关于“黑导”现象产生根源与对策探析

"黑导"是一个没有导游资格、非法从事导游活动的群体",黑导"的存在严重扰乱了正常的旅游市场,损害了导游行业和旅游景区形象。文章从"黑导"的概念入手,界定了"黑导"的概念和类型,分析了其产生的根源,并在此基础上提出了相应的治理对策。

宫腹腔镜联合黑泥鳅导丝介入治疗输卵管性不孕症的临床效果

目的探讨宫腹腔镜联合黑泥鳅导丝介入治疗输卵管性不孕症的临床效果。方法选择2017年7月至2020年1月我院妇产科收诊的120例输卵管性不孕症患者,将其随机分为对照组(60例,腹腔镜下子宫输卵管通液术)和观察组(60例,宫腹腔镜联合黑泥鳅导丝介入)。比较两组的治疗效果。结果观察组的手术时间、住院时间短于对照组,术中出血量少于对照组(P<0.05)。观察组的治疗总有效率高于对照组(P<0.05)。术后7 d,观察组的肿瘤坏死因子-α(TNF-α)、白细胞介素-4(IL-4)、白细胞介素-6(IL-6)水平低于对照组(P<0.05)。观察组的术中疏通率及术后输卵管通畅率、受孕率高于对照组,术中输卵管破裂出血发生率低于对照组(P<0.05)。术后7 d,观察组的C反应蛋白(CRP)、肾上腺素(E)、皮质醇(Cor)水平低于对照组(P<0.05)。术后3个月,观察组的健康调查简表(SF-36)各维度评分高于对照组(P<0.05)。结论宫腹腔镜联合黑泥鳅导丝介入治疗输卵管性不孕症,可缩短手术时间,减少术中出血量,提高治疗总有效率及患者的生活质量,值得临床推广。

Expression of a Wheat S-like RNase (WRN1) cDNA During Natural-and Dark-induced Senescence

An S-like RNase cDNA had been isolated from common wheat (Triticum aestivum L). The transcription of WRN1 mRNA was down-regulated by natural- and dark-induced senescence. But it was not senile-tissue-specific. As the two key histidine residues were replaced, WRN1 may not be active as RNase. Southern blotting analysis showed that WRN1 exists as one of a small gene family in common wheat genome.

聚苯胺/聚乙烯复合电极的制备及性能测定

以低密度聚乙烯(PE)为基体材料,乙烯-醋酸乙烯共聚物(EVA)为增韧剂,聚苯胺(PAn)和炭黑(CB)为导电添加剂制备复合电极板,探讨了原料配比对物理力学性能、电学性能的影响。结果表明,原料配比PE∶EVA∶CB=75%∶5%∶20%时,电极的电阻最小,但是其韧性不佳;当原料配比PE∶EVA∶(CB+PAn)=85%∶5%∶10%时,复合电极板具有最好的韧性能。

Molecular dynamics simulations of strain-dependent thermal conductivity of single-layer black phosphorus

Classical molecular dynamics(MD)simulations ae performed to investigate the effects of mechanical strain on the thermal conductivity of single-layer black phosphorus(SLBP)nanoribbons along different directions at room temperature.The results show that the tensile strain afects the thermal conductivity of nanoribbons by changing thephonon density of state(DOS)and mean free path(M FP).The thermal conductivity shows a sharp enhancement with the tensile strain applied along the armchai diection,while it increases slowly with the strain applied along the zigzag diection.This phenomenon cm be mainly explained by effects of the phonon DOS and MFP.The increasing strain along the armchai direction weakens DOS and strengthens MFP clearly.However,when it comes to the increasing strain along the zigzag deection'DOS enliances significantly while MFP decreases slightly.The findings explore the relationship between the tensile strain and the thermal conductivity reasonably and can provide a reliable method to estimate the MFP of black phosphorus.

Structural Changes of Lignified Tissues from Sugarcane Leaves Induced by Smut （Sporisorium scitamineum） Virulence Factors

Sugarcane leaf shows the classical arrangement of cells, which defines a C4 species. Vascular bundles consist of xylem, phloem and fibres, surrounded by an outer layer ofsclereids and an inner ring of stone cells associated with the phloem. Some sclereids located below and above the vascular bundles act as docking cells and connect the vascular bundle to the internal surfaces of upper and lower layers of the epidermis. A compact mass ofsclereids occupies the total internal volume of the leaf edge. Neither docking cells nor the internal mass of sclereids in the edge were markedly coloured by phloroglucinol, indicating the absence of lignin in their cell walls. However, such staining indicated that fibres of the vascular bundle and the external layer of sclereids were strongly lignified. Incubation of leaf discs with an virulence factors produced by the pathogen Sporisorium scitamineum increased the thickness of the lignified cell walls of sclereids as well as the mid and small xylem vessels, as a possible mechanical defence response to the potential entry of the pathogen. This mechanism was mainly revealed for the resistant cv. Mayari 55-14, whereas lignification decreased for the susceptible cv. B 42231.

