Three-dimensionally preserved minute larva of a great-appendage arthropod from the early Cambrian Chengjiang biota.

A three-dimensionally preserved 2-mm-long larva of the arthropod Leanchoilia illecebrosa from the 520-million-year-old early Cambrian Chengjiang biota of China represents the first evidence, to our knowledge, of such an early developmental stage in a short-great-appendage (SGA) arthropod. The larva possesses a pair of three-fingered great appendages, a hypostome, and four pairs of well-developed biramous appendages. More posteriorly, a series of rudimentary limb Anlagen revealed by X-ray microcomputed tomography shows a gradient of decreasing differentiation toward the rear. This, and postembryonic segment addition at the putative growth zone, are features of late-stage metanauplii of eucrustaceans. L. illecebrosa and other SGA arthropods, however, are considered representative of early chelicerates or part of the stem lineage of all euarthropods. The larva of an early Cambrian SGA arthropod with a small number of anterior segments and their respective appendages suggests that posthatching segment addition occurred in the ancestor of Euarthropoda.

Altered gray matter volume and functional connectivity in medial orbitofrontal cortex of bulimia nervosa patients: A combined VBM and FC study.

Brain structural and functional abnormalities have been shown to be involved in the neurobiological underpinnings of bulimia nervosa (BN), while the mechanisms underlying this dysregulation are unclear. The main goal of this investigation was to explore the presence of brain structural alterations and relevant functional changes in BN. We hypothesized that BN patients had regional gray matter volume abnormalities and corresponding resting-state functional connectivity (rsFC) changes compared with healthy controls. Thirty-one BN patients and twenty-eight matched healthy controls underwent both high-resolution T1-weighted magnetic resonance imaging (MRI) and resting-state functional MRI. Structural analysis was performed by voxel-based morphometry (VBM), with subsequent rsFC analysis applied by a seed-based, whole-brain voxelwise approach using the abnormal gray matter volume (GMV) region of interest as the seed. Compared with the controls, the BN patients showed increased GMV in the left medial orbitofrontal cortex (mOFC). The BN patients also exhibited significantly increased rsFC between the left mOFC and the right superior occipital gyrus (SOG) and decreased rsFC between the left mOFC and the left precentral gyrus, postcentral gyrus, and supplementary motor area (SMA). Furthermore, the z values of rsFC between the left mOFC and right SOG was positively correlated with the Dutch Eating Behavior Questionnaire-external eating scores. Findings from this investigation further suggest that the mOFC plays a crucial role in the neural pathophysiological underpinnings of BN, which may lead to sensorimotor and visual regions reorganization and be related to representations of body image and the drive behind eating behavior. These findings have important implications for understanding neural mechanisms in BN and developing strategies for prevention.

Influence of Y3+, Bi3+ content on photoluminescence of YVO4:Dy3+ phosphor induced by ultraviolet excitation.

YxVO4: 0.01Dy3+ and Y0.99-x V04: 0.01Dy3+, xBi3+ phosphors were synthesized by chemical coprecipitation method. Their crystal structure, micromorphology and photoluminescence (PL) properties were investigated by X-ray diffraction (XRD), scan electron microscopy (SEM) and spectrofluorometer. YxVO4: 0.01Dy3+ and Y0.99--xVO4: 0.01Dy3+, xBi3+ phosphors have a broad excitation band from about 250 to 350 nm including a strongest peak at about 310 nm. Under its excitation, the emission spectra exhibits two sharp peaks, one of which centered at about 483 nm for 4F9/2-->6H15/2 transition of Dy3+ and the other at about 574 nm due to the 4F9/2-->6 H13/2 transition of Dy+. For YxVO4: 0.01Dy3+, (x = 0.94, 0.97, 0.99, 1.01, 1.03) phosphor, with increasing value of x, the body color of phosphor changes from yellow to white and the strongest peak in the excitation spectra shifts a little to shorter wavelength. It is detrimental to luminous intensity when Y3+ content deviates stoichiometric ratio. For Y0.99--x VO4: 0.01Dy3+, xBi3+ (x = 0.01, 0.05, 0.1, 0.15, 0.2, 0.25) phosphor, the samples have extraneous bismuth vanadium oxide phase except for the major tetragonal zircon structure when x > or = 0.20. With increasing value of x, the band edge in the excitation spectra shifts to longer wavelength, the excitation intensity and luminous intensity increase early and decrease late. When the value of x is 0.01, the intensities increase evidently. In addition, the influence of Y3+ or Bi3+ on the color temperature of emission and micromorphology of YVO4:Dy3+ is slight.