高质量发展背景下高职院校创新创业教育提质增效策略研究

高质量发展背景下高职院校创新创业教育需要进行不断创新,提质增效。高职院校应当立足实际需求,通过调整优化双创课程内容和教学形式,与企业深度融合,落实产教融合,推动双创教育提质增效;通过强化双创师资建设,提升双创师资团队教学能力,保障双创教育教学质量;通过完善双创教育评价体系,为高质量双创教育保驾护航;通过搭建实践平台,拓展学生的实践空间。

Metal-to-insulator transitions in 3d-band correlated oxides containing Fe compositions

Metal-to-insulator transitions (MITs),which are achieved in 3d-band correlated transitional metal oxides,trigger abrupt variations in electrical,optical,and/or magnetic properties beyond those of conventional semiconductors.Among such material families,iron(Fe:3d^(6)4s^(2))-containing oxides pique interest owing to their widely tunable MIT properties,which are associated with the various valence states of Fe.Their potential electronic applications also show promise,given the large abundance of Fe on Earth.Representative MIT properties triggered by critical temperature (TMIT) were reported for ReFe_(2)O_(4)(Fe^(2.5+)),ReBaFe_(2)O_(5)(Fe^(2.5+)),Fe_(3)O_(4)(Fe^(2.67+)),Re_(1/3)Sr_(2/3)FeO_(3)(Fe^(3.67+)),Re Cu_(3)Fe_(4)O_(12)(Fe^(3.75+)),and Ca_(1-x)Sr_(x)FeO_(3)(Fe^(4+))(where Re represents rare-earth elements).The common feature of MITs of these Fe-containing oxides is that they are usually accompanied by charge ordering transitions or disproportionation associated with the valence states of Fe.Herein,we review the material family of Fe-containing MIT oxides,their MIT functionalities,and their respective mechanisms.From the perspective of potentially correlated electronic applications,the tunability of the TMITand its resultant resistive change in Fe-containing oxides are summarized and further compared with those of other materials exhibiting MIT functionality.In particular,we highlight the abrupt MIT and wide tunability of TMITof Fe-containing quadruple perovskites,such as Re Cu3Fe4O12.However,their effective material synthesis still needs to be further explored to cater to potential applications.

水泥窑协同处置实验室危险废物的技术应用

通过梳理国内外实验室危险废物环境管理要求和处置现状,结合实际处置经验,总结了利用水泥窑协同处置实验室危险废物的工作流程,提出了针对实验室危险废物危险性的鉴别方法,实验室危险废物的分类和包装要求,以及接收和入窑处置方式。

Metal-organic decomposition growth of thin film metastable perovskite nickelates with kinetically improved quantum transitions

The multiple quantum transitions within d-band correlation oxides such as rare-earth nickelates(RENiO_(3))triggered by critical temperatures and/or hydrogenation opened up a new paradigm for correlated electronics applications,e.g.ocean electric field sensor,bio-sensor,and neuron synapse logical devices.Nevertheless,these applications are obstructed by the present ineffectiveness in the thin film growth of the metastable RENiO_(3)with flexibly adjustable rare-earth compositions and electronic structures.Herein,we demonstrate a metal-organic decompositions(MOD)approach that can effectively grow metastable RENiO_(3)covering a large variety of the rare-earth composition without introducing any vacuum process.Unlike the previous chemical growths for RENiO_(3)relying on strict interfacial coherency that limit the film thickness,the MOD growth using reactive isooctanoate percussors is tolerant to lattice defects and therefore achieves comparable film thickness to vacuum depositions.Further indicated by positron annihilation spectroscopy,the RENiO_(3)grown by MOD exhibit large amount of lattice defects that improves their hydrogen incorporation amount and electron transfers,as demonstrated by the resonant nuclear reaction analysis and near edge X-ray absorption fine structure analysis.This effectively enlarges the magnitude in the resistance regulations in particular for RENiO_(3)with lighter RE,shedding a light on the extrinsic regulation of the hydrogen induced quantum transitions for correlated oxides semiconductors kinetically via defect engineering.

