超紧凑硅基混合表面等离激元光场窄化器件的实验研究

本文设计、制备了一种基于硅基光电子技术的超紧凑混合表面等离激元光场窄化器件,并验证了器件的纳米聚焦性能.实验结果表明,该光场窄化器件利用了长度约为1.23μm的锥形渐变结构,将硅条形波导中的光场聚焦到硅基混合表面等离激元波导中,在1550 nm的近红外波段最高可实现约20倍的非谐振光场增强效应.结构简单,性能优异的硅基混合表面等离激元光场窄化器件,在光场操控、光传感、非线性光学器件、光相变存储等领域中具有潜在的应用价值.

Assessing Maize Drought Hazard for Agricultural Areas Based on the Fuzzy Gamma Model

Drought is one of the severe meteorological disasters and causes of serious losses for agricultural productions, and early assessment of drought hazard degree is critical in management of maize farming. This study proposes a novel method for assessment of maize drought hazard in different growth stages. First, the study divided the maize growth period into four critical growth stages, including seeding, elongation, tasseling, and filling. Second, maize drought causal factors were selected and the fuzzy membership function was established. Finally, the study built a fuzzy gamma model to assess maize drought hazards, and the gamma 0.93 was finally established using Monte Carlo Analysis. Performing fuzzy gamma operation with 0.93 for gamma and classifying the area yielded a map of maize drought hazards with four zones of light, moderate, severe, and extreme droughts. Using actual field collected data, seven selected samples for drought hazard degree were examined, the model output proved to be a valid tool in the assessment maize drought hazard. This model will be very useful in analyzing the spatial change of maize drought hazard and influence on yield, which is significant for drought management in major agricultural areas.

Al2O3保护层对高温下Pt/ZnO/Al2O3电极导电稳定性的影响

本工作研究了Al2O3保护层的厚度对高温下声表面波器件电极导电稳定性的影响,采用激光分子束外延方法在Pt/ZnO/Al2O3电极上制备了不同厚度的Al2O3保护层。通过测量样品高温环境中的实时电阻,发现Al2O3缓冲层的厚度对电极在高温下的导电稳定性的影响非常大。结果表明,没有Al2O3保护层时,Pt/ZnO/Al2O3电极的电阻升温至800℃时开始急剧地增加。当包覆40nm的Al2O3保护层时,电极在升温至900℃以上才出现电阻值剧烈增加的现象。而随着Al2O3保护层厚度的增加,电极的电阻在高温下的导电性能也更加稳定。SEM测试结果表明,经过1000℃、1h的高温测试后,Al2O3保护层越薄的Pt/ZnO/Al2O3电极,结块形成的Pt颗粒越大与不连续的Pt空洞更多。这些结果为制备高温下稳定工作的声表面波器件提供了一条新的思路。

太子参镰刀菌的鉴定及其毒性物质分析

镰刀菌是太子参根腐病的致病菌之一,为了阐释太子参块根中可能分布的镰刀菌种类及其污染的毒素类型。该文对太子参块根中共分离的89株真菌,经ITS2序列鉴定,其中29株为镰刀属菌,占比达到32.5%。进而经β-Tubulin和EF-1α基因鉴定为镰刀菌属的Fusarium avenaceum、F.tricinctum、F.fujikuroi、F.oxysporum、F.graminearum 5个物种。采用LC-MS/MS检测技术对分离菌株产毒分析,发现产生ZEN、DON、T2的菌株分别有18、1、5株,占比分别为62.1%、3.4%、17.2%。其中菌株JK3-3能同时产生ZEN、DON、T23种毒素,菌株BH1-4-1、BH6-5、BH16-2能产生ZEN、T22种毒素。利用PCR检测技术发现,菌株JK3-3能检测到合成这3种毒素的Tri1、Tri7、Tri8、Tri13、PKS13、PKS146个关键合成酶基因,而菌株BH1-4-1、BH6-5、BH16-2能检测到合成ZEN、T22种毒素的Tri8、Tri13、PKS13、PKS144个关键合成酶基因。该结果表明毒素合成关键基因的检出与菌株产生毒素种类具有很高的相关性,毒素的合成严格受到菌株的遗传信息控制。该研究为太子参外源真菌毒素的针对性防控提供了数据基础以及开发PCR快速检测毒素污染的方法提供了可能。

Catheter ablation of persistent atrial fibrillation with and without a history of paroxysmal atrial fibrillation

Background It is unclear whether a history of paroxysmal atrial fibrillation （PAF） would impact the effect of catheter ablation on persistent atrial fibrillation （AF）. This study aimed to compare the effect of catheter ablation on persistent AF with and without a history of PAF. Methods One hundred and eighty-three patients underwent catheter ablation of persistent AF lasting for 〉1 month and were reviewed. Patients were divided into two groups according to whether they had a history of PAF or not. Group I consisted of persistent AF patients with a history of PAF, and group II consisted of persistent AF patients without such a history. All patients received catheter ablation focused on pulmonary vein isolation and were observed for arrhythmia recurrences, which were defined as documented episodes of AF or atrial tachycardia after a blanking period of 3 months. Results One hundred and three patients （60.9%） in group I and sixty-six patients （39.1%） in group II were successfully followed and included in analysis. There were no significant differences in clinical and echocardiographic characteristics between both groups except for a younger age and more male patients in group II. After （15.5±10.7） months of follow-up, 59 （57.3%） patients in group I and 49 （74.2%） patients in group II maintained sinus rhythm free of anti-arrhythmia drugs （P=0.025）. Multivariate analyses found left atrial anteroposterior diameter （P=0.006） and persistent AF with a history of PAF （OR 1.792, 95% CI 1.019-3.152; P=0.043） as the only independent statistical predictors of arrhythmia recurrences. Conclusion The arrhythmia recurrence rate of catheter ablation based on pulmonary vein isolation in persistent AF with a history of PAF was hiQher than those without a history of PAF

