GaN As/InGaAs Superlattice Solar Cells with High N Content in the Barrier Grown by All Solid-State Molecular Beam Epitaxy

We demonstrate nearly i e V GaN0.03As0.97 /In0.09 Ga0.91As strain-compensated short-period superlattice solar cells by all solid-state molecular beam epitaxy. The optimal period thickness for the superlattice growth is achieved to realize high structural quality. Meanwhile, the annealing conditions are optimized to realize a pho- toluminescence （PL） at a low temperature. However, no PL signal is detected at room temperature, which could be reflected by a lower open-circuit voltage of the fabricated devices. The GaN0.03As0.97/In0.09Ga0.91As super- lattice solar cells show a reasonably-high short-circuit current density （Jsc） of over lOmA/cm2. Eurthermore, a concentration behavior is measured, which shows a linear relationship between Jsc and concentration ratios. The extrapolated ideality factor and saturated current density by the concentration action are in good agreement with that extracted by the dark case of the p-i-n diodes.

A Rapid Method for Measuring Seed Protein Content in Cowpea (<i>Vigna unguiculata</i>(L.) Walp)

Cowpea (Vigna unguiculata (L.) Walp), a legume crop that is grown in the worldwide, provides beneficial proteins for human consumption and animal feeding. In comparison, Rapid N analyzer as traditional method, has been widely used to measure protein content through the percentage of total nitrogen in the seed’s grounded powder. Near-Infrared Reflectance (NIR) has commonly been used to measure protein content in soybean seeds using whole grain without the need of seed grinding, which makes it possible to obtain fast results at a lower cost-per-analysis than the traditional combustion method. The specific objective of this study is to test a rapid method for measuring cowpea seed protein content by the NIR analyzer comparing to the traditional rapid N analyzer. A total of 240 cowpea genotypes were used in this study, including six seed coat colors, black, blackeye, browneye, cream, pinkeye, and red with 40 cowpea genotypes. The results showed that a linear relationship exists between the NIR analyzer and the Rapid N analyzer in the six different color groups. The correlation efficiency (r) between the seed protein contents from NIR and Rapid N was higher for pinkeye seed (r = 0.867), blackeye (0.771), cream (0.729), browneye (0.700), and red (0.623), respectively, but lower for black seeds, indicating that the NIR analyzer can be used to measure protein content for cowpea seeds with the five types of seed coat except black. Overview, the cowpea seed protein content measured from the NIR analyzer showed a little higher seed protein content. A series of regression models with different seed coat color have been built to adjust to protein content of colorful cowpea seeds from the NIR analyzer. But, it is not recommended to use for black color seeds due to a very low correlation efficiency (r) value with 0.184.

二氧化碳倍增对植物叶片^(15)N自然丰度的影响

大气CO_(2)浓度上升通常会提高植物生产力并伴随叶片氮含量的下降。然而大气CO_(2)如何影响叶片^(15)N丰度及其相关机理还不清楚。以小麦和向日葵为实验材料,测定了两个CO_(2)浓度(410与820μmol•mol^(-1))处理下叶片的氮同位比值(δ^(15)N)和氮含量。结果表明:小麦和向日葵叶片氮含量随CO_(2)浓度升高呈下降趋势,然而δ^(15)N对CO_(2)浓度倍增的响应存在差异。在高CO_(2)浓度处理下小麦叶片δ^(15)N显著下降6.5‰,而向日葵叶片δ^(15)N小幅上升2.1‰,且叶片和地上部生物量显著增加。基于此,小麦的氮营养特征符合氮同化受限假说,而向日葵符合稀释效应假说。小麦叶片δ^(15)N随叶龄或者细胞年龄的增加而显著下降,因此在利用^(15)N来研究植物氮代谢时需要区分叶龄的影响。整合分析结果表明,CO_(2)浓度升高导致非豆科C_(3)植物的δ^(15)N显著下降达0.3‰,与小麦的研究结果相符。综上所述,限制硝态氮同化是CO_(2)影响植物氮代谢和^(15)N丰度的重要机制。

