Friday, 14 October 2011

Mesophases transitions


An interesting transition is the texture transition inside the nematic phase. We observe in some liquid crystalline compounds a transition from a low-temperature nematic texture which looks like a texture of a smectic phase to a high temperature nematic Schlieren texture. Compounds that have the texture transition are the alkyloxybenzoic acids. Here, you can see a movie of the texture transtion inside the nematic phase of 6OBAC. The sample is heated from the crystal phase. We can see the smectic pahse and then the two following nematic subphases. Click on the image to see the movie.


More details  in my papers:
Texture transitions in binary mixtures of 6OBAC
with compounds of its homologous series
A. Sparavigna;  A. Mello; B. Montrucchio 

Phase Transitions: A Multinational Journal, 1029-0338
Volume 80, Issue 3, 2007, Pages 191 – 201
Abstract 
Texture transitions in the liquid crystalline 
alkyloxybenzoic acid 6OBAC
A. Sparavigna;  A. Mello; B. Montrucchio 
Phase Transitions: A Multinational Journal, 1029-0338
Volume 79Issue 4, 2006, Pages 293 – 303
Abstract 

A new image processing method for enhancing
the detection sensitivity of smooth transitions in liquid crystals

Liquid Crystals, 1366-5855, Volume 24Issue 6, 2001, Pages 841 – 852
Abstract 

novel order transition inside the nematic phase of 
trans -4-hexylcyclohexane-1-carboxylic acid discovered by image processing
Liquid Crystals, 1366-5855, Volume 25Issue 5, 2001, Pages 613 – 620
Abstract 


In the following, three movies show a transition on cooling from the nematic to the smectic phase of an oxadiazole compound. We see a transition from the nemtic to a smectic phase with toric domains.
Clink on images to launch the movies.

  

For more detailsthese are my articles:

Growth of toric domains in mesophases of oxadiazoles
A. Sparavigna;  A. Mello; B. Montrucchio 
Phase Transitions: A Multinational Journal
1029-0338, Volume 81Issue 5, 2008, Pages 471 – 477
Abstract 

Fan-shaped, toric and spherulitic textures of mesomorphic oxadiazoles
A. Sparavigna;  A. Mello; B. Montrucchio 
Phase Transitions: A Multinational Journal
1029-0338, Volume 80Issue 9, 2007, Pages 987 – 998
Abstract 


