Smart prediction of liquefaction-induced lateral spreading

The prediction of liquefaction-induced lateral spreading/displacement(Dh)is a challenging task for civil/geotechnical engineers.In this study,a new approach is proposed to predict Dh using gene expression programming(GEP).Based on statistical reasoning,individual models were developed for two topographies:free-face and gently sloping ground.Along with a comparison with conventional approaches for predicting the Dh,four additional regression-based soft computing models,i.e.Gaussian process regression(GPR),relevance vector machine(RVM),sequential minimal optimization regression(SMOR),and M5-tree,were developed and compared with the GEP model.The results indicate that the GEP models predict Dh with less bias,as evidenced by the root mean square error(RMSE)and mean absolute error(MAE)for training(i.e.1.092 and 0.815;and 0.643 and 0.526)and for testing(i.e.0.89 and 0.705;and 0.773 and 0.573)in free-face and gently sloping ground topographies,respectively.The overall performance for the free-face topology was ranked as follows:GEP>RVM>M5-tree>GPR>SMOR,with a total score of 40,32,24,15,and 10,respectively.For the gently sloping condition,the performance was ranked as follows:GEP>RVM>GPR>M5-tree>SMOR with a total score of 40,32,21,19,and 8,respectively.Finally,the results of the sensitivity analysis showed that for both free-face and gently sloping ground,the liquefiable layer thickness(T_(15))was the major parameter with percentage deterioration(%D)value of 99.15 and 90.72,respectively.

Effects of non-liquefiable crust layer and superstructure mass on the response of 2×2 pile groups to liquefaction-induced lateral spreading

In this research,two shake table experiments were conducted to study the effects of non-liquefiable crust layer and superstructure mass on the responses of two sets of 22 pile groups to liquefactioninduced lateral spreading.In this regard,an inclined base layer overlain by a very loose liquefiable layer was constructed in both models;while only in one model,a non-liquefiable crust layer was built.A lumped mass,being representative of a superstructure,was attached to the cap of one pile group in both models.The models were fully instrumented with various sensors,including acceleration,displacement,and pore water pressure transducers.Also,the piles were instrumented with pair strain gauges to measure pure bending moments induced by cyclic and monotonic loadings associated with ground shaking and lateral spreading,respectively.The results showed that the existence of the non-liquefiable crust layer increases both the maximum and residual soil displacements at the free field and also the maximum bending moments in the piles.The results of the experiments indicated that the crust layer induces a high kinematic lateral soil pressure and force on the piles which are not present in the crustless case.The crust layer increases the pile cap displacement before liquefaction,albeit decreases it after liquefaction,due to the elastic rebound of the piles in the liquefiable layer.The crust layer postpones both liquefaction triggering and dissipation of excess pore water pressure.The existence of the superstructure mass on the pile caps decreases the acceleration amplitude of the pile caps,while increases their maximum displacement.

Large colonic lipoma with a laterally spreading tumor treated by endoscopic submucosal dissection:A case report

BACKGROUND Since fat does not transmit electrical energy well,delayed perforation and postpolypectomy syndrome due to electrical thermal injury are concerns in the endoscopic removal of colonic lipoma.The endoscopic submucosal dissection(ESD)technique concentrates electrical energy conducts to the submucosa,not the adipose tissue.This helps to minimize electrical thermal injury,especially in the case of large colonic lipomas.In rare cases,such as colonic lipomas accompanied by mucosal lesions,it is difficult for endoscopists to decide how to safely remove them.CASE SUMMARY A 78-year-old man underwent colonoscopy for colorectal cancer screening.During colonoscopy,a yellowish submucosal tumor with positive cushion sign was observed in the ascending colon measuring about 4.5 cm.A nodular mucosal lesion of about 2.5 cm was observed on the mucosal surface of the lipoma.The lipoma was so large that it occupied much of the inside of the colon,making it difficult to see the entire laterally spreading tumor(LST)at once.The LST was confined to the surface of the lipoma,which had a semipedunculated shape with a wide neck.The margin of the LST was not observed at the neck of the lipoma.ESD was performed and the colonic lipoma with the LST was successfully removed without complications.After 3 d of hospitalization,the patient was discharged without any symptoms.The final pathology report showed that the lesion consisted of submucosal lipoma and tubulovillous adenoma with lowgrade dysplasia.CONCLUSION ESD is effective and safe for treating a large colonic lipoma with an LST by minimizing electrical thermal injury.

