硫掺杂石墨相氮化碳的光催化固氮性能中氮空穴对氮气分子活化的提升作用（英文）

地球上的氮元素十分丰富并主要以氮气形式存在.然而,由于氮的化学及生物惰性,大多数生物体不能直接吸收氮.因此,人工固氮过程被称为继光合作用之后的第二大化学反应.目前工业上常用的固氮技术为Haber-Bosch法,该方法能耗高且使用的原料氢气十分危险.因此,寻找更加节能、绿色、安全的固氮技术迫在眉睫.石墨相氮化碳作为一种非金属半导体光催化剂近年来受到研究者青睐.氮化碳化学性质稳定,能带宽度适中,且耐酸碱腐蚀.然而,氮化碳的反应活性位较少,量子效率较低,而且由于光能的能量密度较低,反应物N2分子难以活化,因此光催化固氮性能并不理想.有研究报道称晶格缺陷能作为反应活性位活化氮气分子,提高光催化固氮性能.本文采用介质阻挡放电等离子体法制备了硫和氮空穴共掺杂的石墨相氮化碳催化剂,考察了硫的引入对催化剂光催化固氮性能的影响. XRD, UV-Vis和氮气吸附结果表明,掺杂未改变催化剂的比表面积,但使得氮化碳催化剂晶格发生了细微扭曲,且改变了催化剂的电子结构,降低了能带宽度.通过XPS结果推测了硫元素与氮空穴的相对位置,并确定硫元素取代了氮元素,以S–C键的形式掺入到催化剂晶格中.采用N2-TPD法分析了催化剂对氮气分子的吸附能力,发现氮空穴是氮气分子的化学吸附位.硫的引入能促进氮空穴对氮气分子的吸附与活化能力. PL光谱结果证实硫和氮空穴掺杂均对电子空穴对的分离有促进作用.不同气氛下的PL光谱结果表明,光电子能通过氮空穴从催化剂转移至吸附的氮气分子上. DFT计算结果显示,氮气分子吸附在氮空穴上,吸附后的N≡N键长为1.331 A,小于非吸附状态的N≡N键长(1.157 A).而引入硫以后,氮气分子同样吸附在氮空穴上,N≡N键长进一步增大到1.415 A,且氮气分子的吸附能也显著降低.这些结果都说明硫的引入提高了氮空穴对氮气分子的吸附和活化作用.此外,态密度图结果显示,光电子通过氮空穴从催化剂向吸附的氮气分子转移,且引入硫之后吸附的氮气分子上的电子密度明显提高,进一步证实硫的引入对氮气分子的活化作用.

Locoregional radiotherapy in patients with distant metastases of nasopharyngeal carcinoma at diagnosis

Systemic chemotherapy is the basic palliative treatment for metastatic nasopharyngeal carcinoma(NPC); however, it is not known whether locoregional radiotherapy targeting the primary tumor and regional lymph nodes affects the survival of patients with metastatic NPC. Therefore, we aimed to retrospectively evaluate the benefits of locoregional radiotherapy. A total of 408 patients with metastatic NPC were included in this study. The mortality risks of the patients undergoing supportive treatment and those undergoing chemotherapy were compared with that of patients undergoing locoregional radiotherapy delivered alone or in combination with chemotherapy. Univariate and multivariate analyses were conducted. The contributions of independent factors were assessed after adjustment for covariates with significant prognostic associations (P<0.05). Both locoregional radiotherapy and systemic chemotherapy were identified as significant independent prognostic factors of overall survival(OS). The mortality risk was similar in the group undergoing locoregional radiotherapy alone and the group undergoing systemic chemotherapy alone [multi-adjusted hazard ratio(HR)=0.9, P=0.529]; this risk was 60% lower than that of the group undergoing supportive treatment(HR=0.4, P=0.004) and 130% higher than that of the group undergoing both systemic chemotherapy and locoregional radiotherapy(HR=2.3, P<0.001). In conclusion, locoregional radiotherapy, particularly when combined with systemic chemotherapy, is associated with improved survival of patients with metastatic NPC.

