Synaptic development of layer V pyramidal neurons in the prenatal human prefrontal neocortex: a Neurolucida-aided Golgi study

The prefrontal neocortex is involved in many high cognitive functions in humans.Deficits in neuronal and neurocircuitry development in this part of the cerebrum have been associated with various neuropsychiatric disorders in adolescents and adults.There are currently little available data regarding prenatal dendrite and spine formation on projecting neurons in the human prefrontal neocortex.Previous studies have demonstrated that Golgi silver staining can identify neurons in the frontal lobe and visual cortex in human embryos.In the present study,five fetal brains,at 19,20,26,35,and 38 gestational weeks,were obtained via the body donation program at Xiangya School of Medicine,Central South University,China.Golgi-stained pyramidal neurons in layer V of Brodmann area 46 in fetuses were quantitatively analyzed using the Neurolucida morphometry system.Results revealed that somal size,total dendritic length,and branching points of these neurons increased from 26 to 38 gestational weeks.There was also a large increase in dendritic spines from 35 to 38 gestational weeks.These findings indicate that,in the human prefrontal neocortex,dendritic growth in layer V pyramidal neurons occurs rapidly during the third trimester of gestation.The use of human fetal brain tissue was approved by the Animal Ethics Committee of Xiangya School of Medicine,Central South University,China(approval No.2011-045)on April 5,2011.

Research and Analysis of the Error of an Unequal Arm Buoyancy Balance

The basic structure and working principle of an unequal-arm buoyancy balance are introduced in this article. Different kinds of error produeed in the unequal-arm buoyancy balance has been researched and analyzed. First the temperature influence of the crossbeam is analyzed, then the measurement error is calculated; second, the error produced by the pivot and the counterweight system is analyzed, then the corresponding error reduction method is proposed. It is shown that the error reduction method can promote the precision of the buoyancy, which is critical to balance.

Universal Grammar and Second Language Acquisition

Universal Grammar,whose main focus is on first language acquisition,is a major linguistic theory exerting profound influence on second language acquisition.This paper is a tentative explanation to whether the set of rules of UG can still be accountable for SLA.Moreover,some suggestions are given to the future development toward the relationship of UG and SLA.

Tricolor emitting and energy transfer in the phosphor Ba_2ZnSi_2O_7:Ce^(3+),Eu^(3+),Eu^(2+) for white-LED based near-UV chips

The red, green and blue （R/G/B） tricolor emitting phosphors Ba2ZnSi2O7 co-doped with Ce3＋and Eu3＋were synthesized in air atmosphere by a conventional high temperature solid-state reaction technique. All of the excitation spectrum of the phosphor Ba2ZnSi2O7：Ce,Eu showed a strong broad band absorption in the n-UV region whenever monitored by red （630 nm）-emitting or by green （500 nm）-and blue （402 nm）-emitting. Under the excitation of 330 nm, the emission spectrum containing a blue-violet emis-sion band, a green emission and four sharp lines originated from the characteristic transitions of Ce3＋, Eu2＋and Eu3＋ions, of which the relative intensities of the three emission bands could be controlled by the doping concentration of Ce3＋. The ca. CIE chromaticity co-ordinates （x=0.317, y=0.309） of the phosphor Ba1.94ZnSi2O7：0.03Eu,0.01Ce was very close to the standard white （x=0.33, y=0.33）, which suggested that it was a novel single-phased white-light emitting phosphor for LED-based near-UV chip. The mechanisms of energy transfer from Eu2＋to Eu3＋via Ce3＋was also discussed.

Propagation characteristics of the silica and silicon subwavelength-diameter hollow wire waveguides

The basic propagation properties of the silica and silicon subwavelength-diameter hollow wire waveguides have been investigated by comparison. It shows that the silica and silicon subwavelength-diameter hollow wire waveguides have some interesting properties, such as enhanced evanescent field in the cladding, enhanced intensity in the hollow core, and large waveguide dispersion. For the different confinement ability, the enhanced field in the hollow core and cladding of the silica subwavelength-diameter hollow wire is much stronger than that of the silicon one for the same size.