装配式腹板开洞组合梁受力性能试验研究

为研究高强螺栓连接腹板开洞组合梁的受力性能,文中以高强螺栓间距为变化参数,对3根装配简支组合梁试件进行了跨中单调集中加载试验。研究包括高强螺栓在组合梁装配中的受力表现、试件极限承载力、试件的破坏形态及其变形特征。结果表明高强螺栓连接的组合梁试件破坏形态为典型的剪切破坏;螺栓间距对装配式组合梁的整体刚度有较大影响,高强螺栓布置的间距越小,组合梁的组合作用越强,整体刚度也越大,破坏时变形小;高强螺栓的预紧力和螺栓孔容差对组合梁的荷载-滑移性能也有较大影响。研究可为洞口上方高强螺栓连接件的设计、施工以及加固补强提供参考。

Outcome and costs of laparoscopic pancreaticoduodenectomy during the initial learning curve vs laparotomy

AIM:To compare laparoscopic pancreaticoduodenectomy(TLPD) during the initial learning curve with open pancreaticoduodenectomy in terms of outcome and costs.METHODS:This is a retrospective review of the consecutive patients who underwent TLPD between December 2009 and April 2014 at our institution.The experiences of the initial 15 consecutive TLPD cases,considered as the initial learning curve of each surgeon,were compared with the same number of consecutive laparotomy cases with the same spectrum of diseases in terms of outcome and costs.Laparoscopic patients with conversion to open surgery were excluded.Preoperative demographic and comorbidity data were obtained.Postoperative data on intestinal movement,pain score,mortality,complications,and costs were obtained for analysis.Complications related to surgery included pneumonia, intra-abdominal abscess,postpancreatectomy hemorrhage,biliary leak,pancreatic fistula,delayed gastric emptying,and multiple organ dysfunction syndrome.The total costs consisted of cost of surgery,anesthesia,and admission examination.RESULTS:A total of 60 patients,including 30 consecutive laparoscopic cases and 30 consecutive open cases,were enrolled for review.Demographic and comorbidity characteristics of the two groups were similar.TLPD required a significantly longer operative time(513.17 ± 56.13 min vs 371.67 ± 85.53 min,P < 0.001).The TLPD group had significantly fewer mean numbers of days until bowel sounds returned(2.03 ± 0.55 d vs 3.83 ± 0.59 d,P < 0.001) and exhaustion(4.17 ± 0.75 d vs 5.37 ± 0.81 d,P < 0.001).The mean visual analogue score on postoperative day 4 was less in the TLPD group(3.5 ± 9.7 vs 4.47 ± 1.11,P < 0.05).No differences in surgery-related morbidities and mortality were observed between the two groups.Patients in the TLPD group recovered more quickly and required a shorter hospital stay after surgery(9.97 ± 3.74 d vs 11.87 ± 4.72 d,P < 0.05).A significant difference in the total cost was found between the two groups(TLPD 81317.43 ± 2027.60 RMB vs laparotomy 78433.23 ± 5788.12 RMB,P < 0.05).TLPD had a statistically higher cost for both surgery(24732.13 ± 929.28 RMB vs 19317.53 ± 795.94 RMB,P < 0.001)and anesthesia(6192.37 ± 272.77 RMB vs 5184.10 ± 146.93 RMB,P < 0.001),but a reduced cost for admission examination(50392.93 ± 1761.22 RMB vs 53931.60 ± 5556.94 RMB,P < 0.05).CONCLUSION:TLPD is safe when performed by experienced pancreatobiliary surgeons during the initial learning curve,but has a higher cost than open pancreaticoduodenectomy.

