Unraveling the Stray Current-Induced Interfacial Transition Zone(ITZ)Effect on Sulfate Corrosion in Concrete

The rail transit in sulfate-rich areas faces the combined effects of stray current and salt corrosion;however,the sulfate ion transport and concrete degradation mechanisms under such conditions are still unclear.To address this issue,novel sulfate transport and mesoscale splitting tests were designed,with a focus on considering the differences between the interfacial transition zone(ITZ)and cement matrix.Under the influence of stray current,the ITZ played a pivotal role in regulating the transport and mechanical failure processes of sulfate attack,while the tortuous and blocking effects of aggregates almost disappeared.This phenomenon was termed the“stray current-induced ITZ effect.”The experimental data revealed that the difference in sulfate ion transport attributed to the ITZ ranged from 1.90 to 2.31 times,while the difference in splitting strength ranged from 1.56 to 1.64 times.Through the real-time synchronization of splitting experiments and microsecond-responsive particle image velocimetry(PIV)technology,the mechanical properties were exposed to the consequences of the stray currentinduced ITZ effect.The number of splitting cracks in the concrete increased,rather than along the central axis,which was significantly different from the conditions without stray current and the ideal Brazilian disk test.Furthermore,a sulfate ion mass transfer model that incorporates reactivity and electrodiffusion was meticulously constructed.The embedded finite element calculation exhibited excellent agreement with the experimental results,indicating its reliability and accuracy.Additionally,the stress field was determined utilizing analytical methods,and the mechanism underlying crack propagation was successfully obtained.Compared to the cement matrix,a stray current led to more sulfates,more microstructure degradation,and greater increases in thickness and porosity in the ITZ,which was considered to be the essence of the stray current-induced ITZ effect.

大电流密度过渡金属硫族化合物析氢催化剂界面工程展望

氢能是未来可持续社会中理想的能量载体,利用可再生能源电解水制取绿氢的技术受到研究人员的广泛关注.电解水制绿氢技术由实验室向工业应用跨越的前提是发展大电流密度下性能优异且稳定的电催化剂.析氢反应(HER)是一种非均相反应,涉及催化剂-基底、催化剂-电解液、催化剂-气体三个界面.界面性质会影响电化学传质行为、电荷传输行为和催化剂的力学性质,从而影响大电流密度下制氢性能.因此,优化界面结构和性质是提升大电流密度下电解水催化剂性能并解决电解水技术工业应用挑战的关键.二维过渡金属硫族化合物(TMDCs)具有电子结构可调、活性位点丰富、合成方法多样等优势,自1976年首次应用于光电催化水分解反应、加氢脱硫反应以来,已有大量工作报道了TMDCs催化剂应用于HER.本文以TMDCs催化剂为例研究界面工程对大电流密度下HER的提升作用及机制.探讨了电化学反应中上述三个界面上发生的物理化学过程,系统分析了大电流密度下质量传输、电荷传输速率受限和力学强度不足三方面挑战,并总结了适用于大电流密度的催化剂性能描述符.分别归纳了针对以上三个界面的界面工程策略及相应作用,简要概括为:(1)催化剂-基底界面结合力增强、界面电阻降低、界面电子结构调控等策略;(2)催化剂-电解液界面形貌调控、表面化学、电解液环境调控等策略;(3)催化剂-气体界面疏气性调控、外场作用等策略.从反应机理研究、膜电极界面设计及电解槽界面性质调控三个角度对电解水反应界面工程未来的发展与应用提出了建议及展望.在反应机理方面,大电流条件下的界面性质如界面电阻、传质行为等仍需更深入的认识.在膜电极中,催化剂、离子交换膜、离子型聚合物、气体扩散层所形成的多元界面,尤其是催化剂-膜界面、催化剂-气体扩散层界面的结构仍需进一步优化以提升膜电极的活性及稳定性.在电解槽界面性质调控方面,催化剂-基底界面结合力等参数与催化剂寿命间的关系,电解过程中界面处的温度场及流场分布,适配于实际生产系统的电流密度等仍需深入研究.综上,本文从基本物理化学过程、策略及作用、挑战与展望等多个方面介绍了界面工程.本文有助于研究人员理解非均相电化学反应过程中界面的重要作用,提出催化剂、膜电极、电解槽界面设计新策略,并开发新型表征方法以深入对界面性质的认识,推动高效电解水技术的开发及应用.

