固相时间分辨荧光免疫螯合剂 BCPDA 的制备及其标记技术

报道了固相时间分辨荧光免疫螫合剂4,7-二氯磺基苯-1,10-菲罗啉-2,9-二羧酸(BCPDA)的制备方法,BCPDA 标记蛋白质及螫合 Eu³⁺方法,BCPDA-Eu³⁺标记物荧光光谱研究以及固相时间分辨荧光免疫分析法检测甲胎蛋白异质体(AFP-R-LCA)方法的建立.结果表明 BCPDA 能在温合条件下与蛋白质氨基结合并与 Eu³⁺螯合,BCPDA-Eu³⁺蛋白质标记物荧光特性、标记比度、生物结合活性与国外同类产品一致,所建立的检测 AFP-R-LCA 免疫分析法最小检测值0.6ng/ml,为提高我国非放射性同位素标记技术水平奠定了基础.     

What is the usual internal carbon dioxide concentration in C<Subscript>4</Subscript> species under midday field conditions?

The carbon dioxide concentrating system in C₄ photosynthesis allows high net photosynthetic rates (P _N) at low internal carbon dioxide concentrations (C _i), permitting higher P _N relative to stomatal conductance (g _s) than in C₃ plants. This relation would be reflected in the ratio of C _i to external ambient (C _a) carbon dioxide concentration, which is often given as 0.3 or 0.4 for C₄ plants. For a C _a of 360 μmol mol⁻¹ that would mean a C _i about 110–140 μmol mol⁻¹. Our field observations made near midday on three weedy C₄ species, Amaranthus retroflexus, Echinochloa crus-galli, and Setaria faberi, and the C₄ crop Sorghum bicolor indicated mean values of C _i of 183–212 μ mol mol⁻¹ at C _a = 360 μmol mol⁻¹. Measurements in two other C₄ crop species grown with three levels of N fertilizer indicated that while midday values of C _i at high photon flux were higher at limiting N, even at high nitrogen C _i averaged 212 and 196 μmol mol⁻¹ for Amaranthus hypochondriacus and Zea mays, respectively. In these two crops midday C _i decreased with increasing leaf to air water vapor pressure difference. Averaged over all measurement days, the mean C _i across all C₄ species was 198 μmol mol⁻¹, for a C _i/C _a ratio of 0.55. Prior measurements on four herbaceous C₃ species using the same instrument indicated an average C _i/C _a ratio of 0.69. Hence midday C _i values in C ₄ species under field conditions may often be considerably higher and more similar to those of C₃ species than expected from measurements made on plants in controlled environments. Reducing g _s in C₄ crops at low water vapor pressure differences could potentially improve their water use efficiency without decreasing P _N.     

Interactions of Elevated CO2 Concentration and Drought Stress on Photosynthesis in Eucalyptus Cladocalyx F. Muell

Response of net photosynthetic rate (P _N), stomatal conductance (g _s), intercellular CO₂ concentration (c _i), and photosynthetic efficiency (F_v/F_m) of photosystem 2 (PS2) was assessed in Eucalyptus cladocalyx grown for long duration at 800 (C₈₀₀) or 380 (C₃₈₀) μmol mol^-1 CO₂ concentration under sufficient water supply or under water stress. The well-watered plants at C₈₀₀ showed a 2.2 fold enhancement of P _N without any change in g _s. Under both C₈₀₀ and C₃₈₀, water stress decreased P _N and g _s significantly without any substantial reduction of c _i, suggesting that both stomatal and non-stomatal factors regulated P _N. However, the photosynthetic efficiency of PS2 was not altered. This revised version was published online in June 2006 with corrections to the Cover Date.     