Response of single piles and pipelines in liquefaction-induced lateral spreads using controlled blasting

Two full-scale experiments using controlled blasting were conducted in the Port of Tokachi on Hokkaido Island, Japan,to assess the behavior of piles and pipelines subjected to lateral spreading.Test specimens were extensively instrumented with strain gauges to measure the distribution of moment during lateral spreading.This allowed us to compute the loading condition,as well as to conduct damage and performance assessments on the piles and pipelines.This paper presents the test results and discussions on the response of single piles and pipelines observed from the full-scale experiments.Based on the test results,it can be concluded that using controlled blasting successfully liquefied the soil,and subsequently induced lateral spreading.The movements of the single pile,as well as the transverse pipelines,were approximately the same as the free field soil movement.Observed moment distribution of the single pile indicated that global translation of the liquefied soil layer provided insignificant force to the pile.In addition,the degree of fixity at the pile tip significantly affected the moment along the pile as well as the pile head displacement.The pile with a higher degree of fixity at the pile tip had smaller pile head displacement but larger maximum moment.

Response of a pile group behind quay wall to liquefaction-induced lateral spreading:a shake-table investigation

The response of pile foundations near a quay wall under liquefaction-induced lateral spreading remains a complex problem. This study presents the results of a shake-table test on a 2×2 pile group behind a sheet-pile quay wall that was subjected to lateral spreading. The quay wall was employed to trigger liquefaction-induced large lateral ground deformation. The discussions focus on the behavior of the pile and the soil and on the bending moment distributions within the group pile and the restoring force characteristics at the superstructure. Overall, the piles exhibited apparent pinning effects that reduced soil deformation. In addition, the rear-row piles near the quay wall experienced larger bending moments than did the front-row piles, indicating significant pile group effects. The tests showed that lateral spreading could be a primary cause of larger monotonic deformations and bending moments. It can also be concluded that the monotonic bending moments were significantly decreased due to the presence of slow soil flow. The stiffness at the superstructure was reduced because of accumulated excess pore pressure before liquefaction, and it was recovered during lateral spreading. The present study further enhances current understanding of the behavior of low-cap pile foundations under lateral spreading.

MUC5AC/β-catenin expression and KRAS gene alteration in laterally spreading colorectal tumors

AIM： To clarify differences in mucin phenotype, prolif- erative activity and oncogenetic alteration among sub- types of colorectal laterally spreading tumor （LST）. METHODS： LSTs, defined as superficial elevated lesions greater than 10 mm in diameter with a low vertical axis, were macroscopically classified into two subtypes： （1） a granular type （Gr-LST） composed of superficially spread- ing aggregates of nodules forming a fiat-based lesion with a granulonodular and uneven surface; and （2） a non-granular type （NGr-LST） with a flat smooth surface and an absence of granulonodular formation. A total of 69 LSTs, comprising 36 Gr-LSTs and 33 NGr-LSTs, were immunohistochemically stained with MUC2, MUC5AC, MUC6, CD10 （markers of gastrointestinal cell lineage）, p53, 13-catenin and Ki-67 antibodies, and examined for alteration in exon 1 of v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog （KRAS） and exon 15 of v-raf murine sarcoma viral oncogene homologue B1 （BRAF） by poly- merase chain reaction followed by direct sequencing. RESULTS： Histologically, 15 Gr-LST samples were ad- enomas with low-grade dysplasia （LGD）, 12 were high- grade dysplasia （HGD） and 9 were adenocarcinomas invading the submucosa （INV）, while 12 NGr-LSTs demonstrated LGD, 14 HGD and 7 INV. In the proximal colon, MUC5AC expression was significantly higher in the Gr-type than the NGr-type. MUC6 was expressed only in NGr-LST. MUC2 or CD10 did not differ. P53 ex- pression demonstrated a significant stepwise increment in progression through LGD-HGD-INV with both types of LST. Nuclear β-catenin expression was significantly higher in the NGr-type. Ki-67 expression was signifi- cantly higher in the Gr-type in the lower one third zone of the tumor. In proximal, but not distal colon tumors, the incidence of KRAS provided mutation was signifi- cantly higher in the Gr-type harboring a specific muta- tional pattern （G12V）. BRAF mutations （V600E） were detected only in two Gr-LSTs. CONCLUSION： The two subtypes of LST, especially in the proximal colon, have differing phenotypes of gastrointestinal cell lineage, proliferation and activa- tion of Wnt/β-catenin or RAS/RAF/extracellular signal- regulated kinase signaling.