Is total laparoscopic pancreaticoduodenectomy superior to open procedure? A meta-analysis

BACKGROUND Laparoscopy has been widely used in general surgical procedures,but total laparoscopic pancreaticoduodenectomy(TLPD)is still a complex and challenging surgery that is only performed in a small number of patients at a few large academic medical centers.Although the safety and feasibility of TLPD have been established,few studies have compared it with open pancreaticoduodenectomy(OPD)with regard to perioperative and oncological outcomes.Therefore,we carried out a meta-analysis to evaluate whether TLPD is superior to OPD.AIM To compare the treatment outcomes of TLPD and OPD in order to assess the safety and feasibility of TLPD.METHODS We conducted a systematic search of studies comparing TLPD with OPD that were published in the PubMed,EMBASE,and Cochrane Library databases through December 31,2018.The studies comparing TLPD and OPD with at least one of the outcomes we were interested in and with more than 10 cases in each group were included in this analysis.The Newcastle-Ottawa scale was used to assess the quality of the nonrandomized controlled trials and the Jadad scale was used to assess the randomized controlled trials.Intraoperative data,postoperative complications,and oncologic outcomes were evaluated.The metaanalysis was performed using Review Manager Software version 5.3.Random or fixed-effects meta-analyses were undertaken to measure the pooled estimates.RESULTS A total of 4790 articles were initially identified for our study.After screening,4762 articles were excluded and 28 studies representing 39771 patients(3543 undergoing TLPD and 36228 undergoing OPD)were eventually included.Patients who underwent TLPD had less intraoperative blood loss[weighted mean difference(WMD)=-260.08 mL,95%confidence interval(CI):(-336.02,-184.14)mL,P<0.00001],a lower blood transfusion rate[odds ratio(OR)=0.51,95%CI:0.36-0.72,P=0.0001],a lower perioperative overall morbidity(OR=0.82,95%CI:0.73-0.92,P=0.0008),a lower wound infection rate(OR=0.48,95%CI:0.34-0.67,P<0.0001),a lower pneumonia rate(OR=0.72,95%CI:0.60-0.85,P=0.0002),a shorter duration of intensive care unit(ICU)stay[WMD=-0.28 d,95%CI(-2.88,-1.29)d,P<0.00001]and a shorter length of hospital stay[WMD=-3.05 d,95%CI(-3.93,-2.17),P<0.00001],a lower rate of discharge to a new facility(OR=0.55,95%CI:0.39-0.78,P=0.0008),and a lower 30-d readmission rate(OR=0.81,95%CI:0.68-0.95,P=0.10)than those who underwent OPD.In addition,the TLPD group had a higher R0 rate(OR=1.28,95%CI:1.13-1.44,P=0.0001)and more lymph nodes harvested(WMD=1.32,95%CI:0.57-2.06,P=0.0005)than the OPD group.However,the patients who underwent TLPD experienced a significantly longer operative time(WMD=77.92 min,95%CI:40.89-114.95,P<0.0001)and had a smaller tumor size than those who underwent OPD[WMD=-0.32 cm,95%CI:(-0.58,-0.07)cm,P=0.01].There were no significant differences between the two groups in the major morbidity,postoperative pancreatic fistula,delayed gastric emptying,postpancreatectomy hemorrhage,bile leak,gastroenteric anastomosis fistula,intra-abdominal abscess,bowel obstruction,fluid collection,reoperation,ICU admission,or 30-d and 90-d mortality rates.For malignant tumors,the 1-,2-,3-,4-and 5-year overall survival rates were not significantly different between the two groups.CONCLUSION This meta-analysis indicates that TLPD is safe and feasible,and may be a desirable alternative to OPD,although a longer operative time is needed and only smaller tumors can be treated.

Physicochemical properties of arsenic-bearing lime-ferrate sludge and its leaching behaviors

Physicochemical properties and leaching behaviors of two typical arsenic-bearing lime?ferrate sludges(ABLFS),waste acid residue(WAR)and calcium arsenate residue(CAR),are comprehensively described.The chemical composition,morphological features,phase composition and arsenic occurrence state of WAR and CAR are analyzed by ICP?AES,SEM?EDS,XRD,XPS and chemical phase analysis.The toxicity leaching test and three-stage BCR sequential extraction procedure are utilized to investigate arsenic leaching behaviors.The results show that the contents of arsenic in WAR and CAR are2.5%and21.2%and mainly present in the phases of arsenate and arsenic oxides dispersed uniformly or agglomerated in amorphous particles.The leaching concentrations of arsenic excess119and1063times of TCLP standard regulatory level with leaching rates of47.66%and50.15%for WAR and CAR,respectively.About90%of extracted arsenic is in the form of acid soluble and reducible,which is the reason of high arsenic leaching toxicity and environmental activity of ABLFS.This research provides comprehensive information on harmless disposal of ABLFS from industrial wastewater treatment of lime?ferrate process.