遥感卫星接收天线在单链驱动下的力学分析

本文针对某遥感卫星地面接收系统6米口径天线,建立了天线结构的有限元分析模型;采用ANSYS分析计算了在单链驱动、多工况下天线结构的应力及变形情况。依据分析计算结果给出了该天线结构在单链驱动情况下的使用建议。

基于含油污泥热解残渣的路基材料制备与性能评价

通过击实试验、无侧限抗压强度试验和水稳性试验研究了水泥、粉煤灰掺量对含油污泥热解残渣路基材料性能的影响。结果表明:随水泥、粉煤灰掺量的增加,最大干密度和最佳含水量均减小。含油污泥热解残渣路基材料的无侧限抗压强度随水泥掺量的增加而增大,考虑经济性和强度值,选择水泥掺量为4%制备路基材料。随粉煤灰掺量的增加(10%~30%),无侧限抗压强度先增大后减小,粉煤灰掺量存在最优值(20%)。含油污泥热解残渣路基材料的水稳系数随水泥掺量和龄期的增加而增大。

基于MODIS卫星火点数据的浙江省林火时空动态变化特征

【目的】研究森林火灾时空动态变化特征,有助于掌握森林火灾发生规律及变化趋势,为火险期划分和防火资源的合理分配提供科学依据。【方法】本研究基于MODIS卫星火点数据,运用数据统计、Mann-Kendall趋势检验法和滑动t检验,对浙江省2001−2016年森林火灾时空分布特征、变化趋势和防火期的变化进行研究。【结果】(1)2001−2016年浙江省森林火灾整体呈上升趋势,春季、夏季和冬季是林火发生主要季节。其中春、夏两季森林火灾显著增长,秋、冬两季森林火灾呈先上升后下降的变化趋势。浙江省传统定义火险期的林火数量呈下降趋势,而更多的林火在夏季发生,火险期由11月至翌年4月变为1月19日至9月1日,向夏季偏移和延长。(2)浙江省森林火灾空间分布呈现出由西南向东北递减趋势,其中杭州市、衢州市、丽水市和温州市森林火灾发生频率较高,且在防火期、春季和夏季呈上升趋势。【结论】研究建议浙江省加强西南地区及春、夏两季森林火灾监测和防火宣传,适当调整火险期和防火资源时空分配,将有助于抑制浙江省森林火灾的增长趋势。

大兴安岭5种乔木树种燃烧释放PM2.5中水溶性元素特性

采用自主设计的生物质燃烧实验装置,在不同燃烧状态(明燃、阴燃)下,对大兴安岭林区5种典型乔木树种的不同部位(枝、叶、皮)燃烧释放PM2.5中的水溶性元素特性进行研究.结果显示,不同树种间PM2.5的排放因子差异显著,排放范围为(2.408±0.854)^(9.227±1.172)g/kg.5种乔木树种燃烧释放PM2.5中主要检测到Mg、Ca、K等16种元素,其中Ca、K、Zn、Mg 4种元素的排放因子明显大于其它元素.不同树种间元素排放因子差异较大,针叶树的排放因子一般高于阔叶树.除Cd元素外,不同器官间排放的元素总量无明显差异.不同树种不同器官燃烧释放PM2.5中水溶性元素的占比顺序较为一致,其中Ca、K、Zn和Mg 4种元素的排放因子在枝、叶、皮中均较高.此外,燃烧状态对元素排放特征影响较大,Li、Mg、Ca等7种元素的排放因子均表现为明燃显著高于阴燃.