HLA Class I Expressions on Peripheral Blood Mononuclear Cells in Colorectal Cancer Patients

Objective： To investigate the expression change of human leukocyte antigen （HLA） class I on human peripheral blood mononuclear ceils （PBMCs） at both mRNA and protein levels, and to evaluate its roles in the development of colorectal cancer （CRC）. Methods： In the present study, 50 patients with CRC, 35 patients with benign colorectal lesion and 42 healthy volunteers were enrolled. Expression levels of HLA class I mRNA and protein were determined using real-time quantitative reverse transcription PCR （RT-PCR） and flow cytometry analysis, respectively. Results： The expression levels of HLA class I mRNA and proteins were not influenced by age and gender. The relative ratios of HLA class I mRNA were 0.99±0.27 in healthy controls, 0.76±0.19 in benign patients, and 0.48±0.21 in CRC patients. Mean fluorescence intensities of HLA class I were 145.58±38.14 in healthy controls, 102.05±35.98 in benign patients and 87.44±34.01 in CRC patients. HLA class I on PBMCs was significantly down-regulated at both mRNA and protein levels in patients with stage III and IV CRC. CRC patients with lymph node metastasis also showed a decreased HLA class I expression at protein level. Conclusion： HLA class I expressions on PBMCs are associated with staging of CRC and lymph node metastasis. Monitoring the expression of HLA class I on PBMCs may provide useful information for diagnosis and metastasis judgement of CRC.

基于内镜图像深度学习的鼻咽恶性肿瘤检测模型的建立与验证

背景与目的由于鼻咽部解剖位置隐匿且腺体增生频发,活检时恶性肿瘤的阳性率较低,从而导致初诊时鼻咽恶性肿瘤确诊延时或漏诊。本文旨在建立一种人工智能工具——基于深度学习的内镜检查,来检测鼻咽恶性肿瘤。方法建立了一种基于内镜图像的鼻咽恶性肿瘤检测模型(endoscopic imagesbased nasopharyngeal malignancies detection model,eNPM-DM),该模型由基于空间结构的全卷积网络构成,采用单独训练集和验证集对分类和分割进行微调。总共收集了28,966张合格图像。其中,自2008年1月1日至2016年12月31日,从7951例个体中获得了27,536张经活检证实的图像,按照7∶1∶2的比例随机分为训练、验证和测试集。此外,将2017年1月1日到2017年3月31日获得的1430张图像纳入预测集,用以对建立模型的性能与肿瘤专家的评价进行比较。以鼻咽镜图像为背景,对自动分割和专家手工分割进行比较,采用dice相似系数(dice similarity coefficient,DSC)评价eNPM-DM从鼻咽部内镜图像的背景中自动分割出恶性肿瘤区域的效率。结果所有图像经过病理组织学验证,包括正常对照5713(19.7%)例、鼻咽癌(nasopharyngeal carcinoma,NPC)19,107(66.0%)例、其他恶性肿瘤335(1.2%)例和3811(13.2%)例良性病变。在测试集中,eNPM-DM检测恶性肿瘤的总准确率达88.7%[95%置信区间(confidence interval,CI):87.8%–89.5%]。在预测比较阶段,eNPM-DM表现优于专家:总准确率分别为88.0%(95%CI:86.1%–89.6%)和80.5%(95%CI:77.0%–84.0%)。eNPM-DM耗时更短(40 s vs. 110.0±5.8 min),且从背景中自动分割出鼻咽恶性肿瘤区域方面表现优秀,测试集和预测集中的平均DSC分别为0.78±0.24和0.75±0.26。结论 eNPM-DM在鼻咽肿块良性/恶性诊断分类方面优于肿瘤学家评估,并且实现了从鼻咽内镜图像背景中对恶性区域自动分割。

Particle Kinematics Analysis of Droplet Drift in Spraying Operation of Plant Protection UAV