Recovery of valuable metals from zinc leaching residue by sulfate roasting and water leaching

Zinc leaching residue(ZLR),produced from traditional zinc hydrometallurgy process,is not only a hazardous waste but also a potential valuable solid.The combination of sulfate roasting and water leaching was employed to recover the valuable metals from ZLR.The ZLR was initially roasted with ferric sulfate at640°C for1h with ferric sulfate/zinc ferrite mole ratio of1.2.In this process,the valuable metals were efficiently transformed into water soluble sulfate,while iron remains as ferric oxide.Thereafter,water leaching was conducted to extract the valuable metals sulfate for recovery.The recovery rates of zinc,manganese,copper,cadmium and iron were92.4%,93.3%,99.3%,91.4%and1.1%,respectively.A leaching toxicity test for ZLR was performed after water leaching.The results indicated that the final residue was effectively detoxified and all of the heavy metal leaching concentrations were under the allowable limit.

Laparoscopic splenectomy for treatment of splenic marginal zone lymphoma

AIM: To investigate the short-term and long-term ef-ficacy and safety of laparoscopic splenectomy (LS) for treatment of splenic marginal zone lymphoma (SMZL). METHODS: A total of 18 continuous patients who were diagnosed with SMZL and underwent LS in our department from 2008 to 2012 were reviewed. The perioperative variables and long-term follow-up were evaluated. To evaluate the efficacy and safety of this procedure better, we also included 34 patients with liver cirrhosis who underwent LS, 49 patients with immune thrombocytopenia (ITP) who underwent LS, and 20 patients with SMZL who underwent open splenectomy (OS). The results observed in the different groups were compared.RESULTS: No differences were found in the sex and Child-Pugh class of the patients in SMZL-LS, SMZL-OS, ITP, and liver cirrhosis groups. The splenic length of the patients in the SMZL-LS group was similar to that in the SMZL-OS and liver cirrhosis groups but significantly longer than in the ITP group. The SMZL-LS group had a significantly longer operating time compared with the SMZL-OS, ITP, and liver cirrhosis groups, and the SMZL-LS group exhibited significantly less blood loss compared with the SMZL-OS group. No difference was found in the length of the postoperative hospital stay between the SMZL-LS, SMZL-OS, ITP, and liver cirrhosis-LS groups. After surgery, 6 (33.3%) SMZL-LS patients suffered slight complications. During mean fol-low-up periods of 13.6 and 12.8 mo, one patient from the SMZL-LS group and two from the SMZL-OS group died as a result of metastasis after surgery. None of the ITP and liver cirrhosis patients died. CONCLUSION: LS should be considered a feasible and safe procedure for treatment of SMZL in an effort to improve the treatment options and survival of patients.

Laparoscopic splenectomy for splenic littoral cell angioma

AIM:To establish the safety and feasibility of laparoscopic splenectomy(LS) for littoral cell angioma(LCA).METHODS:From September 2003 to November 2013,27 patients were diagnosed with LCA in our institution.These patients were divided into two groups based on operative procedure:LS(13 cases,Group 1) and open splenectomy(14 cases,Group 2).Data were collected retrospectively by chart review.Comparisons were performed between the two groups in terms of demographic characteristics(sex and age); operative outcomes(operative time,estimated blood loss,transfusion,and conversion); postoperative details(length of postoperative stay and complications); and follow-up outcome.RESULTS:LS was successfully carried out in all patients except one in Group 1,who required conversion to hand-assisted LS because of perisplenic adhesions.The average operative time for patients in Group 1 was significantly shorter than that in Group 2(127 ± 34 min vs 177 ± 25 min,P = 0.001).The average estimated blood loss in Group 1 was significantly lower than in Group 2(62 ± 48 m L vs 138 ± 64 m L,P < 0.01).No patient in Group 1 required a blood transfusion,whereas one in Group 2 required a transfusion.Two patients in Group 1 and four in Group 2 suffered from postoperative complications.All the complications were cured by conservative therapy.There were no deaths in our series.All patients were followed up and no recurrence or abdominal metastasis were found.CONCLUSION:LS for patients with LCA is safe and feasible,with preferable operative outcomes and longterm tumor-free survival.