黄河上游灌区稻田N2O排放特征

黄河上游灌区稻田高产区过量施肥现象十分突出,氮肥过量施用引起土壤氮素盈余,导致N₂O排放量增大,由此引起的温室效应引起广泛关注。采用静态箱-气相色谱法研究黄河上游灌区稻田不同施肥处理下N₂O排放特征。试验设置5个施肥处理,包括常规氮肥300 kg/hm²下单施尿素和有机肥配施2个处理,分别用N300和N300-OM代表;优化氮肥240 kg/hm²下单施尿素和有机肥配施2个处理,分别用N240和N240-OM代表;对照不施氮肥用N0代表。试验结果得出,灌区水稻生长季稻田土壤N₂O排放主要集中在水稻分蘖前及水稻生长的中后期,稻田氮肥施用、灌水及土壤温度的变化对N₂O排放通量影响较大,不同处理水稻各生育阶段N₂O累积排放量与稻田土壤耕层NO^-₃-N含量动态变化显著相关。稻田N₂O排放不是黄河上游灌区稻田氮素损失的主要途径,但灌区稻田N₂O排放的增温潜势较大;稻田氮肥过量施用会显著增加N₂O排放量,在相同氮素水平下,有机肥配施会显著增加稻田土壤N₂O的排放量(P＜0.01)。优化施氮能有效减少灌区稻田水稻生长季N₂O排放量。稻田不同处理的水稻整个生长季土壤N₂O排放总量为2.69-3.87 kg/hm²,肥料氮通过N₂O排放损失的百分率仅为0.43%-0.64%。在灌区习惯灌水和高氮肥300 kg/hm²时,N300-OM处理的稻田N₂O排放量达3.87 kg/hm²,在100 a时间尺度上的全球增温潜势(GWPs)为20.76×10⁷ kg CO₂/hm²;优化施氮240 kg/hm²水平下,N240和N240-OM处理的N₂O累计排放量较N300-OM处理,分别降低了1.18 kg/hm²和0.57 kg/hm²,在100 a尺度上每年由稻田N₂O排放引起的GWPs分别降低了6.33×10⁷ kg CO₂/hm²和3.06×10⁷ kg CO₂/hm²。     

早春短命植物鸢尾蒜和准噶尔鸢尾蒜的光合途径

该研究以鸢尾蒜属两种早春短命植物准噶尔鸢尾蒜(Ixiolirion songaricum)和鸢尾蒜(Ixiolirion tataricum)为对象,通过解剖结构、光合参数、稳定碳同位素比值(δ¹³C)和光合关键酶活性分析二者的光合途径。结果发现：(1)显微结构和超微结构显示,两种短命植物的叶脉维管束鞘细胞1层、排列较紧密,鞘细胞内含有较多叶绿体且多离心分布,类似C₄花环结构。(2)准噶尔鸢尾蒜和鸢尾蒜最大净光合速率分别为14.81和15.04 μmol·m^-2·s^-1;两者的CO₂补偿点较低,分别为3.57和2.54 μmol·mol^-1,δ¹³C分别为-25.36±0.55‰和-25.76±1.38‰,光合酶PEPC/Rubisco比值分为别0.244和0.322。(3)最大净光合速率、δ¹³C和PEPC/Rubisco比值均说明两种植物为C₃光合途径,但二者均具有类似C₄的维管束鞘结构、较低的CO₂补偿点和暗呼吸速率,并具有高于部分C₃和C₃ C₄中间型植物的PEPC/Rubisco比值,表明两种短命植物的光合途径并非典型的C₃途径,而是C₃ C₄中间型。     

川西平原小流域不同水体N2O排放特征及驱动因素

氧化亚氮（N₂O）是一种潜在的、强大的温室气体,应该根据京都议定书规定开展监测和削减。河流、水库、鱼塘和沟渠等受人类影响的小流域水生生态系统是氮素生物地球化学循环的活跃区域,更是N₂O重要的源和汇。然而,同一流域不同水体N₂O的排放特征差异及其驱动因素尚不清楚。因此,选择川西平原西河流域作为研究区,于2016年6月到2017年5月连续监测不同水体水气界面的N₂O排放强度,并结合聚类分析解析N₂O排放特征的驱动因素。结果显示,不同水体的N₂O年排放通量差异显著,沟渠的N₂O年排放通量最高（（52.68±36.09）μg m^-2 h^-1）,城市段河流和鱼塘次之（（34.16±23.97）μg m^-2 h^-1和（29.03±31.41）μg m^-2 h^-1）,乡镇段和农区段河流再次（（8.32±28.60）μg m^-2 h^-1和（8.52±9.43）μg m^-2 h^-1）,水库最低（（-16.45±29.76）μg m^-2 h^-1）。除水库表现为N₂O的汇,其他水体均表现为N₂O的排放源。另外,不同水体N₂O排放的季节特征差异显著,农区段河流和农业沟渠表现为夏天最高,冬春最低（P<0.05）,而其他水体均表现为冬春显著高于夏秋（P<0.05）。根据N₂O排放季节特征及其驱动因素可将西河流域水体分为四类：第一类农业类水体的N₂O排放季节特征受气象因素和农业活动的联合驱动;第二类城乡类河流和第三类鱼塘分别受控于人类活动和养殖活动,与降雨温度等气象指标关系较弱;第四类水库主要受控于气象因素。并且,第一类农业类水体已成为大气N₂O排放的重要源,农业氮素管控是区域控制N₂O排放的重点。     