[Objectives]The paper was to study the effect of droplet drift on spray quality of plant protection UAV.[Methods]Based on the theory of multiphase flow and the method of particle kinematics,the force and motion trajectory of droplet sprayed by plant protection UAV were theoretically analyzed and mathematically modeled.On the basis of the assumption of wind speed in the ground layer and the laminar sublayer,that is,it is assumed that the wind speed in the area of wind measurement was approximately a linear distribution,the coupling iterative solution of the equations was carried out.The influence of droplet diameter,flight height,flight speed of plant protection UAV,course angle,wind speed,wind direction,initial droplet velocity and direction of initial velocity on droplet drift were analyzed.The influence of the coupling effect of each factor on droplet drift was further discussed and the distribution of droplet drift concentration was obtained.[Results]The wind speed and direction had much influence on the drift distance of droplets,and the drift distance and the initial velocity angle show a quadratic function distribution.Under the given conditions,the drift distance was the closest when the initial velocity angle was about 20°.The droplet drift was mainly distributed scatteredly around the nozzle.[Conclusions]The study provides a reference for improving the spraying quality of plant protection UAV.

折流板设备中流体停留时间分布与流动形态的对比研究

折流板结构在大空间设备中形成折流通道,以防止短路,从而使流体与换热管和颗粒床等内构件充分接触。停留时间分布(RTD)实验具有简单便捷的优势,针对设备中的短路与如何确定设备合理结构的问题分别设计了几组结构来进行RTD实验与流场数值模拟研究。对比分析结果表明,设备中的短路和死区是相对存在的,通过RTD密度函数曲线的出峰时间及拖尾情况能判断设备中短路与死区的情况,该结论可以为设备设计提供理论依据。利用多釜串联模型的釜数及RTD曲线的出峰时间和方差分析了流量、折流板缺口面积及板距对设备中流体流动形态的影响;研究了设备中的压降,综合考虑设备的能耗和性能,提出了以RTD实验来确定折流板设备合理结构时最合适的釜数、出峰时间及方差。

Minimally invasive surgery alone compared with intensity-modulated radiotherapy for primary stage I nasopharyngeal carcinoma

Background:The National Comprehensive Cancer Network guidelines recommend intensity-modulated radiotherapy(IMRT)as the primary curative treatment for newly diagnosed nasopharyngeal carcinoma(NPC),but the radiation-related complications and relatively high medical costs remain a consequential burden for the patients.Endoscopic nasopharyngectomy(ENPG)was successfully applied in recurrent NPC with radiation free and relatively low medical costs.In this study,we examined whether ENPG could be an effective treatment for localized stage I NPC.Methods:Ten newly diagnosed localized stage I NPC patients voluntarily received ENPG alone from June 2007 to September 2017 in Sun Yat-sen University Cancer Center.Simultaneously,the data of 329 stage I NPC patients treated with IMRT were collected and used as a reference cohort.The survival outcomes,quality of life(QOL),and medical costs between two groups were compared.Results:After a median follow-up of 59.0 months(95%CI 53.4-64.6),no death,locoregional recurrence,or distant metastasis was observed in the 10 patients treated with ENPG.The 5-year overall survival,local relapse-free survival,regional relapse-free survival,and distant metastasis-free survival among the ENPG-treated patients was similar to that among the IMRT-treated patients(100%vs.99.1%,100%vs.97.7%,100%vs.99.0%,100%vs.97.4%,respectively,P>0.05).In addition,compared with IMRT,ENPG was associated with decreased total medical costs($4090.42±1502.65 vs.$12620.88±4242.65,P<0.001)and improved QOL scores including dry mouth(3.3±10.5 vs.34.4±25.8,P<0.001)and sticky saliva(3.3±10.5 vs.32.6±23.3,P<0.001).Conclusions:ENPG alone was associated with promising long-term survival outcomes,low medical costs,and satisfactory QOL and might therefore be an alternative strategy for treating newly diagnosed localized stage I NPC patients who refused radiotherapy.However,the application of ENPG should be prudent,and prospective clinical tri-als were needed to further verify the results.

