宝成线k29+811拱桥流浆腐蚀病害整治施工

本文作者对宝成线k29＋811石拱桥流浆腐蚀病害进行原因分析，详细介绍了整治这一病害的具体方法，提出了施工过程的步骤、质量和安全要求，对做好类似病害整治工作有现实的借鉴作用。

色谱法测定催化剂中碳含量操作条件研究

根据燃烧-色谱法的原理建立了催化剂碳含量的测定方法并开发了催化剂高温定碳仪,通过考察燃烧温度、载气流速、桥流等对催化剂碳含量测定的影响,确定了测定催化剂碳含量的最佳操作条件。实验结果表明,在确定的最佳操作条件下,测定的催化剂碳含量与化学法基本相同。

PGC302在线气相色谱仪的改造

介绍 PGC3 0 2在线气相色相谱仪因原进口色谱柱劣化 ,换用国产色谱柱后 ,在调试过程中 ,样品压力、恒温箱温度、载气流量、测量周期长短、样品各组分保留时间的确定 ,采样、柱切、反吹、平衡阀门开关时间的改变对测量分析的影响及解决办法。

Infrared microthermometry of fluid inclusion in sphalerite:A case study of the Xinqiao deposit in the Middle-Lower Yangtze metallogenic belt

Infrared microthermometry allows direct measurement of fluid inclusions hosted in opaque ore minerals and can provide direct constraints on the evolution of ore-forming fluids.This study presents infrared microthermometry of spherite-hosted fluid inclusions from the Xinqiao deposit in the Middle-Lower Yangtze Metallogenic Belt and sheds new light on the ore genesis of the deposit.Considering that infrared light may lead to non-negligible temperature deviations during microthermometry,some tests were first conducted to ensure the accuracy of the microthermometric measurements.The measurement results indicated that using the lowest light intensity of the microscope and inserting an optical filter were effective in minimizing the possible temperature deviations of infrared microthermometry.All sphalerite-hosted fluid inclusions from the Xinqiao deposit were aqueous.They show homogenization temperature ranging from~200 to 350℃,but have two separate salinity groups(1.0 wt%-10 wt%and 15.1 wt%-19.2 wt%NaCl equivalent).The low-salinity group represents sedimentary exhalative(SEDEX)-associated fluids,whereas the high-salinity group results from modification by later magmatic hydrothermal fluids.Combined with published fluid inclusion data,the four-stage fluid evolution of the Xinqiao deposit was depicted.Furthermore,our data suggest that the Xinqiao deposit was formed by twostage metallogenic events including SEDEX and magmatic-hydrothermal mineralization.

RELIABLE HYSTERESIS CURRENT CONTROLLED DUAL BUCK HALF BRIDGE INVERTER

A highly efficient and re liable topology-dual buck half bridge inverter (DBI) is introduced. The existenc e of discontinuous conduction mode (DCM) operation state requires the bias of in du ctor current for DBI implemented with linear controllers like ramp comparison SP WM (RCSPWM) controllers. A novel operation scheme for DBI and a hysteresis curre nt controlled dual buck half bridge inverter (HCDBI) are proposed. The bias curr ent required by RCSPWM DBI is eliminated and conduction losses are dramatically reduced. HCDBI has greatly improved the modulation performance in DCM region for the benefit of its excellent command tracking capability. The operational schem e and control strategy are presented. Power losses of the conventional half brid ge inverter (CHBI) and HCDBI are compared with mathematical computation, and exp erimental verification is also executed. Both calculational and experimental res ults verify that HCDBI has a superior switching performance over CHBI. Its exce llent high frequency operational capacity provides another access to realize high fre quency operation of inverters.

ZERO-CURRENT AND ZERO-VOLTAGE SWITCHING PWM BOOST FULL-BRIDGE CON VERTER

This paper proposes a zer o current and zero voltage switching (ZCZVS) PWM Boost full bridge (FB) conve rter. With series inductors, the leading switches can realize zero current swit ching (ZCS) in a wide load range using the energy of the output capacitor. Ma king use of parasitic capacitors of the lagging switches and parallel auxiliary i nductance with the primary winding of the transformer, the lagging switches can realize zero voltage switching (ZVS) under any load. Compared with the ZCS PWM Boost FB converter, the new converter has no current duty cycle loss. Operat ional principle and parameter design are analyzed. Experimental results verify the effectiveness of the proposed converter.

