"… I seem […] only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me". – Isaac Newton.
I have recently published another STEM oriented robotic project. It is the ROTAforMI device, a versatile robotic device for controlling the position and orientation of a microscope slide using four degrees of freedom. This prototype is a complementary development of the idea behind the Roto-microscope project. It was inspired by related projects of servo motors-controlled micromanipulators and 3D micro scanners.
The device is entirely 3D printed and is actioned by four small servos controlled by one Arduino Nano microcontroller. The device can be controlled manually using two micro joysticks (and possibly also automatically via a programmed sequence of movements). In addition, a Bluetooth remote can take snapshots with a smartphone’s camera.
The device is made modular to use for different purposes. For example, removing the Y-stage should be sufficient to fit it under a stereomicroscope. Although the electronic interface is quite bulky, the device is simple to assemble and use, and the controlling program is still in its early stages. The ultimate goal is to use it for automatic photo stacking or 3D image reconstruction. Still, we are sure there are other possible applications in which small motion in 3D dimensions and a rotation of the observation stage can be helpful.
This is a prototype, and there is a lot of space for improvements. So we hope you like it, and constructive comments and suggestions are always welcome!
If you want trying to build one, please follow to the link given above.
La Pasqua di quest’anno è stata un’altra occasione per pubblicare il mio tradizionale articolo sulla matematica della forma delle uova degli uccelli. Quest’anno con l’aiuto dei miei figli, abbiamo creato il seguente Instructable educazionale:
Il progetto mira a mostrare come utilizzare un semplice modello matematico per generare la forma 3D di uova di uccelli reali aggiustandone i diversi parametri. I modelli di uova generati possono essere salvati come modello tridimensionale nel formato STL e poi stampati utilizzando una stampante ad estrusione di filamento plastico. L’uovo stampato può essere dipinto o modificato utilizzando un programma di modellistica 3D (per esempio MeshLab, sviluppato in Italy dal Visual Computing Lab of CNR-ISTI) per aggiungere funzionalità per gadget o giocattoli nella forma di uovo. Viene spiegato in dettaglio un esempio di come creare un uovo illuminato internamente con un LED multicolore.
Più recentemente, per divertimento, ho pubblicato sempre su sito Instrutables un altro esempio usando lo stesso approccio:
Inoltre, l’argomento della modellazione della forma delle uova è stato trattato in articoli precedenti e il lettore interessato può integrare le informazioni nel progetto Instructable con quelle fornite nei seguenti articoli:
Nell’Instructable dviene fornito un programma in C++ che dà la possibilità di generare le forma 3D delle uova e salvarle in STL. Può essere utilizzato per la ricerca, l’insegnamento e il divertimento.
Spero che il nostro progetto vi piaccia e commenti e suggerimenti costruttivi sono sempre i benvenuti!
In the previous four parts of this series of articles on the SHM (the links to the other parts are reported at the end of the article), we learned how to apply the Hückel method to conjugated linear and cyclic molecules containing only carbon atoms. However, an unsaturated molecular system can contain hetero atoms that can conjugate their electrons. The contribution of different theoretical chemists has extended the method by including semiempirical terms for the overlapping integrals that consider the presence of non-carbon atoms in the conjugated system. This effort has been summarized by the American chemist A. Streitwieser providing a set of parameters to approximate both Columb and bond integrals in the Hückel determinant [1]. The derivation of these parameters has been discussed in detail by Streiweiser [2] or by Lowe [2]. This article will teach us how to use these parameters to build up the Hückel determinant for this conjugated molecular system.
Il metodo degli orbitali molecolari di Hückel è un metodo quanto meccanico semi-empirico usato per calcolare le proprietà degli orbitali molecolari degli elettroni π in sistemi d’idrocarburici coniugati, come, per esempio, l’etilene, il benzene o il butadiene. In questa serie di articoli, ho riassunto gli aspetti principali della teoria con esempi pratici di applicazioni e programmazione del metodo.
A box without hinges, key, or lid, Yet golden treasure inside is hid.
JRR Tolkien, The Hobbit
Easter 2022 is at the door and the occasion for the traditional appointment to talk about eggs and their mathematical shapes. This year with the help of my sons, we have created the following Instructable for STEM education:
The project aims to show how to use a simple mathematical model to generate the 3D form of real bird eggs utilizing several parameters. The 3D egg models can be saved as an STL file and then printed using a 3D printer. The printed egg can be painted or modified with a CAD program to add functionalities for egg-based gadgets or toys. An example of a modification to create a LED decorated egg is explained in detail.
More recently for fun, I have published another one using the same approach:
The egg modelling topic has been covered in previous article, and the interested reader can complement the information in the Instructable with other information provided in the following articles:
The Instructable gives the possibility to 3D print and modifies the 3D shape of bird eggs. It can be used for research, teaching and fun. I hope you will enjoy it, and constructive comments and suggestions are always welcome!
AUGURO A TUTTI I LETTORI UNA BUONA PASQUA E PACE IN TERRA
WÜNSCHT ALLEN LESERN FROHE OSTERN UND FRIEDEN AUF ERDEN
I WISH TO READER A HAPPY EASTER AND PEACE ON EARTH
It shows how to prepare these simple surfaces and make some interesting observations with them. Like the previous two Instructables, my family help me a lot in preparing it in the very short time of one day. So a big thank you to my wife, Francesco, and, in particular, to Leonardo.