Compensatory effects of elevated CO<Subscript>2</Subscript> concentration on the inhibitory effects of high temperature and irradiance on photosynthetic gas exchange in carrots

We determined the interactive effects of irradiance, elevated CO₂ concentration (EC), and temperature in carrot (Daucus carota var. sativus). Plants of the cv. Red Core Chantenay (RCC) were grown in a controlled environmental plant growth room and exposed to 3 levels of photosynthetically active radiation (PAR) (400, 800, 1 200 μmol m⁻² s⁻¹), 3 leaf chamber temperatures (15, 20, 30 °C), and 2 external CO₂ concentrations (C _a), AC and EC (350 and 750 μmol mol⁻¹, respectively). Rates of net photosynthesis (P _N) and transpiration (E) and stomatal conductance (g _s ) were measured, along with water use efficiency (WUE) and ratio of internal and external CO₂ concentrations (C _i/C _a). P _N revealed an interactive effect between PAR and C _a. As PAR increased so did P _N under both C _a regimes. The g _s showed no interactive effects between the three parameters but had singular effects of temperature and PAR. E was strongly influenced by the combination of PAR and temperature. WUE was interactively affected by all three parameters. Maximum WUE occurred at 15 °C and 1 200 μmol m⁻² s^{− 1} PAR under EC. The C _i /C _a was influenced independently by temperature and C _a. Hence photosynthetic responses are interactively affected by changes in irradiance, external CO₂ concentration, and temperature. EC significantly compensates the inhibitory effects of high temperature and irradiance on P _N and WUE.     

城市化地区典型水体的N2O排放通量特征——以南京市为例

内陆淡水水体是大气中N₂O的重要排放源,然而目前对于内陆典型城市水体N₂O排放通量的监测数据依然匮乏,典型城市水体的N₂O排放特征及驱动因素尚不清楚。本研究选取了南京市江北新区的典型水体,包括湖库、河流、养殖池塘和景观池塘,在2020年5月-2021年4月利用漂浮箱法连续监测了不同水体类型的水-气界面N₂O排放特征,并通过测定水环境特征,探究驱动水体N₂O排放通量的关键因素。研究结果表明,典型城市水体整体均表现为N₂O排放源,河流和养殖池塘的日平均排放通量最大,分别为（503±1236）μg m^-2 d^-1和（508±797）μg m^-2 d^-1,其次为景观池塘（（179±989）μg m^-2 d^-1）,而湖库的N₂O排放通量最小,仅表现为微弱的N₂O排放源（（54±212）μg m^-2 d^-1）。水体的N₂O排放呈现季节性差异,河流和养殖池塘夏季的N₂O排放通量显著高于其他季节（P<0.01）。水体全年N₂O排放数据与水体温度和溶解氧含量（DO）呈显著相关。而在温度较高的5月份-9月份（>20℃）,氮输入成为影响N₂O排放通量的关键因素（P<0.01）,因此控制城市水体的氮输入尤其是在水温较高的夏季是减少N₂O排放的有利措施。此外,由于水文化学条件差异等因素,小型封闭水体包括养殖池塘和景观池塘的N₂O排放通量差异较大,未来应加强监测不同水体的水文化学特征和N₂O的时空排放特征,探讨影响小型封闭水体水-气界面N₂O排放通量的具体驱动因素。此研究为城市区域N₂O排放的精准核算提供了数据支撑,为N₂O排放模型的修正提供了科学依据。     