Experimental study on the width of the turbulent area around bridge pier

At present, the method of calculating the turbulent flow width around the bridge pier is not given in the ＂Standard for Inland River Navigation＂ （GB50139-2004） in China, and the bridge designer usually increases the bridge span in order to ensure the navigation safety, which increases both of the structural design difficulty and the project investments. Therefore, it is extremely essential to give a research on the turbulent flow width around the bridge pier. Through the experiments of the fixed bed and the mobile bed, the factors influencing the turbulent flow width around the bridge pier have been analyzed, such as the approaching flow speed, the water depth, the angles between the bridge pier and the flow direction, the sizes of bridge pier, the shapes of the bridge pier, and the scouting around the bridge pier, etc. Through applying the dimension analytic method to the measured data, the formula of calculating the turbulent flow width around the bridge pier is then inferred.

Influence of water-rich tunnel by shield tunneling on existing bridge pile foundation in layered soils

At present,shield tunneling often needs to pass through a large number of bridge pile foundations.However,there are few studies on the influence of shield tunneling on adjacent pile foundations by combining with groundwater seepage.Based on Winkler model,the calculation equations of shield tunneling on vertical and horizontal displacement of adjacent bridge pile are derived.Meanwhile,full and part three-dimensional finite element models are established to analyze the trend of bridge pier settlement,ground surface settlement trough,vertical and horizontal displacement of the pile and pile stress under three calculation conditions,i.e.,not considering groundwater effect,considering stable groundwater effect and fluid-soil interaction.The results show that the calculated value is small when the effect of groundwater is not considered;the seepage velocity of the soil above the excavation face is faster than that of the surrounding soil under fluid-soil interaction,and after the shield passing,the groundwater on both sides shows a flow trend of“U”shape on the ground surface supplying to the upper part of the tunnel;the vertical displacement of the pile body is bounded by the horizontal position of the top of the tunnel,the upper pile body settles,and the lower pile body deforms upward.The horizontal displacement of pile body presents a continuous“S”shape distribution,causing stress concentration near the tunnel.The calculated results of fluid-soil interaction are in good agreement with the field measured data and accord with the actual situation.

Interleukin-6, desmosome and tight junction protein expression levels in reflux esophagitis-affected mucosa

AIM： To investigate the correlation between the expression levels of interleukin （IL）-6 and proteins in tight junctions （TJs） in the esophageal mucosa of rats modeling different types of reflux esophagitis （RE）, and the ability of aluminum phosphate to protect against RE-induced mucosal damage via these proteins. METHODS： Male SPF Wistar rats aged 56 d were divided randomly into acid RE, alkaline RE, mixed RE, and control groups. Various surgical procedures were performed to establish rat models of acid RE. At 14 d after the procedure, some of the rats started aluminum phosphate treatment. Transmission electron microscopy （TEM） was used to observe the morphological features of TJs and desmosomes in the esophageal epithelium. Immunohistochemical methods and Western blotting were used to measure expression of claudin 1, occludin, ZO-1, JAM-l, DSG-1 and IL-6; reverse transcription polymerase chain reaction （RT- PCR） was used to measure expression of mRNA of claudin 1, occludin, ZO-1, JAM-1, DSG-1 and IL-6. RESULTS： At day 14 alter the procedures, an RE model was established in all subsequently sacrificed rats of groups A, B and C. By both gross and microscopic observation, the mucosa was damaged and thickened as the disease progressed. With TEM observation, a widened intercellular space was noticed, with significantly fewer desmosomes. Immunohistochemistry showed significantly higher levels of all proteins in all RE models compared to control rats at 3 d after operation （65.5% ± 25.6% vs 20.5% ± 2.1%, P 〈 0.05, respectively）. At 14 d after operation, along with continuing hyperplasia in the basal layer, the expression of TJ proteins in individual cells gradually decreased （12.4% ± 2.1% vs 20.5% ± 2.1%, P 〈 0.05, respectively）. Western blottings and RT-PCR showed a directly proportional increase in IL-6 levels in relation to TJ proteins, as compared to controls （0.878 ± 0.024 vs 0.205 ± 0.021 and 0.898±0.022 vs 0.205 ± 0.021, P 〈 0.05, respectively）. Upon treatment with aluminum phosphate, however, these protein levels were restored to normal gradually over 30-60 d in rats with acid RE （30.4% ± 2.1% vs 20.5% ± 2.1%, P 〉 0.05, treated vs untreated, respectively）. These levels increased in the rat with alkaline RE, and this increase was accompanied by continued hyperplasia in comparison with controls （85.5% ± 25.6% vs 20.5% ± 2.1%, P 〈 0.05, respectively）. Furthermore, the expression of TJ proteins was not correlated significantly with that of IL-6 in this group. CONCLUSION： These findings indicate that TJ proteins are highly expressed as an early molecular event involved in RE development, and that IL-6 is an inflammatory factor in this process,