Circulating miRNAs as biomarkers for severe acute pancreatitis associated with acute lung injury

AIM To identify circulating micro(mi)RNAs as biological markers for prediction of severe acute pancreatitis(SAP) with acute lung injury(ALI).METHODS Twenty-four serum samples were respectively collected and classified as SAP associated with ALI and SAP without ALI, and the mi RNA expression profiles were determined by microarray analysis. These mi RNAs were validated by quantitative reverse transcriptionpolymerase chain reaction, and their putative targets were predicted by the online software Target Scan, mi Randa and Pic Tar database. Gene ontology(GO) and Kyoto encyclopedia of genes and genomes(commonly known as KEGG) were used to predict their possible functions and pathways involved.RESULTS We investigated 287 mi RNAs based on microarray data analysis. Twelve mi RNAs were differentially expressed in the patients with SAP with ALI and those with SAP without ALI. Hsa-mi R-1260 b, 762, 22-3 p, 23 b and 23 a were differently up-regulated and hsa-mi R-550 a*, 324-5 p, 484, 331-3 p, 140-3 p, 342-3 p and 150 were differently down-regulated in patients with SAP with ALI compared to those with SAP without ALI. In addition, 85 putative target genes of the significantly dysregulated mi RNAs were found by Target Scan, mi Randa and Pic Tar. Finally, GO and pathway network analysis showed that they were mainly enriched in signal transduction, metabolic processes, cytoplasm and cell membranes.CONCLUSION This is the first study to identify 12 circulating mi RNAs in patients with SAP with ALI, which may be biomarkers for prediction of ALI after SAP.

Esophagojejunostomy after laparoscopic total gastrectomy by Or VilTM or hemi-double stapling technique

AIM: To investigate the feasibility, advantages and disadvantages of two types of anvil insertion techniques for esophagojejunostomy after laparoscopic total gastrectomy.METHODS: This was an open-label prospective cohort study. Laparoscopy-assisted radical total gastrectomy with D2 lymph node dissection was performed in 84 patients with primary non-metastatic gastric cancer confirmed by pre-operative histological examination. Overweight patients were excluded, as well as patients with peritoneal dissemination and invasion of adjacent organs. After total gastrectomy, all patients were randomized into two groups. Patients in Group Ⅰ underwent esophagojejunostomy using a transorally-inserted anvil(Or VilTM), while patients in Group Ⅱ underwent esophagojejunostomy using the hemi-double stapling technique(HDST). Both types of esophagojejunostomy were performed under laparoscopy. Patients' baseline characteristics, preoperative characteristics, perioperative characteristics, short-term postoperative outcomes and operation cost were comparedbetween the two groups. The primary endpoint was evaluation of the surgical outcome(operating time, time of digestive tract reconstruction and time of anvil insertion) and the medical cost of each operation(operation cost and total cost of hospitalization). The secondary endpoints were time to solid diet, post-surgical hospitalization time, time to defecation, time to ambulation and intra-operative blood loss. In addition, complications were assessed and compared. RESULTS: Laparoscopic total gastrectomy and esophagojejunostomy were successfully performed in all 84 patients, without conversion to laparotomy. There were no significant differences in the operative time and time for total gastrectomy between the two groups(287.8 ± 38.4 min vs 271.8 ± 46.1 min, P = 0.09, and 147.7 ± 31.6 min vs 159.8 ± 33.8 min, P = 0.09, respectively). The time for digestive tract reconstruction and for anvil insertion were significantly decreased in Group Ⅱ compared with Group I(47.8 ± 12.1 min vs 55.4 ± 15.7 min, P = 0.01, and 12.6 ± 4.7 min vs 18.7 ± 7.5 min, P = 0.001, respectively). Intraoperative blood loss(96.4 ± 32.7 m L vs 88.2 ± 36.9 m L, P = 0.28), time to defecation(3.5 ± 0.9 d vs 3.2 ± 1.1 d, P = 0.12), time to ambulation(3.9 ± 0.7 d vs 3.6 ± 1.1 d, P = 0.12), time to solid diet(7.6 ± 1.4 d vs 8.0 ± 2.7 d, P = 0.31) and total hospitalization(10.6 ± 2.6 d vs 10.8 ± 3.5 d, P = 0.80) were similar between the two groups. In addition, the total costs of hospitalization were similar between the two groups(73848.7 ± 11781.0 RMB vs 70870.3 ± 14003.5 RMB, P = 0.296), but operation cost was significantly higher in Group I compared with Group Ⅱ(32401.9 ± 1981.6 RMB vs 26961.9 ± 2293.8 RMB, P < 0.001).CONCLUSION: Anvil insertion was faster and easier using the HDST technique compared with Or VilTM, and was more cost-effective. There was no significant difference in safety.