云贵高原喀斯特坡耕地土壤微生物量 C、N、P空间分布

土壤微生物是地球生物演化进程中的先锋种类,具有重要的生态修复功能,但空间分布格局是否存在的争议很大。以云贵高原典型喀斯特坡耕地为对象,基于网格法取样,用经典统计学和地统计学综合分析了土壤微生物生物量的空间变异特征。结果表明,云贵高原喀斯特坡耕地土壤微生物生物量碳(C_mic)、磷(P_mic)以及碳氮比(C_mic/N_mic)适宜,氮(N_mic)的含量较低,变异均很大,空间自相关性明显,最佳拟合模型均为指数模型。块金值C₀较小(0.0016-0.0087),C₀/(C₀+C)均<25%(2.6%-10.2%),变程a较短(22.2-51.0 m),其强烈的空间变异主要由结构性变异引起。Kriging等值线图表明,C_mic、N_mic和C_mic/N_mic的高值区分布在坡的中上部,P_mic的高值区则在坡的中下部和坡脚。云贵高原喀斯特坡耕地土壤微生物不仅存在着小尺度的空间分布格局,而且不同土壤微生物属性的空间分布不同。     

黄土高原冬小麦地N2O排放

从2007年7月1日到2009年6月30日对黄土高原冬小麦地氧化亚氮(N₂O)排放采用静态箱气相色谱法进行了为期2a 的监测。设置2个处理,有小麦田(有小麦生长),无小麦田(出芽初期拔去麦苗)。研究结果表明有小麦田、无小麦田N₂O排放量年际变化不大。有小麦田年均的N₂O 排放量为2.05 kg · N₂O · hm^-2 · a^-1,无小麦田年均的N₂O 排放量为2.28 kg · N₂O · hm^-2 · a^-1 。在冻融交替期,施肥后、翻地后和降雨后无小麦田和有小麦田N₂O排放明显增加,N₂O的季节变化受到这些短期事件的显著影响;有小麦田N₂O排放与地温(P<0.01),气温(P<0.01)和WFPS(P<0.05)显著相关,而无小麦田N₂O排放与这些环境土壤因子都不相关;有小麦田和无小麦田两个处理土壤的WFPS通常都低于60%,可以推断在本地区,硝化反应是N₂O的重要生成源。     

Eu3+‐tetrakis β‐diketonate complexes for solid‐state lighting application

Eu³⁺–β‐diketonate complexes are used, for example, in solid‐state lighting (SSL) or light‐converting molecular devices. However, their low emission quantum efficiency due to water molecules coordinated to Eu³⁺ and low photostability are still problems to be addressed. To overcome such challenges, we synthesized Eu³⁺ tetrakis complexes based on [Q][Eu(tfaa)₄] and [Q][Eu(dbm)₄] (Q1 = C₂₆H₅₆N⁺, Q2 = C₁₉H₄₂N⁺, and Q3 = C₁₇H₃₈N⁺), replacing the water molecules in the tris stoichiometry. The tetrakis β‐diketonates showed desirable thermal stability for SSL and, under excitation at 390 nm, they displayed the characteristic Eu³⁺ emission in the red spectral region. The quantum efficiencies of the dbm complexes achieved values as high as 51%, while the tfaa complexes exhibited lower quantum efficiencies (28–33%), but which were superior to those reported for the tris complexes. The structures were evaluated using the Sparkle/PM7 model and comparing the theoretical and the experimental Judd–Ofelt parameters. [Q1][Eu(dbm)₄] was used to coat a near‐UV light‐emitting diode (LED), producing a red‐emitting LED prototype that featured the characteristic emission spectrum of [Q1][Eu(dbm)₄]. The emission intensity of this prototype decreased only 7% after 30 h, confirming its high photostability, which is a notable result considering Eu³⁺ complexes, making it a potential candidate for SSL.     

Photosynthetic response of wheat and sunflower cultivars to long-term exposure of elevated carbon dioxide concentration

Wheat (Triticum aestivum L. cv. HD 2329 and DL 1266-5) and sunflower (Helianthus annuus L. cv. MSFH 17 and MRSF 1754) plants were grown in field under atmospheric (360±10 cm³ m⁻³, AC) and elevated (650±50 cm³ m⁻³, EC) CO₂ concentrations in open top chambers for entire period of growth and development till maturity. Net photosynthetic rate (P _N) of wheat cvs. when compared at the same internal CO₂ concentration (C _i), by generating P _N/C _i curves, showed lower P _N in EC plants than in AC ones. EC-grown wheat cultivars also showed a lesser response to irradiance than AC plants. In sunflower cultivars, P _N/C _i curves and irradiance response curves were not significantly different in AC and EC plants. CO₂ and irradiance responses of photosynthesis, therefore, further revealed a down-regulation of _{P N} in wheat but not so in sunflower under long-term CO₂ enrichment. Wheat cvs. accumulated in leaves mostly sugars, whereas sunflower accumulated mainly starch. This further strengthened the view that accumulation of excess assimilates in the leaves under EC as starch is not inhibitory to _{P N}.     