Emergency laparoscopic partial splenectomy for ruptured spleen:A case report

Splenic rupture is a common consequence of blunt abdominal trauma. Emergency splenectomy is indicated when conservative management is not effective. With better understanding of the immunologic function of the spleen, surgeons have begun to perform the splenic-preserving surgery. However, it is technical challenge to perform emergency laparoscopic partial splenectomy for patient with spleen rupture. A 15-year-old male patient suffered from grade. spleen injury basing on the American association for the surgery of trauma splenic injury scale. Conservative treatment failed to success basing on the dramatically decreased hemoglobin level. During the laparoscopic exploration, we found that two individual ruptures were associated with the upper pole of spleen. An emergency laparoscopic partial splenectomy was successfully carried out. The operative time was approximate 150 min and the estimated blood loss was 200 mL. The post-operative course was uneventful and the patient was discharged on the 7th post-operative day. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.

Cascade sulfidation and separation of copper and arsenic from acidic wastewater via gas-liquid reaction

Copper and arsenic in acidic wastewater were separated by cascade sulfidation followed by replacement of arsenic in theprecipitates by copper in the solution which was realized by recycling precipitates obtained in the first stage into the initial solution.The effects of reaction time,temperature and H2S dosage on copper and arsenic removal efficiencies as well as the effects of solid-toliquidratio,time and temperature on the replacement of arsenic by copper were investigated.With20mmol/L H2S at50°C within0.5min,more than80%copper and nearly20%arsenic were precipitated.The separation efficiencies of copper and arsenic werehigher than99%by the replacement reaction between arsenic and copper ions when solid-to-liquid ratio was more than10%at20°Cwithin10min.CuS was the main phases in precipitate in which copper content was63.38%in mass fraction.

Interaction mechanism between arsenate and fayalite-type copper slag at high temperatures

The interaction mechanism between sodium arsenate and fayalite-type copper slag at 1200℃was investigated through XRD,XPS,HRTEM,TCLP and other technical means and methods.The results indicated that the proportions of sodium arsenate in the slag and flue gas phases were approximately 30%and 70%,respectively.The addition of sodium arsenate depolymerized the fayalite structure and changed it from a crystalline state to an amorphous state.The fayalite structural changes indicated that the[AsO_(4)]tetrahedron in sodium arsenate combined with the[SiO_(4)]tetrahedron and[FeO_(4)]tetrahedron through bridging oxygen to form a silicate glass structure.The TCLP test results of the samples before and after the high temperature reaction of fayalite and sodium arsenate showed that after high temperature reaction,fayalite could effectively reduce the leaching toxicity of sodium arsenate,reducing the leaching concentration of arsenic from 3025.52 to 12.8 mg/L before and after reaction,respectively.

Consecutive laparoscopic gallbladder and spleen resections in cirrhotic patients

AIM:To evaluate the feasibility,safety,and effectiveness of consecutive laparoscopic cholecystectomy(LC)plus splenectomy(LS)in liver cirrhosis patients.METHODS:From 2003 to 2013,17(group 1)patients with liver cirrhosis complicated by hypersplenism and symptomatic gallstones were treated with combined LC and LS,while 58(group 2)patients with liver cirrhosis and hypersplenism received LS alone.An additional 14(group 3)patients who received traditional open procedures during the same period were included as controls.Data were retrospectively collected and reviewed in regard to demographic characteristics and preoperative,intraoperative and postoperative features.Differences between the three groups were assessed by statistical analysis.RESULTS:The three groups showed no significant differences in the demographic characteristics or preoperative status.However,the patients treated with LC and LS required significantly longer operative time,shorter postoperative stay as well as shorter time of return to the first oral intake,and suffered less intraoperative blood loss as well as fewer postoperative surgical infections than the patients treated with traditional open procedures(group 1 vs group 3,P<0.05 for all).The patients treated with LC and LS showed no significant differences in the intraoperative and postoperative variables from those treated with LS alone(group 1 vs group 2).All patients showed significant improvements in the haematological responses(preoperative period vs postoperative period,P<0.05 for all).None of the patients treated with LC and LS presented with any gallstone-associated symptoms following discharge,while the patients treated with the traditional open procedures expressed complaints of discomfort related to their surgical incisions.CONCLUSION:Consecutive LC and LS is an appropriate treatment option for liver cirrhosis patients with gallstones and hypersplenism,especially for those with Child-Pugh A and B.

