GCSIM: a gas-liquid chromatography simulator for educational purposes

A gas-liquid chromatography simulation program was written for personal computers. A graphic display of a chromatogram is shown by the simulator. The program can be used to illustrate various effects in gas chromatography for demonstrations or lectures. In addition, it can be used as an advanced supplemental instrument simulator in a practical course. Variables include column length, inlet pressure, phase ratio, temperature (both isothermal and linear programming) and detector attenuation. Additional parameters offer a choice between packed and capillary columns, two different detectors, two stationary phases and two carrier gases. The sample composition can be changed to include any solvent and up to six components from a library of 75 at different concentrations

EXSPECTARE: A digital string

The pandemic and labour market shortages in the Dutch healthcare sector have demanded much attention from managers. In many ways the situation has resulted in enormous challenges and dilemmas for everyone working in the healthcare sector, whether as a carer or board member. Healthcare institutions deal with regulations, complicated financial accountability, and social issues. It is not always easy to get recognition for how much the sector serves society. Henk is almost 59 years old and has been working with heart and soul in the sector for Nursing and Care Homes & Homecare (VVT) for decades. The last six years as Chairman of the Board of Exspectare Zorg (Healthcare). It’s an appropriate name for the organisatio

Training software for chiral separations in capillary electrophoresis

A previously published steady-state simulation program for CE was extended with a sub-menu for chiral interaction. The interaction was modelled with a hypothetical (neutral) selector with properties similar to cyclodextrins. A three-type chiral interaction model was implemented in such a way that it was valid for both anionic and cationic analytes. User-defined chiral variables in the model were: the concentration of this chiral selector, the complex formation constants (K) of both non-ionic and ionic analyte species, the relative K differences between the two optical isomers (also for both non-ionic and ionic species) and the mobility of the analyte–selector complex, relative to that of the fully dissociated free analyte. In addition the following non-chiral variables are added: the dependence of the bulk viscosity on the chiral selector concentration and the dependence of the mobilities on the viscosity. Chiral components in the data base are simulated as mixtures of optical isomers with variable enantiomeric concentration ratios. These chiral parameters, together with the original features of the program, provide a very flexible training tool for chiral separations in capillary electrophoresis. For example, determination of the optimum chiral selector concentration can be done in seconds, using the simulation software. Although the software is intended mainly for training purposes, in cases where sufficient details of existing chiral selector–analyte combinations are available, the program is also suitable for method development of chiral separations in CE

Disentangling the historical routes to community assembly in the global epicentre of biodiversity

Aim: The exceptional turnover in biota with elevation and number of species coexisting at any elevation makes tropical mountains hotspots of biodiversity. However, understanding the historical processes through which species arising in geographical isolation (i.e. allopatry) assemble along the same mountain slope (i.e. sympatry) remains a major challenge. Multiple models have been proposed including (1) the sorting of already elevationally divergent species, (2) the displacement of elevation upon secondary contact, potentially followed by convergence, or (3) elevational conservatism, in which ancestral elevational ranges are retained. However, the relative contribution of these processes to generating patterns of elevational overlap and turnover is unknown. / Location: Tropical mountains of Central- and South-America. / Time Period: The last 12 myr. / Major Taxa Studied: Birds. / Methods: We collate a dataset of 165 avian sister pairs containing estimates of phylogenetic age, geographical and regional elevational range overlap. We develop a framework based on continuous-time Markov models to infer the relative frequency of different historical pathways in explaining present-day overlap and turnover of sympatric species along elevational gradients. / Results: We show that turnover of closely related bird species across elevation can predominantly be explained by displacement of elevation ranges upon contact (81%) rather than elevational divergence in allopatry (19%). In contrast, overlap along elevation gradients is primarily (88%) explained by conservatism of elevational ranges rather than displacement followed by elevational expansion (12%). Main / Conclusions: Bird communities across elevation gradients are assembled through a mix of processes, including the sorting, displacement and conservatism of species elevation ranges. The dominant role of conservatism in explaining co-occurrence of species on mountain slopes rejects more complex scenarios requiring displacement followed by expansion. The ability of closely related species to coexist without elevational divergence provides a direct and faster pathway to sympatry and helps explain the exceptional species richness of tropical mountains

Feasibility study report : development and commoditization of the pre- fabricated modular bamboo housing; the ‘Nature BOX’ project

This report indicates the possibilities of Modular Bamboo Panel Housing Construction for China, Ethiopia and Nepal. Bamboo is one of the fastest growing materials in the world. It helps in the binding of CO2, whereas reinforced concrete results in more CO2 emissions caused by the building industry. In general, one hectare of bamboo can bind 70 t C/ha. The feasibility study promotes the use of Bamboo Panels and works to develop two kinds of Prefabricated Bamboo Panel houses for several locations. This paper provides details of fabrication and construction of houses along with illustrations of existing housing and some bamboo prototypes

GPCSIM : an instrument simulator of polymer analysis by size exclusion chromatography for demonstration and training purposes

A computer simulation has been developed with the purpose of demonstrating and visualizing a multitude of effects in the molecular characterization of synthetic polymer mixtures by size exclusion (gel permeation) chromatography. The chromatographic results and their interpretation are influenced by numerous parameters originating from sample, column and instrumentation used (injection, detection etc). The target audience for the software tool consists of polymers scientists, teachers of separation science and students. Especially for the latter audience it is important to stress that the software enables intentional creation of mistakes and learning from these mistakes. What the user can do ranges from visualization (quantitatively) all retention and dispersion effects, validation of experimental setup, checking sensitivity for certain operating conditions, extrapolation current instrument specifications, and in general performing hypothetical experiments. Several examples, such as column choice, band broadening, detection comparison and possible artifacts in the calculation of distributions are presented. This simulator is part of a family of similar tools for gas chromatography, high performance liquid chromatography, micellar electrokinetic chromatography and capillary electrophoresis. They have proved their effectiveness in education of separation science topics at several European universities