Probing the interaction between asphaltene-wax and its effects on the crystallization behavior of waxes in heavy oil via molecular dynamics simulation

High content of asphaltenes and waxes leads to the high pour point and the poor flowability of heavy oil,which is adverse to its efficient development and its transportation in pipe.Understanding the interaction mechanism between asphaltene-wax is crucial to solve these problems,but it is still unclear.In this paper,molecular dynamics simulation was used to investigate the interaction between asphaltenewax and its effects on the crystallization behavior of waxes in heavy oil.Results show that molecules in pure wax are arranged in a paralleled geometry.But wax molecules in heavy oil,which are close to the surface of asphaltene aggregates,are bent and arranged irregularly.When the mass fraction of asphaltenes in asphaltene-wax system(ω_(asp))is 0-25 wt%,the attraction among wax molecules decreases and the bend degree of wax molecules increases with the increase ofω_(asp).Theω_(asp)increases from 0 to 25 wt%,and the attraction between asphaltene-wax is stronger than that among waxes.This causes that the wax precipitation point changes from 353 to 333 K.While theω_(asp)increases to 50 wt%,wax molecules are more dispersed owing to the steric hindrance of asphaltene aggregates,and the interaction among wax molecules transforms from attraction to repulsion.It causes that the ordered crystal structure of waxes can't be formed at normal temperature.Simultaneously,the asphaltene,with the higher molecular weight or the more hetero atoms,has more obvious inhibition to the formation of wax crystals.Besides,resins also have an obvious inhibition on the wax crystal due to the formation of asphalteneresin aggregates with a larger radius.Our results reveal the interaction mechanism between asphaltene-wax,and provide useful guidelines for the development of heavy oil.

Veno-arterial extracorporeal membrane oxygenation for the treatment of obstructive shock caused by venous air embolism:A case report

BACKGROUND Venous air embolism(VAE)is a potentially lethal condition,with a reported incidence rate of about 0.13%,and the true incidence may be higher since many VAE are asymptomatic.The current treatments for VAE include Durant's maneuver,aspiration and removal of air through venous catheters,and hyperbaric oxygen therapy.For critically ill patients,use of cardiotonic drugs and chest compressions remain useful strategies.The wider availability of extracorporeal membrane oxygenation(ECMO)has brought a new option for VAE patients.CASE SUMMARY A 53-year-old female patient with VAE presented to the emergency clinic due to abdominal pain with fever for 1 d and unconsciousness for 2 h.One day ago,the patient suffered from abdominal pain,fever,and diarrhea.She suddenly became unconscious after going to the toilet during the intravenous infusion of ciprofloxacin 2 h ago,accompanied by nausea and vomiting,during which a small amount of gastric contents were discharged.She was immediately sent to a local hospital,where cranial and chest computed tomography showed bilateral pneumonia as well as accumulated air visible in the right ventricle and pulmonary artery.The condition deteriorated despite endotracheal intubation,rehydration,and other treatments,and the patient was then transferred to our hospital.Veno-arterial ECMO was applied in our hospital,and the patient's condition gradually improved.The patient was successfully weaned from ECMO and extubated after two days.CONCLUSION ECMO may be an important treatment for patients with VAE in critical condition.

Tailoring conductive network Zn@NPC@MWCNTs nanocomposites derived from ZIF-8 as high-performance electromagnetic absorber for the whole X-Band

A porous 3D cross-linked conductive network pierced by multi-wall carbon nanotubes(MWCNTs) was successfully designed from zeolitic imidazolate framework-8(ZIF-8). Zn@NPC@MWCNTs composites were tailored by the facile regulating the mass ratios and thermal annealing treatment. Due to the combination of less eddy current loss and dielectric loss together with multiple reflection attenuation caused by a unique structure. With a 10 wt% filler loading, the Zn@NPC@MWCNTs composites carbonized at 800℃ show two high reflection loss(RL) values with different thicknesses. An RL value is-53.18 dB with 4.09 mm thickness in the C-Band(4-8 GHz), and a minimum RL can reach-74.83 d B(10.8 GHz)with a matching thickness of 2.749 mm. The effective absorption bandwidth is 4 GHz(from 8 to 12 GHz,RL ≤-10 d B), which just covers the full X-band. Low cost and easy preparation can also provide advantages to develop MOF-based materials as effective EMW absorbents.

