Involvement of nitrergic neurons in colonic motility in a rat model of ulcerative colitis

BACKGROUND The mechanisms underlying gastrointestinal(GI)dysmotility with ulcerative colitis(UC)have not been fully elucidated.The enteric nervous system(ENS)plays an essential role in the GI motility.As a vital neurotransmitter in the ENS,the gas neurotransmitter nitric oxide(NO)may impact the colonic motility.In this study,dextran sulfate sodium(DSS)-induced UC rat model was used for investigating the effects of NO by examining the effects of rate-limiting enzyme nitric oxide synthase(NOS)changes on the colonic motility as well as the role of the ENS in the colonic motility during UC.AIM To reveal the relationship between the effects of NOS expression changes in NOS-containing nitrergic neurons and the colonic motility in a rat UC model.METHODS Male rats(n=8/each group)were randomly divided into a control(CG),a UC group(EG1),a UC+thrombin derived polypeptide 508 trifluoroacetic acid(TP508TFA;an NOS agonist)group(EG2),and a UC+NG-monomethyl-L-arginine monoacetate(L-NMMA;an NOS inhibitor)group(EG3).UC was induced by administering 5.5%DSS in drinking water without any other treatment(EG1),while the EG2 and EG3 were gavaged with TP508 TFA and L-NMMA,respectively.The disease activity index(DAI)and histological assessment were recorded for each group,whereas the changes in the proportion of colonic nitrergic neurons were counted using immunofluorescence histochemical staining,Western blot,and enzyme linked immunosorbent assay,respectively.In addition,the contractile tension changes in the circular and longitudinal muscles of the rat colon were investigated in vitro using an organ bath system.RESULTS The proportion of NOS-positive neurons within the colonic myenteric plexus(MP),the relative expression of NOS,and the NOS concentration in serum and colonic tissues were significantly elevated in EG1,EG2,and EG3 compared with CG rats.In UC rats,stimulation with agonists and inhibitors led to variable degrees of increase or decrease for each indicator in the EG2 and EG3.When the rats in EGs developed UC,the mean contraction tension of the colonic smooth muscle detected in vitro was higher in the EG1,EG2,and EG3 than in the CG group.Compared with the EG1,the contraction amplitude and mean contraction tension of the circular and longitudinal muscles of the colon in the EG2 and EG3 were enhanced and attenuated,respectively.Thus,during UC,regulation of the expression of NOS within the MP improved the intestinal motility,thereby favoring the recovery of intestinal functions.CONCLUSION In UC rats,an increased number of nitrergic neurons in the colonic MP leads to the attenuation of colonic motor function.To intervene NOS activity might modulate the function of nitrergic neurons in the colonic MP and prevent colonic motor dysfunction.These results might provide clues for a novel approach to alleviate diarrhea symptoms of UC patients.

Enhanced interface properties of diamond MOSFETs with Al2O3 gate dielectric deposited via ALD at a high temperature

The interface state of hydrogen-terminated(C-H)diamond metal-oxide-semiconductor field-effect transistor(MOSFET)is critical for device performance.In this paper,we investigate the fixed charges and interface trap states in C-H diamond MOSFETs by using different gate dielectric processes.The devices use Al_(2)O_(3) as gate dielectrics that are deposited via atomic layer deposition(ALD)at 80℃and 300℃,respectively,and their C-V and I-V characteristics are comparatively investigated.Mott-Schottky plots(1/C2-VG)suggest that positive and negative fixed charges with low density of about 10^(11)cm^(-2) are located in the 80-℃-and 300-℃deposition Al2O3 films,respectively.The analyses of direct current(DC)/pulsed I-V and frequency-dependent conductance show that the shallow interface traps(0.46 eV-0.52 eV and 0.53 eV-0.56 eV above the valence band of diamond for the 80-℃and 300-℃deposition conditions,respectively)with distinct density(7.8×10^(13)eV^(-1)·cm^(-2)-8.5×10^(13)eV^(-1)·cm^(-2) and 2.2×10^(13)eV^(-1)·cm^(-2)-5.1×10^(13)eV^(-1)·cm^(-2) for the 80-℃-and 300-℃-deposition conditions,respectively)are present at the Al2O3/C-H diamond interface.Dynamic pulsed I-V and capacitance dispersion results indicate that the ALD Al_(2)O_(3) technique with 300-℃deposition temperature has higher stability for C-H diamond MOSFETs.