CO_(2)对长庆采出油水物性影响及乳状液稳定机理

二氧化碳(CO_(2))驱作为一项日益完善的采油技术,已经成为提高低渗油田采收率的重要手段,具有适用范围广、开采成本低和洗油效率高等优点。然而,由于CO_(2)特殊的物理和化学性质,其采出液稳定性较常规水驱明显增强,为采出液处理带来了困难。通过光学显微镜、动态光散射、流变学等方法,研究了在不同压力下CO_(2)处理对长庆原油和采出水的物性以及所形成的油包水(W/O)型乳状液稳定性的影响,探究了CO_(2)驱采出液乳化和稳定的影响因素。结果表明,随着CO_(2)压力的增大,CO_(2)驱采出水中Ca^(2+)和Mg^(2+)质量浓度均有所下降,而CO_(3)^(2-)与HCO_(3)^(-)总体含量有所增加,水相pH值略下降,从弱碱性转变为弱酸性。CO_(2)处理导致原油中轻质组分减少,胶质沥青质等重质组分的含量升高,原油极性增强。CO_(2)处理后油的反常温度和析蜡点均升高,原油黏度增加。CO_(2)处理后W/O型乳状液的液滴粒径变小,均一性增强,粒径由2.14μm减小至0.61μm。由于乳状液体系黏度上升以及胶质、沥青质和水中颗粒在油/水界面膜上吸附成膜,从而提高油/水界面膜强度,使得乳状液的稳定性增强。为CO_(2)驱采出液处理工艺提供理论指导和技术支撑。

Exploring Latent Semantic Information for Textual Emotion Recognition in Blog Articles

Understanding people's emotions through natural language is a challenging task for intelligent systems based on Internet of Things(Io T). The major difficulty is caused by the lack of basic knowledge in emotion expressions with respect to a variety of real world contexts. In this paper, we propose a Bayesian inference method to explore the latent semantic dimensions as contextual information in natural language and to learn the knowledge of emotion expressions based on these semantic dimensions. Our method synchronously infers the latent semantic dimensions as topics in words and predicts the emotion labels in both word-level and document-level texts. The Bayesian inference results enable us to visualize the connection between words and emotions with respect to different semantic dimensions. And by further incorporating a corpus-level hierarchy in the document emotion distribution assumption, we could balance the document emotion recognition results and achieve even better word and document emotion predictions. Our experiment of the wordlevel and the document-level emotion predictions, based on a well-developed Chinese emotion corpus Ren-CECps, renders both higher accuracy and better robustness in the word-level and the document-level emotion predictions compared to the state-of-theart emotion prediction algorithms.

Nonlinearity analysis of piezoelectric micromachined ultrasonic transducers based on couple stress theory

This paper studies the static deformation behavior of a piezoelectric micromachined ultrasonic transducer （PMUT） actuated by a strong external electric field. The transducer membrane consists of a piezoelectric layer, a passive layer and two electrode layers. The nonlinearities of the piezoelectric layer caused by electrostriction under a strong electric field are analyzed. Because the thickness of the transducer membrane is on the microscale, the size dependence of the deformation behavior is evaluated using the couple stress theory. The results show that the optimal ratio of the top electrode diameter and the membrane diameter is around 0.674. It is also found that this optimal value does not depend on any other parameters if the thicknesses of the two electrodes are negligible compared with those of the piezo- electric and passive layers. In addition, the nonlinearities of the piezoelectric layer will become stronger along with the increase of the electric field, which means that softening of the membrane stiffness occurs when a strong external electric field is applied. Meanwhile, the optimal thickness ratio for the passive layer and the piezoelectric layer is not equal to 1.0 which is usually adopted by previous researchers. Because there exists size dependence of membrane deforma-tion, the optimal value of this thickness ratio needs to be greater than 1.0 on the microscale.

