DCE-MRI在高、低级别脑胶质瘤及脑膜瘤中的鉴别诊断

目的通过对高、低级别脑胶质瘤和脑膜瘤患者术前行T1动态增强磁共振成像(dynamic contrast-enhanced MRI,DCE-MRI)检查,为上述3种肿瘤的鉴别诊断提供定量依据。材料与方法收集经手术病理证实的脑胶质瘤(低级别胶质瘤7例,高级别胶质瘤12例)和脑膜瘤(良性脑膜瘤13例、间变或恶性脑膜瘤6例)患者各19例,所有患者术前均行DCE-MRI检查。利用血流动力学双室模型Extended Tofts Linear对各组数据进行微血管渗透性定量分析,获取病变实性成分的T1加权信号时间浓度曲线及血流动力学参数[血液渗漏到血管外细胞外间隙速率(转运系数)Ktrans、对比剂血管外细胞外液间隙容积Ve、对比剂血浆容积(血管空间容积分数)Vp],经统计学分析,比较各参数在这3种肿瘤中是否存在统计学差异。结果高级别胶质瘤Ktrans值、Ve值均高于低级别胶质瘤,二者均有统计学差异(P<0.05);高级别胶质瘤Vp值略高于低级别胶质瘤,但无统计学差异;脑膜瘤Ktrans、Ve值均显著高于低级别胶质瘤,二者差异有统计学意义(P<0.05),脑膜瘤Vp值略高于低级别胶质瘤,但无统计学差异;高级别胶质瘤和脑膜瘤的Ktrans值、Ve值、Vp值差异均无统计学意义(P>0.05)。结论 DCE-MRI能有效将低级别与高级别胶质瘤、低级别胶质瘤与脑膜瘤定量区分开来,同时,通过DCE-MRI定量分析提高了脑胶质瘤和侵袭性脑膜瘤诊断的准确率。

MRI钆剂瘘管造影与DCE-MRI联合使用对高位复杂型肛瘘细小分支瘘管及瘘口的诊断价值

目的:MRI钆剂瘘管造影与动态对比增强磁共振成像(dynamic contrast enhanced MRI,DCE-MRI)联合使用,对高位复杂型肛瘘进行诊断,探讨其对高位复杂型肛瘘术前评估的指导意义。方法:收集2014年12月10日至2016年12月10日MRI平扫初步证实为高位复杂型肛瘘但细小内瘘口、分支瘘管显示不清的患者264例,首先行DCE-MRI检查,30 min后再行瘘管内注入钆特酸葡胺4 m L+生理盐水16 m L造影检查同步DCE-MRI扫描。分别对MRI平扫、DCE-MRI及瘘管造影+DCE-MRI诊断结果特异度及敏感度行约登指数、ROC曲线下面积(AUC)进行检验。结果:瘘管造影+DCE-MRI示高位复杂型肛瘘外瘘口、内瘘口及分支瘘管显示清晰,瘘管T1WI、T2WI上呈高信号;脓肿为不规则形或马蹄状,T1WI等、稍低信号,T2WI、脂肪抑制高信号。对照手术结果,瘘管造影+DCE-MRI对于术前诊断对于细小内瘘口及细小分支瘘管的诊断价值明显提高;MRI平扫对于细小瘘管显示约登指数为31.60%,曲线形面积为0.576,对于细小内瘘口约登指数为-23.70%,曲线形面积为0.176;DCE-MRI对于细小瘘管显示约登指数为69.40%,曲线形面积为0.603,对于细小内瘘口约登指数为-4.80%,曲线形面积为0.201;瘘管造影+DCE-MRI对于细小瘘管显示约登指数为87.80%,曲线形面积为0.798,对于细小内瘘口约登指数为79.50%,曲线形面积为0.898。结论:钆剂瘘管造影与DCE-MRI联合使用检查对临床高位复杂型肛瘘的术前评估具有较高指导意义。

有线-无线网络中TFRC丢包区法算法研究

TCP-Friendly Rate Control(TFRC)是一种专门针对多媒体流在Internet中传输的拥塞控制方案,而无线环境中存在的链路质量以及切换等问题严重影响该机制的性能。本文针对此问题,提出了利用有线-无线网络的AP动态地标记分组来区分丢包,并基于此设计了适合有线-无线网络的TFRC-enhance协议。通过NS的模拟验证,相对于其他的端到端丢包区分算法,本文提出的算法准确性更高,并能取得很好的性能。

