Mineral Preservatives in the Wood of Stradivari and Guarneri

Following the futile efforts of generations to reach the high standard of excellence achieved by the luthiers in Cremona, Italy, by variations of design and plate tuning, current interest is being focused on differences in material properties. The long-standing question whether the wood of Stradivari and Guarneri were treated with wood preservative materials could be answered only by the examination of wood specimens from the precious antique instruments. In a recent communication (Nature, 2006), we reported about the degradation of the wood polymers in instruments of Stradivari and Guarneri, which could be explained only by chemical manipulations, possibly by preservatives. The aim of the current work was to identify the minerals from the small samples of the maple wood which were available to us from the antique instruments. The ashes of wood from one violin and one cello by Stradivari, two violins by Guarneri, one viola by H. Jay, one violin by Gand-Bernardel were analyzed and compared with a variety of commercial tone woods. The methods of analysis were the following: back-scattered electron imaging, X-ray fluorescence maps for individual elements, wave-length dispersive spectroscopy, energy dispersive X-ray spectroscopy and quantitative microprobe analysis. All four Cremonese instruments showed the unmistakable signs of chemical treatments in the form of chemicals which are not present in natural woods, such as BaSO4, CaF2, borate, and ZrSiO4. In addition to these, there were also changes in the common wood minerals. Statistical evaluation of 12 minerals by discriminant analysis revealed: a. a difference among all four Cremona instruments, b. the difference of the Cremonese instruments from the French and English antiques, and c. only the Cremonese instruments differed from all commercial woods. These findings may provide the answer why all attempts to recreate the Stradivarius from natural wood have failed. There are many obvious implications with regard to how the green tone wood should be treated, which chould lead to changes in the practice of violin-making. This research should inspire others to analyze more antique violins for their chemical contents

Antihypertensive Drug Guanabenz Is Active In Vivo against both Yeast and Mammalian Prions

Background: Prion-based diseases are incurable transmissible neurodegenerative disorders affecting animals and humans. [br/] Methodology/Principal Findings: Here we report the discovery of the in vivo antiprion activity of Guanabenz (GA), an agonist of a2-adrenergic receptors routinely used in human medicine as an antihypertensive drug. We isolated GA in a screen for drugs active in vivo against two different yeast prions using a previously described yeast-based two steps assay. GA was then shown to promote ovine PrPSc clearance in a cell-based assay. These effects are very specific as evidenced by the lack of activity of some GA analogues that we generated. GA antiprion activity does not involve its agonist activity on a2-adrenergic receptors as other chemically close anti-hypertensive agents possessing related mechanism of action were found inactive against prions. Finally, GA showed activity in a transgenic mouse-based in vivo assay for ovine prion propagation, prolonging slightly but significantly the survival of treated animals. [br/] Conclusion/Significance: GA thus adds to the short list of compounds active in vivo in animal models for the treatment of prion-based diseases. Because it has been administrated for many years to treat hypertension on a daily basis, without major side-effects, our results suggest that it could be evaluated in human as a potential treatment for prion-based diseases

Design study of critical components of second harmonic a 100 kW, 0.4 THz gyrotron oscillator

We present simulation result of the critical components for a second harmonic 0.4 THz, 100 kW gyrotron. The design study of the MIG electron gun has been done by three different simulation codes, CST Particle studio, MICHELLE, EGUN code. Analysis of an interaction cavity and a mode converter will be presented

Design study of a MIG electron gun of a 100 kW, 0.4 THz gyrotron oscillator

We present simulation result of an MIG electron gun for a 0.4 THz, 100 kW gyrotron. The gyrotron is a device to generate very high power at very high frequencies. The magnetron injection gun (MIG) is a critical component in the gyrotron[1]. The design study of the MIG electron gun has been done by three different simulation codes. The EGUN code for 2D has been used for the initial geometry optimization with a 70 kV and 13 A of the electron beam. The MICHELLE code and the CST Particle Studio have been also used and results are compared

Ring Autosomes: Some Unexpected Findings

Ring chromosomes are rare entities, usually associated with phenotypic abnormalities in correlation with the loss of genetic material. There are various breakpoints and sometimes there is a dynamic mosaicism that is reflected in clinical features. Most of the ring chromosomes are de novo occurrences. Our study reflects the experience of three Romanian cytogenetic laboratories in the field of ring chromosomes. We present six cases with ring chromosomes involving chromosomes 5, 13, 18, and 21. All ring chromosomes were identified after birth in children with plurimalformative syndromes. The ring chromosome was present in mosaic form in three cases, and this feature reflects the ring’s instability. In case of ring chromosome 5, we report a possible association with oculo-auriculo-vertebral spectrum

Possibility and design of resonant terahertz emitters based on nanoscale strained silicon plasma wave transistors with enhanced mobility

In this paper, we report the possibility of silicon (Si) plasma wave transistor (PWT) as a resonant terahertz (THz) emitter based on the theoretical analysis focusing on the strained Si with enhanced mobility. Under asymmetric boundary conditions for plasma wave instability, the amplitude of plasma wave in FET channel increases and this plasma wave increment provides the basis of the electromagnetic (EM) wave emission from FET. Because this instability is controlled by manipulation of plasma wave velocity (s) and electron drift velocity (v0), we propose the design window based on s-v0 plot which determines whether the device operates as the resonant THz emitters considering all the required physical conditions. It is expected from the proposed design window that strained Si PWT down to 10nm gate length with enhanced channel mobility of 500cm2??V -1??-1 can operate as a resonant emitter in THz frequency range.close1