Self-screening of the particle-hole interaction and core polarization of the effective two-particle interaction

The diagrams of the Tamm-Dancoff and random-phase approximations (TDA and RPA) have been summed to calculate the core polarization of the effective interaction between two nucleons in the 1s0d and Ip0f shells. The large core-polarization corrections obtained in the TDA and particularly the RPA are strongly reduced when the self-screening corrections to the particle-hole and ground-state correlation vertices are included. The screening corrections serve to suppress the collectivity of the core phonons and in particular stabilize the isoscalar monopole phonon in ⁴⁰Ca against collapse. When screening is included the TDA and RPA give core-polarization corrections which are similar in magnitude and in many cases lead to good agreement with experiment. Because of neglected effects and other uncertainties the qualitative rather than the quantitative features of the results are stressed.     

Near fields of wire antennas by matrix methods

The method of moments [1], [2] is applied to wire antenna near-field problems. Within the general method, two computational procedures are developed. Results of these are compared with those of certain approximate analytical techniques and also with those of other investigators. A treatment for junctions is outlined. Examples are included for a single dipole antenna, for linear arrays of dipoles and also for loop andT-junction radiators.     

Computations and Stability of the Fukui Invariant

T. Fukui introduced an invariant for the blow-analytic equivalence of real singularities. For a nondegenerate analytic function (germ) f, he discovered a formula for computing the one-dimensional invariant, denoted by A(f) := A ₁(f). We find a formula for A(f) for any f (real or complex, degenerate or not). We then define, and characterise, various notions of stability of A(f), using the formula. For real analytic f, the Fukui invariant with sign is defined, and computed by a similar formula. In the case where f is an analytic function of two complex variables, A(f) can also be computed using the tree-model of f.     

Strain and temperature sensitivity of very-thin low-density tantalum films

Low-density tantalum thin films, several-hundred angstroms thick, sputtered at 1500 V can exhibit relatively stable strain-gauge factors of the order ten, after heat treatment at 150 to 200°C. Temperature compensation can be obtained by means of a bridge network energised with a current source.     

Effect of freeze-drying and rehydrating treatment on the thermo-responsive characteristics of poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide) microspheres

Investigations on the effect of freeze-drying and rehydrating treatment on equilibrium volume changes and on the thermo-response rate of poly(N-isopropylacrylamide) (PNIPAM) microspheres were carried out. The experimental results showed that freeze-drying and rehydrating treatment had nearly no effect on the low critical solution temperature and equilibrium volume changes of PNIPAM microspheres. Furthermore, when the PNIPAM microspheres were frozen in only liquid nitrogen through rapid cooling, the response rate of PNIPAM microspheres to environmental temperature change was nearly not affected by the treatment, which was surprisingly different from the macroscopic hydrogel. The dimension effect was responsible for this phenomenon. The micron-sized PNIPAM microsphere itself has a much quicker response rate compared with the bulky hydrogel because the characteristic time of gel deswelling is proportional to the square of a linear dimension of the hydrogel.     

Directed assembly of chiral oxidovanadium(V) methoxides into C4-symmetric metal(I) vanadate-centered quadruplexes: synergistic K+- and Ag+-specific transport

A directed assembly process to form C4-symmetric, vanadate-centered quadruplexes, for the first time, from a given chiral oxidovanadium(V) complex allows for highly efficient K+- and Ag+-specific transport from aqueous phase containing three other alkali metal cations into organic solvents, reminiscent of the K+ specific transport exerted by four homochiral glycine residues of the opening site in KcsA membrane protein.     

Design, synthesis, and biological evaluation of novel alkenylthiophenes as potent and selective CB1 cannabinoid receptor antagonists

A novel class of (5-(pent-1-enyl)thiophen-2-yl)pyrazole antagonists was discovered, many of which exhibited potent CB1 activity and good CB1/2 selectivity, suggesting that along with a 1,3-transposition of the carbonyl of the pyrazole 3-carboxamide, bioisosteric replacement of the conventional pyrazole 5-aryl group with a thienyl ring substituted with an appropriate alkenyl moiety is viable.     

Dinickel complexes of disubstituted benzoate polydentate ligands: mimics for the active site of urease

Two dinickel mimics, [LNi2(DMF)4](ClO4)3 () and [L'Ni2(CH3CN)4](ClO4)3 (), for the active site of urease supported by a disubstituted benzoate polydentate ligand were synthesized and fully characterized, subsequently addition of urea afforded two urea adducts, [LNi2(urea)4](ClO4)3 () and [L'Ni2(urea)4](ClO4)3 ().     

A novel thermoresponsive hydrogel with ion-recognition property through supramolecular host-guest complexation

A novel thermoresponsive hydrogel with ion-recognition property was prepared via free-radical cross-linking copolymerization of N-isopropylacrylamide (NIPAM) with benzo-18-crown-6-acrylamide (BCAm) as host receptor. Both chemical structures and stimuli-sensitive properties of the prepared poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) P(NIPAM-co-BCAm) hydrogel were characterized. The smart hydrogel could respond to both temperature and ion stimuli. When the crown ether units captured Ba2+ and formed stable BCAm/Ba2+ host-guest complexes, the lower critical solution temperature (LCST) of the hydrogel increased due to the repulsion among charged BCAm/Ba2+ complex groups and osmotic pressure within the hydrogel. Whereas crown ethers captured Cs+, the LCST shifted to a lower temperature because of the formation of 2:1 sandwich complexes. Unexpectedly, the LCST of the cross-linked P(NIPAM-co-BCAm) hydrogel in K+ solution did not shift to a higher temperature, which was definitely different from the previously reported linear P(NIPAM-co-BCAm) copolymer in K+ solution. The results of this work provide valuable information for development of dual thermo- and ion-responsive hydrogels which have potential applications in drug controlled-release systems or biomedical fields.     

Real-Time In Situ Volatile Organic Compound Sensing by a Dual-Emissive Polynuclear Ln-MOF with Pronounced LnIII Luminescence Response

Lanthanide metal–organic frameworks (Ln-MOFs) are promising for luminescence detection of volatile organic compound (VOC) vapors, but usually suffer from the silent or quenched Ln³⁺ emission. Herein, we report a new dual-emissive Eu-MOF composed of the coordinatively unsaturated Eu₉ clusters that afford abundant open metal sites to form a confined “binding pocket” to facilitate the preconcentration and recognition of VOCs. Single-crystal structural analyses reveal that specific analytes can replace the OH oscillators in the first coordination sphere of Eu³⁺ and form a unique hydrogen-bonding second-sphere adduct tying adjacent Eu₉ clusters together to minimize their nonradiative vibrational decay. With the promoted Eu³⁺ luminescence, the MOF realizes real-time in situ visual sensing of THF vapor (<1 s) and shows a quantitative ratiometric response to the vapor pressure with a limit of detection down to 17.33 Pa. Also, it represents a top-performing ratiometric luminescent thermometer.