云南省八种主要乔木燃烧释放烟气及颗粒物特性分析

为探究乔木燃烧释放烟气及颗粒物特性,运用自主研发的可燃物燃烧烟气分析系统,对云南省主要乔木树种滇青冈(Cyclobalanopsis glaucoides)、光叶石栎(Lithocarpus mairei)、旱冬瓜(Alnus nepalensis)、华山松(Pinus armandii)、金合欢(Acacia farnesiana)、麻栎(Quercus acutissima)、栓皮栎(Quercus variabilis)、云南油杉(Keteleeria evelyniana)的不同器官(枝、叶、皮)分别进行模拟燃烧,实测其在不同燃烧状态(阴燃明燃)下释放的CO、CO_(2)、C_(x)H_(y)、NO_(x)及PM_(2.5)的排放因子.结果表明:①乔木树种不同器官燃烧释放的烟气中颗粒物排放因子存在差异,其中,在不同燃烧状态下CO、PM_(2.5)、C_(x)H_(y)、NO_(x)的排放因子表现为叶>枝>皮,CO_(2)排放因子表现为叶>皮>枝.②8种乔木明燃下CO、CO_(2)、C_(x)H_(y)、NO_(x)、PM_(2.5)的排放因子平均值分别为(176.52±25.40)(1250.32±168.04)(32.82±8.68)(2.53±0.71)(15.59±5.36)g kg,阴燃下分别为(250.44±37.43)(1062.11±145.95)(44.82±9.97)(1.92±0.57)(22.56±7.28)g kg.CO、C_(x)H_(y)、PM_(2.5)的排放因子呈阴燃>明燃的排放特征,且大部分乔木树种的CO、C_(x)H_(y)、PM_(2.5)排放因子在不同燃烧状态下差异显著.③不同乔木树种燃烧烟气的颗粒物排放因子存在差异,其中CO、CO_(2)、C_(x)H_(y)、PM_(2.5)的排放因子均呈针叶树种>阔叶树种的特征,NO_(x)排放因子表现为阔叶树种>针叶树种的特征,但针、阔叶树种之间差异不显著.④不同燃烧状态下,叶燃烧产生的污染物浓度与其元素含量呈显著正相关,且阴燃状态下3种器官的CO排放因子均与自身碳元素含量呈显著正相关.研究显示,不同可燃物类型和燃烧状态对乔木燃烧释放烟气及颗粒物均有影响,不同器官之间燃烧排放特性存在一定差异,且乔木元素含量对其燃烧释放气体污染物的排放因子具有一定影响.

大兴安岭典型乔木树种燃烧排放非甲烷总烃(NMHCs)的特性

【目的】揭示不同树种燃烧排放非甲烷总烃(NMHCs)的特性,对计算不同森林类型火灾发生过程中的NMHCs总排放量、评估对大气环境和人类健康的影响有重要意义。【方法】以大兴安岭地区典型树种兴安落叶松、樟子松、白桦、蒙古栎和山杨的枝、叶和皮为对象,运用生物质模拟燃烧装置,实测分析5个树种不同燃烧状态下释放NMHCs的排放因子。烟气收集用ASP-DC-1.2型电动采样泵;NMHCs测定用Entech 7100预浓缩系统和Agilent 7890 A/5975型色谱-质谱(GC-MS)联用仪,标准气体为美国Spectra Gases Inc.的57种非甲烷烃混标。【结果】1)共检测出48种NMHCs,其中烷烃19种、烯烃15种、芳烃14种。排放因子最大的10种化合物占总NMHCs排放因子的80.86%,其中异丁烷排放因子最高,占比超过总量的1/3;2)各类化合物的排放因子(mg·kg^-1)范围是:烷烃从樟子松的359.88±101.43到蒙古栎的756.54±205.47,烯烃从白桦的285.02±71.19到兴安落叶松的358.72±92.60,芳烃从樟子松的133.24±33.96到山杨的183.48±48.10;3)5个树种NMHCs平均排放因子(mg·kg^-1)明燃状态为739.81±214.54,阴燃状态为1284.91±405.72;4)叶、枝、皮平均排放因子(mg·kg^-1)分别为1089.26±451.94、918.44±237.80、1029.39±413.84;5)蒙古栎、兴安落叶松、山杨、白桦和樟子松NMHCs排放因子分别为1259.18±331.49、1111.56±248.53、1019.17±270.76、889.05±235.58、782.86±309.07 mg·kg^-1;6)5个树种的平均臭氧生成潜势为3.678 g·kg^-1,烷烃、烯烃和芳烃的臭氧生成潜势分别占总量的16%、73%和11%。【结论】大兴安岭地区5个典型树种燃烧排放3类(烷烃、烯烃、芳烃)共48种非甲烷烃,其中异丁烷的排放因子最高,烯烃臭氧生成潜势最高。非甲烷总烃排放量与燃烧状态相关,阴燃条件下燃烧效率整体较低,NMHCs排放因子显著大于明燃;不同生物质之间的碳含量无显著差异,故NMHCs排放因子未表现出极显著差异,但NMHCs排放因子影响因素众多,导致不同树种燃烧非甲烷总烃平均排放因子不尽相同,顺序为蒙古栎>兴安落叶松>山杨>白桦>樟子松;叶和皮的NMHCs平均排放因子略大于枝。

