A general understanding of asymmetric breakups of a droplet due to the asymmetry of flow fields is developed. Through a volume of fluid method, asymmetric breakups of a droplet suspended in an axisymmetric extensional flow are investigated. A regime map is depicted to show four typical hydrodynamic regimes (no breakup, one-side breakup, retraction breakup and direct breakup). Three major factors critical to an asymmetric breakup (the capillary number Ca determining the cutting speed, the asymmetry A s of the flow field causing the droplet translation and the initial volume ratio r 0) are presented. Based on this analysis, a simple model is proposed to predict the volume ratio r s of two unequal daughter droplets. Differing from the symmetric breakup, the asymmetry effects are studied systematically, which could be extended to direct the study of diverse asymmetric situations.

The asymmetric breakups of a droplet in an axisymmetric cross-like microfluidic device are investigated by using a three-dimensional volume of fluid (VOF) multiphase numerical model. Two kinds of asymmetries (droplet location deviation from the symmetric geometry center and different flow rates at two symmetric outlets) generate asymmetric flow fields near the droplet, which results in the asymmetric breakup of the latter. Four typical breakup regimes (no breakup, one-side breakup, retraction breakup and direct breakup) have been observed. Two regime maps are plotted to describe the transition from one regime to another for the two types of different asymmetries, respectively. A power law model, which is based on the three critical factors (the capillary number, the asymmetry of flow fields and the initial volume ratio), is employed to predict the volume ratio of the two unequal daughter droplets generated in the direct breakup. The influences of capillary numbers and the asymmetries have been studied systematically in this paper. The larger the asymmetry is, the bigger the one-side breakup zone is. The larger the capillary number is, the more possible the breakup is in the direct breakup zone. When the radius of the initial droplet is 20μm, the critical capillary numbers are 0.122, 0.128, 0.145, 0.165, 0.192 and 0.226 for flow asymmetry factor AS=0.05, 0.1, 0.2, 0.3, 0.4 and 0.5, respectively, in the flow system whose asymmetry is generated by location deviations. In the flow system whose asymmetry is generated by two different flow rates at two outlets, the critical capillary numbers are 0.121, 0.133, 0.145, 0.156 and 0.167 for AS=1/21, 3/23, 1/5, 7/27 and 9/29, respectively.

Recently, cold‐adaptation medicine has gotten more and more attention because of its specific significance to health care, military activities, sports performance, and so on. Although numerous studies have focused on respiratory, immune, and circulatory systems as well as skin damage upon cold exposure, the impacts on central nervous system are not well understood. This study explores the effects of chronic cold exposure on the murine central nervous system. To establish a chronic cold‐exposure animal model, adult male mice from postnatal days 40–50 (P40–50) were housed at 0–4°C for 20 days. During the study period, estrogen receptors were labeled via immunohistochemistry, the dendritic spines of visual cortical pyramidal cells were labeled with DiI diolistic assay, and synaptic ultrastructure was observed by transmission electron microscopy. The results showed that cold exposure could inhibit neural proliferation significantly, with an increase of G‐protein‐coupled receptor 30 (GPR30) expression. Chronic cold exposure could also induce a decrease in the dendritic spines of pyramidal cells in visual cortex, along with a decrease in the number of synaptic formations. The ultrastructure of synapses after cold exposure was observed. It was found that pre‐ and postsynaptic membranes were fused, with a vague synaptic cleft. Furthermore, neuronal cytoplasmic and organelle swellings were also observed, along with microtubule disintegration. In conclusion, chronic cold exposure can cause structural and functional changes in the mouse central nervous system, possibly by direct participation of estrogen and its receptor, GPR30, in response to chronic cold exposure. © 2014 Wiley Periodicals, Inc.

Cajal-Retzius cells are reelin-secreting neurons in the marginal zone of the neocortex and hippocampus. The aim of this study was to investigate Cajal-Retzius cells in Alzheimer's disease pathology. Results revealed that the number of Cajal-Retzius cells markedly reduced with age in both wild type and in mice over-expressing the Swedish double mutant form of amyloid precursor protein 695 (transgenic (Tg) 2576 mice). Numerous reelin-positive neurons were positive for activated caspase 3 in Tg2576 mice, suggesting that Cajal-Retzius neuronal loss occurred via apoptosis in this Alzheimer's disease model. Compared with wild type, the number of Cajal-Retzius cells was significantly lower in Tg2576 mice. Western blot analysis confirmed that reelin levels were markedly lower in Tg2576 mice than in wild-type mice. The decline in Cajal-Retzius cells in Tg2576 mice was found to occur concomitantly with the onset of Alzheimer's disease amyloid pathology and related behavioral deficits. Overall, these data indicated that Cajal-Retzius cell loss occurred with the onset and development of Alzheimer's disease.