Amelia Carolina Sparavigna

Saturday, 8 October 2011

Of the Education of an Engineer

"Architecture is a science arising out of many other sciences, and adorned with much and varied learning; by the help of which a judgment is formed of those works which are the result of other arts. Practice and theory  are its parents. Practice is the frequent and continued contemplation of the mode of executing any given work, or of the mere operation of the hands, for the conversion of the material in the best and readiest way. Theory is the result of that reasoning which demonstrates and explains that the material wrought has been so converted as to answer the end proposed. Wherefore the mere practical architect is not able to assign sufficient reasons for the forms he adopts ; and the theoretic architect also fails, grasping the shadow instead of the substance. He who is theoretic as well as practical, is therefore doubly armed; able not only to prove the propriety of his design, but equally so to carry it into execution.
In architecture, as in other arts, two considerations must  be constantly kept in view; namely, the intention, and the matter used to express that intention: but the intention is founded on a conviction that the matter wrought will fully suit the purpose; he, therefore, who is not familiar with both branches of the art, has no pretension to the title of architect. An architect should be ingenious, and apt in the acquisition of knowledge. Deficient in either of these qualities, he cannot be a perfect master.
He should be a good writer, a skillful draftsman, versed in geometry and optics, expert at figures, acquainted with history, informed on the principles of natural and moral philosophy, somewhat of a musician, not ignorant of the sciences both of law and physics, nor of the motions, laws, and relations to each other, of the heavenly bodies. By means of the first named acquirement, he is to commit to writing his observations and experience, in order to assist his memory. Drawing is employed in representing the forms of his designs. Geometry affords much aid to the architect: to it he owes the use of the right line and circle, the level and the square; whereby his delineations of buildings on plane surfaces are greatly facilitated. The science of optics enables him to introduce with judgment the requisite quantity of light, according to the aspect. Arithmetic estimates the cost, and aids in the measurement of the works; this, assisted by the laws of geometry, determines those abstruse questions, wherein the different proportions of some parts to others are involved. Unless acquainted with history, he will be unable to account for the use of many ornaments which he may have occasion to introduce. ...
Many other matters of history have a connexion with architecture, and prove the necessity of its professors being well versed in it. Moral philosophy will teach the architect  to be above meanness in his dealings, and to avoid arrogance: it will make him just, compliant and faithful to his employer ; and what is of the highest importance, it will prevent avarice gaining an ascendancy over him: for he should not be occupied with the thoughts of filling his coffers, nor with the desire of grasping every thing in the shape of gain, but, by the gravity of his manners, and a good character, should be careful to preserve his dignity. In these respects we see the importance of moral philosophy; for such are her precepts. That branch of philosophy which the Greeks call phusiologia, or the doctrine of physics, is necessary to him in the solution of various problems; as for instance, in the conduct of water, whose natural force, in its meandering and expansion over flat countries, is often such as to require restraints, which none know how to apply, but those who are acquainted with the laws of nature: nor, indeed, unless grounded in the first principles of physics, can he study with profit the works of Ctesibius, Archimedes, and many other authors who have written on the subject.
Music assists him in the use of harmonic and mathematical proportion. It is, moreover, absolutely necessary in adjusting the force of the balistae, catapultae, and scorpions...
Astronomy instructs him in the points of the heavens, the laws of the celestial bodies, the equinoxes, solstices, and courses of the stars; all of which should be well understood, in the construction and proportions of clocks. Since, therefore, this art is founded upon and adorned with so many different sciences, I am of opinion that those who have not, from their early youth, gradually climbed up to the summit, cannot, without presumption, call themselves masters of it. Perhaps, to the uninformed, it may appear unaccountable that a man should be able to retain in his memory such a variety of learning ; but the close alliance with each other, of the different branches of science, will explain the difficulty. For as a body is composed of various concordant members, so does the whole circle of learning consist in one harmonious system. Wherefore those, who from an early age are initiated in the different branches of learning, have a facility in acquiring some knowledge of all, from their common connexion with each other...
For in such a variety of matters, it cannot be supposed that the same person can arrive at excellence in each, since to be aware of their several niceties and  bearings, cannot fall within his power. We see how few of those who profess a particular art arrive at perfection in it, so as to distinguish themselves: hence, if but few of those practising an individual art, obtain lasting fame, how should the architect, who is required to have a knowledge of so many, be deficient in none of them, and even excel those who have professed any one
exclusively. ...
I beseech you, O Caesar, and those who read this my work, to pardon and overlook grammatical errors; for I write neither as an accomplished philosopher, an eloquent rhetorician, nor an expert grammarian, but as an architect: in respect, however, of my art and its principles, I will lay down rules which may serve as an authority to those who build, as well as to those who are already somewhat acquainted with the science."

From "The Architecture", by Marcus Vitruvius Pollio

Friday, 7 October 2011

Solid angle

A Lecture on Solid Angle, by Ben Kravitz
http://www.stanford.edu/~bkravitz/research/solidangle.pdf
"In order to talk about solid angles, we fi rst need to talk about projections. There are lots of diff erent kinds of projections, some of which you already know. We should begin with a very simple defi nition of what a projection is, and then we'll get more complex as we go along. A projection is the transformation of points and lines in one plane onto another plane by connecting corresponding points on the two planes with parallel lines".

Wednesday, 5 October 2011

Theory and practice

From the post
Teaching: Theory or practice? by Marcus Wilson Aug 07

"What’s clear is that many teachers take the view that theory is the opposite of practice. Since, in teaching, it is clearly the practice that matters (since it’s what the students experience) this leads to the conclusion that theory is irrelevant and there is no benefit in engaging with it. ... The fallacy is the implicit assumption that theory and practice are unconnected. (I mean, you don’t have experimental physicists and theoretical physicists working in complete isolation from each other, so why expect that with teaching?) What you believe about student learning will influence the way you teach, whether you formally acknowledge it or not. That’s become clear for me as I think about my teaching practice. I have my own ‘beliefs’, or my own models, call them ‘theories’, of how students learn, and these influence how I teach."