基于树轮化学元素分析的林火历史信号初探

【目的】分析森林火灾对柳杉(Cryptomeria fortunei)树轮中化学元素含量的影响,揭示林火发生与树轮中化学元素含量变化的相关规律,为林火历史的研究探索新方法。【方法】以福建周宁县2015年发生林火的过火区域、距离火场<500 m区域和距离火场>1500 m区域柳杉2010-2019年树轮为研究对象,采用电感耦合等离子体质谱法(ICP-MS)检测树轮中P、K、Ca、Mg、B、Cu、Fe、Mn、Zn、Na、Al、Ni共12种化学元素的含量,分析其在林火发生前后的变化与相关性。【结果】大部分元素(B、Mn、Ca、Cu、Zn和Ni)含量最大值出现在火灾发生后第1年,或最小值出现在火灾发生后第2年。过火区域中林火对于B和Mn元素影响较为明显,主要表现在:B和Mn含量在林火前后具有显著差异性;Mn含量在火灾发生前与火灾发生当年呈负相关,但与火灾发生后第1年呈正相关;B与Mn元素间含量在火灾发生当年呈强相关性。此外,采样点距离火场区域的距离对Ca、Fe、Ni、Cu和Zn元素含量有显著影响,主要表现在:距离火场区域越远,Fe、Ni、Cu、Zn元素含量在林火前后的差异性越显著,Cu和Zn元素含量在火灾发生前与火灾发生当年的相关性越高,Fe、Ni、Cu和Zn元素间含量在火灾发生前与火灾发生后第2年的相关性越高。【结论】树木年轮中的化学元素含量变化可作为林火历史信号示踪器。

我国不同林区典型乔木树种枝叶燃烧碳排放特性

【目的】对我国不同林区典型乔木树种燃烧释放含碳物质排放特性的研究,可为了解含碳气体和颗粒物对大气环境和全球碳循环的影响提供科学依据。【方法】本研究运用自主设计的生物质燃烧系统,模拟东北林区、南方林区和西南林区共19种典型乔木树种枝、叶燃烧,分析不同树种、不同树种类型及不同林区的含碳气体(CO_(2)、CO和C_(x)H_(y))、颗粒物排放(PM_(2.5))和颗粒物中碳质组分(元素碳EC和有机碳OC)之间的排放因子差异。【结果】(1)CO_(2)、CO、EC、OC、PM_(2.5)排放因子最高的树种均为马尾松,分别为(1588.00±104.43)g/kg、(324.80±11.60)g/kg、(28.45±4.12)g/kg、(3.42±0.58)g/kg和(12.03±1.46)g/kg,且树种间枝与叶排放因子有明显差异。(2)不同林区中,针叶树种的含碳物质排放因子普遍高于阔叶树,且针叶树的含碳物质排放因子占比高于阔叶树。(3)不同林区树种平均排放因子均存在显著性差异,其中南方林区CO_(2)、CO、EC、OC的平均排放因子最高,分别为(1344.49±61.18)g/kg、(259.40±14.54)g/kg、(2.18±0.41)g/kg和(7.96±0.98)g/kg。【结论】本研究揭示了我国不同林区典型乔木树种燃烧释放含碳物质排放特性,有利于精准研究林火对区域碳循环影响及大范围碳排放估算。