基于数据挖掘的中医治疗疟疾用药规律分析

目的挖掘中医治疗疟疾的用药规律。方法从中药的性、味、归经、药效等基本属性方面进行统计分析。在药物关联的基础上,构建了中药关联复杂网络。通过聚类分析得到治疗疟疾的核心药物。应用Apriori算法对核心药物的关联规则进行分析。结果357种草药在461首治疗疟疾的处方中共使用3,194次。在药材方面,使用频率最高的依次是甘草、黄连、柴胡、地骨皮等。在药效方面,使用频率最高的依次是补益、解表、清热、理气和化湿类药等。在药性方面,使用频率最高的依次是温、平、寒等。在药味方面,使用频率最高的是辛、苦、甘等。在归经方面,使用频率最高的依次是脾、肺、胃等。聚类分析得到甘草、半夏、柴胡、常山等核心药物61味。应用Apriori关联规则分析,得到12条二项规则(药对)和6条三项规则(药物组合),其中柴胡和黄芩是治疗疟疾的核心药对。结论柴胡和黄芩是治疗疟疾的核心药对,该药对与白术组合,可用于治疗温疟和寒疟;与陈皮或地黄组合,可用于治疗瘴疟;与人参、当归组合,可用于治疗劳疟;与鳖甲组合,可用于治疗疟母。

调控Pt_(3)Zn合金化程度改善酸性氧还原活性与稳定性

Pt基催化剂是氧还原反应的优良催化剂,改善其活性和稳定性是燃料电池商业化的关键。本文利用金属有机框架衍生的氮掺杂碳材料为载体,通过浸渍、冻干和简单热处理的方法合成了Pt/NC、Pt3Zn/NC-L和Pt3Zn/NC-H催化剂,平均粒径均在2 nm左右。在Pt中引入Zn元素引起其晶格收缩,使Pt-Pt键变短,优化了Pt与含氧中间体的结合,增强氧还原反应的活性。在高合金化程度的Pt3Zn/NC-H催化剂上,氧还原反应的半波电位为0.903 V,较商业Pt/C正移57 mV。0.9 V下的质量活性和面积比活性分别是商业Pt/C的4.50倍和3.33倍。在O2饱和的0.1 mol·L^(-1) HClO4溶液,0.6~1.0 V(vs.RHE)进行10000周稳定性测试,商业Pt/C的质量活性和面积比活性分别衰减25.00%和23.80%,而在Pt3Zn/NC-H催化剂上未观察到衰减。

Constraints on individual supermassive binary black holes using observations of PSR J1909-3744

We perform a search for gravitational waves(GWs) from several supermassive binary black hole(SMBBH) candidates(NGC 5548, Mrk 231, OJ 287, PG 1302–102, NGC 4151, Ark 120 and 3C 66B) in long-term timing observations of the pulsar PSR J1909-3744 obtained using the Parkes radio telescope.No statistically significant signals were found. We constrain the chirp masses of those SMBBH candidates and find the chirp mass of NGC 5548 and 3C 66B to be less than 2.4 × 10^9 M⊙ and 2.5 × 10^9 M⊙(with 95% confidence), respectively. Our upper limits remain a factor of 3 to 370 above the likely chirp masses for these candidates as estimated from other approaches. The observations processed here provide upper limits on the GW strain amplitude that improve upon the results from the first Parkes Pulsar Timing Array data release by a factor of 2 to 7. We investigate how information about the orbital parameters can help to improve the search sensitivity for individual SMBBH systems. Finally, we show that these limits are insensitive to uncertainties in the Solar System ephemeris model.