Read the post at
http://sciblogs.co.nz/physics-stop/2011/08/07/teaching-theory-or-practice/

Friday, 30 September 2011

Speed of neutrino and cosmic consequences

Let me report a part of the discussion on the speed of neutrinos by Wikipedia
"In September 2011 the OPERA collaboration released calculations showing velocities of 17-GeV and 28-GeV neutrinos exceeding the speed of light in their experiments. The authors write, "Despite the large significance of the measurement reported here and the stability of the analysis, the potentially great impact of the result motivates the continuation of our studies in order to investigate possible still unknown systematic effects that could explain the observed anomaly." This result had not been detected by previous experiments, and lies in contrast to several others. For instance, photons and neutrinos from SN 1987A were observed to have an agreement in transit time to about 1 part in 450 million, with even this difference being accounted for by light being impeded by the material of the star early in its journey. The OPERA results, in contrast, suggested that neutrinos were traveling faster than light by a factor of 1 in 40,000, i.e. that neutrino speed is 1.0000248(28) c. Had neutrinos from SN 1987A (a supernova, approximately 168,000 light-years from Earth, http://en.wikipedia.org/wiki/SN_1987A) traveled faster than light by this factor, they would have arrived at Earth several years before the photons; this was not observed to be the case. However, neutrinos from the supernova had orders of magnitude less energy than the neutrinos observed in the OPERA experiment, as the authors point out."

Friday, 23 September 2011

Neutrino: fast and furious

Here the news of the day! Neutrinos are faster than light!
http://www.guardian.co.uk/science/2011/sep/23/faster-light-neutrinos
"Scientists at the Opera (Oscillation Project with Emulsion-tRacking Apparatus) experiment in Gran Sasso, Italy, found that beams of neutrinos sent to its detectors from Cern, 730km away in Geneva, arrived earlier than they should have."

Thursday, 22 September 2011

Coherers as “energy catalyzers”

Coherers as “energy catalyzers”
Amelia Carolina Sparavigna
Dipartimento di Fisica,
Politecnico di Torino, Torino, Italy

Abstract: A device defined as an “energy catalyzer”, able to give thermal energy at the expense of electric energy, has aroused a great popular interest. In fact, the confidence on this device does not allow its discussion. Some known features are intriguing, which can therefore become the starting point for a discussion on old coherers and the Branly effect. We could define the coherers as a sort of “energy catalyzers”.

------------

On Wednesday September 21, 2011, from the news of RAI, the Italian broadcaster, I learned that a new device for energy production was on the way for industrial developments. I had not immediately realized the features of this device, but I memorized the fact that it was based on water, nickel powders and current, that I saw sparkling in the video clip.  After searching on the Web, I found that the announced device was the energy catalyzer, E-Cat, under patent request by its inventor, Andrea Rossi. The development of prototypes was due to the work of Rossi and Sergio Focardi, University of Bologna. It seems that they have announced a device able of producing more than 10 kilowatts of heat power, while only consuming a fraction of that. "On January 14, 2011, they gave the Worlds' first public demonstration of a nickel-hydrogen fusion reactor capable of producing a few kilowatts of thermal energy. At its peak, it is capable of generating 15,000 watts with just 400 watts input required. In a following test the same output was achieved but with only 80 watts of continual input" [1]. The item is also reporting that the inventor prefers to invoke a catalyzer process, not to a cold fusion. There are so many Web pages on the E-Cat, that it is impossible to list them, but an exhaustive one is the corresponding Wikipedia item [2]. It is there that we can find the reference to the patent [3], which is about a "method and apparatus for carrying out a highly efficient exothermal reaction between nickel atoms and hydrogen atoms, in a tube, preferably, though not exclusively made of a metal, filled by a nickel powder and heated to a high temperature preferably, though not necessarily, from 150 to 5000°C, by injecting hydrogen into said metal tube said nickel powder being pressurized, preferably, though not necessarily, to a pressure from 2 to 20 bars ".

The confidence on this device does not allow its discussion. And in fact, the aim of my paper is not a discussion on E-Cat, but on what the poor information on it suggested me. Some features of the device attracted my interest: they are the metal powders, the high temperatures and the sparks of electricity. In fact I read recently about all these things together in a old book published in 1904, entitled Elements of Physics, by Fernando Sanford,  professor at the Stanford University, one of the members of the group of scientists who came there to create the  pioneer faculty in 1891. In [4], I discussed the experiments of Sanford on the electric photography and the fact that, several years after in 1939, the fringes around the electrically photographed objects had been rediscovered by Semyon Kirlian. Of course the book written by Sanford is quite old, but, in my opinion, it has to be appreciated due to the fact that it is based on the description of experiments. The book is then quite interesting from the point of view of experimental physics and for its history. A chapter is devoted to electric radiation and electric waves. Let us remember that Fernando Sanford was talking of experiments, which, at his times were revolutionizing physics and technology. Reading the book we learn that a new device was used in laboratories, the Coherer (see Fig.1).  Let me report the Laboratory Exercise 119 of the book.