可燃物化学性质对燃烧释放PM_(2.5)元素成分的影响

通过自主设计的燃烧装置,对云南省6种典型乔木树种的不同器官(枝、叶、皮)室内模拟阴、明燃两种燃烧过程,收集燃烧排放颗粒物(PM_(2.5))并测定K、Mg等8种元素排放因子,比较不同燃烧状态释放PM_(2.5)中元素含量的差异,同时分析各元素排放因子与可燃物自身元素含量之间的相关性.结果表明:可燃物中K、Mg和Ca元素含量较高,范围为(137.74~4670.70)mg/kg,微量元素Mn含量突出;阔叶可燃物元素含量普遍高于针叶,器官间元素含量差异显著;燃烧释放PM_(2.5)中K、Na元素排放因子较高,范围为(0.4269~4.9321)~(0.6311~3.0856)mg/kg,微量元素Zn较高、Cu最少,范围为(0.0409~0.3670)~(0.0029~0.0458)mg/kg,常量元素高于微量;树种间元素排放因子表现针叶高于阔叶,器官间较可燃物自身差异增大;燃烧状态对排放因子存在影响,常量元素普遍表现为明燃>阴燃,微量元素无明显规律;PM_(2.5)与可燃物各元素含量比值中,Na元素最高,其余元素占比普遍0~1%范围,微量元素含量比高于常量,针叶高于阔叶;可燃物的化学性质对其排放特性影响显著,可燃物与PM_(2.5)的元素间相关性较高,相关水平普遍达0.600以上,器官间不同元素相关水平表现为:常量元素普遍高于微量元素,针叶略高于阔叶,叶>皮>枝,明燃高于阴燃.

一款结构光三维扫描测量装置的设计

结构光三维扫描仪具有高速度、高精度、获取的点云密集等特点,得到了市场的广泛认可,广泛应用于精细化测量领域。基于时间相位展开算法和双目视觉原理,利用工业相机和光栅投影仪构建了一套结构光栅三维扫描测量实验装置,较为全面地阐述了设计方案和设计步骤,为从事三维结构光测量的研究者和应用开发者提供了一种参考方案。实验结果表明,该装置能够有效地支持结构光扫描,具有较高的测量精度。

N and P resorption in a pioneer shrub(Artemisia halodendron) inhabiting severely desertified lands of Northern China

Nutrient resorption is an important conservation mechanism for plants to overcome nutrient limitation in the less fertile area of desertifled land. In the semi-arid Horqin Sandy Land of Northern China, the shrub Artemisia ha/odendron usually colonizes into the bare ground of severely desertified land as a pioneer species. It is, therefore, expected that A. ha/odendron will be less dependent on current nutrient uptake through efficient and proficient re- sorption of nutrients. In this study, we found that averaged nitrogen （N） and phosphorus （P） concentrations in se- nesced leaves significantly varied from 12.3 and 1.2 mg/g in the shifting sand dune to 15.9 and 1.9 mg/g in the fixed sand dune, respectively, suggesting that foliar N and P resorption of A. ha/odendron were more proficient in the shifting sand dune. In particular, positive relationships between nutrient concentrations in senesced leaves and soil nutrient availability indicate that A. ha/odendron in infertile habitats is more likely to manage with a low level of nu- trients in senesced leaves, giving this species an advantage in infertile soil. Moreover, foliar N- and P-resorption efficiencies and proficiencies showed limited inter-annual variability although annual precipitation varied greatly among 2007-2009. However, N and P resorption of A. ha/oc/endron were not more efficient and proficient than those previously reported for other shrubs, indicating that the pioneer shrub in sand dune environments does not rely more heavily than other plants on the process of resorption to conserve nutrients. Incomplete resorption of nutrients in A. halodendron suggests that senesced-leaf fall would return litter with high quality to the soil, and thereby would indirectly improve soil nutrient availability. The restoration of desertified land, therefore, may be ac- celerated after A. halodendron pioneers into shifting sand dunes.