A novel stellar spectrum denoising method based on deep Bayesian modeling

Spectrum denoising is an important procedure for large-scale spectroscopical surveys. This work proposes a novel stellar spectrum denoising method based on deep Bayesian modeling. The construction of our model includes a prior distribution for each stellar subclass, a spectrum generator and a flow-based noise model. Our method takes into account the noise correlation structure, and it is not susceptible to strong sky emission lines and cosmic rays. Moreover, it is able to naturally handle spectra with missing flux values without ad-hoc imputation. The proposed method is evaluated on real stellar spectra from the Sloan Digital Sky Survey(SDSS) with a comprehensive list of common stellar subclasses and compared to the standard denoising auto-encoder. Our denoising method demonstrates a superior performance to the standard denoising auto-encoder, in respect of denoising quality and missing flux imputation. It may be potentially helpful in improving the accuracy of the classification and physical parameter measurement of stars when applying our method during data preprocessing.

Erythropoietin upregulates growth associated protein-43 expression and promotes retinal ganglion cell axonal regeneration in vivo after optic nerve crush

In this study, we established a rat model of optic nerve crush to explore the effects of erythropoietin on retinal ganglion cell axonal regeneration. At 15 days after injury in erythropoietin treated rats, retinal ganglion cell densities in regions corresponding to the 1/6, 3/6 and 5/6 ratios of the retinal radius were significantly increased. In addition, the number of growth associated protein-43 positive axons was significantly increased at different distances （50, 250 and 500 pm） from the crush site after erythropoietin treatment. Erythropoietin significantly increased growth associated protein-43 protein levels in the retina after crush injury, as determined by westem blot and immunofluorescence analysis. These results demonstrate that erythropoietin protects injured retinal ganglion cells and promotes axonal regeneration.

SYNTHESIS AND CHARACTERIZATION OF ORGANOMONTMORILLONITE AND POLYAMIDE 66/MONTMORILLONITE NANOCOMPOSITES

The montmorillonites (MMTs), layered, smectite-type silicates, were premodified by two different methods prior to the polymer melt intercalation. In one case MMTs were modified with cetyltrimethylammonium bromide (CTAB), and termed as organomontmorillonites (OMMTs); in the other case MMTs were modified by nylon, and the products were called modified montmorillonites (MMMTs). The effects of CTAB and nylon on the MMTs were investigated by using TG and WAXD. The results show that interlayer spacings of CTAB and nylon modified MMTs are larger than that of sodium MMTs. Then, polyamide 66 (PA 66)/MMT nanocomposites were obtained through the method of melt intercalation of polymers. The nanocomposites were characterized by WAXD, TEM and Molau experiments. The results indicate that the MMTs disperse homogeneously in the PA 66 matrix. The mechanical properties of nanocomposites, such as tensile properties and flexural properties, were also measured and show a tendency to increase with increase of MMT content and reach the maximum values at 5phr MMT content. The heat distortion temperature (HDT) of the nanocomposites (7 phr) is about 32 K higher than that of pure PA 66.

Explosive eye injuries: characteristics, traumatic mechanisms, and prognostic factors for poor visual outcomes