A novel power-combination method using a time-reversal pulse-compression technique

The electromagnetic time-reversal(TR)technique has the characteristics of spatiotemporal focusing in a time-reversal cavity(TRC),which can be used for pulse compression,thus forming an electromagnetic pulse with high peak power.A time-reversed pulse-compression method in a single channel has high pulse compression gain.However,single channel pulse compression can only generate limited gain.This paper proposes a novel TR power-combination method in a multichannel TRC to obtain higher peak power based on TR pulse-compression theory.First,the TR power-combination model is given,and the crosstalk properties of the associated channel and the influence of the reversal performance are studied.Then,the power-combination performances for the TR pulse compression,such as combined signal to noise ratio(SNR)and combined compression gain,are analyzed by numerical simulation and experimental methods.The results show that the proposed method has obvious advantages over pulse-compression methods using a single channel cavity,and is more convenient for power combination.

内镜黏膜下剥离术治疗老年人大肠侧向发育型肿瘤的初步研究

目的回顾性对比分析老年人与中青年人大肠侧向发育型肿瘤(LST)的临床病理特点,探讨内镜黏膜下剥离术(ESD)对老年人大肠侧向发育型肿瘤的治疗效果。方法选取2011年9月-2016年9月在外院及该院检查发现,并在该院拟行ESD的LST患者,其中老年组(≥60岁)53例,中青年组(30~59岁)37例,比较老年组和中青年组的性别、病变形态分型、病变部位、病理类型、手术方法、平均住院时间及术后并发症等情况。结果病变形态分型,老年人以结节混合型(LST-G-M)为主,与中青年组比较,差异有统计学意义(P <0.05);中青年组以平坦隆起型(LST-NG-F)为主,与老年组比较,差异有统计学意义(P <0.05);两组pit pattern分型,老年人以Ⅲ_L型、Ⅳ型为主,青年组以Ⅱ型、Ⅲ_L型为主,Ⅱ型两组比较,差异有统计学意义(P <0.05);两组患者病变好发于直肠,尤其以老年组明显,与中青年组比较差异有统计学意义(P <0.05),其次是升结肠,其余均少见,左半结肠的发病率高于右半结肠;病理情况,老年组以管状绒毛状腺瘤为主,容易伴局部癌变,与中青年组比较差异有统计学意义(P <0.05)。结论老年人LST是大肠癌发病的高危人群,若老年人检查发现LST,排除手术禁忌后应及时行内镜下切除;ESD是治疗大肠LST的重要手段,尤其适合老年人LST的治疗,值得临床运用与推广。

经口内镜下肌切开术治疗贲门失弛缓症的初步研究(附27例报告)

目的探讨经口内镜下肌切开术(POEM)治疗贲门失弛缓症(AC)的疗效。方法收集2014年5月-2016年3月遵义医学院附属医院消化内科收住入院的27例确诊为AC的患者,并实施POEM术,总结手术完成情况、手术前后临床症状、食管测压、术后并发症及随访过程等资料。结果 27例患者行POEM治疗的成功率为100.0%,1例患者发现皮下气肿,1例患者发现少量气胸,行POEM患者中随访症状较前明显改善,食管测压较前亦有显著变化(P<0.05)。结论 POEM治疗AC的短期疗效肯定,术后能够明显缓解吞咽困难等症,但其长期疗效及远期并发症仍有待进一步随访和观察。

5-羟色胺在消化系统中的作用研究进展

5-羟色胺(5-HT)是一种广泛分布于哺乳动物组织内且高度保守的神经信号传导物质,在大脑皮质及神经突触中含量特别丰富,并作为抑制性神经递质发挥作用,而外周组织中的5-HT 则参与了肌肉收缩、血压调控、血小板聚集等众多生理调节过程。近年来研究发现除了中枢及外周神经系统,消化系统中也有5-HT 的广泛表达,并在消化系统各器官的生理、病理过程中起着重要的调控作用,然而却鲜少有学者进行系统的总结。该文将综述5-HT 在消化系统中的表达变化、调控机制及相关研究进展,为后期研究消化系统疾病与神经内分泌关系提供依据,为治疗消化系统相关疾病提供新的方向及治疗靶点。

Influence of aluminium nitride as a foaming agent on the preparation of foam glass-ceramics from high-titanium blast furnace slag

To effectively reuse high-titanium blast furnace slag （TS）, foam glass-ceramics were successfully prepared by powder sintering at 1000℃. TS and waste glass were used as the main raw materials, aluminium nitride （AIN） as the foaming agent, and borax as the fluxing agent. The influence of the amount of A1N added （lwt%-5wt%） on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing A1N content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the aver- age pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AIN.