Multicompartment and patchy particles attract much attention recently due to their great potentials in many fields such as drug delivery systems and photonic crystal materials. The controlled coalescence of droplets might be a promising approach to fabricate such particles since different droplets might be composed of distinct components or might contain diverse functional solutes. Through a two-dimensional boundary element method, we investigate the controlled adhesion of small droplets to specific locations of a main drop via careful flow control at inlets and outlets of a skillfully designed microfluidic device at low Reynolds numbers. This paper presents an original procedure to construct anisotropic particles assisted by microfluidics. By alternating extensional and rotational flow at the central cavity of the micro-device, it is possible to make small droplets adhere to the main drop one by one at expected location and thus fabricate patchy particles with multiple patches at expected angles in two dimensions.

The sensor of the taste is the taste bud. The signals originated from the taste buds are transmitted to the central nervous system through the gustatory taste nerves. The chorda tympani nerve (innervating the taste buds of the anterior tongue) and glossopharyngeal nerve (innervating the taste buds of the posterior tongue) are the two primary gustatory nerves. The injuries of gustatory nerves cause their innervating taste buds atrophy, degenerate and disappear. The related taste function is also impaired. The impaired taste function can be restored after the gustatory nerves regeneration. The rat model of cross-regeneration of gustatory nerves is an important platform for research in the plasticity of the central nervous system. The animal behavioral responses and the electrophysiological properties of the gustatory nerves have changed a lot after the cross-regeneration of the gustatory nerves. The effects of the injury, regeneration and cross-regeneration of the gustatory nerves on the taste function in the animals will be discussed in this review. The prospective studies on the animal model of cross-regeneration of gustatory nerves are also discussed in this review. The study on the injury, regeneration and cross-regeneration of the gustatory nerves not only benefits the understanding of mechanism for neural plasticity in gustatory nervous system, but also will provide theoretical basis and new ideas for seeking methods and techniques to cure dysgeusia.

The dynamic responses of a slab track on transversely isotropic saturated soils subjected to moving train loads are investigated by a semi-analytical approach. The track model is described as an upper Euler beam to simulate the rails and a lower Euler beam to model the slab. Rail pads between the rails and slab are represented by a continuous layer of springs and dashpots. A series of point loads are formulated to describe the moving train loads. The governing equations of track-ground systems are solved using the double Fourier transform, and the dynamic responses in the time domain are obtained by the inverse Fourier transform. The results show that a train load with high velocity will generate a larger response in transversely isotropic saturated soil than the lower velocity load, and special attention should be paid on the pore pressure in the vicinity of the ground surface. The anisotropic parameters of a surface soil layer will have greater influence on the displacement and excess pore water pressure than those of the subsoil layer. The traditional design method taking ground soil as homogeneous isotropic soil is unsafe for the case of RE < 1 and RG < 1, so a transversely isotropic foundation model is of great significance to the design for high train velocities.

Studies have shown that there are strong interactions between gustatory and visceral sensations in the central nervous system when rats ingest sweet foods or solutions. To investigate the role of the subdiaphragmatic vagi in transmitting general visceral information during the process of drinking sweet-tasting solutions, we examined the effects of subdiaphragmatic vagotomy on the intake of 0.5 mol/L sucrose, 0.005 mol/L saccharin or distilled water over the course of 1 hour in rats deprived of water. Results showed no significant difference in consumption of these three solutions in vagotomized rats. However, rats in the sham-surgery group drank more saccharin solution than sucrose solution or distilled water. Moreover, the intake of distilled water was similar between vagotomized rats and sham-surgery group rats, but significantly less sucrose and saccharin were consumed by vagotomized rats compared with rats in the sham-surgery group. These findings indicate that subdiaphragmatic vagotomy reduces intake of sweet-tasting solution in rats, and suggest that vagal and extravagal inputs play a balanced role in the control of the intake of sweet-tasting solutions. They also suggest that subdiaphragmatic vagotomy eliminates the difference in hedonic perception induced by sweet-tasting solutions compared with distilled water.

目的:探讨APPSWE转基因小鼠发育过程中视皮质神经元凋亡规律.方法:取不同发育时间的(P0、P7、P14、P30、P90、P180) APPSWE转基因模型鼠与同时间点野生型小鼠,用Nissl染色法观察视皮质细胞形态,免疫组织化学观察视皮质细胞内caspase-3表达变化.结果:随着小鼠的生长发育,P14以后,模型组视皮质神经元caspase-3阳性细胞密度比对照组高.结论:APPSWE转基因小鼠发育中的视皮质神经细胞过度凋亡可能与阿尔茨海默病的发生、发展具有联系.