Cobalt (II) complex with novel unsymmetrical tetradentate Schiff base (ON) ligand: in vitro cytotoxicity studies of complex,interaction with DNA/protein,molecular docking studies,and antibacterial activity

[C₂₀H₁₇N₃O₂] and cobalt (II) complex [Co(L²)(MeOH)₂].ClO₄, (L² = 4-((E)-1-((2-(((E)-pyridin-2-ylmethylene) amino) phenyl) imino) ethyl) benzene-1, 3-diol) novel Schiff base has been synthesiszed and chracterized by Fourier transform infrared, UV–vis, ¹H-NMR spectroscopy, and elemental analysis techniques. The interaction of Co(II) complex with DNA and BSA was investigated by electronic absorption spectroscopy, fluorescence spectroscopy, circular dichroism, and thermal denaturation studies. Our experiments indicate that this complex could strongly bind to CT-DNA via minor groove mechanism. In addition, fluorescence spectrometry of BSA with the complex showed that the fluorescence quenching mechanism of BSA was of static type. The complex exhibited significant in vitro cytotoxicity against three human cancer cell lines (JURKAT, SKOV3, and U87). The molecular docking experiment effectively proved the binding of complex to DNA and BSA. Finally, antibacterial assay over gram-positive and gram-negative pathogenic bacterial strains was studied.     

Synthesis and luminescence properties of two novel lanthanide (III) complexes of acetophenonylcarboxymethyl sulphoxide

A novel ligand containing multiple coordinating groups (sulfinyl, carboxyl and carbonyl groups), acetophenonylcarboxymethyl sulphoxide, was synthesized. Its corresponding two lanthanide (III) binary complexes were synthesized and characterized by element analysis, molar conductivity, FT‐IR, TG‐DTA and UV spectroscopy. Results showed that the composition of these complexes was REL₃L^‐ (ClO₄)₂·3H₂O (RE = Eu (III), Tb (III); L = C₆H₅COCH₂SOCH₂COOH; L^‐ = C₆H₅COCH₂SOCH₂COO^‐). FT‐IR results indicated that acetophenonylcarboxymethyl sulphoxide was bonded with an RE (III) ion by an oxygen atom of the sulfinyl and carboxyl groups and not by an oxygen atom of the carbonyl group due to high steric hinderance. Fluorescent spectra showed that the Tb (III) complex had excellent luminescence as a result of a transfer of energy from the ligand to the excitation state energy level (⁵D₄) of Tb (III). The Eu (III) complex displayed weak luminescence, attributed to low energy transfer efficiency between the triplet state energy level of its ligand and the excited state (⁵D₀) of Eu (III). As a result, the Tb (III) complex displayed a good antenna effect for luminescence. The fluorescence decay curves of Eu (III) and Tb (III) complexes were also measured. Copyright © 2012 John Wiley & Sons, Ltd.     

The acetylene-ethylene assay for n(2) fixation: laboratory and field evaluation

The methodology, characteristics and application of the sensitive C₂H₂-C₂H₄ assay for N₂ fixation by nitrogenase preparations and bacterial cultures in the laboratory and by legumes and free-living bacteria in situ is presented in this comprehensive report. This assay is based on the N₂ase-catalyzed reduction of C₂H₂ to C₂H₄, gas chromatographic isolation of C₂H₂ and C₂H₄, and quantitative measurement with a H₂-flame analyzer. As little as 1 μμmole C₂H₄ can be detected, providing a sensitivity 10³-fold greater than is possible with ¹⁵N analysis.