Effects of structural characterizations on fragility functions of bridges subject to seismic shaking and lateral spreading

This paper evaluates the seismic vulnerability of different classes of typical bridges in California when subjected to seismic shaking or liquefaction-induced lateral spreading. The detailed structural configurations in terms of superstructure type, connection, continuity at support and foundation type, etc. render different damage resistant capability. Six classes of bridges are established based on their anticipated failure mechanisms under earthquake shaking. The numerical models that are capable of simulating the complex soil-structure interaction effects, nonlinear behavior of columns and connections are developed for each bridge class. The dynamic responses are obtained using nonlinear time history analyses for a suite of 250 earthquake motions with increasing intensity. An equivalent static analysis procedure is also implemented to evaluate the vulnerability of the bridges when subjected to liquefaction-induced lateral spreading. Fragility functions for each bridge class are derived and compared for both seismic shaking （based on nonlinear dynamic analyses） and lateral spreading （based on equivalent static analyses） for different performance states. The study finds that the fragility functions due to either ground shaking or lateral spreading show significant correlation with the structural characterizations, but differences emerge for ground shaking and lateral spreading conditions. Structural properties that will mostly affect the bridges＇ damage resistant capacity are also identified.

Numerical analyses of pile performance in laterally spreading frozen ground crust overlying liquefiable soils

Lateral spread of frozen ground crust over liquefied soil has caused extensive bridge foundation damage in the past winter earthquakes.A shake table experiment was conducted to investigate the performance of a model pile in this scenario and revealed unique pile failure mechanisms.The modelling results provided valuable data for validating numerical models.This paper presents analyses and results of this experiment using two numerical modeling approaches： solid-fluid coupled finite element（FE） modeling and the beam-on-nonlinear-Winkler-foundation（BNWF） method.A FE model was constructed based on the experiment configuration and subjected to earthquake loading.Soil and pile response results were presented and compared with experimental results to validate this model.The BNWF method was used to predict the pile response and failure mechanism.A p-y curve was presented for modelling the frozen ground crust with the free-field displacement from the experiment as loading.Pile responses were presented and compared with those of the experiment and FE model.It was concluded that the coupled FE model was effective in predicting formation of three plastic hinges at ground surface,ground crust-liquefiable soil interface and within the medium dense sand layer,while the BNWF method was only able to predict the latter two.

Empirical models for predicting lateral spreading considering the effect of regional seismicity

A revised empirical model has been developed for predicting liquefaction-induced lateral spreading displacement （LD） as a function of both response spectral acceleration derived from strong-motion attenuation models and geotechnical parameters from Youd＇s LD data set （Youd website）. This revised model is different from the model of Zhang and Zhao, which overcame some drawbacks of earlier models for predicting lateral spreading and was primarily used in Japan and the western U.S. The revised model can potentially be applied anywhere if ground shaking （in terms of 5% damped acceleration or displacement response spectra） can be estimated using local strong-motion attenuation relationships. The revised model is examined using data from Japan and the western U.S. and applied to Turkey and New Zealand, where the ground shaking is estimated using appropriate strong-motion attenuation relationships for each region. The accuracy of the revised model is evaluated by comparing its predicted lateral displacements with those measured in actual earthquakes. The results show that the revised model can account for the effects of local seismicity on lateral spreading displacements and is comparable with existing prediction models.