Prediction model for atmospheric corrosion of 7005-T4 aluminum alloy in industrial and marine environments

Accelerated corrosion tests of the 7005-T4 aluminum alloy were conducted to determine a suitable service life prediction method by using alternating wet–dry cycles in three kinds of solutions. The morphology and composition analysis of the corrosion product revealed that slight corrosion occurred on the surfaces of the samples immersed in a 0.25 wt% Na_2S_2O_8 solution. However, pitting corrosion occurred on the surfaces of the samples immersed in a 3.5 wt% NaCl solution, whereas exfoliation corrosion occurred on the surfaces of the samples immersed in a mixture of 0.25 wt% Na_2S_2O_8 and 3.5 wt% NaCl solutions. A power exponent relationship was observed between the mass loss and exposure time of the 7005-T4 aluminum alloy immersed in the three kinds of solutions. In the mixture of 0.25 wt% Na_2S_2O_8 and 3.5 wt% NaCl solutions, the mass loss of the aluminum alloy yielded the maximum value. Based on the calculation of the correlation coefficients, the alternating wet–dry procedure in a 3.5 wt% NaCl solution could be used to predict the corrosion behavior of 7005-T4 aluminum alloy exposed in the atmosphere of Qingdao, China. The prediction model is as follows: T = 104.28×t^(0.91), where T is the equivalent time and t is the exposure time.

China organ donation and transplantation update: the Hangzhou Resolution

The much-anticipated change in the practice of organ donation and transplantation in China is now underway and affirmed by an important Hangzhou Resolution promulgated at the 2013 China Transplant Congress.Support of the National Health and Family Planning Commission On October 29,2013,in a meeting of the National Health and Family Planning Commission (NHFPC)officials with Jie-Fu Huang,Head of National Organ Transplant Committee(OTC), Hai-Bo Wang,Director of China Organ Transplant Response System (COTRS)

Detection and differentiation of early hepatocellular carcinoma from cirrhosis using CT perfusion in a rat liver model

BACKGROUND： Functional imaging such as CT perfusion can detect morphological and hemodynamic changes in he- patocellular carcinoma （HCC）. Pre-carcinoma and early HCC nodules are difficult to differentiate by observing only their hemodynamics changes. The present study aimed to investi- gate hemodynamic parameters and evaluate their differential diagnostic cut-off between pre-carcinoma and early HCC nodules using CT perfusion and receiver operating characteristic （ROC） curves. METHODS： Male Wistar rats were randomly divided into control （n=20） and experimental （n=70） groups. Diethylnitrosamine （DEN） was used to induce pre-carcinoma and early HCC nodules in the experimental group. Perfusion scanning was carried out on all survival rats discontinuously from 8 to 16 weeks. Hepatic portal perfusion （HPP）, hepatic arterial fraction （HAF）, hepatic arterial perfusion （HAP）, hepatic blood volume （HBV）, hepatic blood flow （HBF）, mean transit time （MTT） and permeability of capillary vessel surface （PS） data were provided by mathematical deconvolution model. The perfusion parameters were compared among the three groups of rats （control, pre-carcinoma and early HCC groups） using the Kruskal-Wallis test and analyzed with ROC curves. Histological examination of the liver tissues with hematoxylin and eosin staining was performed after CT scan.RESULTS： For HPP, HAF, HBV, HBF and MTT, there were significant differences among the three groups （P〈0.05）. HAF had the highest areas under the ROC curves： 0.80 （control vs pre-carcinoma groups） and 0.95 （control vs early HCC groups） with corresponding optimal cut-offs of 0.37 and 0.42, respectively. The areas under the ROC curves for HPP was 0.79 （control vs pre-carcinoma groups） and 0.92 （control vs early HCC groups） with corresponding optimal cut-offs of 136.60 mL/min/100 mg and 108.47 mL/min/100 mg, respectively. CONCLUSIONS： CT perfusion combined with ROC curve analysis is a new diagnosis model for distinguishing between pre-carcinoma and early HCC nodules. HAF and HPP are the ideal reference indices.