CO_2-triggered gelation for mobility control and channeling blocking during CO_2 flooding processes

CO2 flooding is regarded as an important method for enhanced oil recovery （EOR） and greenhouse gas control. However, the heterogeneity prevalently dis- tributed in reservoirs inhibits the performance of this technology. The sweep efficiency can be significantly reduced especially in the presence of ＂thief zones＂. Hence, gas channeling blocking and mobility control are important technical issues for the success of CO2 injection. Normally, crosslinked gels have the potential to block gas channels, but the gelation time control poses challenges to this method. In this study, a new method for selectively blocking CO2 channeling is proposed, which is based on a type of CO2-sensitive gel system （modified polyacry- lamide-methenamine-resorcinol gel system） to form gel in situ. A CO2-sensitive gel system is when gelation or solidification will be triggered by CO2 in the reservoir to block gas channels. The CO2-sensitivity of the gel system was demonstrated in parallel bottle tests of gel in N2 and CO2 atmospheres. Sand pack flow experiments were con- ducted to investigate the shutoff capacity of the gel system under different conditions. The injectivity of the gel system was studied via viscosity measurements. The results indi- cate that this gel system was sensitive to CO2 and had good performance of channeling blocking in porous media. Advantageous viscosity-temperature characteristics were achieved in this work. The effectiveness for EOR in heterogeneous formations based on this gel system was demonstrated using displacement tests conducted in double sand packs. The experimental results can provide guideli- nes for the deployment of theCO2-sensitive gel system for field applications.

6-(N,N-Dimethylamino)-2-naphthoylacryl Acid:a Highly Selective and Sensitive Fluorescent Sensor of Copper(Ⅱ)

A novel fluorescent probe,6-（N,N-dimethylamino）-2-naphthoylacryl acid（ACADAN） was designed and synthesized as a fluorescent sensor for Cu^2＋ in aqueous media.Significant amplification of fluorescence signals without causing any discernible change of maximum fluorescence emission wavelength（λ max） was observed upon the addition of Cu^2＋.Importantly,ACADAN is capable of recognizing Cu^2＋ selectively in aqueous media in the presence of various biologically relevant metal ions and the prevalent toxic metal ions in the environment with high sensitivity（detection limit was 0.1 μmol/L）.

Luminescent properties of thermally activated delayed fluorescence molecule with intramolecular π-π interaction between donor and acceptor

Influence of intramolecular π-π interaction on the luminescent properties of thermally activated delayed fluorescence（TADF） molecule（3, 5-bis（3,6-di-tert-butyl-9 H-carbazol-9-yl）-phenyl）（pyridin-4-yl） methanone（DTCBPY） is theoretically studied by using the density functional theory（DFT） and time-dependent density functional theory（TD-DFT）.Four conformations（named as A, B, C, and D） of the DTCBPY can be found by relax scanning, and the configuration C corresponds to the luminescent molecule detected experimentally. Besides, we calculate the proportion of each conformation by Boltzmann distribution, high configuration ratios（44% and 52%） can be found for C and D. Moreover, C and D are found to exist with an intramolecular π-π interaction between one donor and the acceptor; the intramolecular interaction brings a smaller Huang-Rhys factor and reduced reorganization energy. Our work presents a rational explanation for the experimental results and demonstrates the importance of the intramolecular π-π interaction to the photophysical properties of TADF molecules.

Enhanced adsorption behavior of Nd(III) onto D113-III resin from aqueous solution

An enhanced adsorption and desorption procedure of Nd（Ⅲ） onto D113-Ⅲ resin were prepared with various chemical methods. Batch studies were carried out with various pH, contact time, temperature and initial concentrations, and then column studies were conducted. The results showed that the optimal adsorption condition was at pH value of 6.90. The process was fast initially and arrived equilibrium within 60 h. The resin exhibited a high Nd（Ⅲ） uptake as 232.56 mg/g at 298 K. The adsorption data fitted well with pseudo-second-order kinetic model. Thermodynamic parameters were studied, which indicated that the adsorption process was spontaneous and endothermic. Thomas model was delineated here to predict the breakthrough curves based on the experimental column study data. In the elution test, 1 mol/L HCl solution could achieve a satisfactory elution rate, which indicated that D113-1/1 resin could be regenerated and reused. Finally, the IR spectroscopic technique was undertaken, and a novel adsorption mechanism was proposed.