Unconscious sedation/analgesia with propofol versus conscious sedation with fentanyl/midazolam for catheter ablation of atrial fibrillation:a prospective,randomized study

Catheter ablation of atrial fibrillation （AF） has been ,increased dramatically recently. However, it is an unpleasant procedure with intolerable pain without sedation. Propofol and fentanyl/midazolam have been widely used in painful clinical examination and cardiovascular procedures with established safety and efficacy. Propofol, alfentanyl and midazolam were administrated for catheter ablation in some electrophysiological labs for a less painful procedure. However, there is few published work on the sedation regimen for catheter ablation of AF.

Mitral isthmus ablation in patients with prosthetic mitral valves

Background Previous studies have investigated the technique of linear ablation at the mitral isthmus （MI） in patients with idopathic atrial fibrillation （AF）, but MI ablation in patients with prosthetic natural mitral valves （MVs） was not described in detail. Present study sought to summarize our initial experience of ablating MI in patients with prosthetic MVs Methods Patients with drug refractory AF and prosthetic MVs were eligible for this study, and the patients with natural MVs but received MI ablation served as control group. Left atrium （LA） mapping and ablation was carried out guided by CARTO system. The anatomy of MI was assessed via computer topography scan. Results During the study period, a consecutive of 19 patients （male/female=12/7, mean age of （48±6） years） with prosthetic MVs （16 with metal valves, 3 with biologic valves） entered for AF ablation, other 35 patients served as control group. In study group, mapping along MI documented lower voltages （（2.0±1.0） vs. （3.1±1.3） mV, P=-0.002）, more fragmented potentials （19/19 vs. 20/15, P 〈0.001 ）, and higher impedance （（132±34） vs. （110±20） Ω, P=0.004）. After initial ablation, more residual gaps along the MI lesions were found in study group （2.4±0.4 vs. 1.7±0.3, P 〈0.001）. The mean length of MI （（6.2±3.3） vs. （7.1±2.3） cm, P=-0.25） was comparable between 2 groups, but the MI in study group was much thicker （（3.1±1.8） vs. （2.1±1.07） cm, P=0.01） and all were found as pouch type （19/19 vs. 2/35, P 〈0.001）. The follow-up results were comparable （65.1% vs. 72.3%, P=-0.30）. Conclusion For patients with prosthetic MVs, linear ablation at MI could be successfully carried out despite anatomical and pathological changes.

Sinus node, phrenic nerve and electrical connections between superior vena cava and right atrium： lessons learned from a prospective study

Background When performing superior vena cava isolation, the major concerns are inadvertent ablation on sinus node and right phrenic nerve. However, little is known about the spatial relationship of electrical connections between superior vena cava and right atrium with the sinus node and phrenic nerve locations among individual patients.Methods We studied 87 patients （male/female 60/27, mean age of （51±9） years） with atrial fibrillation. Before superior vena cava isolation, the sinus node site was defined by right atrium activation mapping during sinus rhythm and the right phrenic nerve site was localized via pacing manoeuvre. Superior vena cava was isolated by ablation at the electrical connection under the guidance of circular mapping catheter. The sites of sinus node, phrenic nerve and electrical connections were noted. Continuous variables were compared using Student＇s t test. A P value 〈0.05 was considered statistically significant.Results Right atrium activation mapping revealed that the sinus node located at the anterior lateral segment of superior vena cava-right atrium junction in all patients. In 82 patients with detectable diaphragmatic stimulations, the phrenic nerve sites were predominantly at the lateral segment （70/82） with anterior lateral and anterior segments for a few patients. A total of 165 electrical connections were located among all 87 patients, and this averaged 1.8±0.6 （1-3） per patient. The anterior septum （72 patients （43.6%））, the anterior wall （40 （24.2%））, and the posterior septum （35 （35.4%）） of superior vena cava-right atrium junction were the electrical connection regular sites. Superior vena cava was isolated in all patients. Two patients developed sinus bradycardia, with 3 mild superior vena cava stenosis and 2 phrenic nerve palsy.Conclusions The sinus node, phrenic nerve and electrical connection sites were distributed along the superior vena cava-right atrium junctions at expected locations for most patients. The electrical connections were separated from the sinus node and phrenic nerve sites. With the activation mapping of right atrium and pacing along superior vena cava-right atrium junctions, the sinus node and phrenic nerve were localized and superior vena cava isolated in most patients.

Transient ST-segment elevation after transseptal puncture for atrial fibrillation ablation in two cases

The present report demonstrates two cases of transient inferior ST-segment elevation accompanied by profound hypotension and bradycardia immediately after transseptal puncture for catheter ablation of atrial fibrillation. This rare complication of transseptal puncture was resolved quickly within several minutes. The most likely mechanism of this phenomenon is coronary vasospasm, although coronary embolism can not be ruled out completely. This complication is characterized as follows： （1） The right coronary artery might be the most likely involved vessel and therefore myocardial ischemia usually occurs in the inferior wall of left ventricular; （2） Reflex hypotension and bradycardia by the Bezold-Jarisch reflex secondary to inferior ischemia often occur at the same time. Though it appears to be a transient and completely reversible phenomenon, there are still potential life-threatening risks because of myocardial ischemia and profound haemodynamic instability. Clinical cardioloaists should be aware of this rare comolication and orooerlv deal with it.