EXPERIMENTAL STUDY OF THE MORPHOLOGY OF CEREBRAL BRIDGING VEIN

To investigate the morphological properties of pig cerebral bridging vein. Methods. The morphology and fibre arrangement of 15 cerebral bridging veins obtained from 7 Danish Yorkshire landrace pigs were observed. Results. There was a narrow region at the junction of the cerebral bridging veins and superior sagittal sinus termed“ outflow cuff segment". The diameter and length of outflow cuff segment were much smaller and the thickness was higher than those of the cerebral bridging veins (P0.05). Conclusions. There were differences in fibre arrangement and morphological properties between the outflow cuff segment and the cerebral bridging vein, just like a resistance valve, the outflow cuff segment may play an important role in stabilizing cerebral venous outflow and regulating intracranial pressure.

Experimental study on aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds

In this study, experiments were carried out to investigate aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds using a 1:25 scaled sectional model wind-tunnel testing. Pressure measurements of two typical sections, one train-head section and one train-body section, at the windward and leeward tracks were conducted under the smooth and turbulence flows with wind attack angles between-6° and 6°, and the corresponding aerodynamic force coefficients were also calculated using the integral method. The experimental results indicate that the track position affects the mean aerodynamic characteristics of the vehicle, especially for the train-body section. The fluctuating pressure coefficients at the leeward track are more significantly affected by the bridge interference compared to those at the windward track. The effect of turbulence on the train-head section is less than that on the train-body section. Additionally, the mean aerodynamic force coefficients are almost negatively correlated to wind attack angles, which is more prominent for vehicles at the leeward track. Moreover, the lateral force plays a critical role in determining the corresponding overturning moment, especially on the train-body section.

Spatiotemporal distribution characteristics of bridge deck runoff

The spatiotemporal characteristics of bridge deck runoff under a natural rainfall event are explored. The Taizhou Bridge is taken as a study case,and a hydrodynamic model based on the two-dimensional shallow water equations is used to analyze the runoff characteristics. The results indicate that the runoff velocity rate and depth are positively related to rainfall intensity,yet they have different response degrees to it. The inlet’s effect degree on lane water film has a positive relationship with rainfall intensity. A natural logarithm function( R^2= 0.706) can illustrate this relationship. However,the inlet’s effect degree on ponding at the curb shows a negative relationship with the rainfall intensity. A negative exponential function( R^2= 0.824) can reveal this relationship. With the decrease in the longitudinal slope SL,the ponding depth at the curb increases significantly at the bridge approach slab,whereas the lane water film thickness( WFT) is almost unchanged,but the lane WFT increases greatly at the location with the minimum longitudinal slope. It is concluded that the characteristics of the bridge deck runoff present apparent spatiotemporal differences,the inlet ’s effects on bridge deck runoff are quantitatively correlated with rainfall intensity, and the effective drainage measures are necessary for the bridge approach slab.

Heparin bridge therapy and post-polypectomy bleeding

AIM To identify risk factors for post-polypectomy bleeding(PPB), focusing on antithrombotic agents. METHODS This was a case-control study based on medical records at a single center. PPB was defined as bleeding that occurred 6 h to 10 d after colonoscopic polypectomy and required endoscopic hemostasis. As risk factors for PPB, patient-related factors including anticoagulants, antiplatelets and heparin bridge therapy as well as polyp- and procedure-related factors were evaluated. All colonoscopic hot polypectomies, endoscopic mucosal resections and endoscopic submucosal dissections performed between January 2011 and December 2014 were reviewed. RESULTS PPB occurred in 29(3.7%) of 788 polypectomies performed during the study period. Antiplatelet or anticoagulant agents were prescribed for 210(26.6%)patients and were ceased before polypectomy except for aspirin and cilostazol in 19 cases. Bridging therapy using intravenous unfractionated heparin was adopted for 73 patients. The univariate analysis revealed that anticoagulants, heparin bridge, and anticoagulants plus heparin bridge were significantly associated with PPB(P < 0.0001) whereas antiplatelets and antiplatelets plus heparin were not. None of the other factors including age, gender, location, size, shape, number of resected polyps, prophylactic clipping and resection method were correlated with PPB. The multivariate analysis demonstrated that anticoagulants and anticoagulants plus heparin bridge therapy were significant risk factors for PPB(P < 0.0001). Of the 29 PPB cases, 4 required transfusions and none required surgery. A thromboembolic event occurred in a patient who took anticoagulant. CONCLUSION Patients taking anticoagulants have an increased risk of PPB, even if the anticoagulants are interrupted before polypectomy. Heparin-bridge therapy might be responsible for the increased PPB in patients taking anticoagulants.