Melatonin ameliorates experimental hepatic fibrosis induced by carbon tetrachloride in rats

AIM:To investigate the protective effects of melatonin on carbon tetrachloride(CCl4)-induced hepatic fibrosis in experimental rats.METHODS:All rats were randomly divided into normal control group,model control group treated with CCl4 for 12 wk,CCl4+NAC group treated with CCl4+NAC(100 mg/kg,i.p.)for 12 wk,CCl4+MEL-1 group treated with CCl4+melatonin(2.5 mg/kg)for 12 wk,CCl4+MEL-2 group treated with CCl4+ melatonin(5.0 mg/kg)for 12 wk,and CCl4+MEL-3 group treated with CCl4+melatonin(10 mg/kg).Rats in the treatment groups were injected subcutaneously with sterile CCl4(3 mL/kg,body weight)in a ratio of 2:3 with olive oil twice a week.Rats in normal control group received hypodermic injection of olive oil at the same dose and frequency as those in treatment groups.At the end of experiment,rats in each group were anesthetized and sacrificed.Hematoxylin and eosin(HE)staining and Van Gieson staining were used to examine changes in liver pathology.Serum activities of alanine aminotransferase(ALT),aspartate aminotransferase(AST)and protein concentration weremeasured with routine laboratory methods using an autoanalyzer.Hydroxyproline(HYP)content in liver and malondialdehyde(MDA)and glutathione peroxidase(GPx)levels in liver homogenates were assayed by spectrophotometry.Serum hyaluronic acid(HA),laminin(LN),and procollagenⅢN-terminal peptide(PⅢNP)were determined by radioimmunoassay.RESULTS:Pathologic grading showed that the fibrogenesis was much less severe in CCl4+MEL3 group than in model control group(u=2.172,P<0.05),indicating that melatonin(10 mg/kg)can significantly ameliorate CCl4-induced hepatic fibrotic changes.The serum levels of ALT and AST were markedly lower in CCl4+MEL treatment groups(5,10 mg/kg)than in model control group(ALT:286.23 ±121.91 U/L vs 201.15±101.16 U/L and 178.67 ±103.14 U/L,P=0.028,P=0.007;AST:431.00 ±166.35 U/L vs 321.23±162.48 U/L and 292.42 ±126.23 U/L,P=0.043,P=0.013).Similarly,the serum laminin(LN)and hyaluronic acid(HA)levels and hydroxyproline(HYP)contents in liver were significantly lower in CCl4+MEL-3 group(10 mg/kg)than in model control group(LN:45.89±11.71μg/L vs 55.26± 12.30μg/L,P=0.012;HA:135.71±76.03μg/L vs 201.10±68.46μg/L,P=0.020;HYP:0.42±0.08 mg/g tissue vs 0.51±0.07 mg/g tissue,P=0.012).Moreover,treatment with melatonin(5,10 mg/kg)significantly reduced the MDA content and increased the GPx activity in liver homogenates compared with model control group(MDA:7.89±1.49 noml/mg prot vs 6.29±1.42 noml/mg prot and 6.25±2.27 noml/mg prot,respectively,P=0.015,P=0.015;GPx:49.13± 8.72 U/mg prot vs 57.38±7.65 U/mg prot and 61.39± 13.15 U/mg prot,respectively,P=0.035,P=0.003).CONCLUSION:Melatonin can ameliorate CCl4-induced hepatic fibrosis in rats.The protective effect of melatonin on hepatic fibrosis may be related to its antioxidant activities.

Role of Black Carbon-Induced Changes in Snow Albedo in Predictions of Temperature and Precipitation during a Snowstorm

In this study the authors apply the chemistry version of the Weather Research and Forecasting model （WRF-Chem） to examine the impacts of black carbon （BC）-induced changes in snow albedo on simulated temperature and precipitation during the severe snowstorm that occurred in southern China during 0800 26 January to 0800 29 January 2008 （Note that all times are local time except when otherwise stated）. Black carbon aerosol was simulated online within the WRF-Chem. The model resuits showed that surface-albedo, averaged over 27-28 January, can be reduced by up to 10% by the deposition of BC. As a result, relative to a simulation that does not consider deposition of BC on snow/ice, the authors predicted surface air temperatures during 27-28 January can differ by -1.95 to 2.70 K, and the authors predicted accumulated precipitation over 27-28 January can differ by -2.91 to 3.10 mm over Areas A and B with large BC deposition. Different signs of changes are determined by the feedback of clouds and by the availability of water vapor in the atmosphere.

