Conductivity of irradiated Kapton in relation to energy loss of ions and electrons

Abstract

We have studied the effects of 2.5 MeV electron irradiation and ion (C, N, F, Si and Kr) bombardment on the electrical conductivity of a polyimide (Kapton-H) with ion energies ranging between 320 keV (N) and 1.25 GeV (Kr). In this wide range of situations we have tried to sort out the respective effects of nuclear and electronic excitation energy losses.

For all ion irradiation the conductivity is found to scale with the electronic excitation absorbed dose: i.e. a power law of conductivity versus absorbed dose with an exponent around 9 is observed. At a given absorbed dose (in Gray units) the efficiency of each ion to enhance conductivity is found to be proportional to the electronic energy loss; electrons are much less efficient than ions and thus collective excitations are required to achieve this process.

The nuclear energy loss can perhaps play some role at conductivities higher than 100 Ω^?1 m^?1, but its effects are negligible in the range explored here.     

Ideal-Symmetric and Semiprime Rings

Lambek extended the usual commutative ideal theory to ideals in noncommutative rings, calling an ideal A of a ring R symmetric if rst ∈ A implies rts ∈ A for r, s, t ∈ R. R is usually called symmetric if 0 is a symmetric ideal. This naturally gives rise to extending the study of symmetric ring property to the lattice of ideals. In the process, we introduce the concept of an ideal-symmetric ring. We first characterize the class of ideal-symmetric rings and show that this ideal-symmetric property is Morita invariant. We provide a method of constructing an ideal-symmetric ring (but not semiprime) from any given semiprime ring, noting that semiprime rings are ideal-symmetric. We investigate the structure of minimal ideal-symmetric rings completely, finding two kinds of basic forms of finite ideal-symmetric rings. It is also shown that the ideal-symmetric property can go up to right quotient rings in relation with regular elements. The polynomial ring R[x] over an ideal-symmetric ring R need not be ideal-symmetric, but it is shown that the factor ring R[x]/xⁿR[x] is ideal-symmetric over a semiprime ring R.     

Host–Guest Chemistry of a Bis‐Calix[4]pyrrole Derivative Containing a trans/cis‐Switchable Azobenzene Unit with Several Aliphatic Bis‐Carboxylates

The azobenzene unit used as a photochemically and thermally switchable linker in the assembly of a bis‐calix[4]pyrrole receptor provides a means to modulate the binding of bis‐carboxylates of significant biological importance in cancer research. Conversely, the complexation of different bis‐anionic guests has significant kinetic effects on both the photochemical and thermal trans/cis isomerization of the azobenzene unit.     

Area-Minimizing Currents mod 2Q: Linear Regularity Theory

We establish a theory of Q -valued functions minimizing a suitable generalization of the Dirichlet integral. In a second paper the theory will be used to approximate efficiently area minimizing currents mod(p) when p = 2Q , and to establish a first general partial regularity theorem for every p in any dimension and codimension . © 2020 Wiley Periodicals LLC.     

Fabrication of high-mechanical-resistance Bragg gratings in single-mode optical fibers with continuous-wave ultraviolet laser side exposure

The mechanical resistance of single-mode fibers containing fiber Bragg gratings inscribed with cw UV laser irradiation is almost identical to that of pristine fiber. The median breaking strength of the gratings' Weibull distribution is more than 5 GPa, and the m value is of the order of 70. Based on a dynamic fatigue model, a Bragg grating lifetime of 50 years with a failure probability of 0.001 is predicted, assuming a constant applied stress of 0.96 GPa.     

Electrostatic interactions between a protein and oppositely charged micelles

Micellar solutions made of a fully fluorinated surfactant, LiPFN, form water-soluble complexes with lysozyme in a wide concentration range. Such complexes are stabilized by electrostatic and, very presumably, double-layer interactions. The mixtures were investigated by combining electrophoretic mobility, DLS, and dielectric relaxation methods. The former gives information on the surface charge density of protein-micelle complexes and indicates that the resulting adducts retain a negative charge (i.e., charge neutralization is incomplete). The double-layer thickness of proteins, micelles, and protein-micelle complexes is also connected to the dielectric relaxation frequency. Changes in particle size (inferred by DLS), charge density, and double-layer thickness are closely interrelated to each other. A model was developed to quantify such properties.     

The N-terminal 1-16 peptide derived in vivo from protein seminal vesicle protein IV modulates alpha-thrombin activity: potential clinical implications

We have previously shown that seminal vesicle protein IV (SV-IV) and its 1-70 N-terminal fragment have anti-inflammatory activity and modulate anti-thrombin III (AT) activity. Moreover, mass spectrometry analysis of purified SV-IV has shown that the protein was found to be highly heterogeneous and 14% of the total SV-IV molecules are truncated forms, of particular interest the 1-16, 1-17, and 1-18 peptides. In this work we report experimental data which demonstrate that the 1-16 peptide (P1-16) possesses a marked effect on the AT activity by preventing the formation of the thrombin-AT complex. We found that the formation of thrombin-AT complex is markedly decreased in the presence of P1-16 used at equimolar concentration with thrombin as evaluated with SDS-PAGE. We also monitored the conformational changes of thrombin in the presence of different P1-16 concentrations, and calculated the K(d) of thrombin/P1-16 system by circular dichroism technique. The probable interaction sites of P1-16 with thrombin have been also evaluated by molecular graphics and computational analyses. These results have potential implications in the treatment of sterility and thrombotic diseases.     

Improved high-performance liquid chromatography-diode array detection method for the determination of phenolic compounds in leaves and peels from different apple varieties

Hydroxycinnamic acids derivatives, monomeric and oligomeric flavan-3-ols, flavonols, and dihydrocalcones are four of the major polyphenolic groups found in apples leaves and peels. A simple extraction with minimal pre-treatment and a high-performance liquid chromatography-diode array detection determination are optimized and validated, in order to identify and quantitate the polyphenolic profile of leaves and peels of four apples varieties (Gala, Topaz, Golden Delicious, and Florina). The improved chromatographic method has led to better separation of some known polyphenols in a single course, and diode-array detection has been used for the previsional identification of some polyphenolic compounds not available as standards. Because the mobile phase and the chromatographic column are compatible with a mass spectrometer, this method could investigate the unknown flavanols, flavonols, hydrocinnamic acid derivatives, and chalcone-related compounds found in apple leaves and peel extracts analyzed.