A curative-intent endoscopic surgery for postradiation nasopharyngeal necrosis in patients with nasopharyngeal carcinoma

Background:Postradiation nasopharyngeal necrosis(PRNN)is a severe complication after radiotherapy in patients with nasopharyngeal carcinoma(NPC),which can severely affect the quality of life and threaten the patient’s life.Only 13.4%-28.6%of patients can be cured by traditional repeated endoscopic debridement.Here,we introduced an innovative curative-intent endoscopic surgery for PRNN patients and evaluated its clinical efficacy.Methods:Clinical data of 72 PRNN patients who underwent radical endoscopic necrectomy,followed by reconstruc-tion using a posterior pedicle nasal septum and floor mucoperiosteum flap were analyzed to determine the efficacy of this surgery.The endpoints were complete re-epithelialization of the nasopharyngeal defect,relief of headache,and overall survival(OS).Results:All surgeries were successfully performed without any severe postoperative complications or death.The median value of numeric rating scales of pain decreased from 8 before surgery to 0 after surgery(P<0.001).Fifty-one patients(70.8%)achieved complete re-epithelialization of the nasopharyngeal defect.The number of cycles of radiotherapy(odds ratio[OR],7.254;95%confidence interval[CI]1.035-50.821;P=0.046),postoperative pathological result(OR,34.087;95%CI 3.168-366.746;P=0.004),and survival status of flap(OR,261.179;95%CI 17.176-3971.599;P<0.001)were independent risk factors of re-epithelialization of the nasopharyngeal defects.Postoperative patho-logical result(hazard ratio[HR],5.018;95%CI 1.970-12.782;P=0.001)was an independent prognostic factor for OS.The 2-year OS rate of the entire cohort was 77.9%.Conclusion:Curative-intent endoscopic necrectomy followed by construction using the posterior pedicle nasal septum and floor mucoperiosteum flap is a novel,safe,and effective treatment of PRNN in patients with NPC.

Development and validation of an endoscopic images-based deep learning model for detection with nasopharyngeal malignancies

Background:Due to the occult anatomic location of the nasopharynx and frequent presence of adenoid hyperpla-sia,the positive rate for malignancy identification during biopsy is low,thus leading to delayed or missed diagnosis for nasopharyngeal malignancies upon initial attempt.Here,we aimed to develop an artificial intelligence tool to detect nasopharyngeal malignancies under endoscopic examination based on deep learning.Methods:An endoscopic images-based nasopharyngeal malignancy detection model(eNPM-DM)consisting of a fully convolutional network based on the inception architecture was developed and fine-tuned using separate training and validation sets for both classification and segmentation.Briefly,a total of 28,966 qualified images were collected.Among these images,27,536 biopsy-proven images from 7951 individuals obtained from January 1st,2008,to December 31st,2016,were split into the training,validation and test sets at a ratio of 7:1:2 using simple randomiza-tion.Additionally,1430 images obtained from January 1st,2017,to March 31st,2017,were used as a prospective test set to compare the performance of the established model against oncologist evaluation.The dice similarity coef-ficient(DSC)was used to evaluate the efficiency of eNPM-DM in automatic segmentation of malignant area from the background of nasopharyngeal endoscopic images,by comparing automatic segmentation with manual segmenta-tion performed by the experts.Results:All images were histopathologically confirmed,and included 5713(19.7%)normal control,19,107(66.0%)nasopharyngeal carcinoma(NPC),335(1.2%)NPC and 3811(13.2%)benign diseases.The eNPM-DM attained an overall accuracy of 88.7%(95%confidence interval(CI)87.8%-89.5%)in detecting malignancies in the test set.In the prospective comparison phase,eNPM-DM outperformed the experts:the overall accuracy was 88.0%(95%CI 86.1%-89.6%)vs.80.5%(95%CI 77.0%-84.0%).The eNPM-DM required less time(40 s vs.110.0±5.8 min)and exhibited encouraging performance in automatic segmentation of nasopharyngeal malignant area from the background,with an average DSC of 0.78±0.24 and 0.75±0.26 in the test and prospective test sets,respectively.Conclusions:The eNPM-DM outperformed oncologist evaluation in diagnostic classification of nasopharyngeal mass into benign versus malignant,and realized automatic segmentation of malignant area from the background of nasopharyngeal endoscopic images.