Scour and Scour Countermeasures at Bridge Sites

This paper examines scour and scour countermeasures at bridge piers and abutments. Abutment scour is by far more complex than its counterpart associated with piers because of the possibility of the presence of a floodplain. Notwithstanding this, the mechanism of scour at both piers and abutments is very similar; moreover, the failure mechanisms associated with both armoring and flow-altering countermeasures are not very different. In rivers with a floodplain, abutment scour becomes much more complex. In cases where the abutment ends at or near to the floodplain, it can initiate bank erosion, which clearly is an important erosion problem that is quite distinct from the customary scour at either an abutment in rivers without a floodplain or a pier. For this reason, abutment scour can be very site-specific while pier-scour is more generic in nature. To this end, the ability to identify the type of abutment scour that may form in a particular channel is closely related to an engineer's ability to propose devices for effective scour countermeasure.By summarizing research efforts on using riprap as a pier or abutment countermeasure over the past few decades, this paper highlights the deficiencies of riprap in arresting pier scour. To this end, different failure mechanisms are identified. They are shear failure, winnowing failure, edge failure, bedform-induced failure and bed-degradation induced failure. Each failure mechanism can singly or, more likely, combine to cause the eventual breakdown of the riprap layer. The study shows that a riprap layer is vulnerable to other failure mechanisms even though it is adequately designed against shear failure, rendering it ineffective in arresting scour.

Self-expanding metallic stents drainage for acute proximal colon obstruction

AIM: To clarify the usefulness of the self-expanding metallic stents (SEMS) in the management of acute proximal colon obstruction due to colon carcinoma before curative surgery.METHODS: Eighty-one colon (proximal to spleen flex) carcinoma patients (47 males and 34 females,aged 18-94 years,mean = 66.2 years) treated between September 2004 and June 2010 for acute colon obstruction were enrolled to this study,and their clinical and radiological features were reviewed.After a cleaning enema was administered,urgent colonoscopy was performed.Subsequently,endoscopic decompression using SEMS placement was attempted.RESULTS: Endoscopic decompression using SEMS placement was technically successful in 78 (96.3%) of 81 patients.Three patients’ symptoms could not be relieved after SEMS placement and emergent operation was performed 1 d later.The site of obstruction was transverse colon in 18 patients,the hepatic flex in 42,and the ascending colon in 21.Following adequate cleansing of the colon,patients’ abdominal girth was decreased from 88 ± 3 cm before drainage to 72 ± 6 cm 7 d later,and one-stage surgery after 8 ± 1 d (range,7-10 d) was performed.No anastomotic leakage or postoperative stenosis occurred after operation.CONCLUSION: SEMS placement is effective and safe in the management of acute proximal colon obstruction due to colon carcinoma,and is considered as a bridged method before curative surgery.

Effect of Downward Seepage on Turbulent Flow Characteristics and Bed Morphology around Bridge Piers

In this work, experimental investigations have been pursued to analyse the influence of downward seepage on the turbulent characteristics of flow and corresponding changes in vortex structure around circular bridge pier in alluvial channel. Experiments were conducted in sand bed channel with circular piers of different sizes for no seepage, 10% seepage and 20% seepage cases. The measurement of turbulent flow statistics such as velocity and Reynolds stresses is found to be negative within the scour hole at upstream of the pier whereas application of downward seepage retards the reversal of the flow causing a decrement in the velocity and Reynolds stresses. Higher Reynolds shear stress prevails at the downstream side because of the production of wake vortices. Contribution of all bursting events to the total Reynolds shear stress production has been observed to increase with downward seepage. The analysis of integral scale suggest that size of eddies increases with seepage, which is responsible for increase in particle mobility. Initially rate of scouring is more which abatements gradually with expanding time as well as with the increased of downward seepage. Presence of downward seepage reduces the depth and length of vortex and shifts towards downstream side of the pier.