Background: Explosions can produce blast waves, high-speed medium, thermal radiation, and chemical spatter,leading to complex and compound eye injuries. However, few studies have comprehensively investigated the clinical features of different eye injury types or possible risk factors for poor prognosis.Methods: We retrospectively reviewed all consecutive records of explosive eye injuries(1449 eyes in 1115 inpatients)in 14 tertiary referral hospitals in China over 12 years(between January 1, 2008 and December 31, 2019). Data on demographics, eye injury types, ocular findings, treatments, and factors affecting visual prognosis were extracted from a standardized database of eye injuries and statistically analyzed.Results: Mechanical ocular trauma accounted for 94.00% of explosion-related eye injuries, among which intraocular foreign bodies(IOFBs) resulted in 55.17% of open globe injuries(OGIs) and contusion caused 60.22% of close globe injuries(CGIs). Proliferative vitreous retinopathy(PVR) was more common in perforating(47.06%) and IOFB(26.84%)than in penetrating(8.79%) injuries, and more common with laceration(24.25%) than rupture(9.22%, P<0.01).However, no difference was observed between rupture and contusion. Ultimately, 9.59% of eyes were removed and the final vision was ≤4/200 in 45.82% of patients. Poor presenting vision [odds ratio(OR)=5.789], full-thickness laceration of the eyeball ≥5 mm(OR=3.665), vitreous hemorrhage(OR=3.474), IOFB(OR=3.510), non-mechanical eye injury(NMEI, OR=2.622), rupture(OR=2.362), traumatic optic neuropathy(OR=2.102), retinal detachment(RD,OR=2.033), endophthalmitis(OR=3.281), contusion(OR=1.679), ciliary body detachment(OR=6.592), zone Ⅲ OGI(OR=1.940), and PVR(OR=1.615) were significant negative predictors for poor visual outcomes(P<0.05).Conclusions: Explosion ocular trauma has complex mechanisms, with multiple eyes involved and poor prognosis. In lethal level Ⅰ explosion injuries, eyeball rupture is a serious condition, whereas contusion is more likely to improve. In level Ⅱ injuries, IOFBs are more harmful than penetrating injuries, and level Ⅳ represents burn-related eye injuries.PVR is more associated with penetrating mechanisms than with OGI. Identifying the risk predictors for visual prognosis can guide clinicians in the evaluation and treatment of ocular blast injuries.

Improved methods for cloning and detection in the yeast two hybrid assay

The yeast two-hybrid (Y2H) mating assay is a powerful method for detecting protein-protein interactions. Firstly, the gene of interest is cloned into specific Y2H vectors. Although multiple innovations in cloning methods were made in the past two decades, the conventional cloning method of restriction-enzyme (RE) digestion followed by ligation is still widely used. Unfortunately, many researchers, especially new-comers, often encounter difficulties in cloning a gene into a desired vector. Secondly, interaction between two proteins is commonly detected by growth of the diploids in specific media. This step takes about two weeks. Here, we describe improved cloning and detection procedures for the Y2H assay that accelerate the research progress. The changes in procedures involve running an agarose gel after the doubly digested vector and insert are ligated in the cloning step to determine the efficiency of RE digestion and ligation, and performing an additional replica-plating on plates for earlier assessment of interaction in the detection step. We show an example of Y2H interaction between Trs23 and Trs120 (respective subunits of TRAPP I and TRAPP II), as a proof of concept. By following the improved methods described here, the chances of successful cloning increased and the time for the whole Y2H experimental process is significantly shorter.

完全腔镜下腹直肌后修补术治疗产后腹直肌分离经验分享

目的探讨完全腹腔镜下腹直肌后修补手术(TES)微创治疗产后腹直肌分离(DRA)的临床疗效。方法对2022年3—7月四川大学华西医院收治的4例产后DRA患者的临床资料进行分析,患者均行TES术,腹直肌后置入15 cm×20 cm聚丙烯疝修补网片加强修复,无需钉枪固定,无需防粘连补片。观察患者术中及术后恢复情况,采用门诊、微信及电话联系进行术后随访,记录患者术后恢复及并发症发生情况。结果4例患者均顺利完成完全TES手术,无中转开腹,2例合并脐疝,1例合并白线疝,平均手术时间168 min,术后第1天数字分级法疼痛评分平均为2分,术后拔除引流管时间约2.5 d,术后无并发症发生,术后平均住院时间为3.5 d。4例患者均获得术后随访,随访时间分别为术后1、3、6、9、12个月,无复发病例,无并发症发生。结论TES治疗产后DRA是安全、经济、有效的。