Laterally spreading tumors:Limitations of computed tomography colonography

AIM: To prospectively investigate the detection rate of laterally spreading tumors (LSTs) of the colorectum by computed tomography (CT) colonography (CTC).

Laterally spreading tumor-like primary rectal mucosa-associated lymphoid tissue lymphoma:A case report

BACKGROUND Colorectal mucosa-associated lymphoid tissue(MALT)lymphoma is a rare disease,and only a few cases have been reported to date.It has no specific clinical presentations and shows various endoscopic appearances.There is no uniform consensus on its treatment.With the advancement of endoscopic technology,endoscopic treatment has achieved better results in individual case reports of early-stage patients.CASE SUMMARY We report a case of rectal MALT in a 57-year-old Chinese man with no symptoms who received endoscopy as part of a routine physical examination,which incidentally found a 25 mm×20 mm,laterally spreading tumor(LST)-like elevated lesion in the rectum.Therefore,he was referred to our hospital for further endoscopic treatment.Complete and curable removal of the tumor was performed by endoscopic submucosal dissection.We observed enlarged and dilated branch-like vessels similar to those of gastric MALT lymphoma on magnifying endoscopy with narrow-band imaging.And immunopathological staining showed hyperplastic capillaries in the mucosa.Histopathological findings revealed diffusely hyperplastic lymphoid tissue in the lamina propria,with a visible lymphoid follicle structure surrounded by a large number of diffusely infiltrated lymphoid cells that had a relatively simple morphology and clear cytoplasm.In addition,immunohistochemical analysis suggested strongly positive expression for CD20 and Bcl-2.Gene rearrangement results showed positivity for IGH-A,IGH-C,IGK-B,and IGL.Taking all the above findings together,we arrived at a diagnosis of extranodal marginal zone B-cell lymphoma of MALT lymphoma. Positron emission tomography-computed tomographyexamination showed no other lesions involved. The patient will be followed byperiodic endoscopic observation.CONCLUSIONIn conclusion, we report a case of rectal MALT with an LST-like appearancetreated by endoscopic submucosal dissection. Further studies will be needed toexplore the clinical behavior, endoscopic appearance, and treatment of rectalMALT.

Predictors for malignant potential and deep submucosal invasion in colorectal laterally spreading tumors

BACKGROUND Colorectal laterally spreading tumors(LSTs)with malignant potential require en bloc resection by endoscopic submucosal dissection(ESD),but lesions with deep submucosal invasion(SMI)are endoscopically unresectable.AIM To investigate the factors associated with high-grade dysplasia(HGD)/carcinoma and deep SMI in colorectal LSTs.METHODS The endoscopic and histological results of consecutive patients who underwent ESD for colorectal LSTs in our hospital from June 2013 to March 2019 were retrospectively analyzed.The characteristics of LST subtypes were compared.Risk factors for HGD/carcinoma and deep SMI(invasion depth≥1000μm)were determined using multivariate logistic regression.RESULTS A total of 323 patients with 341 colorectal LSTs were enrolled.Among the four subtypes,non-granular pseudodepressed(NG-PD)LSTs(85.5%)had the highest rate of HGD/carcinoma,followed by the granular nodular mixed(G-NM)(77.0%),granular homogenous(29.5%),and non-granular flat elevated(24.2%)subtypes.Deep SMI occurred commonly in NG-PD LSTs(12.9%).In the adjusted multivariate analysis,NG-PD[odds ratio(OR=16.8,P<0.001)and G-NM(OR=7.8,P<0.001)subtypes],size≥2 cm(OR=2.2,P=0.005),and positive non-lifting sign(OR=3.3,P=0.024)were independently associated with HGD/carcinoma.The NG-PD subtype(OR=13.3,P<0.001)and rectosigmoid location(OR=8.7,P=0.007)were independent risk factors for deep SMI.CONCLUSION Because of their increased risk for malignancy,it is highly recommended that NG-PD and G-NM LSTs are removed en bloc through ESD.Given their substantial risk for deep SMI,surgery needs to be considered for NG-PD LSTs located in the rectosigmoid,especially those with positive nonlifting signs.