Constructing a coplanar heterojunction through enhancedπ-πconjugation in g-C_(3)N_(4)for efficient solar-driven water splitting

Adjusting the electronic structure of graphitic carbon nitride(g-C_(3)N_(4))photocatalyst throughπ-πconju-gation is an effective method to achieve efficient photogenerated carrier separation.One key challenge ofπ-πconjugation control is to tune the degree of such conjugation without destroying the g-C_(3)N_(4)struc-ture.Herein we report a conceptual design that achieves a coplanar heterojunction by enhancing theπ-πconjugation via the doping of crystalline g-C_(3)N_(4)using a conjugated double bond ring molecule,1,3,5-benzenetriol,during calcination process.The selection of the dopant enables the facile creation of a unique coplanar heterojunction which not only retains the pristine network structure of g-C_(3)N_(4),but remarkably promotes separation and transfer of photogenerated carriers through the enhancedπ-conjugated endogenous electric field.As a result,the new g-C_(3)N_(4)photocatalyst efficiently photocatalyti-cally produces hydrogen from water under visible light irradiation with a high H 2 production rate up to 94.94μmol/h,and a notable external quantum efficiency of 16.4%at 420 nm.

DWI及动态增强MRI在淋巴结病变鉴别诊断中的价值

目的探讨磁共振扩散加权成像(DWI)以及动态增强MRI(DCE-MRI)在颈部淋巴结病变鉴别诊断中的价值。方法使用GE1.5T磁共振扫描仪及颈部相控阵线圈,46例单侧或双侧颈部淋巴结肿大患者(26例恶性病变,20例良性病变)。全部病例使用体线圈行SE-EPIDWI序列扫描,采用全方位扩散梯度及6个b值扫描,DWI扫描时间40～52s。分析46例病例中淋巴结的DWI与表观扩散系数(ADC)值的特点,并行动态增强MRI和常规MRI增强检查,分析比较良、恶性淋巴结病变的MRI征象,计算病灶峰值增强率Emax,峰值时间Tmax,最大强化速率Slopemax,并根据病变最高强化区ROI的测量值,绘制病灶的时间-信号强度曲线(SI-Time曲线)。结果在DWI序列扫描中,良性和恶性淋巴结均呈高信号,恶性淋巴结组的平均ADC值为(0.834±0.192)×10-3mm2/s,良性淋巴结组为(1.687±0.252)×10-3mm2/s,恶性淋巴结组平均ADC值明显小于良性淋巴结组(P<0.05),两者间差异有统计学意义。良性淋巴结病变时间-信号强度曲线多表现为Ⅰ型,而恶性淋巴结多为Ⅲ型,Ⅱ型曲线均可见于良性和恶性淋巴结病变。结论DWI可作为颈部良、恶性淋巴结病变鉴别诊断的一种快速可行的新方法,具有一定的临床价值。通过动态增强进一步揭示病变的血流动力学特征,有助于对淋巴结病变作出准确的定性诊断,更能有效地鉴别诊断良、恶性淋巴结病变。

MR扩散加权成像与动态增强扫描对乳腺良恶性病变诊断作用

目的探讨DWI与动态增强扫描相结合在乳腺病变鉴别诊断中的作用。方法分析60例经手术病理检查证实的乳腺疾病患者的DWI与动态增强扫描资料,对两种诊断方法的结果进行分析。结果 DWI、动态增强扫描对乳腺疾病的敏感性均较高,特异性略低。结论 DWI信号特征、ADC值测量与动态增强扫描结合,对乳腺良恶性病变的鉴别诊断有较高的临床应用价值。

Dissipative particle dynamics simulation of wettability alternation phenomena in the chemical flooding process