Risk factor for ischemic-type biliary lesion after ABO-incompatible living donor liver transplantation

AIM: To evaluate the risk factors for ischemic-type biliary lesion(ITBL) after ABO-incompatible(ABO-I) adult living donor liver transplantation(ALDLT).METHODS: Among 141 ALDLTs performed in our hospital between 2008 and 2014, 27(19%) were ABO-I ALDLT and 114 were ABO-identical/compatible ALDLT. In this study, we extensively analyzed the clinico-pathological data of the 27 ABO-I recipients to determine the risk factors for ITBL after ABO-I ALDLT. All ABO-I ALDLT recipients underwent an identical B-cell depletion protocol with preoperative rituximab, plasma exchange(PE), and operative splenectomy. The median follow-up period after transplantation was 26 mo. The clinical outcomes of the 27 ABO-I ALDLT recipients were compared with those of 114 ABO-identical/compatible ALDLT recipients.RESULTS: ITBL occurred in four recipients(14.8%) between 45 and 112 d after ABO-I ALDLT. The overall survival rates were not different between ABO-I ALDLT and ABO-identical/compatible ALDLT(P = 0.303). Among the ABO-I ALDLT recipients, there was no difference between patients with ITBL and those without ITBL in terms of B-cell and T-cell count, serum isoagglutinin titers, number of PEs, operative time and transfusion, use of graft infusion therapy, or number of remnant B-cell follicles and plasma cells in the spleen. However, the perioperative NK cell counts in the blood of patients with ITBL were significantly higher than those in the patients without ITBL(P < 0.05). Preoperative NK cell count > 150/μL and postoperative NK cell count > 120/μL were associated with greater relative risks(RR) for development of ITBL(RR = 20 and 14.3, respectively, P < 0.05). CONCLUSION: High NK cell counts in a transplant recipient's blood are associated with ITBL after ABO-I ALDLT. Further research is needed to elucidate the molecular mechanism of NK cell involvement in the development of ITBL.

Potential therapeutic significance of increased expression of aryl hydrocarbon receptor in human gastric cancer

AIM： To determine the functional significance of aryl hydrocarbon receptor （AhR） in gastric carcinogenesis, and to explore the possible role of AhR in gastric cancer （GC） treatment. METHODS： RT-PCR, real-time PCR, and Western blotting were performed to detect AhR expression in 39 GC tissues and five GC cell lines. AhR protein was detected by immunohistochemistry （IHC） in 290 samples： 30 chronic superficial gastritis （CSG）, 30 chronic atrophic gastritis （CAG）, 30 intestinal metapiasia （IN）, 30 atypical hyperplasia （AH）, and 70 GC. The AhR agonist tetrachlorodibenzo-para-dioxin （TCDD） was used to treat AGS cells. MTr assay and flow cytometric analysis were performed to measure the viability, cell cycle and apoptosis of AGS cells.RESULTS： AhR expression was significantly increased in GC tissues and GC cell lines. IHC results indicated that the levels of AhR expression gradually increased, with the lowest levels in CSG, followed by CAG, IM, AH and GC. AhR expression and nuclear translocation were significantly higher in GC than in precancerous tissues. TCDD inhibited proliferation of AGS cells via induction of growth arrest at the G1-S phase. CONCLUSION： AhR plays an important role in gastric carcinogenesis. AhR may be a potential therapeutic target for GC treatment.