A microfluidic analog of the four-roll mill has been designed to generate all flow types including extensional flow, shear flow and rotational flow [Lee et al. Appl. Phys. Lett. 90, 074103 (2007)]. Boundary element methods are powerful tools to study interfacial dynamics of droplets in microchannels due to its high facility in describing the complex geometries and the various boundary conditions. Through a two-dimensional (2D) spectral boundary element method, effects of the geometry and the volume flow rate on the elongation and rotation of droplets in this microfluidic four-roll mill (MFRM) are investigated in this paper. Behaviors of deforming or rotating droplets trapped in a MFRM are determined by the size of orifices connecting the channels (inlets and outlets) and the central cavity, and the volume flow rate of the continuous phases (CP) pumped into and out of the device, especially for the rotation of droplets. Through an approximate analysis of order of magnitude, a simple conclusion that the average angular velocity of the rotation is proportional to the volume flow rate of CP at inlets and the radius of the central cavity is presented, which is testified by the numerical calculation. Besides, the appropriate radius of the central cavity which directly determines the size of the orifices is specified through the analysis of the flow fields. These results are helpful in designing a MFRM with a much larger depth than the width of the micro-channel for the purpose of microfluidic rheometry.

Tumor necrosis factor-related apoptosis-inducing ligand or Apo2 ligand is a member of the tumor necrosis factor superfamily of cytokines that induces apoptosis upon binding to its death domain-containing transmembrane receptors, death receptors 4 and 5 (DR4, DR5). However, DR5 is also expressed in the developing CNS where it appears to play a role unrelated to apoptosis, and instead may be involved in the regulation of neurogenesis. We report on the distribution of DR5 expression in mouse hippocampus, cerebellum, and rostral migratory stream (RMS) of olfactory bulb from embryonic (E) day 16 (E16) to postnatal (P) day (P180). At E16, DR5-positive cells were distributed widely in embryonic hippocampus with strong immunostaining in the developing dentate gyrus. In newborn hippocampus, DR5-positive cells were predominantly located in proliferative zones, such as dentate gyrus, subventricular zone, and RMS. After postnatal day 7 (P7), the number of DR5-positive cells decreased, and cells with intense fluorescence were primarily restricted to the subgranular layer (SGL), although the granular cell layer showed weak fluorescence. After P30, only few DR5-positive cells were found in SGL, and mature granule cells were negative for DR5 expression. To address whether DR5 expression is a restricted to progenitor cells and newborn neurons, we performed 5-bromo-deoxyuridine labeling. We report that proliferative cells in the SGL selectively express DR5, with lower levels of expression in cells positive for doublecortin, a marker of newborn neurons. In addition, the stem cells in intestine, cerebellum, and RMS were also demonstrated to be DR5-positive. In the meantime, in cerebellum, DR5-positive cells were also positive for glial fibrillary acidic protein, a marker of proliferative Bergmann cells. We conclude that DR5 is selectively expressed by neuroprogenitor cells and newborn neurons, suggesting that the DR5 death receptor is likely to play a key role in neuroproliferation and differentiation.

To investigate the potential ability of the nitrite to induce neuronal differentiation of PC12 cells, cultured PC12 cells planted on matrigel in the presence or absence of sodium nitrite were employed as model, nerve growth factor (NGF) served as a positive control. After 48 h, sodium nitrite enhanced cell viability and vascular endothelial growth factor (VEGF) secretion. Same as the effect of NGF, sodium nitrite (1.4 mmol x L(-1)) treated cultures contained a greater proportion of cells bearing neurites and neurites were much longer than those found in negative control cultures (P < 0.05). Compared with the negative control, sodium nitrite (1.4 mmol x L(-1)) also upregulated the expression of VEGF mRNA (P < 0.05) and hypoxia inducible factor 1 alpha (HIF-1 alpha) or VEGF protein expression (P < 0.05) in cultures of PC12 cells. On the other hand, these effects of the sodium nitrite were likely mediated by HIF-1alpha, since their effects were antagonized by addition of HIF-1alpha inhibitor YC-1. Taken together, these results suggest that low doses of sodium nitrite could induce neurite outgrowth in PC12 cells by activating the HIF-1alpha-VEGF pathway.

Aims: Our aim is to investigate the effects of prenatal alcohol exposure (PAE) on the development of retinal bipolar and horizontal cells. Methods: The alterations of the retinal bipolar and horizontal cells in P7, P14 and P30 mice were observed after PAE, with immunofluorescent labeling and DiI diolistic assay. Results: The retinal development of filial pups was affected by PAE in a dose-dependent and long-term manner. The number of bipolar cells of alcohol groups was significantly lower than that of the control, and the dendritic receptive field of horizontal cells was also significantly smaller than those of the control groups (P< 0.01). Conclusion: PAE was able to cause retarded development of pup retinal neural cells.