Wettability alternation phenomena is considered one of the most important enhanced oil recovery （EOR） mechanisms in the chemical flooding process and induced by the adsorption of surfactant on the rock surface. These phenomena are studied by a mesoscopic method named as dissipative particle dynamics （DPD）. Both the alteration phenomena of water-wet to oil-wet and that of oil-wet to water-wet are simulated based on reasonable definition of interaction parameters between beads. The wetting hysteresis phenomenon and the process of oil-drops detachment from rock surfaces with different wettability are simulated by adding long-range external forces on the fluid particles. The simulation results show that, the oil drop is liable to spread on the oil-wetting surface and move in the form of liquid film flow, whereas it is likely to move as a whole on the waterwetting surface. There are the same phenomena occuring in wettability-alternated cases. The results also show that DPD method provides a feasible approach to the problems of seepage flow with physicochemical phenomena and can be used to study the mechanism of EOR of chemical flooding.

Development and analysis of a novel AF11-2 aptamer capable of enhancing the fluorescence of aflatoxin B1

Aflatoxin B1(AFB1)is one of the most common mycotoxins that threatens human health.As singlestranded oligonucleotides with high affinity and specificity,aptamers have incomparable effect on the targeted detection of AFB1.Herein,after 11 rounds of selection and analysis using a modified affinity chromatography-based SELEX strategy,the truncated 37 nt aptamer AF11-2 was successfully obtained.The aptamer shows good detection performance for AFB1,and can sensitively detect AFB1 in the range of 100-1000 nmol/L,with a detection limit of 42 nmol/L.In the detection of pretreated edible peanut oil samples,AF11-2 aptamer also showed a high recovery rate and good stability for AFB1,and achieved satisfactory results.In addition,AF11-2 aptamer can significantly enhance the fluorescence ability of AFB1,which is not available in traditional Afla17-2-3 aptamer.After molecular docking analysis,it was found that AF11-2 and Afla17-2-3 had different nucleotide binding sites for AFB1.Afla17-2-3 binds to the carbonyl O of AFB1,while AF11-2 binds to the pyrrolic O of AFB1,which may be the main reason that AF11-2 can enhance the fluorescence of AFB1.

肝脏肉芽肿的CT表现与病理分析

目的探讨肝脏肉芽肿的早期和晚期CT表现并与病理对照分析,进一步提高对本病的认识和诊断的准确性。方法对31例经手术病理证实的肝脏肉芽肿进行回顾性分析,全部行上腹CT平扫、动态增强扫描。结果肉芽肿早期病灶,平扫为边缘模糊的低密度灶,形态可为圆形、花瓣型、索条形,增强动脉期不均匀强化或明显强化,持续至门脉期、延迟期有逐渐增加的趋势。31例肝脏肉芽肿共35个病灶,其中9个为早期肉芽肿。纤维化期平扫示边界清晰的低密度灶,形态为圆形、卵原形等,增强无明显强化或边缘环状强化,31例肝脏肉芽肿共35个病灶,26个为纤维化期病灶。结论肝脏肉芽肿的多期CT表现可以反映其所处的病理时期,可以与肝脏的其它肿物鉴别。

Regulated CO adsorption by the electrode with OH^(-) repulsive property for enhancing C–C coupling

Electrochemical CO_(2) reduction driven by renewable electricity is one of the promising strategies to store sus-tainable energy as fuels.However,the selectivity of value-added multi-carbon products remains poor for further application of this process.Here,we regulate CO adsorption by forming a Nafion layer on the copper(Cu)electrode that is repulsive to OH^(-),contributing to enhanced selectivity of CO_(2) reduction to C_(2) products with the suppression of C 1 products.The operando Raman spectroscopy indicates that the local OH^(-)would adsorb on part of active sites and decrease the adsorption of CO.Therefore,the electrode with repulsive to OH^(-)can adjust the concentration of OH^(-),leading to the increased adsorption of CO and enhanced C–C coupling.This work shows that electrode design could be an effective strategy for improving the selectivity of CO_(2) reduction to multi-carbon products.

