Electron-phonon interaction in the solid form of the smallest fullerene C20_{20}

The electron-phonon coupling of a theoretically devised carbon phase made by assembling the smallest fullerenes C$_{20}$ is calculated from first principles. The structure consists of C$_{20}$ cages in an {\it fcc} lattice interlinked by two bridging carbon atoms in the interstitial tetrahedral sites ({\it fcc}-C$_{22}$). The crystal is insulating but can be made metallic by doping with interstitial alkali atoms. In the compound NaC$_{22}$ the calculated coupling constant $\lambda/N(0)$ is 0.28 eV, a value much larger than in C$_{60}$, as expected from the larger curvature of C$_{20}$. On the basis of the McMillan's formula, the calculated $\lambda$=1.12 and a $\mu^*$ assumed in the range 0.3-0.1 a superconducting T$_c$ in the range 15-55 K is predicted.Comment: 7 page

New insight into cataract formation -- enhanced stability through mutual attraction

Small-angle neutron scattering experiments and molecular dynamics simulations combined with an application of concepts from soft matter physics to complex protein mixtures provide new insight into the stability of eye lens protein mixtures. Exploring this colloid-protein analogy we demonstrate that weak attractions between unlike proteins help to maintain lens transparency in an extremely sensitive and non-monotonic manner. These results not only represent an important step towards a better understanding of protein condensation diseases such as cataract formation, but provide general guidelines for tuning the stability of colloid mixtures, a topic relevant for soft matter physics and industrial applications.Comment: 4 pages, 4 figures. Accepted for publication on Phys. Rev. Let

Suppression of inelastic bound state resonance effects by the dimensionality of atom-surface scattering event

We develop a multidimensional coupled channel method suitable for studying the interplay of bound state resonance and phonon assisted scattering of inert gas atoms from solid surfaces in one, two and three dimensions. This enables us to get insight into the features that depend on the dimensionality of inelastic resonant processes typically encountered in low energy He atom scattering from surfaces, in general, and to elaborate on the observability of recently conjectured near threshold resonances in scattering from Einstein phonons, in particular.Comment: 2 figure

Effect of Hydrostatic Compression on the Energy of the 14.4-kev Gamma Ray from Fe^(57) in Iron

The energy of the recoil-free fraction of they rays emitted by nuclei bound in solids1 has been found to be affected by temperature and by electronic configuration. The latter effect has been named the "isomeric" shift. Compression of a solid should influence the energy through both of these mechanisms. We have measured the effect of hydrostatic compression at 295°K on the energy hν of the recoil-free 14.4-kev γ rays emitted by 0.1-μsec Fe^(57) bound in metallic iron

Despite its role in assembly, methionine 35 is not necessary for amyloid β-protein toxicity

Author Manuscript 2011 June 1.An important component of the pathologic process underlying Alzheimer’s disease is oxidative stress. Met[superscript 35] in amyloid β-protein (Aβ) is prone to participating in redox reactions promoting oxidative stress, and therefore is believed to contribute significantly Aβ-induced toxicity. Thus, substitution of Met[superscript 35] by residues that do not participate in redox chemistry would be expected to decrease Aβ toxicity. Indeed, substitution of Met[superscript 35] by norleucine (Nle) was reported to reduce Aβ toxicity. Surprisingly, however, substitution of Met[superscript 35] by Val was reported to increase toxicity. Aβ toxicity is known to be strongly related to its self-assembly. However, neither substitution is predicted to affect Aβ assembly substantially. Thus, the effect of these substitutions on toxicity is difficult to explain. We revisited this issue and compared Aβ40 and Aβ42 with analogs containing Met[superscript 35]→Nle or Met[superscript 35]→Val substitutions using multiple biophysical and toxicity assays. We found that substitution of Met[superscript 35] by Nle or Val had moderate effects on Aβ assembly. Surprisingly, despite these effects, neither substitution changed Aβ neurotoxicity significantly in three different assays. These results suggest that the presence of Met[superscript 35] in Aβ is not important for Aβ toxicity, challenging to the prevailing paradigm, which suggests that redox reactions involving Met35 contribute substantially to Aβ-induced toxicity.Alzheimer's Association (Grant IIRG- 07-5833)National Institutes of Health (U.S.) (Grant AG027818