Observational signatures of close binaries of supermassive black holes in active galactic nuclei

Inspired by the General Relativity for many decades,experimental physicists and astronomers have a solid dream to detect gravitational waves(GWs)from mergers of black holes,which came true until the excellent performance of the Laser Interferometer Gravitational-Wave Observatory(LIGO)at hundreds Hz.Nano-Hz GWs are expected to be radiated by close-binaries of supermassive black holes(CB-SMBHs;defined as those with separations less than^0.1 pc)formed during galaxy mergers and detected through the Pulsar Timing Array(PTA)technique.As of the writing,there remains no nano-Hz GWs detection.Searching for CB-SMBHs is also observationally elusive though there exist a number of possible candidates.In this review,we focus on observational signatures of CB-SMBHs from theoretic expectations,simulations and observations.These signatures appear in energy distributions of multiwavelength continuum,long term variations of continuum,jet morphology,reverberation delay maps and spectroastrometry of broad emission lines,AGN type transitions between type-1 and type-2(changing-look),and gaseous dynamics of circumbinary disks,etc.Unlike hundred-Hz GWs from stellar mass black hole binaries,the waveform chirping of nano-Hz GWs is too slow to detect in a reasonable human timescale.We have to resort to electromagnetic observations to measure orbital parameters of CB-SMBHs to test nano-Hz GW properties.Reverberation mapping is a powerful tool for probing kinematics and geometry of ionized gas in the gravitational well of SMBHs(single or binary)and therefore provides a potential way to determine orbital parameters of CB-SMBHs.In particular,a combination of reverberation mapping with spectroastrometry(realized at the Very Large Telescope Interferometer)will further reinforce this capability.The Atacama Large Millimeter/submillimeter Array(ALMA)and the forthcoming Square Kilometre Array(SKA)are suggested to reveal dynamics of circumbinary disks through molecular emission lines.

Dielectric thin films for GaN-based high-electron-mobility transistors

The effects of dielectric thin films on the performance of GaN-based high-electron-mobility transistors （HEMTs） were reviewed in this work. Firstly, the nonpolar dielectric thin films which act as both the surface passivation layers and the gate insulators of the high-frequency GaN-based high-electron-mobility transistors were presented. Furthermore, the influences of dielectric thin films on the electrical properties of two-dimensional electron gas （2DEG） in the A1GaN/GaN hetero-structures were ana- lyzed. It was found that the additional in-plane biaxial tensile stress was another important factor besides the change in surface potential profile for the device perfor- mance improvement of the A1GaN/GaN HEMTs with dielectric thin films as both passivation layers and gate dielectrics. Then, two kinds of polar gate dielectric thin films, the ferroelectric LiNbO3 and the fluorinated A1203, were compared for the enhancement-mode GaN-based HEMTs, and an innovative process was proposed. At last, high-permittivity dielectric thin films were adopted as passivation layers to modulate the electric field and accordingly increase the breakdown voltage of GaN-based HEMTs. Moreover, the polyimide embedded with Cr particles effectively increased the breakdown voltage of GaNbased HEMTs. Finally, the effects of high-permittivity dielectric thin films on the potential distribution in the drift region were simulated, which showed an expanded electric field peak at the drain-side edge of gate electrode.

AlN-based surface acoustic wave resonators on platinum bottom electrodes for high-temperature sensing applications

Surface acoustic wave（SAW） resonators with Pt/AlN/Si and Pt/AlN/Pt/Si configurations were fabricated by lift-off photolithography techniques. High-temperature performances of both configurations were investigated for temperature sensor applications. AlN films grown on Ptcoated Si substrates exhibit a lower（002） preferred orientation than those grown on Si substrates. The center frequencies of Pt/AlN/Si and Pt/AlN/Pt/Si configurations at room temperature are 424.1 and 456.4 MHz, respectively.The SAW was limited by Pt bottom electrodes to propagate in AlN layer. The temperature coefficient of frequency（TCF） values of Pt/AlN/Si and Pt/AlN/Pt/Si configurations are-51.6 × 10^-6 and-69.2 × 10^-6℃^-1, respectively.Compared with that of Pt/AlN/Si configuration, the TCF value of Pt/AlN/Pt/Si configuration decreases by 34.1 %.AlN resonator with the Pt floating bottom electrodes provides a large, quasi-constant temperature sensitivity which is suitable for temperature sensor applications.