带N策略的双阶段休假M/M/1排队系统驱动的流体模型性能分析

基于工厂订单装配系统的运行机制,本文构建并分析了具有N策略和两种混合休假策略的M/M/1排队系统驱动的流体模型。首先对驱动系统进行描述,将马尔可夫过程的无穷小生成元写成块状雅克比矩阵形式。引入库存量建立三维马尔可夫过程,得到稳态下流体排队满足的微分方程组,运用矩阵分析方法和Laplace变换(LT)方法得出系统平稳库存量的数学表达式。进而运用Laplace-Stieltjes变换(LST)导出稳态条件下缓冲器的平均库存量。最后,利用数值分析,给出参数变化对系统性能指标的影响。

草酸钠干燥和贮存方式对四氧化二氮N值标定影响研究

通过对比2种干燥方式,研究草酸钠干燥方式对N值标定的影响。对草酸钠的贮存方式进行了探讨,研究干燥后草酸钠在3种贮存条件下对N值测定的影响。研究了不同环境湿度对N值测定的影响,确定实验室环境的最佳湿度范围。进一步考证西北气候下草酸钠的最适宜干燥方式和贮存条件,从而保证N值标定的准确有效进行。

V含量对AlCrTiNbV_(x)N薄膜结构和摩擦学性能影响

为了探究V含量对AlCrTiNbV_(x)N薄膜结构和摩擦学性能的影响,使用磁控溅射仪在304不锈钢基体上制备AlCrTiNbV_(x)N薄膜。使用X射线衍射仪(XRD)、扫描电镜(SEM)等分析薄膜结构,使用纳米压痕仪、材料表面综合测试仪等表征薄膜力学性能和摩擦学性能。结果表明,AlCrTiNbV_(x)N薄膜均呈面心立方结构,在(200)晶面呈择优取向,衍射角向右偏移。AlCrTiNbV_(1.0)N薄膜在(200)晶面的偏移角度最大,晶面间距最小。随着V含量的增加,AlCrTiNbV_(x)N薄膜的硬度和弹性模量先增大后减小,AlCrTiNbV_(x)N的摩擦系数和磨痕宽度先减小后增大。AlCrTiNbV_(1.0)N薄膜具有最大的薄膜硬度和弹性模量,最小的摩擦系数和磨痕宽度,摩擦学性能最好。主要磨损机理为磨粒磨损、粘着磨损和氧化磨损。

拉晶工艺参数对N型单晶硅氧含量的影响研究

TOPCon电池基板是以N型硅片为主,N型硅片的氧含量在一定程度上影响着TOPCon电池的转换效率。本文采用直拉法进行单晶硅的拉制,通过调整埚转、氩气流量和炉压来研究拉晶工艺参数对N型单晶硅氧含量的影响。数值模拟分析和实验结果表明:坩埚转速的增加会抑制浮力-热毛细漩涡,减少熔体界面处SiO的挥发,提高硅熔体内部和单晶硅棒氧含量;增大氩气流量和降低炉压可增大熔体界面处SiO的质量流量,有效促进SiO挥发,减少固液界面处氧含量,从而降低单晶硅棒氧含量。根据单晶硅氧含量测试和EL检测结果可知,坩埚转速5 r/min、氩气流量100 L/min和炉压1 200 Pa时拉制的N型单晶硅氧含量最低,电池端同心圆比例也是最低的。本文研究结果可为N型单晶硅棒降氧提供一定思路。

Variation of nitric oxide emission potential in plants: a possible link to leaf N content and net photosynthetic activity

