nucleation and crystal growth of a small organic molecule from solution is reported. Preliminary data imply the separation of a non-diffracting phase prior to the appearance of crystalline solid.

Energy is becoming a major topic in human geography, due to its fundamental importance to the functioning of contemporary societies and its link to anthropogenic climate change because of atmospheric emissions of greenhouse gases from coal, oil, natural gas, and biofuels. Human geographers have sought to understand the relations between energy and society, and their implications for people and the planet. This entry outlines some of the main ways that geographers have approached the analysis of energy. Section one focuses on geographical issues relating to energy generation and supply, highlighting the significant landscape changes brought about by extensive energy production and the complex politics and conflicts that can follow. Section two focuses on the geographies of energy consumption, and summarizes the alternative ways that researchers can seek to understand the underlying drivers of energy consumption. Finally, section three discusses the multiple forms of inequality and injustice that can result from the production and consumption of energy, before focusing particularly on the issue of energy poverty.

We present a mathematical model describing the inward solidification of a slab, a circular cylinder and a sphere of binary melt kept below its equilibrium freezing temperature. The thermal and physical properties of the melt and solid are assumed to be identical. An asymptotic method, valid in the limit of large Stefan number S, is used to decompose the moving boundary problem for a pure substance into a hierarchy of fixed-domain diffusion problems. Approximate, analytical solutions are derived for the inward solidification of a slab and a sphere of a binary melt which are compared with numerical solutions of the unapproximated system. The solutions are found to agree within the appropriate asymptotic regime of large Stefan number and small time. Numerical solutions are used to demonstrate the dependence of the solidification process upon the level of impurity and other parameters. We conclude with a discussion of the solutions obtained, their stability and possible extensions and refinements of our study.

To better understand the complicated phenomena in a precipitation process, computational fluid dynamics (CFD) is utilized to account for reactions, crystallization, mixing, and their interactions. The moment transformations of the population balances taking into account the chemical and crystallization kinetics are integrated into a CFD solver to describe the generation and transportation of the crystal phase. The current work applies this CFD tool to simulate the reactive precipitation process in a semibatch crystallizer, which is widely used in chemical and pharmaceutical industries. BaSO4 precipitation is employed as an example system. The influence of hydrodynamics in the stirred tank, as characterized by the impeller speed and feed location, on the distribution of supersaturation and the subsequent crystal size distribution is investigated. The numerical predictions are validated with measurements and can be used as an aid in the optimization of semibatch precipitator design.

This chapter begins by looking at the use of the information available in phase diagrams to define the nature of the crystalline phase that will appear under a given set of conditions of temperature, pressure, and composition. The phase rule tells us under which conditions certain systems can be in equilibrium. The chapter then examines the nature of the driving force for crystallization processes and outlines some typical techniques used for preparing crystalline materials, including suspension crystallization and the solidification of melts. Crystallization is a kinetic process and, traditionally, chemists are familiar with the use of reagent concentration to describe the driving force for the chemical rate process. However, in the case of crystallization, the concentration range over which the process can occur is limited by the equilibrium composition of the system corresponding to the conditions chosen.

This chapter explores crystals in formulated products. Having developed a process for preparing a product in a crystalline form, it is important to appreciate that these crystals usually then have to be transformed into a product. In some cases, this is achieved by further chemical reaction, in others by formulation. Formulation is a generic term given to the collection of physical processes such as milling, mixing, dissolution, tableting, and melting that transform individual single components into multicomponent products. Perhaps the most important component of a formulated product is the active ingredient which, although isolated in the production plant as a crystalline material with appropriate characteristics for purity and bulk handling, must now be present in a form suitable for maximizing its effectiveness in its end use. The chapter then considers crystals as property controllers, before looking at crystallization controllers.

This chapter describes the characteristics of continuous and batch crystallizers. The ‘mixed product removal’ assumption of the MSMPR crystallizer ensures that crystals of all sizes have the same mean residence time, which is also equal to that of the solution. If crystals have mean residence times that depend on their size, considerable extra flexibility of operation is achieved and greater variations in the crystal size distribution are possible. Meanwhile, batch crystallizers are widely used in the production of speciality, agro-, and pharmaceutical chemicals where the production rates are comparatively low. In discussing batch crystallization, the emphasis tends to be on the mode of operation rather than on the design of a specific piece of equipment.

This chapter assesses polymorphism, which is the ability of some molecules to adopt more than one crystal structure. When preparing materials by crystallization, it is important to recognize and to be able to control this phenomenon, because each polymorph has its own unique combination of mechanical, thermal, and physical properties. The production of specific and well-defined polymorphs is therefore crucial in chemical manufacture. In the chemical and pharmaceutical industry, the demand for high yields and high production rates has forced chemists and engineers to operate processes far from equilibrium, so exacerbating the tendency to form polymorphic structures that, for a given temperature, pressure, and composition, are not the most stable. Such unstable structures will eventually undergo phase transitions to more stable phases. This transformation process and its structural and thermodynamic basis are the subjects of the chapter.

This chapter addresses number balances and size distribution modelling. Together with the crystal morphology, the crystal size distribution (CSD) produced within a crystallizer is of crucial importance in determining the ease and efficiency of subsequent solid–liquid separation steps, the suitability of crystals for further processing, their caking and storage characteristics, and the eventual customer appeal of the product. The size distribution influences the supersaturation at which the crystallizer operates and so has an effect on the crystal nucleation and growth rates, crystal morphology and purity, fouling of solid surfaces, and the stability of operation. The most revealing way to explore these interactions is by making use of the number or population balance. The chapter then looks at the continuous mixed suspension mixed product removal (MSMPR) crystallizer.

From Molecules to Crystallizers begins by stating that crystallization is one of the oldest separation processes used in the chemical industry and is still one of the most important. It is also going through an exciting renaissance, the text argues, with the result that it is becoming yet more central to the needs of the modern chemical industry. As well as its long-standing use in the commodity chemicals business, it is central to the fine and speciality areas. The emphasis on crystallization has thus been changing from the simple production of bulk solid particles to one in which ever higher standards and reproducibility of particle size, size distribution, crystal form and particle morphology are demanded in both product and process development.

This chapter focuses on crystal morphology. The overall shape of a crystal—often called its habit, form, or morphology—is a vital parameter in determining the viability of both processes and products. It is usual to distinguish between ‘equilibrium’ and ‘growth’ morphologies. Morphology is determined by two factors: the symmetry of the internal crystal structure, which is manifest in the point group symmetry of the crystal form; and the relative growth rates of the faces bounding the crystal, which are related to the energetics of molecule or ion attachment to the crystal surfaces. The surface-specific nature of this attachment process means that crystal morphology can be dramatically influenced by external factors such as the level of supersaturation, temperature, the growth solvent, and solution purity.