Photorefractive Effect in an Azobenzene Chromophore Side Groups Polymer

We have analyzed the photorefractive（PR） effect of a polymer composite was reported which combines a novel bi-functional poly（N-vinyl）-3-[p-nitrophenylazo]carbazolyl（PVNPAK） and 2,4,7-trinitro-9-fluorenone（TNF）. PVNPAK was synthesized by a post-azo-coupling reaction, with an azo derivative as the electrooptic chromophore and carbazolyl as photoconductive moiety. The asymmetric two-beam coupling gain of 13.9 cm-1 and diffraction efficiency of 1.2% for poled polymer film fabricated using a corona poling are obtained at the wavelength of 647.1 nm, confirming photorefractivity. We interpreted this result as the orientational enhancement, in which the spatial charge field may enhance the modulated orientation of the azobenzen chromophore. It is unexpected that the photorefractive gain of 9.5 cm-1 for the unpoled polymer film also was observed without external field in two-beam coupling（TBC） experiment. This phenomenon is attributed to a light-induced orientational grating when the azobenzene groups are illuminated by polarized light.

IVIM-DWI与DCE-MRI定量参数在鼻咽癌近期疗效预测中的应用研究

目的探讨体素内不相干运动扩散加权成像(IVIM-DWI)和动态增强磁共振成像(DCE-MRI)的定量参数在鼻咽癌近期疗效预测中的应用价值。方法搜集2017年1月至2018年4月经鼻咽镜活检病理证实并行诱导化疗和同步放化疗的鼻咽癌患者共56例。所有患者均于治疗前行IVIM-DWI和DCE-MRI检查,经后处理测量得到相应的IVIM-DWI参数值:表观扩散系数(ADC)、真实扩散系数(D)、灌注相关扩散系数(D~*)和灌注分数(f);DCE-MRI参数值:容积运转常数(K^(trans))、速率常数(K_(ep))、血管外细胞外容积分数(V_e)和血浆容积分数(V_p)。于同步放化疗结束6个月后再次行MRI检查,根据肿瘤缓解情况,将患者分为治愈组和残留组。分析两组治疗前IVIM-DWI和DCE-MRI各参数的相关性。结果治愈组治疗前ADC值和D值均较残留组低(P值均<0.05),K^(trans)值较残留组高,差异有统计学意义(P<0.05)。其余各参数差异无统计学意义。ADC、D和K^(trans)预测诱导化疗和同步放化疗结束后6个月疗效的受试者工作特征(ROC)曲线下面积(AUC)分别为0.664、0.759、0.711(P值均<0.05)。结论治疗前IVIM-DWI和DCE-MRI定量参数值可对鼻咽癌患者诱导化疗+同步放化疗的近期疗效进行预估,为鼻咽癌个体化治疗提供依据。

Nucleation and epitaxy growth of high-entropy REBa_(2)Cu_(3)O_(7-δ)(RE=Y,Dy,Gd,Sm,Eu)thin films by metal organic deposition

High-entropy REBa_(2)Cu_(3)O_(7-δ)(RE=Y_(0.7)+Dy_(0.2)+Gd_(0.2)+Sm_(0.2)+Eu_(0.2))(HE-REBCO) superconducting films doped with multiple rare earth elements were successfully fabricated with thickness up to 800 nm by a trifluoroacetate-metal organic deposition(TFA-MOD).The enhanced entropy change ΔS of the HEREBCO system promotes the c-axis growth of REBCO thin film in the competition with a/b-axis growth.The microstructure and element distribution were investigated by the transmission electron microscopy(TEM) and energy dispersive spectroscopy(EDS).The results show that HE-REBCO films have a great amount of stacking defects,lattice distortions and various rare earth oxides.Furthermore,the microstrain of HE-REBCO films increases significantly compared to the undoped YBCO and(Y,Dy)BCO films.Finally,the superco nducting critical temperature(T_c^(onset)) of HE-REBCO films is about 93 K,and the in-field properties are significantly improved,especially at the temperature of about 77 K.The maximum pinning force density(F_(p,max)) of the HE-REBCO samples at 77 K is 1.7 times higher than that of the undoped YBCO films.