Aims Ecological systems,especially soils,have been recently recognized as an important source of atmospheric nitric oxide(No).However,the study on the contribution of plants to atmospheric No budget is significantly lagged.The specific objectives of this study are to reveal the phylogenetic variation in No emission potential existing in various plant species and find out the possible leaf traits affecting No emission potential.Methods We measured No emission potential,leaf N and C content,C:N ratio,specific leaf area,net photosynthetic rate(Pn)and estimated photosynthetic N use efficiency(PNuE)of 88 plant species.Further investigation of the relationships between No emission potential and leaf traits were performed by simple linear regression analysis and pair-wise correlation coefficients analysis.Important Findingsmajor results are as follows:(1)No emission from plant species exhibited large variations,ranging from 0 to 41.7 nmol m^(−2) h^(−1),and the species frequency distributions of No emission potential could be fitted to a log-normal curve.(2)among 88 species,No emission potential was the highest in Podocarpus macrophyllus,but lowest in Zanthoxylum nitidum and Vernicia montana.(3)No emission potential has strong correlation to leaf N content,Pn and PNuE.The variations in No emission potential among diverse plant species may be closely related to leaf N level and net photosynthetic ability.

Effect of Reducing Chemical Fertilizer on Rice Yield,Output Value,Content of Soil Carbon and Nitrogen after Utilizing the Milk Vetch

A located field experiment was carried out to study the effects of different amount of chemical fertilizer usage on rice yield,economic benefits of rice,soil carbon（C） and total nitrogen（TN） under ploughing back of Chinese milk vetch for 5consecutive years.Six treatments were included in the experiment,they are CK（unfertilized）,CF（100% chemical fertilizer with the amount of N,P2O5,K2 O being150,75,120 kg/hm^2respectively）,A1（22 500 kg/hm^2 Chinese milk vetch and 100%chemical fertilizer）,A2（Chinese milk vetch and 80% nitrogen and potassium fertilizer and 100% phosphate fertilizer）,A3（Chinese milk vetch and 60% nitrogen and potassium fertilizer and 100% phosphate fertilizer）,A4（Chinese milk vetch and 40% nitrogen and potassium fertilizer and 100% phosphate fertilizer）.The results were as follows：application of fertilizer could increase the yield of rice,while Chinese milk vetch combined with fertilizer application had a much more increase effect in rice yield.Under the condition of milk vetch application with 22 500 kg/hm^2,the early rice yield of the treatment A1 was significantly increased by 7.7% compared with that of CF.And the yield of treatment A3 was basically identical to or slight increase in comparison with that of CF.Decreasing amount of fertilizers cloud improve output value of rice in the case of the utilization of Chinese milk vetch.The treatment A1 increased output value of rice by 5.92% in comparison of CF,and treatment A2 was by 4.08% in the next.Treatment A4 showed much better effect in increasing soil organic carbon and total nitrogen in the paddy soil than those of treatments applying mineral fertilizer only.There was a significant reduction on soil organic carbon and TN in treatment A2 in comparison with that of CF.In general,amount of application of milk vetch with 22 500 kg/hm^2 could replace chemical fertilizer partially,it also could improve rice yield,decrease the production cost,and raise the utilization efficiency of nutrients.

The influence of lipid-extraction on theδ^(13)C of mesopelagic and demersal fish in the South China Sea:modification and application of lipid normalization models

Mesopelagic fish,the most important daily vertically migrating community in the oceans,are characterized by high lipid content which may obscure the interpretation of stable isotopes analysis.Demersal fish,which are important consumers in the food web dominated by mesopelagic fish,also have a high lipid content.Here we collected 127 fish samples from the South China Sea and evaluated the effect of lipid contents on△δ^(13)C of mesopelagic and demersal fish.In lipid-extracted mesopelagic fish,the C/N content ratio(<5.5)shows a clear correlation withΔδ^(13)C(the offset of bulk and lipid-extractedδ^(13)C values),especially in non-migratory and semi-migratory species;these values were less correlation in demersal fish.Based on our results,we suggest that mesopelagic and demersal fish in different regions of the South China Sea should be studied separately using appropriate correction models and less fit for the traditional model.Moreover,the C/N content ratio should be used cautiously for establishing the lipid normalization model,especially for the fish in migratory mesopelagic fish and demersal fish.Our results also reveal that mesopelagic fish across nearby regions could be analyzed together.The new models described here can be applied in future studies of mesopelagic and demersal fish in the South China Sea.

