Influence of dissipation on solitary wave solution to generalized Boussinesq equation

This paper uses the theory of planar dynamic systems and the knowledge of reaction-diffusion equations,and then studies the bounded traveling wave solution of the generalized Boussinesq equation affected by dissipation and the influence of dissipation on solitary waves.The dynamic system corresponding to the traveling wave solution of the equation is qualitatively analyzed in detail.The influence of the dissipation coefficient on the solution behavior of the bounded traveling wave is studied,and the critical values that can describe the magnitude of the dissipation effect are,respectively,found for the two cases of b_3<0 and b_3>0 in the equation.The results show that,when the dissipation effect is significant(i.e.,r is greater than the critical value in a certain situation),the traveling wave solution to the generalized Boussinesq equation appears as a kink-shaped solitary wave solution;when the dissipation effect is small(i.e.,r is smaller than the critical value in a certain situation),the traveling wave solution to the equation appears as the oscillation attenuation solution.By using the hypothesis undetermined method,all possible solitary wave solutions to the equation when there is no dissipation effect(i.e.,r=0)and the partial kink-shaped solitary wave solution when the dissipation effect is significant are obtained;in particular,when the dissipation effect is small,an approximate solution of the oscillation attenuation solution can be achieved.This paper is further based on the idea of the homogenization principles.By establishing an integral equation reflecting the relationship between the approximate solution of the oscillation attenuation solution and the exact solution obtained in the paper,and by investigating the asymptotic behavior of the solution at infinity,the error estimate between the approximate solution of the oscillation attenuation solution and the exact solution is obtained,which is an infinitesimal amount that decays exponentially.The influence of the dissipation coefficient on the amplitude,frequency,period,and energy of the bounded traveling wave solution of the equation is also discussed.

Changes of dynamical balance of free radicals induced by levodopa in rat glia-containing mesencephalic culture fluid

BACKGROUND ： Parkinson disease is neurodegenerative disorders, characterized by a progressive and selective degeneration of nigrostdatal dopaminergic pathway. Its main clinical symptoms include bradykinesia, dgidity, rest tremor and disturbances in balance. Levodopa （L-DOPA） is the ＂gold standard＂ for the symptomatic treatment of Parkinson disease, but L-DOPA is toxic to dopaminergic neurons and the chronic administration of L-DOPA often causes the side effects of motor such as ＂on-off ＂, etc., and its mechanism still has not been completely clarified. OBJECTIVE ： To observe the changes of the content of glutathione （GSH）, activities of glutathione peroxidase （GSH-Px） and superoxide dismutase （SOD） and content of malondialdehyde （MDA） in gila-containing mesencephalic culture fluid after L-DOPA of different concentrations were added. DESIGN： A comparative observation. SETTINGS ： Department of Neurology, Affiliated Hospital of Taishan Medical University; Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology. MATERIALS ： The experiment was carried out in the Basic Research Institute, Taishan Medical University from December 2003 to September 2004. Ten postnatal newborn SD rats （within 2 days） were selected, either male or female. Fetal bovine serum （DMEM/F12） was from Gibco Company; L-DOPA and glial fibrillary acidic protein （GFAP） from Sigma Company. Kits for determination of GSH, GSH-Px, SOD and MDA were purchased from Nanjing Jiancheng Bioengineering Research Institute. METHODS ： Gila-containing mesencephalic culture fluid were placed in 24-well culture plate, and L-DOPA of 50, 100 and 500 μmot/L was added to each group, the blank control group was also set. The glia-containing mesencephalic culture fluid selected at 4, 24, 48 and 72 hours respectively to determine the GSH content with colorimetdc quantitative technique, GSH-Px activity with colorimetdc method, SOD activity with xanthine oxidase method and MDA content with thiol-barbituric acid method. MAIN OUTCOME MEASURES ： GSH and MDA contents, GSH-Px and SOD activities in the glia-containing mesencephalic culture fluid at 4, 24, 48 and 72 hours after L-DOPA of different concentrations were added. RESULTS ： In the glia-containing mesencephalic culture fluid after 100 μmol/L L-DOPA was added for 24, 48 and 72 hours, the GSH contents were lower than those in the blank control group [（174.14±39.28）, （161.55± 40.79）, （144.97±57.59） mg/L; （220.66±32.61）, （221.10±32.98）, （220.43±31.98） mg/L, P 〈 0.05]; The GSH-Px activities were lower than those in the blank control group [（4.03±1.05）, （3.99±1.12）, （3.47±1.00） μmol/L; （5.45±1.14）, （5.69±1.21）, （5.49±1.28） μmol/L, P 〈 0.05]; The SOD activities were also lower than those in the blank control group [（42.02±5.08）, （39.38±5.34）, （38.87±5.75）kNU/L; （51.35±8.87）, （51.78±8.96）, （50.99± 9.09） kNU/L, P 〈 0.05]; Whereas the MDA contents were higher than those in the blank control group [（3.51 ± 1.05）, （3.99±1.03）, （4.45±1.58） μmol/L; （2.09±1.13）, （2.18±1.29）, （2.01±1.05） μmol/L, P〈 0.05]. In the gli- a-containing mesencephalic culture fluid after 100 μmol/L L-DOPA was added for 4, 24, 48 and 72 hours, the GSH contents were （172.27±26.07）, （140.15±61.44）, （137.30±50.87）, （121.09±66.07） mg/L, the GSH-Px activities were （3.89±1.20）, （3.56±1.23）, （3.38±1.18）, （3.01±1.09） μmol/L, the SOD activities were （38.18±6.75）, （35.23±7.85）, （4.59±1.24）, （31.42±7.01） kNU/L, which were all lower than those in the blank control group （P 〈 0.05-0.01 ）; The MDA contents were （3.65±0.86）, （3.87±1.14）, （4.59±1.24）, （4.79±1.32） μmol/L, which were higher than those in the blank control group （P 〈 0.05-0.01）. In the gila-containing mesencephalic culture fluid added by 50 μmol/L L-DOPA, the GSH and MDA contents, GSH-Px and SOD activities at each time point were all close to those in the blank control group （P〉 0.05）. CONCLUSION ： L-DOPA of certain concentration can destroy the dynamical balance of free radicals in glia-containing mesencephalic culture fluid, and accelerate the degeneration of neurons, which are in concentration- and time-dependent manners.