Dongsha erosive channel on northern South China Sea Shelf and its induced Kuroshio South China Sea Branch

Based on a data base of multi-channel seismic profiles covered over Dongsha plateau of the northern South China Sea margin, we found that the sea bed morphology of northern South China Sea margin had been changed dramatically after Dongsha uplifting, that sedimentary layer since Miocene age had been eroded with maximum eroded thickness more than 1000 m, and that an erosive channel had been formed of 20 km in width and 200 km in length and several hundreds meters in depth on the outer shelf of northern South China Sea. The erosive channel is parallel to the 600 m isobath line, stretching from northeast to the southwest north of Dongsha uplift. The Kuroshio intrudes the South China Sea through Luzon Strait both in winter time and summer time, and in the northern South China Sea margin area, the intruded Kuroshio Branch takes the form of Pacific-Indian Ocean Through Flow (PITH) in winter time, while the Luzon Strait Subsurface Inflow (LSSIF) in summer time, the routes of both PITH and LSSIF coincide well with the distribution of the erosive channel. After climbing from the northern slope up to the northern shelf, and after joined by the southward flow from the middle northern shelf of South China Sea, the Kuroshio Branch is strengthened and thus is able to erode the sea floor, and the shape of the erosive channel is a result of the long-term interaction between the Kuroshio South China Sea Branch and the Dongsha outer shelf sea floor.

AXL receptor signalling suppresses p53 in melanoma through stabilization of the MDMX-MDM2 complex

Deregulation of the tyrosine kinase signalling is often associated with tumour progression and drug resistance, but its underlying mechanisms are only partly understood. In this study, we investigated the effects of the receptor tyrosine kinase AXL on the sta- biUty of the MDMX-MDM2 heterocomplex and the activity of p53 in melanoma cells. Our data demonstrated that AXL overexpres- sion or activation through growth arrest-specific 6 （Gas6） Ugand stimulation increases MDMX and MDM2 protein levels and decreases p53 activity. Upon activation, AXL stabilizes MDMX through a post-translational modification that involves phosphoryl- ation of MDMX on the phosphosite Ser314, leading to increased affinity between MDMX and MDM2 and favouring MDMX nuclear translocation. Ser314 phosphorylation can also protect MDMX from MDM2-mediated degradation, leading to stabilization of the MDMX-MDM2 complex. We identified CDK4/6 and p38 MAPK as the two kinases mediating AXL-induced modulation of the MDMX-MDM2 complex, and demonstrated that suppression of AXL, either through siRNA silencing or pharmacological inhibition, increases expression levels of p53 target genes P21, MDM2, and PUMA, improves p53 pathway response to chemotherapy, and sensitizes cells to both Cisplatin and Vemurafenib. Our findings offer an insight into a novel signalling axis linking AXL to p53 and provide a potentially druggable pathway to restore p53 function in melanoma.

Holographic p-Wave Superconductors in Quintessence AdS Black Hole Spacetime

We construct a holographic p-wave superconductor model in the background of quintessence AdS black hole with an SU（2） Yang-Mills gauge field and then probe the effects of quintessence on the holographic p-wave superconduc- tor. We investigate the relation between the critical temperature and the state parameter of quintessence, and present the numerical results for electric conductivity. It is shown that the condensation of the vector field becomes harder as the absolute value of the state parameter increases. Unlike the scalar condensate in the s-wave model, the condensation of the vector field in p-wave model can occur in the total value range of the state parameter wq of quintessence. These results could help us know more about holographic superconductor and dark energy.

Electrical conductivities of two granite samples in southern Tibet and their geophysical implications

There are clear differences in the electrical conductivities of the crustal granites of the Qinghai-Tibet Plateau.Because these granites are among the major rock types on the Qinghai-Tibet Plateau, it is very important to detect the electrical conductivity of granites under high temperatures and pressures to study the electrical conductivity structure of this area. Using impedance spectroscopy at a frequency range of 10.1–106 Hz, the electrical conductivity of the muscovite-granite collected from Yadong was investigated at a confining pressure of 1.0 GPa and temperatures ranging from 577 to 996 K, while the electrical conductivity of the biotite-granite collected from Lhasa was investigated at a pressure of 1.0 GPa and temperatures ranging from587 to 1382 K. The calculated activation enthalpies of the Yadong muscovite-granite sample is 0.92 eV in the low-temperature range(577–919 K) and 2.16 eV in the high-temperature range(919–996 K). The activation enthalpies of the Lhasa biotite-granite sample is 0.48 eV in the low-temperature range(587–990 K) and 2.06 eV in the high-temperature range(990–1382 K). The change in the activation enthalpies of the granites at different temperature ranges may be associated with the dehydration of the two samples. The electrical conductivities of the granite samples obtained in the laboratory using impedance spectroscopy correspond well with field observations conducted near the sampling points, both in terms of the actual conductivity values and the observed variations between the low-temperature and high-temperature regimes. This correlation of laboratory and field conductivities indicates that the conductivities of the crustal rocks in the two regions closely correspond to granite conductivities.We calculated the electrical conductivities of muscovite-granite and biotite-granite samples using the effective medium and HS boundary models. When applied to the crustal rocks of southern Tibet, the results of the geophysical conductivity profiles lie within the range of laboratory data. Thus, the electrical characteristics of the crustal rocks underlying the southern Qinghai-Tibet Plateau can largely be attributed to granites, with the large changes to high conductivities at increasing depths resulting from the dehydration of crustal rocks with granitic compositions.