Effects of Nitrogen Content and Austenitization Temperature on Precipitation in Niobium Micro-alloyed Steels

The influences of nitrogen content and austenitization temperature on Nb（C, N） precipitation in niobium micro-alloyed steels were studied by different methods： optical microscopy, tensile tests, scanning electron mi- croscopy, transmission electron microscopy, physicochemical phase analysis, and small-angle X-ray scattering. The results show that the strength of the steel with high nitrogen content is slightly higher than that of the steel with low nitrogen content. The increase in the nitrogen content does not result in the increase in the amount of Nb（C,N） precipitates, which mainly depends on the niobium content in the steel. The mass fraction of small-sized Nb（C, N） precipitates （1--10 nm） in the steel with high nitrogen content is less than that in the steel with low nitrogen con- tent. After austenitized at 1 150 ℃, a number of large cuboidal and needle-shaped particles are detected in the steel with high nitrogen content, whereas they dissolve after austenitized at 1 200 ℃ and the Nb（C,N） precipitates become finer in both steels. Furthermore, the results also show that part of the nitrogen in steel involves the formation of al- loyed cementite.

低蛋白质日粮添加N-氨甲酰谷氨酸对断奶仔猪生长性能和肠道健康的影响

文章旨在研究低蛋白质日粮添加N-氨甲酰谷氨酸(N-carbamylglutamic,NCG)对断奶兰西民猪生长性能和肠道健康的影响,试验将120只健康、4周龄体重相近、出生时间相近的仔猪随机分为4组(A组为对照组:服用低蛋白质日粮;N1组:低蛋白质日粮+0.05%水平NCG;N2组:低蛋白质日粮+0.10%水平NCG;N3组:低蛋白质日粮+0.15%水平NCG)每组3个重复,每次重复10头猪。结果显示,(1)与A组相比,1~14 d,N3组日采食量比对照组提高5.55%(P<0.05),各试验组料重比与日增重相较于对照组差别显著(P<0.05)。15~28 d,N1、N2、N3组日采食量相较于对照组显著提高(P<0.05),分别增长9.8%(N1组)、7.5%(N2组)、8.3%(N3组),日增重相较于对照组有显著增长(P<0.05),分别提高21.6%(N1组)、19.1%(N2组)、13.7%(N3组)。试验周期中,在日粮中添加0.05%(N1组)、0.10%(N2组)、0.15%(N3组)NCG后,日增重相较于对照组分别提高13.2%(N1组)、5.4%(N2组)、15.4%(N3组),日采食量分别提高10.3%(N1组)、7.1%(N2组)、12.5%(N3组)(P<0.05)。(2)SigA含量与对照组相比差异不显著(P>0.05),但有升高趋势。(3)3个试验组血液常规指标相对于对照组有细微变化,但仍处于正常生理范围内。由以上分析发现,NCG对仔猪健康无有害作用,且能提高每日采食量与每日增重,降低料重比,增加SigA含量,提高肠道免疫及其保护作用。

青海东部农区引进燕麦品种各器官C、N、P生态化学计量学特征变化研究

以4个引种燕麦(Avena sativa)为典型代表,对其不同生育时期根、茎、叶中的C、N、P含量及其化学计量学特征进行测定,探讨不同生育时期燕麦C、N、P元素含量及其化学计量比的变化规律,为燕麦饲草的科学收获提供理论依据。结果表明:燕麦全株C、N、P含量分别为322.30~333.97、17.42~75.62、2.74~5.42 mg·g^(-1),燕麦根C、N、P含量分别为298.42~317.92、11.47~73.71、2.82~3.42 mg·g^(-1),燕麦茎C、N、P含量分别为311.25~338.86、10.15~75.16、2.44~5.06 mg·g^(-1),燕麦叶C、N、P含量分别为330.80~372.47、30.64~113.80、2.59~8.65 mg·g^(-1);各器官间C、N、P含量表现为叶>茎>根。此外,燕麦各器官C、N、P含量的积累过程具有一定季节特征,C含量积累过程受生育时期影响较小,表现出较强的稳定性;而N和P含量的积累过程受生育时期影响较大,其在拔节期~抽穗期均高于开花期~乳熟期。燕麦各器官C∶N、C∶P和N∶P分别为4.42~24.44、70.72~124.56和6.56~17.28,其中C∶N、C∶P在开花期~乳熟期均高于拔节期~抽穗期;N∶P则规律相反。