Preliminary experience of hybrid endoscopic submucosal dissection by duodenoscope for recurrent laterally spreading papillary lesions

BACKGROUND The management strategies for recurrent ampullary adenoma after endoscopic papillectomy are still controversial.Patients with the recurrent papillary lesions need to receive repetitive endoscopic interventions due to the limitations of conventional endoscopic techniques.AIM To assess the feasibility,efficacy,and safety of hybrid endoscopic submucosal dissection(ESD)by duodenoscope for recurrent,laterally spreading papillary lesions.METHODS We enrolled two patients with recurrent,laterally spreading,duodenal papillary adenomas with no intraductal extension confirmed by follow-up between March 2017 and September 2018.After marking the resection borders of the lesion using a dual knife,a submucosal cushion was created by injecting a mixture of saline solution,methylene blue,and adrenaline.A total circumferential incision and submucosal excision was performed by dual knife combined with insulated-tip diathermic knife,and then the lesion was ligated and resected using an electric snare.Endoscopic hemostasis was applied during the endoscopic procedures.Moreover,the endoscopic retrograde cholangiopancreatography(ERCP)procedures,including selective cannulation and stent implantation of biliary and pancreatic ducts,were performed.Additionally,we performed endoclip closure for mucosal defect after ESD.RESULTS Hybrid ESD using a duodenoscope and biliary and pancreatic stent placement were performed successfully in two patients.The endoscopic size of recurrent papillary lesions was no more than 2 cm.Generally,the average total procedure time was 95.5 min,and the procedure time of ESD and ERCP was 38.5 min and 15.5 min,respectively.No serious complications occurred during the intraoperative and postoperative periods.The histopathological examination revealed tubulovillous adenoma negative for neoplastic extension at the cut margin in both patients.The duodenoscopic follow-up and histopathology of biopsy specimens at 3 mo after ESD showed no residual or recurrent lesions in ampullary areas in both cases.Both cases have been followed up with no recurrence to June 2020.CONCLUSION Hybrid ESD by duodenoscope is technically challenging,and may be curative for recurrent,laterally spreading papillary adenomas<2 cm.It should be performed cautiously in selected patients by experienced endoscopists.

Investigation of lateral spreading current in the 4H-SiC Schottky barrier diode chip

Lateral current spreading in the 4H-SiC Schottky barrier diode(SBD)chip is investigated.The 4H-SiC SBD chips with the same vertical parameters are simulated and fabricated.The results indicate that there is a fixed spreading resistance at on-state in current spreading region for a specific chip.The linear specific spreading resistance at the on-state is calculated to be 8.6Ω/cm in the fabricated chips.The proportion of the lateral spreading current in total forward current(Psp)is related to anode voltage and the chip area.Psp is increased with the increase in the anode voltage during initial on-state and then tends to a stable value.The stable values of Psp of the two fabricated chips are 32%and 54%.Combined with theoretical analysis,the proportion of the terminal region and scribing trench in a whole chip(Ksp)is also calculated and compared with Psp.The Ksp values of the two fabricated chips are calculated to be 31.94%and 57.75%.The values of Ksp and Psp are close with each other in a specific chip.The calculated Ksp can be used to predict that when the chip area of SiC SBD becomes larger than 0.5 cm2,the value of Psp would be lower than 10%.