Non-invasive evaluation of liver stiffness after splenectomy in rabbits with CCl_4-induced liver fibrosis

AIM To investigate the diagnostic performance of liver stiffness measurement(LSM) by elastography point quantification(Elast PQ) in animal models and determine the longitudinal changes in liver stiffness by Elast PQ after splenectomy at different stages of fibrosis.METHODS Liver stiffness was measured in sixty-eight rabbits with CCl4-induced liver fibrosis at different stages and eight healthy control rabbits by Elast PQ. Liver biopsies and blood samples were obtained at scheduled time points to assess liver function and degree of fibrosis. Thirty-one rabbits with complete data that underwent splenectomy at different stages of liver fibrosis were then included for dynamic monitoring of changes in liver stiffness by Elast PQ and liver function according to blood tests.RESULTS LSM by Elast PQ was significantly correlated with histologic fibrosis stage(r = 0.85, P < 0.001). The optimal cutoff values by Elast PQ were 11.27, 14.89, and 18.21 k Pa for predicting minimal fibrosis, moderate fibrosis, and cirrhosis, respectively. Longitudinalmonitoring of the changes in liver stiffness by Elast PQ showed that early splenectomy(especially F1) may delay liver fibrosis progression.CONCLUSION Elast PQ is an available, convenient, objective and non-invasive technique for assessing liver stiffness in rabbits with CCl4-induced liver fibrosis. In addition, liver stiffness measurements using Elast PQ can dynamically monitor the changes in liver stiffness in rabbit models, and in patients, after splenectomy.

Effect of transport agent boron triiodide on the synthesis and crystal quality of boron arsenide

Cubic boron arsenide(BAs)has attracted great attention due to its high thermal conductivity,however,its controllable,stable,and ideal preparation remains challenging.Herein,we investigated the effect of iodine-containing transport agents I_(2) and boron triiodide(BI_(3))on BAs synthesized and grown through chemical vapor transport.Results show that similar to the commonly used I_(2),BI_(3) accelerates the synthesis and improves the mass fraction of BAs from ~12% to over 90% at 820℃ and 1.5 MPa,a value beyond the promoting effect of only increasing temperature and pressure.Both agents enhance the quality of BAs crystals by reducing the full width at half maximum by up to 10%-20%.I_(2) agglomerates the grown crystals with twin defects(~50 nm wide),and BI_(3) improves the crystal anisotropy and element uniformity of BAs crystals with narrow twins(~15 nm wide)and increases the stoichiometry ratio(~0.990)to almost 1.Owing to the boron interstitials from the excessive boron supply,the spacing of layers in {111} increases to 0.286 nm in the presence of I_(2).Owing to its coordinated effect,BI_(3) only slightly influences the layer spacing at 0.275 nm,which is close to the theoretical value of 0.276 nm.In the chemical vapor transport,the anisotropic crystals with flat surfaces exhibit single-crystal characteristics under the action of BI_(3).Different from that of I_(2),the coordinated effect of BI_(3) can promote the efficient preparation of high-quality BAs crystal seeds and facilitate the advanced application of BAs.

Iron extraction from lead slag by bath smelting

A new bath smelting process was proposed to recover iron for solid wastes reduction.99.79%of iron metallization,99.61%of iron recovery,pig iron with93.58%Fe,0.021%S,0.11%P,1.38%C,0.22%Si,0.01%Pb and0.031%Zn were achievedafter the wastes were smelted at1575°C for20min under C/Fe molar ratio of1.6and basicity of1.2.The produced pig iron could beused in steel-making.This study provides a way for recycling iron from smelting slag and hydrometallurgical residue.