Effect of strain rate difference between inside and outside groove in M-K model on prediction of forming limit curve of Ti6Al4V at elevated temperatures

The influence of initial groove angle on strain rate inside and outside groove of Ti6Al4V alloy was investigated.Based on the evolution of strain rate inside and outside groove,the effect of strain rate difference on the evolution of normal stress and effective stress inside and outside groove was also analyzed.The results show that when linear loading path changes from uniaxial tension to equi-biaxial tension,the initial groove angle plays a weaker role in the evolution of strain rate in the M-K model.Due to the constraint of force equilibrium between inside and outside groove,the strain rate difference makes the normal stress inside groove firstly decrease and then increase during calculation,which makes the prediction algorithm of forming limit convergent at elevated temperature.The decrease of normal stress inside groove is mainly caused by high temperature softening effect and the rotation of groove,while the increase of normal stress inside groove is mainly due to strain rate hardening effect.

Comparison between computed tomography and magnetic resonance imaging in clinical diagnosis and treatment of tibial platform fractures

BACKGROUND Tibial plateau fracture is one of the common fracture types.It occurs mainly in teenagers and is usually caused by a fall.After the occurrence of fracture,knee swelling,pain,limited activity,etc.greatly affect the patient’s exercise habits and lifestyle.X-ray,computed tomography(CT)and magnetic resonance imaging(MRI)were used in this examination.X-rays are relatively new and easy to operate.However,there are some errors in the observation of fracture collapse and fracture displacement.In recent years,CT and MRI have been actively used to diagnose various types of clinical fractures.They have more diagnostic power than X-ray film.However,some scholars believe that CT is also prone to errors in clinical application.The volume effect leads to missed diagnosis and misdiagnosis in some cases,while the multidirection scanning of MRI technology can effectively overcome the shortcomings of CT.To facilitate the selection of clinical examination regimens,this study further observed the diagnostic ability of these two regimens in the diagnosis of tibial plateau fractures.AIM To explore the value of nuclear MRI and CT in the clinical diagnosis of tibial plateau fractures.METHODS A total of 120 patients with tibial plateau fractures admitted from September 2017 to August 2019 were included.All patients were examined by nuclear MRI and CT scanning.The results were sent to senior physicians in our hospital to complete the diagnosis.RESULTS Nuclear magnetic resonance showed the same effects as CT in four aspects:fracture displacement,bone defect,fracture site and fracture comminution.There was no significant difference in the score data(P>0.05).Nuclear magnetic resonance and CT tended to be consistent in the B3,C2 and C3 fracture diagnosis coincidence rate,combined injury detection rate and fracture detection rate.The diagnostic coincidence rate of type B1,B2 and C1 fractures and the accuracy rate of overall fracture classification indicated that the MRI technique was significantly better than that of CT(P>0.05).CONCLUSION MRI and CT have good diagnostic typing in the diagnosis of tibial plateau fractures,but MRI is more accurate and may be preferred.

EGFR Gene Mutation and Methodological Evaluation in 399 Patients with Non-small Cell Lung Cancer