PBL教学是一种不同于传统方式的教学方法.本文以实践为基础,在基础医学教育中进行PBL教学的探索,重点阐述了PBL教学实践的实施流程和关键步骤,以期为PBL教学在基础医学领域的发展提供有益的参考.

A laboratory model experiment system for subgrade drainage is designed and processed (declared a national invention patent); and the study of the subgrade moisture migration and laboratory underground drainage experiment under the influence of groundwater level fluctuation is conducted. By changing the height of the groundwater level, the dynamic response of subgrade humidity is studied in the case of without any waterproof measures, adding ordinary sand cushion, new drain material as underground waterproof and drainage base; and its effect of subgrade is evaluated. The results show that under the influence of the groundwater level fluctuation, the moisture of subgrade near the groundwater changes with the water table accordingly, the upper soil moisture has a relatively substantial increase because of the capillary action; when the water table is low, sand cushion plays a good waterproof and drainage effect; when the water table is high, the rise height of capillary water within the sand cushion is higher than the height of the sand cushion; and the subgrade moisture has a greater changes; new drainage materials can prevent the capillary water entering into the subgrade effectively; and it has good waterproof and drainage effects.

随着计算机技术和网络的迅速发展，为了降低组织考试的人力、物力和成本，提高教学质量，我们设计并实现了人体解剖学网络化实验考试图像系统，解决了传统考试中存在的问题，使考试手段更科学、学生成绩更真实可靠。

To investigate the effects of estrogen on cerebral angiogenesis in vitro,the authors employed cultured endothelial cells planted on matrigel in the presence or absence of estrogen as model,captured the capillary-like tube induced by estrogen,and analysed with computer software.The results indicated that estrogen dose-dependently stimulates VEGF secretion and VEGF induces cerebral angiogenesis.In contrast,some dose testosterone has no significant effect.The authors concluded that estrogen stimulated cultured brain microvascular endothelial cells neovascularization mediated by the increased VEGF secretion.

AIMS Our aim is to investigate the effects of prenatal alcohol exposure (PAE) on the development of retinal bipolar and horizontal cells. METHODS The alterations of the retinal bipolar and horizontal cells in P7, P14 and P30 mice were observed after PAE, with immunofluorescent labeling and DiI diolistic assay. RESULTS The retinal development of filial pups was affected by PAE in a dose-dependent and long-term manner. The number of bipolar cells of alcohol groups was significantly lower than that of the control, and the dendritic receptive field of horizontal cells was also significantly smaller than those of the control groups (P < 0.01). CONCLUSION PAE was able to cause retarded development of pup retinal neural cells.

The values of shear strength parameters,c and φ,estimated by two linear regression methods from data of rock or soil triaxial test are different.To reveal the basic cause of differences between the two regression methods,the principle of linear regression based on the least square method is analyzed thoroughly.The results estimated by regressing maximum principal stress with minor principal stress are the best values,while the results obtained by regressing maximum shear stress with average normal stress are not reliable.Modification for least square method of the latter regression method is done to obtain uniform results.Formulas for calculating modified regression coefficients are deduced.It is proved that results by the two methods after modification are the same;and they are applied to calculate the shear strength parameters in triaxial tests of phyllite.The results show that to rock or soil triaxial test,the values of shear strength parameters calculated by the two methods after modification are also the same best and unbiased estimations.

The cerebellum is a highly conserved structure in the central nervous system of vertebrates, and is involved in the coordination of voluntary motor behavior. Supporting this function, the cerebellar cortex presents a layered structure which requires precise spatial and temporal coordination of proliferation, migration, differentiation, and apoptosis events. The formation of the layered structure in the developing cerebellum remains unclear. The present study investigated the development of the cerebellar cortex. The results demonstrate that the primordium of the cerebellum comprises the ependymal, mantle, and marginal layers at embryonic day 12 (E12). Subsequently, the laminated cerebellar cortex undergoes cell proliferation, differentiation, and migration, and at about postnatal day 0 (PO), the cerebellar cortex presents an external granular layer, a molecular layer, a Purkinje layer, and an internal granular layer. The external granular layer is thickest at P6/7 and disappears at P20. From PO to P30, the internal granular cells and the Purkinje cells gradually differentiate and develop until maturity. Apoptotic neurons are evident in the layered structure in the developing cerebellar cortex. The external granular layer disappears gradually because of cell migration and apoptosis. The cells of the other layers primarily undergo differentiation, development, and apoptosis.