甘南黄河流域4种典型林分土壤C、N、P化学计量特征

土壤碳(C)、氮(N)、磷(P)是参与植物光合作用和影响生态系统初级生产力的主要元素。甘南高原是黄河流域重要的生态屏障,为了解该区不同林分土壤养分状况的差异,选取该区4种典型林分:云杉林、华北落叶松林、巴山冷杉林以及岷江冷杉糙皮桦混交林为研究对象,研究土壤C、N、P化学计量特征。结果表明:(1)岷江冷杉及糙皮桦混交林土壤C、N含量最高,云杉林土壤N、P含量最低。不同林分间P含量差异显著(P<0.05),不同土层间C、N含量差异均显著(P<0.05)。(2)云杉林土壤C∶N值显著高于其他林分,岷江冷杉及糙皮桦混交林土壤N∶P及C∶P高于其他林分。(3)海拔、土壤pH、容重与土壤含水量是影响土壤养分的重要因素。土壤C含量与N、P含量均显著相关(P<0.05)。总体来说,不同林分土壤化学计量特征具有显著差异,混交林土壤养分状况较纯林好,未来森林管理和植被建设中,可以通过选择合适的树种和提高树种多样性有效改善森林土壤质量。

N含量对Ti(C,N)基金属陶瓷微观组织结构和性能的影响

针对Ti(C, N)基金属陶瓷在烧结过程中存在明显脱氮行为的问题,采用氮分压烧结方法是实现微观组织结构可控和获得优异性能的关键之一。制备了3种不同氮含量的Ti(C, N)基金属陶瓷,研究了氮含量和烧结温度对合金芯部和表面梯度层微观组织结构和性能的影响。结果表明:随着氮含量增加,合金芯部Ti(C,N)黑芯数量越多,黑芯外环的厚度越薄,同时硬质相晶粒越细;随着烧结温度升高,样品氮分解压力逐渐增大,由开始的渗氮现象转变为脱氮现象。当烧结温度为1 470℃时,合金表面发生了渗氮反应,形成一层无环黑芯聚集层,且其厚度随着合金氮含量的增加而减少;当烧结温度增加至1 530℃时,合金表面发生了脱氮反应,形成了一层灰色固溶体层,且随着合金中氮含量的增加,脱氮反应加剧,固溶体层厚度也越厚。研究发现,在1 470℃和0.8 kPa氮分压下烧结的样品,为含氮量最高的合金,具有最薄的黑芯聚集层和最细的硬质相晶粒,表现出较佳的综合性能。

GC-MS/MS法测定药品中N-亚硝胺类化合物的含量

使用GC-MS/MS方法测定药品中N-亚硝胺类化合物N-亚硝基二甲胺(NDMA)、N-亚硝基二乙胺(NDEA)、N-亚硝基二异丙胺(NDIPA)的含量,解决基质干扰对3种化合物的灵敏度的影响,实现药品中N-亚硝胺类化合物的痕量检测。实验选取甲醇作为提取试剂,超声提取后,定容上机。该方法操作步骤简单,定量限低于FDA检测方法的定量限。精密度和加标回收率均满足分析测试要求。检出限均为0.375 ng/mL,溶液稳定性和耐用性重复性(RSD)都在10%以内,加标回收率达到90%~120%。