The effect of slow deep breathing relaxation exercise on pain levels during and post chest tube removal after coronary artery bypass graft surgery

Objectives:This study aimed to evaluate the effectiveness of slow deep breathing relaxation exercise(SDBRE)in reducing patients’pain levels during chest tube removal(CTR)post coronary artery bypass grafting(CABG)surgery.Methods:In 2019,fifty post-CABG patients were conveniently selected from a cardiac intensive care unit in Jordan’s major referral heart institute.The patients were randomly assigned to either an intervention group or a control group.A total of 25 patients were assigned into the experimental group who received slow deep breathing relaxation Exercise(SDBRE)alongside the conventional care before CTR.The remaining 25 patients constituted the control group(50%)that had CTR following conventional care.The Visual Analogue Scale(VAS)was used to measure the participants’pain levels during three phases:before CTR(Time 1),5-min post CTR(Time 2),and 15-min post CTR(Time 2)to compare the intervention effect between the two groups.Results:The data analysis findings for the control and intervention group of patients showed that there was a statistically significant decline in their pain level across time for both groups(H¼32.71,P<0.01;H=47.23,P<0.01)respectively.The intervention group had significantly lower pain levels than the control group at Time 2(3.50[1.20,5.30]vs.7.90[7.00,9.00],P<0.01)and Time 3(0.00[0.00,1.30]vs.3.60[2.40,4.10]P<0.01).Conclusions:Using SDBRE during CTR is an effective technique for reducing pain which can minimize the need for analgesics and their associated adverse effects.

Bridge Pressure Flow Scour at Clear Water Threshold Condition

Bridge pressure flow scour at clear water threshold condition is studied theoretically and experimentally.The flume experiments reveal that the measured scour profiles under a bridge are more or less 2-dimensional;all the measured scour profiles can be described by two similarity equations,where the horizontal distance is scaled by the deck width while the local scour by the maximum scour depth;the maximum scour position is located just under the bridge about 15% deck width from the downstream deck edge;the scour begins at about one deck width upstream the bridge while the deposition occurs at about 2.5 deck widths downstream the bridge;and the maximum scour depth decreases with increas-ing sediment size,but increases with deck inundation.The theoretical analysis shows that:bridge scour can be divided into three cases,i.e.downstream unsubmerged,partially submerged,and totally submerged.For downstream unsubmerged flows,the maximum bridge scour depth is an open-channel problem where the conventional methods in terms of critical velocity or bed shear stress can be applied;for partially and totally submerged flows,the equilibrium maximum scour depth can be described by a scour and an inundation similarity number,which has been confirmed by experiments with two decks and two sediment sizes.For application,a design and field evaluation procedure with examples is presented,including the maximum scour depth and scour profile.

How to Extend the Bridge Density Functional Approximation to the Confined Non-hard Sphere Fluid

A theoretical method was proposed to extend a bridge density functional approximation （BDFA） for the non-uniform hard sphere fluid to the non-uniform Lennard-Jones （LJ） fluid. The DFT approach for LJ fluid is simple, quantitatively accurate in a wide range of coexistence phase and external field parameters. Especially, the DFT approach only needs a second order direct correlation function （DCF） of the coexistence bulk fluid as input, and is therefore applicable to the subcritical temperature region. The present theoretical method can be regarded as a non-uniform counterpart of the thermodynamic perturbation theory, in which it is not at the level of the free energy but at the level of the second order DCF.the National Natural Science Foundation of China （No. 20546004） and the Natural Science Foundation of Education Department of Hunan Province （No.04C711）.

SOFT SWITCHED SYNCHRONOUS RECTIFIER WITH PHASE-SHIFTED FULL BRIDGE CONVERTER AND ITS SMALL-SIGNAL ANALYSIS

By using the output inductors and body capacitances without adding any component compared with hard switching synchronous rectifier,the topology of a soft switched synchronous rectifier with phase-shifted full bridge zero voltage switching DC/DC converter is proposed. The converter efficiency is maximized due to soft switching of the full bridge MOSFETs and the synchronous MOSFETs, and also the low conduction loss of synchronous MOSFET. The operation principles of the circuit are analyzed in detail and the small-signal model is derived, also the converter dynamic characteristics are analyzed. Frequency responses of transfer functions under different values of transformer primary leakage inductance are discussed. The experimental results were obtained from a 400 V input and 100 A/12 V output DC/DC converter operating at 100 kHz. The results show that the converter efficiency is 2% higher in rated power than traditional diode rectifier.