Oral bacteria colonize and compete with gut microbiota in gnotobiotic mice

The oral microbiota is associated with oral diseases and digestive systemic diseases.Nevertheless,the causal relationship between them has not been completely elucidated,and colonisation of the gut by oral bacteria is not clear due to the limitations of existing research models.The aim of this study was to develop a human oral microbiota-associated (HOMA) mouse model and to investigate the ecological invasion into the gut.By transplanting human saliva into germ-free (GF) mice,a HOMA mouse model was first constructed.16S rRNA gene sequencing was used to reveal the biogeography of oral bacteria along the cephalocaudal axis of the digestive tract.In the HOMA mice,84.78% of the detected genus-level taxa were specific to the donor.Principal component analysis (PCA) revealed that the donor oral microbiota clustered with those of the HOMA mice and were distinct from those of specific pathogen-free (SPF) mice.In HOMA mice,OTU counts decreased from the stomach and small intestine to the distal gut.The distal gut was dominated by Streptococcus,Veillonella,Haemophilus,Fusobacterium,Trichococcus and Actinomyces.HOMA mice and human microbiota-associated (HMA) mice along with the GF mice were then cohoused.Microbial communities of cohoused mice clustered together and were significantly separated from those of HOMA mice and HMA mice.The Source Tracker analysis and network analysis revealed more significant ecological invasion from oral bacteria in the small intestines,compared to the distal gut,of cohoused mice.In conclusion,a HOMA mouse model was successfully established.By overcoming the physical and microbial barrier,oral bacteria colonised the gut and profiled the gut microbiota,especially in the small intestine.

Moisture-induced degradation of the narrow-band red-emitting SrLiAl3N4:Eu2+phosphor

The degradation of materials plays an important role in their application and service process. In this work, the moisture-induced degradation of SrLiAl3 N4：Eu2＋（SLAN）, a very promising narrow-band redemitting phosphor, was comprehensively investigated by treating it in two different moisture conditions in order to reveal the potential mechanism and optimize the luminescence properties. The degradation rate gradually slows down with the decreasing environmental humidity indicating that water plays a key role in the degradation. Moreover, we take the other option with 100% humidity at different temperatures for rapid degradation. In the rapid degradation, the luminescence of SLAN is quenched quickly and the phase and micro structure change obviously, with the phosphor being bleached. The host turns into NH_3, Al_2 O_3, Sr_3 Al_2（OH）_（12） and LiAl_2（OH）_7 finally. It is further confirmed that the rapid degradation occurs with the help of water and the phosphor is oxidized during this process.

Assouad dimensions of Moran sets and Cantor-like sets

We obtain the Assouad dimensions of Moran sets under suitable condition. Using the homogeneous set introduced in [J. Math. Anal. Appl., 2015, 432：888 917], we also study the Assouad dimensions of Cantor-like sets.