氮氩流量比对NiTiAlCrN涂层抗空蚀性能的影响

通过改变通入氮气与氩气的比例,探究不同N含量NiTiAlCrN涂层的结构与性能。采用X射线衍射仪、扫描电镜、能谱仪等表征涂层材料的组织结构和形貌,超声振动空蚀机对涂层进行空蚀实验,探究NiTiAlCrN涂层空蚀破坏的机理。结果表明,NiTiAlCrN涂层呈面心立方结构,在(111)和(200)晶面呈现择优取向。随着氮氩流量比增加,硬度、弹性模量和抗空蚀性能先升高后降低。氮氩流量比为1∶1时涂层的结构最致密,晶粒最细,硬度最高,抗空蚀性能最强。氮氩流量比为3∶2时涂层所能承受的弹性势能最大,韧性最强,但抗空蚀的能力低于氮氩流量比为1∶1时的涂层,说明硬度比弹性模量对涂层抗空蚀方面的影响更大。在空蚀坑的内壁发现大量的Cr_(2)O_(3)、Al_(2)O_(3)等具备抗空蚀性的氧化物,减轻微射流的冲击,降低对涂层的进一步损坏。

Microstructure and mechanical properties of Ti(C, N)-based cermets with different molybdenum contents

The microstructure and mechanical properties of Ti(C, N)-based cermets with different content Mo were studied. Different Mo contents were added into Ti(C, N)-based cermets. Effect of sintering temperature on mechanical properties of the cermets was also investigated. Specimens were fabricated by conventional powder metallurgy techniques and vacuum sintered at different temperatures. The microstructure and the fracture morphology were investigated using scanning electron microscope. Transverse strength and hardness were measured. The results show that the microstructure is uniform and the thickness of rim phase is moderate when the content of Mo is 8%. The mechanical properties are the best when the content of Mo is 8% and the sintering temperature is 1450℃.

HPLC-MS/MS法测定注射用盐酸头孢甲肟中7种N-亚硝胺类杂质

目的建立高效液相色谱-串联质谱法(HPLC-MS/MS)同时测定注射用盐酸头孢甲肟中7种N-亚硝胺类基因毒性杂质(N-亚硝基二甲胺、N-亚硝基二乙胺、N-亚硝基二乙醇胺、N-亚硝基-N-甲基苯胺、N-亚硝基-N-乙基苯胺、N-亚硝基二异丙胺、N-亚硝基二正丁胺)。方法色谱柱为ACE EXCEL 3 C18-AR(3μm,100 mm×4.6 mm),流动相为0.1%甲酸甲醇溶液(A)-0.1%甲酸(B),梯度洗脱,流速0.6 mL·min^(-1),采用APCI离子源,以正离子、多重反应监测(MRM)模式进行检测。结果7种N-亚硝胺类基因毒性杂质在1~20ng·mL^(-1)与峰面积线性关系良好。回收率在78.9%~89.6%,RSD均小于6.1%。检测限低于1.5ng·g^(-1)。样品中各杂质均未检出。结论该方法灵敏度高、专属性强,可用于注射用盐酸头孢甲肟中7种N-亚硝胺类基因毒性杂质的质量控制。

小长山岛3种大型海藻组织碳、氮含量和δ^(15)N值的环境指示意义

大型海藻组织碳、氮含量及δ^(15)N值的变化对于指示营养盐来源及营养盐评价研究具有重要的意义。为探究大型海藻组织碳、氮含量及δ^(15)N值的变化特征,于2020年7月至2021年6月逐月分析了小长山岛潮间带孔石莼(Ulva pertusa)、角叉菜(Chondrus ocellatus)、鼠尾藻(Sargassum thunbergii)3种大型海藻组织的碳、氮含量和δ^(15)N值的变化,并对其生长环境中海水的理化因子进行了测定。结果发现:孔石莼组织的氮含量与海水中的NO_(3)-N和DIN含量之间存在显著的相关性,角叉菜组织的氮含量与海水中的NH 3-N含量之间也存在显著的相关性。然而,大型海藻组织的碳含量和C/N比值与海水中的碳、氮营养盐之间并无显著的相关性。孔石莼组织的δ^(15)N值与海水中的NO_(3)-N和DIN含量之间也存在显著的相关性。因此,孔石莼适于用作NO_(3)-N和DIN来源的指示藻种。结果指示小长山岛潮间带海水中具有供大型海藻生长利用的充足的营养盐,其主要受到生活污水和养殖排放的影响。