Statistical properties of ideal photons in a two-dimensional dye-filled spherical cap cavity

Within the framework of quantum statistical mechanics,we have proposed an exact analytical solution to the problemof Bose-Einstein condensation(BEC)of harmonically trapped two-dimensional(2D)ideal photons.We utilize this analyticalsolution to investigate the statistical properties of ideal photons in a 2D dye-filled spherical cap cavity.The resultsof numerical calculation of the analytical solution agree completely with the foregoing experimental results in the BEC ofharmonically trapped 2D ideal photons.The analytical expressions of the critical temperature and the condensate fractionare derived in the thermodynamic limit.It is found that the 2D critical photon number is larger than the one-dimensional(1D)critical photon number by two orders of magnitude.The spectral radiance of a 2D spherical cap cavity has a sharppeak at the frequency of the cavity cutoff when the photon number exceeds the critical value determined by a temperature.

Enhanced Electrocatalytic Activity by RGO/MWCNTs/NiO Counter Electrode for Dye-sensitized Solar Cells

We applied the reduced graphene oxide/multi-walled carbon nanotubes/nickel oxide(RGO/MWCNTs/Ni O)nanocomposite as the counter electrode(CE) in dye-sensitized solar cells(DSSCs) on fluorine-doped tin oxide substrates by blade doctor method. Power conversion efficiency(PCE) of 8.13 % was achieved for this DSSCs device, which is higher than that of DSSCs devices using Ni O, RGO, and RGO/Ni O-CE(PCE = 2.71 %, PCE = 6.77 % and PCE = 7.63 %). Also, the fill factor of the DSSCs devices using the RGO/MWCNTs/Ni O-CE was better than that of other CEs. The electron transfer measurement of cyclic voltammetry and electrochemical impedance spectroscopy showed that RGO/MWCNTs/Ni O film could provide fast electron transfer between the CE and the electrolyte, and high electrocatalytic activity for the reduction of triiodide in a CE based on RGO/MWCNTs/Ni O in a DSSC.

How does a woodpecker work? An impact dynamics approach

To understand how a woodpecker is able accelerate its head to such a high velocity in a short amount of time,a multi-rigid-segment model of a woodpecker＇s body is established in this study.Based on the skeletal specimen of the woodpecker and several videos of woodpeckers pecking,the parameters of a three-degree-of-freedom system are determined.The high velocity of the head is found to be the result of a whipping effect,which could be affected by muscle torque and tendon stiffness.The mechanism of whipping is analyzed by comparing the response of a hinged rod to that of a rigid rod.Depending on the parameters,the dynamic behavior of a hinged rod is classified into three response modes.Of these,a high free-end velocity could be achieved in mode II.The model is then generalized to a multihinge condition,and the free-end velocity is found to increase with hinge number,which explains the high free-end velocity resulting from whipping.Furthermore,the effects of some other factors,such as damping and mass distribution,on the velocity are also discussed.

Cooper Molecules: Second Pairing of Cooper Pairs in Gapless Superconductor CeCoIn5

We establish a quantum field theory of phase transitions in gapless superconductor CeCoIn5.It is found that uniform Cooper pair gases with pure gradient interactions with negative coefficient can undergo a Bardeen–Cooper–Schrieffer(BCS)condensation below a critical temperature.In the BCS condensation state,bare Cooper pairs with opposite wave vectors are bound into Cooper molecules,and uncoupled bare Cooper pairs are transformed into a new kind of quasiparticle,i.e.,the dressed particles.The Cooper molecule system is a condensate or a superfluid,and the dressed particle system is a normal fluid.The critical temperature is derived analytically.The critical temperature of the superconductor CeCoIn5 is obtained to be Tc=2.289 K,which approaches the experimental data.The transition from the BCS condensation state to the normal state is a first-order phase transition.

中国传染病学的先驱——江南名医吴有性

乱世疫情自明末崇祯帝登基到清顺治帝入关问鼎中原,这短短的三十年间,中国战乱四起,局势动荡。明朝自万历帝之后开始逐渐衰落,“明之衰,衰于正、嘉以后,至万历朝则加甚焉。明亡之征兆,至万历而定”,当时的明王朝已是“如沸鼎同煎,无一片安乐之地”。张献忠、李自成及各地的农民起义风起云涌,山海关外的清军虎视眈眈,加上天灾不断,当时的大明王朝已是摇摇欲坠,百姓的正常生产生活秩序被打破,而各地接连不断爆发的疫情似乎成为压垮明王朝的最后一根稻草。

吴方言名词小考

吴方言是我国主要的方言之一,现主要分布在江苏东南部及浙江东北部的大部分地区,而且用吴方言创作的文学作品较多,从六朝的子夜吴歌到明清的方言小说,资料十分丰富。但随着时代的变迁,吴方言也有了较大变化,一些用词虽然口头上还在说,但在文章上已经很少见了,有的则是有音无字,有的则是找一音近的字来代替本意字。本文对一些吴方言中常说常写,或容易误写的词作考证。