Endoscopic management of difficult laterally spreading tumors in colorectum

Due to the advent of the screening programs for colorectal cancer and the era of quality assurance colonoscopy the number the polyps that can be considered difficult,including large(>20 mm)laterally spreading tumors(LSTs),has increased in the last decade.All LSTs should be assessed carefully,looking for suspicious areas of submucosal invasion(SMI),such as nodules or depressed areas,describing the morphology according to the Paris classification,the pit pattern,and vascular pattern.The simplest,most appropriate and safest endoscopic treatment with curative intent should be selected.For LST-granular homogeneous type,piecemeal endoscopic mucosal resection should be the first option due to its biological low risk of SMI.LST-nongranular pseudodepressed type has an increased risk of SMI,and en bloc resection should be mandatory.Underwater endoscopic mucosal resection is useful in situations where submucosal injection alters the operative field,e.g.,for the resection of scar lesions,with no lifting,adjacent tattoo,incomplete resection attempts,lesions into a colonic diverticulum,in ileocecal valve and lesions with intra-appendicular involvement.Endoscopic full thickness resection is very useful for the treatment of difficult to resect lesions of less than 20 up to 25 mm.Among the indications,we highlight the treatment of polyps with suspected malignancy because the acquired tissue allows an exact histologic risk stratification to assign patients individually to the best treatment and avoid surgery for low-risk lesions.Endoscopic submucosal dissection is the only endoscopic procedure that allows completes en bloc resection regardless of the size of the lesion.It should therefore be indicated in the treatment of lesions with risk of SMI.

Investigation of the lateral spread of erbium ions implanted in silicon crystal

The erbium ions at energy of 400 keV and dose of 5× 10^15 ions/cm^2 were implanted into silicon single crystals at room temperature at the angles of 0°,45° and 60°. The lateral spread of 400 keV erbium ions implanted in silicon sample was measured by the Rutherford backscattering technique. The results show that the measured values were in good agreement with those obtained from the prediction of TRIM＇98 （Transport of Ions in Matter） and SRIM2006 （Stopping and Range of Ions in Matter） codes.

188例侧向发育型肿瘤内镜及临床病理学分析

目的总结并评价结直肠侧向发育型肿瘤(laterally spreading tumor,LST)的内镜及临床病理特征。方法回顾性分析2010年12月至2019年12月首都医科大学附属北京世纪坛医院消化内科经内镜下治疗并诊断为LST的患者,根据LST病变内镜下特点,分为颗粒型LST(granular LST,LST-G)及非颗粒型LST(non-granular LST,LST-NG)两个亚组和四个亚型,总结并分析患者的临床一般资料、内镜下特征、组织病理特征、治疗方法等相关资料。结果(1)内镜下特征:共收集176例LST患者(188处病变),LST-NG亚组病变最多,LST病变直径为(22.48±12.26)mm(10~65 mm),LST-G组病变直径大于LST-NG组(P<0.001);LST-G及LST-NG好发于升结肠,LST-G较LST-NG更好发于直肠(χ^(2)=42.360,P<0.001);NICE分类对非肿瘤性息肉及癌和癌前病变诊断的敏感性为97.9%,特异性为82.6%,Kappa值为0.820(P<0.001),NICE分型与病理金标准具有很高的一致性。(2)病理特征:LST亚组均以管状腺瘤为主,LST-NG的癌变率包括HGIN为41.9%,高于LST-G的16.7%(χ^(2)=14.63,P<0.01);LST亚组间微卫星不稳定状态、p53的表达和Ki-67增殖指数差异均无统计学意义(P>0.05)。(3)治疗方式:结肠病变多选择使用EMR及ESD治疗,直肠病变多选择ESD及手术治疗(χ^(2)=19.596,P<0.01),<20 mm的病变多选用EMR治疗,20~<30 mm的病变多选用ESD治疗,≥30 mm的病变,手术治疗的比例逐渐升高(χ^(2)=102.725,P<0.01)。结论LST的临床特性及内镜下表现存在一定的特殊性,临床应重视识别LST病变,提高LST的检出,并对于不同病变采取合适的治疗方案。