Hydrophobic and super-hydrophobic surfaces are ubiquitous in the natural world. You do not need to search much to find good examples: just walk out in your garden after a light rain and look at the plenty of weed leaves pearly decorated by water droplets. If you have an ornamental pond, you may have even the chance to see floating better examples of plants having a super-hydrophobic surface. Notably, wettability in Nature is present in a different form that subtle differences in the function and effect on the water droplets. Plant leaves need to keep their surfaces clean for light-harvesting efficiency. A water repellent leaves let water drops roll over its surface and mechanically remove dust particles. This effect was first noted on leaves of the Lotus plant, and for that reason, it is also called the Lotus effect.
Several novel technological materials exploit the properties of super-hydrophobic. For example, in your kitchen, Teflon pans are used to avoid sticking food residuals and therefore easily cleaned. Your car windows are teated to let the water easily roll over the surface.
Candle soot is an artificial material that is easy to produce and can be used to demonstrate some of the properties of the (super)-hydrophobic surface existing in nature.
I am happy to announce our second Instructable project. Like the first one, it was a long-standing idea that was rolling in my mind for a long time. The current limited travelling mobility due to the COVID offered more time to develop this idea during my vacation. In a joyful collaboration with my son Leonardo, we managed to realize this useful device in a very short time.
This project aimed to develop a device that integrated with a cheap USB microscope allows taking 3D pictures of small samples. The project is meant to be an education STEM activity to learn using Arduino, 3D image reconstruction, and 3D printing by creating a useful piece of equipment for doing some exciting science activity. Like my previous project, it is also a moment to share good and educative time with my family and in particular, my elder son Leonardo that helped me in creating this instructable and evaluating the device as an enthusiastic STEM student. This time, also my lovely wife helps me to make a video of the assembly of the equipment!
The roto-microscope allows controlling the position of a simple USB microscope around the sample. This allows to take accurate pictures from different angles and not just from the top as in the traditional microscopes. This is not a new idea as there are professional microscopes. However, this device means to be affordable for a student and still provides some similar results and a lot of fun in building it. Other similar and excellent OpenSource projects are available (see, for example, the Ladybug microscope, the Lego microscope, and the OpenScan project), our project adds an additional option and I hope that you enjoy making it as we did!
If you find it an interesting device then instructions on how to build it are on our Instructable.
In this new series, I will post slides of seminars or lessons that I have delivered in the past years. Some of the reported information is updated, but still helpful. In some cases, I have added descriptions of the slide contents or references to other articles or the original paper where I describe my research results. I hope you like the presentation, and remember to add your feedback and subscribe to have email notifications about my new blog posts.
In 1648, Isaac Newton published his first edition of the Principia Mathematica, one of the greatest scientific masterpieces of all time. On page 12 of this magnum opus, the famous three laws that bear his name and from which classical mathematical physics evolved are enunciated. More than 350 years after that publication, the same laws formulated to explain the motion of stars and planets remain valuable for us when trying to simplify the description of the atomic world. In the first decades of the last century, the birth of quantum mechanics marked the beginning of the detailed description of atomic physics. The equation of Schrödinger, to the same extent as Newton’s equations, allowed for the mathematically elegant formulation of the shining theoretical intuitions and the experimental data accumulated in the previous decades. Although this equation could be used in principle to describe any molecular system’s physicochemical behaviour, it is impossible to resolve analytically when the number of electrons is more than two. The invention of electronic computers after World War II facilitated the numerical solution of this equation for polyatomic systems. However, despite the continuous and rapid development of computer performance, the ab-initio quantum-mechanical approach to describe static and dynamic properties of molecules containing hundreds or even thousands of atoms, as for biological macromolecules, is still far from becoming a standard computational tool. This approach requires many calculations that can be proportional to , where N is the total number of electrons in the system. It was clear that a reduction, using ad hoc approximations, of the description of the dynamic behaviour of atoms using a classic physics model would be necessary to overcome this problem. In the classical representation, the electrons on the atoms are not explicitly considered, but their mean-field effect is taken into account. Alder and Wainwright performed the first simulation of an atomic fluid using this approximation approximately 63 years ago (1957). They developed and used the method to study simple fluids by means of a model representing atoms as discs and rigid spheres. These first pioneer studies mark the birth of the classical molecular dynamics (MD) simulation technique. The successive use of more realistic interaction potentials has allowed obtaining simulations comparable to experimental data, showing that MD can be a valuable tool for surveying the microscopical properties of physical systems. The first simulations of this type were carried out by Rahman and Verlet (1964): in these simulations, a Lennard-Jones-type potential was used to describe the atomic interactions of argon in the liquid state. Another significant hallmark in this field was the simulation of the first protein (the bovine pancreatic trypsin inhibitor) by McCammon and Karplus in 1977. In the following years, the success obtained in reproducing structural properties of proteins and other macromolecules led to a great spread of the MD within structural biology studies. The continuous increase of computer power and improvement of programming languages has concurred with further refinement of the technique. Its application was progressively expanded to more complex biological systems comprising large protein complexes in a membrane environment. In this way, MD is becoming a powerful and flexible tool with applications in disparate fields, from structural biology to material science.