Susceptibility-weighted Imaging in Thrombolytic Therapy of Acute Ischemic Stroke

Objective： To provide a comprehensive and latest overview of susceptibility-weighted imaging （SWI） in the application of thrombolysis in acute ischemic stroke, and to update the decision-making effect and clinical value of SWI on identifying stroke patients suitable for thrombolytic therapy and possible benefits and risks followed. Data Sources： Literatures referred to this review were collected from PubMed, Medline, and EMBASE published till May 2017, using the search terms including susceptibility-weighted imaging, gradient-echo, T2＊, thrombolysis, recombinant tissue plasminogen activator （rt-PA）, thrombolytic therapy, and stroke. Study Selection： Papers in EngLish or with available English abstracts were considered, with no limitation of study design. References were also identified from the bibliographies of identified articles and the authors＇ files. Results： SW1 is of guiding significance for thrombolytic therapy in stroke patients, it can predict the location and length of thrombus and ischemic penumbra. It is worthy of noting that susceptibility vessel sign （SVS） on SWI can be used to predict recanalization after thrombolytic therapy and whether it is better to implement endovascular thrombolectonqy in combination or alone. SW1 is sensitive in detecting cerebral microbleed （CMB）, and CMB might not be a contraindication for thrombolytic therapy, yet CMBs in multiple loci could possibly be related to intracranial hemorrhage （ICH） after thrombolysis. SVS and CMB on SWI sequence are of instructive value in performing antiplatelet therapy after thrombolytic therapy. Cerebral venous change on SWI is related to lower recanalization rate and poor outcome after thrombolysis. Conclusions： It seems that SWI can be applied to guide individualized thrombolytic therapies and assist clinicians in making better decisions by weighing benefits and risks. However, there still exist controversies about the relationship between signs on SWI and thrombolytic therapy.

Relationship between Apolipoprotein Superfamily and Parkinson＆#39;s Disease

Objective： Parkinson＆#39;s disease （PD） is featured with motor disorder and nonmotor manifestations including psychological symptoms, autonomic nervous system dysfunction, and paresthesia, which results in great inconvenience to the patients＆#39;life. The apolipoprotein （Apo） superfamily, as a group of potentially modifiable biomarkers in clinical practice, is of increasing significance in the diagnosis, evaluation, and prognosis of PD. The present review summarized the current understanding and emerging findings of the relationship between Apo superfamily and PD. Data Sources：All literatures were identified by systematically searching PubMed, Embase, and Cochrane electronic databases with terms＆quot;Parkinson disease,＆quot; ＆quot;apolipoprotein,＆quot; and their synonyms until May 2017. Study Selection： We have thoroughly examined titles and abstracts of all the literatures that met our search strategy and the full text if the research is identified or not so definite. Reference lists of retrieved articles were also scrutinized for additional relevant studies. Results： The levels of plasma ApoA1 are inversely correlated with the risk of PD and the lower levels of ApoA1 trend toward association with poorer motor performance. Higher ApoD expression in neurons represents more puissant protection against PD, which is critical in delaying the neurodegeneration process of PD. It is suggested that APOE alleles are related to development and progression of cognitive decline and age of PD onset, but conclusions are not completely identical, which may be attributed to different ApoE isoforms. APOJ gene expressions are upregulated in PD patients and it is possible that high ApoJ level is an indicator of PD dementia and correlates with specific phenotypic variations in PD. Conclusions： The Apo superfamily has been proved to be closely involved in the initiation, progression, and prognosis of PD. Apos and their genes are of great value in predicting the susceptibility of PD and hopeful to become the target of medical intervention to prevent the onset of PD or slow down the progress. Therefore, further large-scale studies are warranted to elucidate the precise mechanisms of Apos in PD.

Surface curvature-confined strategy to ultrasmall nickel-molybdenum sulfide nanoflakes for highly efficient deep hydrodesulfurization

Size-controlled synthesis of two-dimensional(2D)catalysts with low stacking numbers and small nanoflake lengths is crucial for promoting the catalytic performance in diverse heterogeneous catalysis.Herein,we report a facile and general“surface curvature-confined synthesis”strategy to modulate the slab lengths and stacking numbers of 2D transition metal sulfides by controlling the strain induced by different surface curvature of supports.An efficient NiMo sulfide with shorter slab length(average 3.71 nm),less stacking number(1–2 layers)and more edge active sites is synthesized onto ZSM-5 zeolites with the average size of 100 nm,which shows superior kHDS value of dibenzothiophene(14.05×10^−7 mol/(g·s)),enhanced stability up to 80 h,and high direct desulfurization selectivity(>95%).This design concept is also proved to be generally applicable to modulate the slab lengths and stacking numbers of other 2D catalysts such as MoS2 and WS2 nanoflakes,which shows great potentials for developing more ultrasmall 2D catalysts with controlled sizes and excellent catalytic activities.