小探头超声内镜在结直肠侧向发育型肿瘤浸润深度评估中的应用

目的分析小探头超声内镜评估结直肠侧向发育型肿瘤(LST)黏膜下层浸润的准确率及其影响因素。方法回顾性分析2018年6月-2021年8月就诊于该院内镜中心拟行内镜黏膜下剥离术(ESD)治疗的213例结直肠LST患者(共268处病灶)的临床资料。总结结直肠LST的临床病理特征和小探头超声内镜检查结果,分析超声内镜检查准确率及其影响因素。结果小探头超声内镜评估准确率为93.28%,不同病变表面形态的小探头超声内镜评估准确率比较,差异有统计学意义(P=0.000)。多因素Logistic回归分析显示,结节混合型和假凹陷型病变是影响小探头超声内镜评估准确率的危险因素。结论结直肠LST是一种特殊的肿瘤,小探头超声内镜评估其浸润深度,具有较高的准确率。病变表面形态是影响小探头超声内镜评估准确率的危险因素,当病变为结节混合型和假凹陷型时,易影响其评估准确率。

某越江综合管廊河谷场地液化流滑侧向扩展研究

液化引起河流阶地横向流滑会对长江下游的自然环境和建筑环境造成巨大破坏。然而,长江下游宽河谷场地尺寸达几千米,场地存在厚且松软的沉积层,土层分布极不均匀。土壤的非线性和千米级横向变形限制了该类场地数值模拟的可计算性。针对长江下游宽河谷场地地形的复杂性和地层的特殊性,并结合实际工程所在场地地质剖面,建立了长江下游宽河谷场地精细化模型。采用已建立的砂土液化大变形粘弹塑性本构模型和ALE方法,解决了该类场地流滑大变形模拟困难。考虑地震波类型和强度的影响,分析了宽河谷微倾斜场地液化分布特征和侧向流滑规律。结果表明:微倾斜可液化场地坡底处土层的液化程度最为严重,微倾斜岸坡场地河床发生了明显的液化侧向扩展地震破坏,揭示了宽河谷微倾斜可液化岸坡场地侧向扩展的空间变位特征,上述原因主要是由于宽河谷不同位置处土单元应力状态差异性所造成;通过与场地液化侧向扩展震害等级评价标准进行对比,进一步明确了该长江下游宽河谷微倾斜岸坡场地液化流滑侧向扩展的震害特征及其程度。

大肠侧向发育型肿瘤的内镜表现及病理特征

目的分析大肠侧向发育型肿瘤(LSTs)的内镜表现和病理特征,为术前充分评估肿瘤风险及选择治疗策略提供参考依据。方法回顾性分析2019年1月—2023年12月承德医学院附属医院内镜治疗的LSTs患者临床资料,分析病灶部位、大小、形态分型、组织学类型等方面临床和病理特征。结果共168个病例,病灶形态分型以颗粒型为主,占72.6%(122/168);病理类型以腺瘤为主,占78.6%(132/168)。组织学类型主要表现为低级别上皮内瘤变,占83.3%(140/168)。直径≥20 mm的LSTs多见于直肠,主要呈结节混合型,癌变率高于直径<20 mm的LSTs,分别为33.3%、46.3%和24.1%(P<0.05);而直径<20 mm的LSTs多见于升结肠,主要呈颗粒均一型,分别为45.0%和50.0%(P<0.05)。直肠LSTs病灶最大径中位数大于右半结肠及左半结肠,主要呈结节混合型,癌变率高于右半结肠及左半结肠,分别为[25(22,30)mm、67.5%和34.9%,P<0.05]。癌变组病灶最大径中位数大于低级别上皮内瘤变组,多见于直肠,主要呈结节混合型,分别为[25(22,30)mm、53.6%和67.9%,P<0.05];而低级别上皮内瘤变组病灶多见于升结肠,主要呈颗粒均一型,分别为37.1%和41.1%(P<0.05)。结论大肠LSTs临床及病理特征具有一定的特异性,直肠是直径≥20 mm且癌变的LSTs最常见的部位,其病灶形态以结节混合型为主,LSTs恶变潜能与病灶部位、直径及病灶形态有关。