Nighttime electron density enhancements at middle and low latitudes in East Asia

Nighttime enhancements in ionospheric electron density at mid- and low-latitudes are investigated by using the critical frequency of the F2-1ayer （foF2） data measured from ionosonde stations at Okinawa （26.3°N, 127.8°E, Geomagnetic 15.3°N）, Yamagawa （31.2°N, 130.6°E, Geomagnetic 20.4°N）, Kokubunji （35.7°N, 139.5°E, Geomagnetic 25.5°N）, and Wakkanai （45.4°N, 141.7°E, Geomagnetic 35.4°N） in East Asia during several solar cycles. The results show that there are obvious seasonal and solar activity dependencies of the nighttime electron density enhancements. The enhancements are termed pre-midnight enhancement and post-midnight enhancement, according to the local time when the enhancement appeared. The former has a higher occurrence probability in summer months than in winter months. In contrast, the latter has a larger occurrence probability in winter months than in summer months. Moreover, the nighttime enhancements in electron density are more likely to occur at lower solar activity. These seasonal and solar activity variations of the nighttime enhancements in electron density can be explained in terms of the combined effects of downward plasma flux from the plasmasphere and the neutral winds.

Multi-responsive red solid emitter: Detection of trace water and sense of relative humidity

A multi-responsive D-A type compound(CYQ)based on pyrone and triphenylamine was designed and successfully synthesized. The target compound exhibited distinct aggregation-enhanced emission(AEE) effect.Solvatochromic experiment and density functional theory(DFT) indicated CYQ possessed excellent intramolecular charge transfer(ICT) ability. Besides, its mechanofluorochromic property(MFC) was found with a 37 nm redshift. Powder wide-angle X-ray diffraction(PXRD) and differential scanning calorimetry(DSC) measurements were performed to demonstrate the transformation from the crystalline to amorphous states upon grinding. Surprisingly,CYQ displayed a hypersensitive response to trace water in organic solvents with an excellent detection limit as low as 0.0096% in tetrahydrofuran(THF). Furthermore, it was found that the fluorescent intensity of CYQ declined progressively upon humidity rise, and its color change can be witnessed by naked eyes. Therefore, the relative humidity(RH) sensing strategy guarantees the AIEgen to become a colorimetric sensor under various conditions.

增强磁共振与SPECT肾动态显像评估移植肾肾小球滤过率的对比分析

目的 对比分析动态对比增强磁共振（DCE-MRI）与单光子发射计算机断层成像术（SPECT）肾动态显像测定移植肾肾小球滤过率（GFR）的准确性.方法 选取60例2015年12月至2016年7月接受肾移植手术的受者,分别采用DCE-MRI及SPECT测定其移植肾GFR,并与内生肌酐清除率（Ccr）进行对比,对两组结果行统计分析.结果 60例受者中,矫正Ccr为（60.63±24.83）ml·min-1 ·1.73 m-2,SPECT和MRI测得的矫正移植肾GFR（GFR-SPECT和GFR-MRI）分别为（65.31±17.08）和（50.44±22.78）ml·min-1·1.73 m-2.以矫正Ccr为基础值,GFR-SPECT偏倚为4.69ml·min-1 ·1.73 m-2,精度为23.76 ml·min-1 ·1.73m-2;GFR-MRI偏倚为-10.18 ml·min-1 ·1.73 m-2,精度为13.87 ml·min-1·1.73m-2.Ccr与GFR-SPECT的相关系数（r）=0.406,P＜0.01,直线回归方程为Ccr=34.169＋0.591＆#215;GFR（SPECT）;Ccr与GFR-MRI的r=0.833,P＜0.01,直线回归方程为Ccr=22.298＋0.831＆#215;GFR（MRI）;MRI所测得GFR与Ccr线性关系更为显著.GFR-SPECT和GFR-MRI的r=0.342,P＜0.01,直线回归方程为GFR（SPECT）=16.192＋0.342＆#215;GFR（MRI）,二者呈弱相关.通过Bland-Altman分析,GFR-SPECT的可信区间为95.3 ml·min-1 ·1.73 m-2,GFR-MRI的可信区间为62.3ml·min-1·1.73m-2,MRI的可信区间更窄.结论 与SPECT相比,DCE-MRI测得GFR与矫正Ccr偏倚较大,但与矫正Ccr具有更好的相关性及一致性.DCE-MRI在评估移植肾及尿路解剖结构的同时,同样能准确地评价移植肾功能.