地幔过渡带下部的低黏滞度层造成了俯冲板片的滞留

对过渡带中滞留板片的形成和演化,目前仍然存在许多模糊不清的认识。前人的很多研究多基于二维模型,因此对于板片地震结构的解释很困难。美国科罗拉多大学的科学家运用不同Clapeyron斜率,基于真实的尖晶石一后尖晶石相变和板块运动历史的地幔对流三维球状模型,对过去130Ma的俯冲板片运动进行了模拟,并与三种不同的地震层析成像模型进行了对比,试图通过这种方法找到控制过渡带内板片滞留的条件。

Allometric response of perennial Pennisetum centrasiaticum Tzvel to nutrient and water limitation in the Horqin Sand Land of China

Optimal partitioning theory （OPT） suggests that plants should allocate relatively more biomass to the organs that acquire the most limited resources. The assumption of this theory is that plants trade off the biomass allocation between leaves, stems and roots. However, variations in biomass allocation among plant parts can also occur as a plant grows in size. As an alternative approach, allometric biomass partitioning theory （APT） asserts that plants should trade off their biomass between roots, stems and leaves. This approach can minimize bias when comparing biomass allocation patterns by accounting for plant size in the analysis. We analyzed the biomass allo- cation strategy of perennial Pennisetum centrasiaticum Tzvel in the Horqin Sand Land of northern China by treating samples with different availabilities of soil nutrients and water, adding snow in winter and water in summer. We hypothesized that P. centrasiaticum alters its pattern of biomass allocation strategy in response to different levels of soil water content and soil nitrogen content. We used standardized major axis （SMA） to analyze the allometric rela- tionship （slope） and intercept between biomass traits （root, stem, leaf and total biomass） of nitrogen/water treat- ments. Taking plant size into consideration, no allometric relationships between different organs were significantly affected by differing soil water and soil nitrogen levels, while the biomass allocation strategy of P. centrasiaticum was affected by soil water levels, but not by soil nitrogen levels. The plasticity of roots, leaves and root/shoot ratios was ＇true＇ in response to fluctuations in soil water content, but the plasticity of stems was consistent for trade-offs between the effects of water and plant size. Plants allocated relatively more biomass to roots and less to leaves when snow was added in winter. A similar trend was observed when water was added in summer. The plasticity of roots, stems and leaves was a function of plant size, and remained unchanged in response to different soil nitrogen levels.

Low specific on-resistance GaN-based vertical heterostructure field effect transistors with nonuniform doping superjunctions

A novel Ga N-based vertical heterostructure field effect transistor（HFET） with nonuniform doping superjunctions（non-SJ HFET） is proposed and studied by Silvaco-ATLAS,for minimizing the specific on-resistance（RonA） at no expense of breakdown voltage（BV）.The feature of non-SJ HFET lies in the nonuniform doping concentration from top to bottom in the n-and p-pillars,which is different from that of the conventional Ga N-based vertical HFET with uniform doping superjunctions（un-SJ HFET）.A physically intrinsic mechanism for the nonuniform doping superjunction（non-SJ） to further reduce RonA at no expense of BV is investigated and revealed in detail.The design,related to the structure parameters of non-SJ,is optimized to minimize the RonA on the basis of the same BV as that of un-SJ HFET.Optimized simulation results show that the reduction in RonA depends on the doping concentrations and thickness values of the light and heavy doping parts in non-SJ.The maximum reduction of more than 51% in RonA could be achieved with a BV of 1890 V.These results could demonstrate the superiority of non-SJ HFET in minimizing RonA and provide a useful reference for further developing the Ga N-based vertical HFETs.