Design and Performance Analysis of Axial Flux Permanent Magnet Machines with Double-Stator Dislocation Using a Combined Wye-Delta Connection

Conventional fractional slot concentrated winding three-phase axial flux permanent magnet machines have an abundance of armature reaction magnetic field harmonics which deteriorate the torque performance of the machine.This paper presents a double-stator dislocated axial flux permanent magnet machine with combined wye-delta winding.A wye-delta(Y-△)winding connection method is designed to eliminate the 6 th ripple torque generated by air gap magnetic field harmonics.Then,the accurate subdomain method is adopted to acquire the no-load and armature magnetic fields of the machine,respectively,and the magnetic field harmonics and torque performance of the designed machine are analyzed.Finally,a 6 k W,4000 r/min,18-slot/16-pole axial flux permanent magnet machine is designed.The finite element simulation results show that the proposed machine can effectively eliminate the 6 th ripple torque and greatly reduce the torque ripple while the average torque is essentially identical to that of the conventional three-phase machines with wye-winding connection.

Isothermal reduction kinetics of zinc calcine under carbon monoxide

The reduction kinetics of zinc calcine under a CO atmosphere was evaluated by isothermal reductive roasting in a temperature range of 600-800℃.The extent of reaction of zinc calcine was measured using thermogravimetry(TG),and the decomposition mechanism of zinc ferrite in zinc calcine was analyzed based on variations in the soluble zinc and ferrous contents.The results indicate that the reaction was controlled by the nucleation of the products,with an apparent activation energy of 65.28 k J/mol.The partial pressure of CO affected the reaction rate more strongly than the CO intensity(defined as PCO/(PCO+PCO2)).The generation rate of zinc oxide was higher than that of ferrous oxide;therefore,the nucleation of ferrous oxide is the rate-determining step of the reaction.

International expert consensus on laparoscopic pancreaticoduodenectomy

Importance:While laparoscopic pancreaticoduodenectomy(LPD)is being adopted with increasing enthusiasm worldwide,it is still challenging for both technical and anatomical reasons.Currently,there is no consensus on the technical standards for LPD.Objective:The aim of this consensus statement is to guide the continued safe progression and adoption of LPD.Evidence Review:An international panel of experts was selected based on their clinical and scientific expertise in laparoscopic and open pancreaticoduodenectomy.Statements were produced upon reviewing the literature and assessed by the members of the expert panel.The literature search and its critical appraisal were limited to articles published in English during the period from 1994 to 2019.The Web of Science,Medline,and Cochrane Library and Clinical Trials databases were searched,The search strategy included,but was not limited to,the terms'laparoscopic','pancreaticoduodenectomy,'pancreatoduodenectomy','Whipple's operation',and'minimally invasive surgery'.Reference lists from the included articles were manually checked for any additional studies,which were included when appropriate.Delphi method was used to establish expert consensus and the AGREE II-GRS Instrument was applied to assess the methodological quality and externally validate the final statements.The statements were further discussed during a one-day face-to-face meeting at the 1st Summit on Minimally Invasive Pancreatico-Biliary Surgery in Wuhan,China.Findings:Twenty-eight international experts from 8 countries constructed the expert panel.Sixteen statements were produced by the members of the expert panel.At least 80%of responders agreed with the majority(80%)of statements.Other than three randomized controlled trials published to date,most evidences were based on level 3 or 4 studies according to the AGREE II-GRS Instrument.Conclusions and Relevance:The Wuhan international expert consensus meeting on LPD has produced a set of clinical practice statements for the safe development and progression of LPD.LPD is currently in its development and exploration stages,as defined by the international IDEAL framework for surgical innovation.More robust randomized controlled trial and registry study are essential to proceed with the assessment of LPD.

腹腔镜胰腺外科手术的临床实践和研究

针对胰腺外科疾病独特的特点,笔者就所在中心对腹腔镜不同胰腺术式在临床实践与研究方面的经验进行归纳总结。一、腹腔镜胰体尾切除术(一)腹腔镜保留脾脏的胰体尾切除术腹腔镜保留脾脏的胰体尾切除术主要针对胰体尾部的良性或低度恶性肿瘤,目前保脾的方式有Kimure和Warshaw法。