Relativistic Spin-Isospin Dependent Response Function of Nucleus

A full relativistic formalism is employed to derive the relativistic particle-hole and delta-hole excitation polariza tion insertion of pion propagator in nuclear matter.The spin-isospin-dependent response function of nucleus at high energy-momentum transfer is calculated with the nuclear matter approximation.The short range correlation effect,two-nucleon absorption and nucleus form factor effects are included in the calculation.The position and width of the resonance peak of the spin-isospin mode are reproduced and found to be coincident with experiment data.The position of the peak and its width is sensitive to Landau-Migdal parameter g'which is about 0.6.

Effects of Back Massages on Stress Observed in Students Preparing for the National License Examination

We measured serum level of cortisol and lactate, the stiffness of trapezius, skin blood flow and VAS before and after the back massages of 25 senior college students, who had sent stressful days for 11 months starting from April, preparing for the national license examination. These students usually had complaints of stiffness of shoulder and/or lumber. Back massages significantly reduced the level of serum cortisol from 8.85 ± 0.78 to 5.95 ± 0.68 μg/dl, without affecting that of lactate. The treatment also improved the stiffness of the trapezius of students with complaints from 63.24 ± 0.78 to 59.12 ± 0.78 after the treatment without affecting skin blood flow (SKBF). In addition, back massages reduced the VAS value at the same time. These results indicate that back massages of the student are effective to improve the physical and psychological conditions of the students.

The effect of alkyl chain branching positions on the electron mobility and photovoltaic performance of naphthodithiophene diimide(NDTI)-based polymers

Conjugated polymers are widely used in organic optoelectronic devices due to their solution processability, thermal stability and structural diversity. Generally, alkyl side chains must be utilized to increase the solubility of final polymers in the processing solvent. However, the effects of different type alkyl chains on the properties of n-type photovoltaic polymers have rarely been investigated. In this article, we synthesized three naphthodithiophene diimide（NDTI） based polymers containing bulky alkyl chains with different branching position, named as NDTI-1, NDTI-2 and NDTI-3, respectively. We systematically investigated the effect of different branching point on the molecular packing, charge transport and photovoltaic performance. When moving the branching point away from the backbone, the intermolecular interaction became stronger, which could be proved by 2D grazing incidence wide angle X-ray scattering（GIWAXS） measurement. Therefore, the electron mobilities in organic field-effect transistors gradually increased from 2.11×10-3 cm2 V/-1 s-1 for NDTI-1 to 4.70×10-2 cm2 V/-1 s-1 for NDTI-2 and 9.27×10-2 cm2 V/-1 s-1 for NDTI-3,which are quite high values for polymers with face-on orientation. In addition, the NDTI-2 and NDTI-3 thin films exhibited redshifted absorption spectra compared with NDTI-1. When blending with three classic donor polymers PBDB-T, PTB7-Th and PE61, NDTI-2 based devices always showed the higher power conversion efficiencies（PCEs） than the other two polymers（beside the comparable result of PTB7-Th:NDTI-3 combination） as a result of the high photocurrent response and high fill factor. Our results indicate that bulky alkyl chain with branching point at 2-position should be a good and safe choice for the design of naphthodithiophene diimide-based and even naphthalene diimide-based n-type photovoltaic polymers.