Single-phase and gram-scale routes toward nearly monodisperse Au and other noble metal nanocrystals

Single-phase approaches are introduced for the synthesis of nearly monodisperse Au and other noble metal nanocrystals. The new approaches possess all the advantages of the popular Brust method. With weak ligands or surfactants for the metal ions, the control of the size and size distribution of the nanocrystals in synthesis in the size range between 1 and 15 nm was achieved via maintaining balanced nucleation and growth by tuning the activities of the metal precursors and reducing reagents. Because only weak ligands are employed in the new synthetic schemes, surface modification and functionalization of the resulting nanocrystals can be readily carried out.     

2×40 Gb/s OCDM using superstructure fiber Bragg gratings en/decoder

A 7-chip, 280 Gb/s optical code-division multiplexing (OCDM) system incorporating quaternary phase coding and decoding superstructured fiber Bragg gratings (SSFBGs) is experimentally demonstrated. Only ordinary phase masks and sub-micrometer precision are needed to fabricate the encoding and decoding SSFBGs. Interchannel interference noise is also considered and evaluated, 2-channel 40 (Gb/s)/channel(2×40 Gb/s) signal transmission is demonstrated.     

Preconcentration of rare earth elements on silica gel loaded with 1-phenyl-3-methyl-4-benzoylpyrazol-5-one prior to their determination by ICP-AES.

A new chelating resin, silica gel loaded with 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (PMBP), was prepared and used for the preconcentration of trace amounts of rare earth elements (REEs) in water samples prior to their determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). REEs (La, Eu, Yb and Y) were quantitatively retained on the column packed with modified silica gel in the pH range 5 - 8 and separated from the matrix, and then recovered by eluting with 2.0 mol L(-1) HNO3. The adsorption capacity of modified silica gel for La, Eu, Yb and Y was 0.208, 0.249, 0.239 and 0.224 mmol g(-1), respectively. The method has been successfully applied for the determination of La, Eu, Yb and Y in geological and environmental samples with satisfactory results.     

有机玻璃中条形药包爆炸破碎区发展过程的高速摄影研究

采用高速摄影方法，对有机玻璃中条形装药爆炸破碎区的发展过程进行了研究。结果表明，爆炸后形成的破碎区大致可分为柱部和端部两部分，其发展特征是，由条形装药柱中部向两端过渡的破坏区扩展速度逐渐减慢。     

Derivation of mixture distributions and weighted likelihood function as minimizers of KL-divergence subject to constraints

In this article, mixture distributions and weighted likelihoods are derived within an information-theoretic framework and shown to be closely related. This surprising relationship obtains in spite of the arithmetic form of the former and the geometric form of the latter. Mixture distributions are shown to be optima that minimize the entropy loss under certain constraints. The same framework implies the weighted likelihood when the distributions in the mixture are unknown and information from independent samples generated by them have to be used instead. Thus the likelihood weights trade bias for precision and yield inferential procedures such as estimates that can be more reliable than their classical counterparts.     

Cooperation and charity in spatial public goods game under different strategy update rules

Human cooperation can be influenced by other human behaviors and recent years have witnessed the flourishing of studying the coevolution of cooperation and punishment, yet the common behavior of charity is seldom considered in game-theoretical models. In this article, we investigate the coevolution of altruistic cooperation and egalitarian charity in spatial public goods game, by considering charity as the behavior of reducing inter-individual payoff differences. Our model is that, in each generation of the evolution, individuals play games first and accumulate payoff benefits, and then each egalitarian makes a charity donation by payoff transfer in its neighborhood. To study the individual-level evolutionary dynamics, we adopt different strategy update rules and investigate their effects on charity and cooperation. These rules can be classified into two global rules: random selection rule in which individuals randomly update strategies, and threshold selection rule where only those with payoffs below a threshold update strategies. Simulation results show that random selection enhances the cooperation level, while threshold selection lowers the threshold of the multiplication factor to maintain cooperation. When charity is considered, it is incapable in promoting cooperation under random selection, whereas it promotes cooperation under threshold selection. Interestingly, the evolution of charity strongly depends on the dispersion of payoff acquisitions of the population, which agrees with previous results. Our work may shed light on understanding human egalitarianism.     

Comparative study of electrochemical capacitance of multi-walled carbon nanotubes before and after chopping

In the work, short multi-walled carbon nanotubes (S-CNTs) were synthesized by chopping conventional μm-long multi-walled carbon nanotubes (L-CNTs) under ultrasonication in H₂SO₄/HNO₃ mixed acids. A comparative electrochemical investigation performed in 6 M KOH solution demonstrated that a specific capacitance (SC) of ca. 14.6 μF cm⁻² was delivered by the S-CNTs with the specific surface area (SSA) of 207 m² g⁻¹, much larger than that of ca. 10.1 μF cm⁻² for the L-CNTs with the SSA of 223 m² g⁻¹, the reason for which was that S-CNTs with two open ends, due to good ion penetrability, provided more entrances for electrolyte ions to access the inner surface easily through their shorter inner pathway so as to enhance their SSA utilization and geometric SC. The surface structure disruption of S-CNTs, owing to ultrasonication and oxidation during chopping process, deteriorated their electronic conductivity and resulted in an inferior power property in contrast to L-CNTs.