The purpose of the present study was to study the characteristics of epidemic growth factor receptor(EGFR)gene distribution in patients with non-small cell lung cancer(NSCLC),and to detect the mutation rate of EGFR gene by Sanger sequencing and amplification refractory mutation system(ARMS)-PCR.Paraffin-embedded sections of NSCLC tissues from 399 NSCLC patients diagnosed in Renmin Hospital of Wuhan University were collected,103 of them were detected for exons 18-21 mutation of EGFR by Sanger sequencing method,296 cases were detected for exons 18-21 mutation by ARMS-PCR method.DNA extraction of both groups was performed with Qiagen QLAamp DNA FFPE Tissue KIT.Comparisons of detection rates between the two methods were conducted by row X list chi-square test.The total mutation rate of EGFR gene detected by Sanger sequencing was 21.4%,exons 18-21 and combined mutation rates were 1.0%,9.7%,1.0%,7.8%and 2.0%,respectively.And the proportions were 4.7%,45.2%,4.7%,36.3%and 9.4%respectively.The total mutation rate detected by ARMS-PCR was 51.4%,exons 18-21 and combined mutation rates were 2.7%,27%,1.7%,18.2%and 1.7%,respectively.The proportions were 5.3%,52.6%,3.3%,35.5%and 3.3%respectively.Further analysis of mutation rate showed that there was significant difference between the two methods in detecting total mutation of EGFR gene(P<0.001).There were significant differences in mutation detection rates of exons 19 and 21(P<0.001,P<0.05),but there were no significant differences in other exons.And there was no significant difference in mutation detection rates between the two methods.The mutation rate of EGFR gene in NSCLC patients was 50%.And exon 19 deletion was the most common mutation type,followed by exon 21 mutation.Compared with Sanger sequencing method,ARMS method is more sensitive with significant advantages in detecting exon 19 deletions and exon 21 mutations,which can be widely used in clinical detection of EGFR gene mutations.The results of this study will further guide patients with advanced NSCLC to select TKI targeted drugs,and provide clinical diagnostic basis for targeted therapy of NSCLC patients.

Research on the prognosis of different types of microvessels in bladder transitional cell carcinoma

BACKGROUND At present,there is controversy on the role of microvessel density(MVD)in tumors as a prognostic indicator of bladder transitional cell carcinoma(BTCC).However,the MVD in tumors is simply classified based on the expression of several different vascular markers,which has not been related to analytical research on the prognosis of patients with BTCC.AIM To explore the classification of blood vessels in tumors and studied the relationship between MVD and the prognosis of patients with BTCC.METHODS The tissue mass was detected by tissue microarray and immunohistochemical analysis with monoclonal antibodies against CD31,CD34,CD105,and vascular smooth muscle actin to investigate the MVD in BTCC.The measurement data are expressed as the mean±SD.The difference between the groups was analyzed by the t-test,the counting data were analyzed byχ2 test.The Kaplan-Meier survival curve was estimated by the product-limit method.The log-rank time-series test was employed to compare the tumor-free survival curves.RESULTS The MVD was closely related to the pathological grade,invasive depth,and prognosis of BTCC.Significant differences were found between grade I and grade II,grade II and grade III,superficial and invasive type,and the tumor-free survival group and the recurrence or metastasis group(P<0.01).Multivariate analysis showed that undifferentiated MVD was an independent prognostic factor for patient survival time.An inverse correlation between undifferentiated tumor MVD and differentiated tumor MVD in BTCC was also shown.CONCLUSION The classification of blood vessels in BTCC could act as an important prognostic indicator and may also be of great significance in the treatment of cancer.

Trends and sex differences in atrial fibrillation hospitalization and catheter ablation at tertiary hospitals in China from 2013 to 2016

BACKGROUND Catheter ablation for atrial fibrillation(AF)is commonly performed worldwide.However,the clinical charac-teristics of hospitalized patients with AF and national trends in catheter ablation at tertiary hospitals in China remain unreported.METHODS This study used the Chinese national database(Hospital Quality Monitoring System)from 2013 to 2016,which is a mandatory database that collects the front page of patients’medical records for hospital accreditation,to describe the clinical cha-racteristics of patients with AF as an overall cohort and as subgroups divided by catheter ablation and sex.RESULTS Of 597,919 AF patients first admitted,57,983 patients underwent catheter ablation[56,384 cases(97.2%)of radiofre-quency ablation and 1599 cases(2.8%)of cryoablation]at 746 tertiary hospitals.Nearly 10%of patients hospitalized with AF at ter-tiary hospitals in China underwent catheter ablation,and the percentage of patients undergoing catheter ablation was on the rise bet-ween 2013 and 2016,and the number of cases increased by 2.5 times.Compared with AF patients who did not undergo catheter ablation,those who did were younger,more frequently male,and had fewer baseline comorbidities.Although the overall CHA_(2)DS_(2)-VASc score revealed over half of the patients were high-risk,patients who underwent catheter ablation were mostly low-risk(71.2%of males and 59.1%of females).Considering in-hospital adverse events,the overall pericardial tamponade and all-cause death incidences were 0.2%(0.6%in the ablation group)and 1.2%(0.1%in the ablation group),respectively;both of which were higher in females than males.CONCLUSIONS In this study,AF patients who underwent catheter ablation were relatively young,had a low thrombosis risk,and had few comorbidities and adverse events.Females were older and experienced more complications than males.

