On the valence regime in the (CexLa1−x)Be13 system

High-field magnetization, susceptibility and heat capacity data for the (Ce_xLa_1?x)Be₁₃ system are presented. A mixed valence behaviour is followed through the whole system with a n_f occupation number increasing from 0.65 toward 1 with increasing Ce dilution. For x ? 0.1 a Kondo regime is possible.     

Low-temperature properties of the Ce(Pd1−xNix) system

The influence of substituting Pd by Ni is described in Ce(Pd_1-xNi_x)₃ alloys with x taken up to about 0.25. Thermal and magnetization measurements point out a transition from a non-magnetic state (CePd₃) to a ferromagnetic state for x > 0.05, with a Curie temperature K. The Ce-L_2,3 absorption edges and magnetic circular dichroism (XMCD) study reveals the coexistence of strong 4f hybridization and ferromagnetic order. The Ce-L_2,3 XMCD signal measured in CePd₃ demonstrates that in the Ce-based dense Kondo materials only the 4f¹ channel gives a magnetic response.Received: 2 September 2003, Published online: 15 March 2004PACS: 75.20.Hr Local moment in compounds and alloys; Kondo effect, valence fluctuations, heavy fermions - 75.30.Mb Valence fluctuation, Kondo lattice, and heavy-fermion phenomena - 71.10.Hf Non-Fermi-liquid ground states, electron phase diagrams and phase transitions in model systems     

Magnetic properties of some rare earth monoxides LnO (Ln = Pr,Nd, Sm) mixed valence state of SmO

In this paper we present the first results of magnetization measurements performed up to 40 kGauss between 1.4°K and 300°K on several Rare-Earth monoxides obtained by high-pressure synthesis. For PrO and NdO the thermal variation of the susceptibilities well agrees with a Pr³⁺ and Nd³⁺ state of the Rare Earth atoms. Such a result is in good agreement with the lattice parameter measurements. For SmO, whereas a nearly Sm³⁺ state ($\text{J =}\text{5}\text{2}$) is expected from our crystallographical and X-ray absorption data, the magnetic susceptibility is mainly temperature independent. A similar behaviour has been observed on intermediate valence compounds like SmB₆, SmS under pressure. We conclude that SmO may be also in this so-called intermediate valence state.     

Allicin,the Odor of Freshly Crushed Garlic: A Review of Recent Progress in Understanding Allicin’s Effects on Cells

The volatile organic sulfur compound allicin (diallyl thiosulfinate) is produced as a defense substance when garlic (Allium sativum) tissues are damaged, for example by the activities of pathogens or pests. Allicin gives crushed garlic its characteristic odor, is membrane permeable and readily taken up by exposed cells. It is a reactive thiol-trapping sulfur compound that S-thioallylates accessible cysteine residues in proteins and low molecular weight thiols including the cellular redox buffer glutathione (GSH) in eukaryotes and Gram-negative bacteria, as well as bacillithiol (BSH) in Gram-positive firmicutes. Allicin shows dose-dependent antimicrobial activity. At higher doses in eukaryotes allicin can induce apoptosis or necrosis, whereas lower, biocompatible amounts can modulate the activity of redox-sensitive proteins and affect cellular signaling. This review summarizes our current knowledge of how bacterial and eukaryotic cells are specifically affected by, and respond to, allicin.     

Visualizing tributyltin (TBT) in bacterial aggregates by specific rhodamine-based fluorescent probes

Here we present the first examples of fluorescent and colorimetric probes for microscopic TBT imaging. The fluorescent probes are highly selective and sensitive to TBT and have successfully been applied for imaging of TBT in bacterial Rhodobacter ferrooxidans sp. strain SW2 cell-EPS-mineral aggregates and in cell suspensions of the marine cyanobacterium Synechococcus PCC 7002 by using confocal laser scanning microscopy.     

The valence of cerium under high pressure

The valence of Ce metal shifts from 3.03 to only 3.32 (±0.02) between 0 and 120 kbar at 300 K. It is trapped by a deep minimum of the free energy which lies near valence 3.25 and is caused by strong interconfigurational mixing. In the á phase the valence is independent of pressure because of the coexistence of two crystallographic phases. The energy of promotion from Ce³⁺ to Ce⁴⁺ is found to be 1.9 eV.     

Dynamical Behavior of the Multibondic and Multicanonic Algorithm In The 3D q-State Potts Model

We investigate the dynamical behavior of the recently proposed multibondic cluster Monte Carlo algorithm in applications to the three-dimensional q-state Potts models with q= 3, 4, and 5 in the vicinity of their first-order phase transition points. For comparison we also report simulations with the standard multicanonical algorithm. Similar to the findings in two dimensions, we show that for the multibondic cluster algorithm the dependence of the autocorrelation time on the system size Vis well described by the power law V , and that the dynamical exponent is consistent with the optimal random walk estimate = 1. For the multicanonical simulations we obtain, as expected, a larger value of 1.2.