简易合成具有增强电荷转移的Z型CeO_(2)/C_(3)N_(4)异质结用于光催化CO_(2)还原

利用太阳能将CO_(2)转化为增值燃料,对于实现全球碳中和的目标具有重要意义,而光生电荷的有效分离是提高光催化CO_(2)还原效率的重要影响因素.在此,我们报道了一种简易的原位剥离和转化策略,将CeO_(2)纳米颗粒均匀分布在超薄多孔C_(3)N_(4)纳米片上,合成了新型的CeO_(2)/C_(3)N_(4)异质结构.C_(3)N_(4)的超薄多孔结构不仅可以增加比表面积以提供更多的活性位点,还可以有效缩短光生电子空穴的迁移距离以避免复合.此外,高度分散的CeO_(2)与C_(3)N_(4)之间具有紧密的界面接触,使更多的电荷通过界面进行转移.合成的CeO_(2)/C_(3)N_(4)异质结构具有带隙匹配的Z型结构,可以有效延长光诱导电荷载流子的寿命并提升光催化剂的氧化还原能力.与传统块状C_(3)N_(4)相比,合成的CeO_(2)/C_(3)N_(4)异质结在没有贵金属作为助催化剂和没有牺牲剂条件下显示出约5倍的CO_(2)光还原性能的提升.这项工作为用于可持续能源转换的直接Z型光催化剂的设计和实际应用提供了一种新策略.

The confined growth of few-layered and ultrashort-slab Ni-promoted MoS_(2)on reduced graphene oxide for deep-degree hydrodesulfurization

Hydrodesulfurization(HDS)is an essential process in clean fuel oil production,however,the huge challenge is the synthesis of the catalyst with plentiful active sites.Here,we have shown the design of few-layered,ultrashort Ni-Mo-S slabs dispersed on reduced graphene oxide(Ni-Mo-S/rGO-A)based on anchoring[PMo_(12)O_(40)]3−clusters and Ni^(2+)on polyethyleneimine(PEI)-modified graphite oxide.Structural characterizations(transmission electron microscopy(TEM),X-ray absorption fine structure(XAFS),etc.)show that Ni-Mo-S slabs with predominant monolayer and partial substitution of edge Mo atoms by isolated Ni atoms have rich accessible edge Ni-Mo-S sites and high sulfurization degree.All virtues endow it with plentiful edge-active sites,and consequently,the enhanced performance for hydrodesulfurization of dibenzothiophene(DBT).The hydrodesulfurization proceeds via a more-favorable direct desulfurization(DDS)route with a reaction rate constant(kHDS)of 48.6×10^(−7)mol·g^(−1)·s^(−1)over Ni-Mo-S/rGO-A catalyst,which is 4.3 times greater than that over traditional Ni-Mo-S/Al_(2)O_(3)catalyst and at the forefront of reported catalysts.

Vehicle-bridge coupled vibrations in different types of cable stayed bridges

Numerical analyses of the coupled vibrations of vehicle-bridge system and the effects of different types of cable stayed bridges on the coupled vibration responses have been presented in this paper using ANSYS. The bridge model and vehicle model were independently built which have no internal relationship in the ANSYS. The vehicle-bridge coupled vibration relationship was obtained by using the APDL program which subsequently imposed on the vehicle and bridge models during the numerical analysis. The proposed model was validated through a field measurements and literature data. The judging method, possibility, and criterion of the vehicle-bridge resonance （coupled vibrations） of cable stayed bridges （both the floating system and half floating system） under traffic flows were presented. The results indicated that the interval time between vehicles is the main influence factor on the resonance excitation frequency under the condition of equally spaced traffic flows. Compared to other types of cable stayed bridges, the floating bridge system has relatively high possibility to cause vehicle-bridge resonance.