Spectrum and polarization of laser light scattered by solids

Laser light scattering from yttrium-iron garne

Faunistical records and annotations for a better knowledge of the Tajikistani moth and butterfly fauna (Lepidoptera: Noctuoidea, Papilionoidea)

On the basis of 3333 specimens, geographical, spatial and temporal records of 225 noctuid and 37 papilionoid Lepidoptera species are given for the better knowledge of the fauna of Tajikistan. The following 25 species are recorded as new for the Tajikistani fauna: Agrotis golickei Ershov, 1871, Amphipyra cancellata Warren, 1911, Anapoma riparia (Boisduval, 1829), Archanara insoluta (Warren, 1911), Autophila einsleri Amsel, 1935, A. laetifica (Staudinger, 1901), A. maculifera Staudinger, 1888, Callopistria latreillei (Duponchel, 1827), Chazaria incarnata (Freyer, 1838), Chersotis lehmanni Varga, Gyulai, Ronkay et Ronkay 2013, Cirrhia tunicata (Graeser, 1890), Conistra pseudopolitina Hacker, 1990, Cryphia maeonis (Lederer, 1865), Cucullia tecca Püngeler, 1906, Dichagyris naumanni Varga, 1996, Episema minuta Boursin et Ebert, 1976, Eugnorisma cuneiferum Varga et L. Ronkay, 1994, Hypena opulenta (Christoph, 1877), Lophoterges varians Ronkay, 2005, Mniotype dubiosa (Bang-Haas, 1912), Namangana cretacea Staudinger, 1888, Nonagria puengeleri pringlei (Wiltshire, 1958), Orthosia reshoefti Hrebaly et Plante, 1994, Oxytripia orbiculosa (Esper, 1799) and Shargacucullia zerkowitzi (Boursin, 1934). The hitherto unknown female of Perigrapha heidi Hreblay, 1996 and male of Orthosia reshoefti are described. The taxonomic and nomenclatorial problems of Polymixis roehrei Boursin, 1961 are discussed, resulting the new synonymy Dasysternum colluta Draudt, 1934 = Polymixis roehrei Boursin, 1961, syn. n. New distributional data for Ostheldera kondara Varga et Ronkay, 1991 (Darvaz Mts.) are given with some additional comments on the female genitalia characters in comparison with those of O. minna Ronkay et Varga, 1994

A globális éghajlatváltozás várható hatásai a növényvédelemben

A légköri CO2 koncentráció és az egyéb üvegházhatásért felelős gázok koncentrációjának növekedése miatt a Föld éghajlata melegszik és a klíma változik. Összeállításban a legfontosabb üvegházhatást kiváltó tényezők általános hatásait vizsgáljuk a növénypatogén mikroorganizmusokra, kártevő rovarokra és a gyomnövényekre, bemutatják a növény természetes ellenálló képességének útjait az abiotikus stressz-hatásokkal szemben. A megemelkedett CO2 koncentráció és a globális hőmérséklet-növekedés megváltoztatja a károsítók viselkedését, egyrészt, mert a megváltozott légköri CO2 tartalom miatt megváltozik fejlődési sebességük és a kiváltott tünetek ill. károk mértéke. Másrészt a megváltozott körülmények miatt megváltoznak maguk a növények is, amelyek ugyancsak változtatják a kórokozók fertőzési jellemzőit, a rovarok fejlődését is. Az előbb említett két fő tényező károsítókra gyakorolt hatása szerteágazó, egyes esetekben stimuláló, más esetekben gátló hatásokra kell számítanunk. Emiatt a hatások eredőjét nehéz tudományosan is megalapozott módon megjósolni. Mindehhez hozzá kell tenni azt is, hogy az éghajlatváltozás a mezőgazdasági régiók eltolódását is maga után vonhatja, és ez kiváltja a termesztett növények és azok károsítóinak változását is. Ennek következménye lehet az is, hogy az új területen megjelenő növénybetegségek és állati kártevők azokat a természetes növényi társulásokat is megváltoztathatják, amelyek azelőtt nem voltak kitéve a kultúrnövényeket károsító – számos esetben sokkal agresszívebb – fajoknak vagy változatoknak