"Take a glass tube of about a centimeter bore and six or eight centimeters long, fit the ends with corks through which copper wires can be passed, and fill the tube between the corks with brass or iron filings. Thrust copper wires through the corks and into the iron filings until their ends are one or two centimeters apart. Connect these wires in circuit with one or more voltaic cells and a tolerably sensitive galvanometer. The resistance of the filings to the passage of a current should be so great that the galvanometer is slightly, if at all, deflected. Bring an electric machine near, and pass sparks from one discharging knob into one of the wires which enter the tube. The resistance should fall so that the galvanometer is deflected through nearly 90°.  This instrument is called a Coherer. The passage of the electric discharge into the small metallic particles in the tube apparently causes them to cling together so that they make better electric contact than before.  After your coherer has become sensitive enough to allow the passage of a suitable current, increase its resistance again by tapping gently on the glass and causing the particles to separate. Then move the electric machine to a distance of a few feet from the coherer and turn the handle and cause sparks to pass between the discharging knobs of the machine. If your coherer has been properly adjusted, the galvanometer will be deflected again, showing that the resistance of the coherer has been again diminished. By a little care in the adjustment, and by using a sensitive galvanometer, the coherer will respond to a spark at a distance of several yards. ... The Coherer described above is similar to the receiver used in "wireless telegraphy." The Coherer is connected between a battery and a telegraph sounder, and is attached to a long wire or other conductor suspended at some height. A similar conductor is suspended at the sending station, and is connected with the spark gap of the electric machine or induction coil. The oscillations in the receiving conductor are accordingly partly due to resonance, and they are sufficient to lower the resistance of the coherer so that a signal can be made through it. An automatic tapper jars the particles apart, so that the signal is momentary unless the instrument is sensitized by another spark. "


Fig.1. The Coherer in the book written by F. Sanford.

The device described by Sanford is a radio signal detector used in the receivers of wireless telegraphy at the beginning of the twentieth century. The coherer was invented, around 1890, by Édouard Branly [5]. As Sanford is telling, it consisted of a tube or capsule containing two electrodes spaced a small distance apart, with metal filings between them. It works because of the "Branly effect". To have this effect, it is necessary a thin resistive layer between the grains, to have an initial high resistance. The effect is not observed with noble metal grains, cleaned from any surface contaminant [6]. Therefore, the coherer works because the metal particles cling together, that is, cohere after being subjected to the radio frequency electricity. This provokes a reduction in the coherer's electrical resistance, which is persistent after the radio signal. To receive another signal, the device needs a de-coherer mechanism, able to tap the coherer, mechanically disturbing the particles and resetting them to the high resistance state. As Wikipedia [5] is telling "Coherence of particles by radio waves is an obscure phenomenon that is not well understood even today", but several recent experiments with metal particles seem to confirm that particles cohere by a micro-weld phenomenon, caused by radio frequency electricity fluxing across the small contact area between particles. This phenomenon is probably involving a tunnelling of charge carriers across an imperfect junction between conductors, as deeply discussed in Ref.6. In fact, in this reference the author is proposing to relate the Branly effect to the induced tunnelling effect first described by François Bardou and Dominique Boosé, asserting then that the effect is mainly governed by an electrical tunnel effect [7].

In the work published in 2001 [7], Bardou and Boosé theoretically proposed that the tunnelling probability of a particle through a potential barrier could be enhanced by striking the particle when the centroid of its wave packet is reflecting on the barrier. This is applied to Branly effect as discussed in [6] in the following way. “In a granular metallic medium microscopic grains are electrically isolated one from the other by a metal oxide nanometric layer ... When a voltage is applied to the medium, electrons are accelerated and they do reflect on the potential barriers. At the time of the reflection, these electrons can be kicked forward or backward by the short electromagnetic pulses present in the external electromagnetic field. … The enhanced transmission induced by the momentum transfer produces an increased electrical current, that for some events become large enough to permit a local heating in the metal grains thanks to the Joule effect. Eventually a welding of the grains can occur and when a percolation path has formed the electrical resistance of the medium drops down going from an exponential dependence on the applied voltage to a linear one”. Reference 6 is also reporting that Auerbach demonstrated in 1898 that a coherer could be made conducting by an acoustic excitation in the audible range of the spectrum. According to [6], this means that acoustical waves, by giving vibrations to tunnel barriers between the metallic grains, could be responsible of an induced tunnelling.

