Improving the use of mercury bis(phenyltellurolate) as efficient start for the synthesis of ternary clusters and polymers

Hg(TePh)₂ reacts with AgCl/PMe₂Ph and AgClO₄/PPh₃ to give the ternary clusters [(PhTe)₄Ag₂Hg₂(Cl)₂]_n (1) and [(PhTe)₁₆Ag₄Hg₆Py₄] · H₂O (2). While 1 assembles polymeric, bidimensional layers, 2 attains high symmetric moieties in which the occupational relationship is 40%/60% for the Ag⁺ and Hg²⁺ ions, respectively.     

Base-mediated intramolecular cyclization of (2-propargyl ether) arylimines: an approach to 3-amino-benzofurans

We present here a practical synthesis of functional 3-amino-benzofurans through base-promoted intramolecular cyclization of (2-propargyl ether) arylimines. A systematic study of the cyclization system revealed that the presence and the amount of base played an essential role in this reaction. The results showed that the cyclization proceeded cleanly and smoothly under mild reaction conditions, employing potassium tert-butoxide as base, THF as solvent, at room temperature in a short reaction time (1 h). The generality of this reaction has been established with (2-propargyl ether) arylimines having both electron-withdrawing and electron-donating groups.     

Effect of electric field switching on the electrophoretic mobility of single-stranded DNA molecules in polyacrylamide gels

We have examined the effects of pulsed electric fields on the separation of single-stranded DNA molecules in polyacrylamide sequencing gels. Using different electric field pulsing regimens, the mobilities of single-stranded DNA molecules can be retarded or increased as compared to conventional electrophoresis. These results indicated that pulsed field techniques can be applied to gel electrophoresis of small single-stranded DNA molecules.     

Spin Entropy

Two types of randomness are associated with a mixed quantum state: the uncertainty in the probability coefficients of the constituent pure states and the uncertainty in the value of each observable captured by the Born’s rule probabilities. Entropy is a quantification of randomness, and we propose a spin-entropy for the observables of spin pure states based on the phase space of a spin as described by the geometric quantization method, and we also expand it to mixed quantum states. This proposed entropy overcomes the limitations of previously-proposed entropies such as von Neumann entropy which only quantifies the randomness of specifying the quantum state. As an example of a limitation, previously-proposed entropies are higher for Bell entangled spin states than for disentangled spin states, even though the spin observables are less constrained for a disentangled pair of spins than for an entangled pair. The proposed spin-entropy accurately quantifies the randomness of a quantum state, it never reaches zero value, and it is lower for entangled states than for disentangled states.     

Influence of temperature on the colloidal stability of the F-DPPC and DPPC liposomes induced by lanthanum ions

The influence of La(3+) on the colloidal stability of liposomes made up by two zwitterionic phospholipids, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1-palmitoyl-2-[16-fluoropalmitoyl-phosphatidylcholine (F-DPPC), in aqueous media has been investigated by dynamic light scattering and electrophoretic mobility. The critical aggregation concentration (c.a.c.) of La(3+) for F-DPPC and DPPC liposomes were experimentally obtained, and the results were compared with theoretical predictions using the Derjaguin-Landau-Verwey-Overbeek theory. In order to evaluate the influence of the state of the bilayer on the stability of liposomes, all experiments were performed at temperatures below and above the chain-melting phase-transition temperature of lipids (transition temperature of lipids). Changes in the size of both types of liposomes and high values of polydispersity in the presence of La(3+) showed that these ions induce aggregation of liposomes at 25 °C and at 60 °C. At 25 °C, when the bilayer of F-DPPC liposomes is interdigited, DPPC liposomes are more resistant to aggregation than the liposomes formed with F-DPPC. However, this difference disappears at 60 °C, when both bilayers have the same conformation. The experimental results also indicate that the c.a.c. is higher at 60 °C than at 25 °C for both types of liposomes. In fact, it has been observed by dynamic light scattering measurements that aggregation of liposomes at 25 °C can be prevented by increasing the solution temperature for La(3+) concentrations near to the c.a.c. Moreover, the behavior of these liposomes in the presence of the ion was studied at temperatures above and below the transition temperature of the phospholipids.     

Utilization of nondestructive techniques for analysis of the Martian meteorite NWA 6963 and its implications for astrobiology

Martian meteorites are excellent study materials for understanding the present and past of Mars, as they are important historical astrophysical artifacts because they possess information about Martian geological evolution and physical and chemical characteristics. In our case, we analyzed the NWA 6963 Martian meteorite classified as basaltic shergottite because of its chemical structure. A computerized microtomography (μCT) study in the NWA 6963 Martian meteorite provided us with 2D and 3D images that were extremely useful for ascertaining the internal structure of the analyzed sample and gave us the opportunity to find a crumpled material with a very peculiar structural format. In addition, it was possible to observe through the μCT that this encrusted material also has a completely different density of the meteorite. Calcium, strontium, and potassium were detected qualitatively, among others through the technique of X‐ray fluorescence.