First description of B chromosomes in the family Auchenipteridae,Parauchenipterus galeatus (Siluriformes) of the São Francisco River basin (MG,Brazil)

B chromosomes are considered additional and non-essential; they likely originate from A chromosomes and follow a distinct evolution. In fish, approximately half of the Neotropical species with B chromosomes are Characiformes and 35% are Siluriformes. There has been no report of B chromosomes in Auchenipteridae until this moment. B chromosomes found in a population of Parauchenipterus galeatus from the São Francisco River basin in the state of Minas Gerais (Brazil) were small, metacentric, totally heterochromatic and exhibited intra-individual and inter-individual variation. The diploid number was 58 chromosomes (22 metacentric, 16 submetacentric, 12 subtelocentric and 8 acrocentric). The nucleolar organizing regions were simple and the heterochromatin intercalated in the ribosomal sites, characterized by CMA₃ and DAPI fluorochromes, was of a GC-rich constitution. The 5S rDNA genes were located in an intercalary position in only one chromosome pair. An hypothesis about the origin of the B chromosomes in P. galeatus and a review on B chromosomes in catfish are also presented in this study.     

A finite element analysis for the temperature field produced by a moving heat source

Using moving mesh finite element method we discuss the temperature field produced by a moving heat source with the variable thermal conductivity and with the raUioative and convective boundary conditions in a wide range of the velocity. The temperature-time relationships at various velocities in the static and moving coordinate systems are studied. The steady-state temperature distributions at various velocities in the moving coordinate systems are given. The temperature field produced by the plastic deformation at the process region (a region very near the crack tip) is also studied, and the results show that the highest temperature at the process region is lower than 1000℃ or 1832℉     

Catalytic chameleon dendrimers

Dendrimers with boronic ester end-groups and an iron porphyrin core were synthesized and characterized. The dendrimer termini were reversibly exchanged by the addition of appropriate diol molecules. According to molecular dynamics (MD) simulations, the exchange of termini may lead to changes in the conformational behavior of the dendrimer, specifically regarding the average position of the end groups relative to the core. The spatial steric disposition attained with different termini was shown to significantly affect epoxidation reaction activity and selectivity with various alkenes, thus allowing for an original way to control and adjust catalytic behavior under alternating environments.     

Shears band in the 105Sn nucleus

The structure of ¹⁰⁵Sn has been investigated through the ⁵⁰Cr(⁵⁸Ni,2pn) reaction at a beam energy of 210 MeV. In addition to an extension of the spherical level scheme, a regular sequence of dipole transitions has been found. The experimental results are in agreement with the prediction of Tilted Axis Cranking calculations, which satisfactorily explain the properties of the band.     

A Sol-Gel Synthesis for Thermally Stable Aniline/Silica Material

Aniline/silica sol-gel material was obtained. The aniline was immobilized on the silica surface using chloropropyltrimethoxysilane as bridge reagent. The base activator NaH was used to produce a fast SN₂ reaction between the base and the alkylorganosilane. The resulting modified silica was characterized by elemental analysis and infrared spectroscopy using an oven cell. The organic coverage on the surface was proportional to the organic precursor concentration. The aniline/silica materials are thermally stable up to 300°C, in high vacuum.     

g-factor of the first excited 4+ states in156Gd and158Gd

Relative g-factor of the first 2⁺ and 4⁺ states have been measured with the transient field technique in¹⁵⁶Gd and¹⁵⁸Gd. The precession of gamma rays depopulating the levels under study were observed, after passing through thin polarized gadolinium. The observed values agree with the predictions of the rotational model, i.c. g(4⁺)= g(2⁺), while contrasting the hypothesis that in¹⁵⁶Gd the g-factor of the 4⁺ is reduced with respect to the 2⁺, because of rotational alignment.     

A cryogenic underground observatory for rare events: CUORE, an update

CUORE is a proposed tightly packed array of 1000 TeO₂ bolometers, each being a cube 5 cm on a side with a mass of 750 g. The array consists of 25 vertical towers, arranged in a square of 5 towers by 5 towers, each containing ten layers of four crystals. The design of the detector is optimized for ultralow-background searches for neutrinoless double beta decay of ¹³⁰Te (33.8% abundance), cold dark matter, solar axions, and rare nuclear decays. A preliminary experiment involving 20 crystals of various sizes (MIBETA) has been completed, and a single CUORE tower is being constructed as a smaller scale experiment called CUORICINO. The expected performance and sensitivity, based on Monte Carlo simulations and extrapolations of present results, are reported.     

In-band M1 and E2 transition rates and collective structures in Ba

Subpicosecond mean lifetimes of eight excited states in ¹²⁸Ba populated via the ⁹⁶Zr(³⁶S,4n) reaction were measured by the Doppler-shift attenuation (DSA) technique using a line-shape analysis. The differential decay-curve method (DDCM) was applied for the lifetime determination. The B(E2) values in the yrast band indicate that the first band-crossing is with a proton S-band. The configuration πh_11/2d_5/2 of the negative-parity semi-decoupled bands is confirmed by the measured B(E2, I → I − 2) and B(M1, I → I − 1) transition strengths. The higher-lying “dipole” band in ¹²⁸Ba can be described as a high-K four-quasiparticle band built on the prolate configuration (πh_11/2d_5/2) (νh_11/2g_7/2).     

Effects of multiple blade interaction on the containment of blade fragments during a rotor failure

A finite element analysis is used to study the impact and the containment aspects of rotor blade fragments that are produced during a aircraft jet engine rotor failure. The impact and containment studies are performed on a ring-type containment structure and various fragment types are considered in this study. For each type of fragment, the ring thickness is varied incrementally and the ring response, residual kinetic energy level of the fragments, magnitude of impact forces and the overall containment or failure are determined. First, only a single fragment is considered and the rotor is assumed to contain no other blades. Next, the remaining blades are introduced and the effects of multiple collisions with the other blades on the containment are analyzed. The explicit, nonlinear finite element code Dyna3d is used for the numerical computations in this study and the results are compared with the experimental results performed on a T58 rotor at the spin facility of the Naval Air Propulsion Test Center.