Neodymium β-diketonate glyme complexes: Synthesis and characterization of volatile precursors for MOCVD applications

The monoglyme [CH₃OCH₂CH₂OCH₃] and diglyme [CH₃O(CH₂CH₂O)₂CH₃] adducts of the neodymium tris-hexafluoroacetylacetonato [Nd(hfa)₃·monoglyme·H₂O and Nd(hfa)₃·diglyme] have been synthesised in a single step reaction. They have been characterized by elemental analyzes, mass spectrometry, and IR spectroscopy. Single crystal X-ray diffraction studies provide evidence of a mononuclear nine-coordinated complex with a monocapped square antiprismatic structure for the Nd(hfa)₃·diglyme (monoclinic system, space group P2₁/n; a = 9.7717(2), b = 15.5723(4), c = 20.5620(5) Å, β = 103.668(2)°; Z = 4). The Nd(hfa)₃·monoglyme·H₂O consists of asymmetric units containing two similar molecules (monoclinic system, space group = C2; a = 16.7057(4), b = 12.2579(4), c = 29.3734(5) Å, β = 101.170(3)°, Z = 8).The mass transport properties of these adducts have been investigated by thermogravimetric analysis which revealed high volatility and good thermal stability with a residue left lower than 3%. The Nd(hfa)₃·diglyme has been successfully applied to the low-pressure metal organic chemical vapor deposition (MOCVD) of NdBa₂Cu₃O_7−δ thin films.     

Habituation Is More Than Learning to Ignore: Multiple Mechanisms Serve to Facilitate Shifts in Behavioral Strategy

Recent work indicates that there are distinct response habituation mechanisms that can be recruited by different stimulation rates and that can underlie different components (e.g., the duration or speed) of a single behavioral response. These findings raise the question: why is “the simplest form of learning” so complicated mechanistically? Beyond evolutionary selection for robustness of plasticity in learning to ignore, it is proposed in this article that multiple mechanisms of habituation have evolved to streamline shifts in ongoing behavioral strategy. Then, speculations are offered regarding the implications of this reconceptualization of habituation for approaching the analysis of mechanisms of more complex forms of learning and memory.     

In situ feeding tactics of short-nosed fruit bat (Cynopterus sphinx) on mango fruits: evidence of extractive foraging in a flying mammal

We report a sequence of behaviors exhibited by the short-nosed fruit bat Cynopterus sphinx while feeding on fruits of Mangifera indica. They peel off the outer skin to form a feeding area of about 3–6 cm diameter. Such food preparatory behaviors were more pronounced on larger mangoes. Bats competed among themselves to feed on the mangoes that had such feeding areas exposed. Individuals that spent a considerable amount of time on food preparatory behaviors actively secured the fruits. Altogether, these behaviors indicate that Cynopterus bats might have learnt, over evolutionary time, and developed behaviors that facilitate efficient processing and feeding of fruits such as mangoes. It appears that actions exhibited by C. sphinx in peeling off the outer skin of mangoes exemplify “extractive foraging”, a behavior that is prominently known in large-brained mammals. Thus, our findings will have implications on the distribution and evolution of extractive foraging and “technical intelligence” among mammalian lineages.     

Glutamatergic and GABAergic neurons in pontine central gray mediate opposing valence-specific behaviors through a global network

1. Download : Download high-res image (96KB)
2. Download : Download full-size image

     

Locomotion of free-swimming ghost knifefish: anal fin kinematics during four behaviors

The maneuverability demonstrated by the weakly electric ghost knifefish (Apteronotus albifrons) is a result of its highly flexible ribbon-like anal fin, which extends nearly three-quarters the length of its body and is composed of approximately 150 individual fin rays. To understand how movement of the anal fin controls locomotion we examined kinematics of the whole fin, as well as selected individual fin rays, during four locomotor behaviors executed by free-swimming ghost knifefish: forward swimming, backward swimming, heave (vertical) motion, and hovering. We used high-speed video (1000 fps) to examine the motion of the entire anal fin and we measured the three-dimensional curvature of four adjacent fin rays in the middle of the fin during each behavior to determine how individual fin rays bend along their length during swimming. Canonical discriminant analysis separated all four behaviors on anal fin kinematic variables and showed that forward and backward swimming behaviors contrasted the most: forward behaviors exhibited a large anterior wavelength and posterior amplitude while during backward locomotion the anal fin exhibited both a large posterior wavelength and anterior amplitude. Heave and hover behaviors were defined by similar kinematic variables; however, for each variable, the mean values for heave motions were generally greater than for hovering. Individual fin rays in the middle of the anal fin curved substantially along their length during swimming, and the magnitude of this curvature was nearly twice the previously measured maximum curvature for ray-finned fish fin rays during locomotion. Fin rays were often curved into the direction of motion, indicating active control of fin ray curvature, and not just passive bending in response to fluid loading.     

Multifaceted luminance gain control beyond photoreceptors in Drosophila

1. Download : Download high-res image (139KB)
2. Download : Download full-size image

     

Anterior hypothalamic parvalbumin neurons are glutamatergic and promote escape behavior

1. Download : Download high-res image (156KB)
2. Download : Download full-size image

     

Stress undermines reward-guided cognitive performance through synaptic depression in the lateral habenula

1. Download : Download high-res image (206KB)
2. Download : Download full-size image

     

模拟失重不同时长对大鼠抑郁样行为的影响

目的 本研究旨在观察不同持续时间的模拟失重对大鼠抑郁样行为和海马超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的影响，以探究其影响及可能的作用机制。方法 采用后肢悬挂（HLS）尾吊法模拟大鼠失重状态。将大鼠分为对照组和不同模拟失重时间尾吊组（尾吊时长分别为1、2、3、4周）。采用旷场实验（OFT）、新物体识别实验（NORT）、强迫游泳实验（FST）观察大鼠抑郁样行为，采用酶联免疫吸附试验（ELISA）法测定海马SOD和CAT活性。结果 OFT结果显示，与对照组相比，HLS不同时间大鼠的僵滞时间增加（P<0.05，P<0.01）。在NORT中，与对照组相比，HLS不同时间大鼠对新物体的探索潜伏期增加，探索次数和时间减少（P<0.05，P<0.01）。在FST中，与对照组相比，HLS不同时间大鼠在FST中的不动时间增加，攀爬次数减少（P<0.05，P<0.01）。与对照组相比，HLS不同时间组大鼠海马组织中SOD和CAT水平均下降（P<0.05，P<0.01）。结论 短时间或长时间的失重都会导致大鼠产生类抑郁样行为。