Physics of Polymorphic Transitions in CeRuSn

We report a detailed study of the polymorphic transitions in ternary stannide CeRuSn on high quality single crystals through a combination of X-ray diffraction experiments conducted at 300, 275 and 120 K, and measurements of the thermal expansion, magnetization, and resistivity, along main crystallographic axes. In addition, the transition was followed as a function of pressure up to 0.8 GPa. The present X-ray diffraction data show that the room temperature polymorph consists of the lattice doubled along the c axis with respect to the CeCoAl-type structure consistent with previous reports. Upon cooling, the compound undergoes two successive transitions, first to a quintuple (290 K) and than to a triple CeCoAl superstructure at 225 K. The transitions are accompanied by a tremendous volume change due to a strong shrinking of the lattice along the c axis, which is clearly observed in thermal expansion. We advance arguments that the volume collapse originates from an increasing number of crystallographically inequivalent Ce sites and the change of ratio between the short and long Ce-Ru bonds. The observed properties of the polymorphic transition in CeRuSn are reminiscent of the transition in elementary Cerium, suggesting that similar physics, i.e., a Kondo influenced transition and strong lattice vibrations might be the driving forces

Biodiversity into your hands - A call for a virtual global natural history 'metacollection'

10.1186/1742-9994-10-55Frontiers in Zoology101

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

Magnetic, Thermal and Transport Properties of YbPt2Si2YbPt_2Si_2 and Yb2Pt3Si5Yb_2Pt_3Si_5 Single Crystals

Single crystals of $YbPt_{2}Si_{2}$ and $Yb_{2}Pt_{3}Si_{5}$ have been prepared by solvent growth method with Sn flux, characterized by X-ray diffraction and by EDX microprobe analysis and investigated by measurement of magnetization, specific heat and electrical resistivity as functions of temperature and magnetic field. $YbPt_{2}Si_{2} (Yb_{2}Pt_{3}Si_{5})$ crystalizes in the tetragonal $CaBe_{2}Ge_{2}$-type (orthorhombic $U_{2}Co_{3}Si_{5}$-type) structure. Both compounds exhibit metallic resistivity behavior without visible anomaly, which could be connected with onset of magnetic ordering. Neither the specific heat shows any sign of magnetic ordering down to 0.5 K. The corresponding temperature dependences of the magnetic susceptibility of both compounds behave qualitatively similar, which is reminiscent of spin fluctuation behavior: a broad maximum at high temperatures, a shallow minimum at lower temperatures, followed by an upturn with further cooling the crystal, which can be suppressed by applying a sufficient magnetic field. The rather low values of the γ-coefficients of the specific heat (~25÷35 mJ·mol·$K^{-2}$) do not support the mixed valence scenario discussed in literature for $YbPt_{2}Si_{2}$

Structural and Magnetic Properties of the PrNi 1-x

Polycrystalline samples of $PrNi_{1-x}Cu_{x}Al$ series were studied by X-ray diffraction, magnetization and specific heat. The hexagonal ZrNiAl-type structure is preserved in the whole series. Compounds with x up to 0.4 order antiferromagnetically with the Néel temperatures between 3 and 5 K. The rest of the compounds (x = 0.5-0.9) exhibits a transition into a spin glass state below the freezing temperatures around 4 K. The analysis of the specific heat data reveals a quasi-doublet ground state well separated from higher crystal field levels in the whole series

Magnetic Order in TbPdIn

The magnetic structure in TbPdIn was investigated by neutron diffraction experiments. The results reveal a long-range magnetic structure with propagation vector (0,0,0) and the Tb moments forming a non-collinear structure within the basal plane that is unchanged over the whole temperature region below the ordering temperature of 66 K

Structural and Magnetic Properties of the PrNi1−xCuxAlPrNi_{1-x}Cu_{x}Al Series

Polycrystalline samples of $PrNi_{1-x}Cu_{x}Al$ series were studied by X-ray diffraction, magnetization and specific heat. The hexagonal ZrNiAl-type structure is preserved in the whole series. Compounds with x up to 0.4 order antiferromagnetically with the Néel temperatures between 3 and 5 K. The rest of the compounds (x = 0.5-0.9) exhibits a transition into a spin glass state below the freezing temperatures around 4 K. The analysis of the specific heat data reveals a quasi-doublet ground state well separated from higher crystal field levels in the whole series

Larval Morphology and Biology of the New Zealand-Chilean Genera Cylomissus

Minoshima, Yûsuke N., Fikáček, Martin, Gunter, Nicole, Leschen, Richard A. B. (2015): Larval Morphology and Biology of the New Zealand-Chilean Genera Cylomissus Broun and Anticura Spangler (Coleoptera: Hydrophilidae: Rygmodinae). The Coleopterists Bulletin 69 (4): 687-712, DOI: 10.1649/0010-065x-69.4.687, URL: http://dx.doi.org/10.1649/0010-065x-69.4.68