Let us also consider the recent experiments with particle coherers by Falcon et al. [8]. They reported on observations of the electrical transport within a chain of metallic beads, which were slightly oxidised.  As the applied current is increased, a transition from an insulating to a conductive state is observed. The authors are proposing that the transition comes from an electro-thermal coupling, at the micro-contacts between each bead. Due to these contacts, the current flows through them, generating a high local heating. This heating increases the local contact areas, enhancing the conduction.  This current-induced temperature rise, up to 1050°C, results in the micro-soldering of the contact points, even for low voltages.

If we define an “energy catalyzer” as a device able to produce change in, or transform energy, the coherer acts in such a manner, where the catalyst is an electromagnetic pulse. Let us hope that as soon as possible, an open report on E-Cat is published, in order to understand the role of hydrogen in it.  In this device, is any tunnelling present? Is it there a tunnelling able to give a fusion of nickel and hydrogen to have copper in a proton capture as told in [9]? Is there any kicking mechanism? What we find in [9] is that the paper is just reporting the results “obtained with a process and apparatus not described here (in [9]) in detail and protected by patent in 90 countries, consisting of a system whose heat output is up to hundred times the electric energy input. As a consequence, the principle of the conservation of energy ensures that processes involving other energy forms are occurring in our apparatus”. And in the conservation of energy we trust.

 References
1. http://peswiki.com/index.php/Directory:Andrea_A._Rossi_Cold_Fusion_Generator
2. http://en.wikipedia.org/wiki/Energy_Catalyzer
3. http://www.wipo.int/pctdb/en/wo.jsp?IA=IT2008000532&DISPLAY=DESC
4. A.C. Sparavigna, Fernando Sanford and the "Kirlian effect", arXiv:1105.1266v1 [physics.pop-ph], http://arxiv.org/ftp/arxiv/papers/1105/1105.1266.pdf
5. http://en.wikipedia.org/wiki/Coherer
6. C. Hirlimann, Understanding the Branly effect, arXiv:cond-mat/0703495v1 [cond-mat.mtrl-sci], http://arxiv.org/ftp/cond-mat/papers/0703/0703495.pdf
7. D. Boosé and F. Bardou, A quantum evaporation effect, Europhys. Lett., 53, 1-7 (2001).
8.  E. Falcon, B. Castaing, and M. Creyssels,  Nonlinear electrical conductivity in a 1D granular medium, The European Physical Journal B, 38,  475-483 (2004)
9. S. Focardi and A. Rossi, A new energy source from nuclear fusion, http://www.lenr-canr.org/acrobat/FocardiSanewenergy.pdf

E-cat patent

METHOD AND APPARATUS FOR CARRYING OUT NICKEL AND HYDROGEN EXOTHERMAL REACTIONS
http://worldwide.espacenet.com/publicationDetails/biblio?CC=WO&NR=2009125444&KC=&FT=E&locale=en_EP
http://www.wipo.int/pctdb/en/wo.jsp?IA=IT2008000532&DISPLAY=DESC

Wednesday, 21 September 2011

E-cat by Rossi&Focardi

"he Energy Catalyzer (sometimes shortened to E-Cat) is an apparatus built by inventor Andrea Rossi, with support from his scientific consultant, physicist and emeritus professor Sergio Focardi. The 2009 patent application claims "a method and apparatus for carrying out nickel and hydrogen exothermal reactions," with production of copper. Although the patent cites previous works on cold fusion, one statement by Rossi asserted that it is not cold fusion, but rather LENR, Low-Energy Nuclear Reaction. A similar system, but yielding considerably less power, had previously been described by Focardi et al."
Read
http://en.wikipedia.org/wiki/Energy_Catalyzer

Ny Teknik tested the energy catalyzer - NyTeknik

"The energy catalyzer was demonstrated publicly for first time on the 14th January 2011. According to its inventor Andrea Rossi it has a closed reactor of steel that is loaded with nickel powder plus secret catalysts and pressurized with hydrogen."

Ny Teknik tested the energy catalyzer - NyTeknik