Strategies for targeting the DNA damage response for cancer therapeutics

The DNA damage response is critical for cells to maintain genome stability and survival. In this review, we discuss approaches to targeting critical elements of the DNA damage response for radiosensitization and chemosensitization. In addition, we also discuss strategies for targeting DNA damage response and DNA repair defects in cancer cells for synthetic lethality.

Low temperature Pmmm and C2/m phases in Sr_2CuO_(3+δ) high temperature superconductor

A new low temperature Pmmm(120 K) phase was found in high temperature superconductor Sr_2 CuO_(3+δ), which was indicated as a pure electronic phase by resonant x-ray diffraction at Cu K-edge. As shown by x-ray absorption fine structure(EXAFS) and x-ray absorption near edge structure(XANES) at Cu K-edge, the strong charge density redistribution and local lattice fluctuations around Cu site at the onset of phase transition were due to the occurrence of superconductive coherence, the redistribution and fluctuation finished at Tc. Finally, the electron–lattice interaction was mainly elaborated to understand the superconductivity of Sr_2 CuO_(3+δ).

First-principles study of structural,electronic,elastic,and thermal properties of Imm2-BC

Using the first-principles method, we predict an orthorhombic boron–carbon binary structure with sp^ace group Imm2.This structure is verified to be dynamically and mechanically stable, and possesses a cavity of 27.5 ~2 that makes it a potential molecular sieve material. The C sp^2 and sp^3 hybridized bonding in Imm2 BC is an important factor for its structural stability. The energy band calculations reveal that Imm2 BC is a semiconductor with a band gap of 1.3 eV and has a promising application in the electro-optic field. The lattice thermal conductivity along the crystal [100] direction at room temperature is 186 W·m^(-1)·K^(-1), that is about 5 times higher than those along the [010] and [001] directions, which stems from the different group velocity along the crystal direction. Moreover, the acoustic-optical coupling is important for heat transp^ort in Imm2 BC, and the contribution of optical phonons to lattice thermal conductivity in the [100], [010], and [001]directions is 49%, 59%, and 61%, resp^ectively. This study gives a fundamental understanding of the structural, electronic,elastic, and heat transp^ort properties in Imm2 BC, further enriching the family of boron–carbon binary compounds.

Prognostic Factors Related to In-hospital Death in Children with Biliary Atresia:Analysis of a Nationwide Inpatient Database

Background and Aims:Patients with biliary atresia(BA)are prone to hepatic decompensation,which might eventually lead to death.This study aimed to identify the possible risk factors affecting in-hospital death in BA patients in China.Methods:We collected data from the Hospital Quality Monitoring System,a national inpatient database.All patients aged up to 2 years old with a diagnosis of BA were included.The subjects were divided to three groups,including Kasai portoenterostomy(KP),liver transplantation(LT),and no surgery.Logistic regression with Firth’s method was performed to identify potential influencing variables associated with in-hospital death.Results:During the year 2013 to 2017,there were 14,038 pediatric admissions with a diagnosis of BA.The proportion of in-hospital death in pediatric BA admissions was 1.08%.Compared with patients under six months,there was a higher risk of in-hospital death for children aged six months to 1 year and 1–2 years old.Clinical signs,including cirrhosis,variceal bleeding,and hepatic encephalopathy,were significantly associated with the risk of in-hospital death.In no surgery group,compared to those in Beijing and Shanghai,BA patients admitted in other districts had a lower risk of in-hospital death(OR=0.39,95%CI:0.21,0.70).However,in the LT group,patients admitted in other districts had a higher risk of in-hospital death(OR=9.13,95%CI:3.99,20.87).Conclusions:In-hospital survival remains unsatisfactory for pediatric BA patients with severe complications.Furthermore,more resources and training for BA treatment,especially LT,are essential for districts with poor medical care in the future.