A simple, rapid and effective procedure utilizing syringe-type assay chambers is described for the analysis of C₂H₂-reducing activity in the field. Applications to field samples included an evaluation of N₂ fixation by commercially grown soybeans based on over 2000 analyses made during the course of the growing season. Assay values reflected the degree of nodulation of soybean plants and indicated a calculated seasonal N₂ fixation rate of 30 to 33 kg N₂ fixed per acre, in good agreement with literature estimates based on Kjeldahl analyses. The assay was successfully applied to measurements of N₂ fixation by other symbionts and by free living soil microorganisms, and was also used to assess the effects of light and temperature on the N₂ fixing activity of soybeans. The validity of measuring N₂ fixation in terms of C₂H₂ reduction was established through extensive comparisons of these activities using defined systems, including purified N₂ase preparations and pure cultures of N₂-fixing bacteria.

With this assay it now becomes possible and practicable to conduct comprehensive surveys of N₂ fixation, to make detailed comparisons among different N₂-fixing symbionts, and to rapidly evaluate the effects of cultural practices and environmental factors on N₂ fixation. The knowledge obtained through extensive application of this assay should provide the basis for efforts leading to the maximum agricultural exploitation of the N₂ fixation reaction.

     

Reduction of structural dimensionality through incorporation of auxiliary ligands in lanthanide tetracyanoplatinates

The synthesis of a series of lanthanide tetracyanoplatinates containing the auxiliary ligands 1,10′-phenanthroline (phen) or 2,2′-bipyridine (bpy) have been carried out by reaction of Ln³⁺ nitrate salts with phen or bpy and potassium tetracyanoplatinate in solvent systems containing dimethylsulfoxide and dimethylformamide. The use of these solvents has lead to the isolation of [{Ln(DMSO)₂(C₁₂H₈N₂)(H₂O)₃}₂Pt(CN)₄](Pt(CN)₄)₂·2C₁₂H₈N₂·4H₂O (Ln = Eu (Eu-1), Tb (Tb-1), Yb(Yb-1)), [Ln(DMF)₃(C₁₂H₈N₂)(H₂O)₂NO₃]Pt(CN)₄ (Ln = La (La-2), Eu (Eu-2), Tb (Tb-2)), and [Ln(DMF)₃(C₁₀H₈N₂)(H₂O)₂NO₃]Pt(CN)₄ (Ln = La (La-3), Sm (Sm-3), Eu (Eu-3), Tb (Tb-3)) in the form of single crystals. Single-crystal X-ray diffraction has been used to investigate their structural features. The use of DMSO versus DMF as the solvent results in markedly different structural features. Eu-1 contains [{Eu(DMSO)₂(C₁₂H₈N₂)(H₂O)₃}₂Pt(CN)₄]²⁺ complex cations where the two Eu³⁺ centers are linked by a trans-bridging Pt(CN)₄²⁻ anion to form a dimeric lanthanide complex cation. An additional uncoordinated Pt(CN)₄²⁻ anion balances charge. Eu-2 and Eu-3 consist of zero-dimensional salts with [Eu(DMF)₃(C₁₂H₈N₂)(H₂O)₂(NO₃)]²⁺ or [Eu(DMF)₃(C₁₀H₈N₂)(H₂O)₂(NO₃)]²⁺ complex cations, respectively, and only non-coordinated Pt(CN)₄²⁻ anions. Photoluminescence measurements illustrate that the Eu³⁺ and Tb³⁺ compounds for all three structure types display enhanced emission due to intramolecular energy transfer from the coordinated cyclic amines.     

Effects of the interaction between ozone and carbon dioxide on gas exchange,ascorbic acid content,and visible leaf symptoms in rice leaves

Tropospheric ozone (O₃) decreases photosynthesis, growth, and yield of crop plants, while elevated carbon dioxide (CO₂) has the opposite effect. The net photosynthetic rate (P _N), dark respiration rate (R _D), and ascorbic acid content of rice leaves were examined under combinations of O₃ (0, 0.1, or 0.3 cm³ m⁻³, expressed as O⁰, O^0.1, O^0.3, respectively) and CO₂ (400 or 800 cm³ m⁻³, expressed as C⁴⁰⁰ or C⁸⁰⁰, respectively). The P _N declined immediately after O₃ fumigation, and was larger under O^0.3 than under O^0.1. When C⁸⁰⁰ was combined with the O₃, P _N was unaffected by O^0.1 and there was an approximately 20 % decrease when the rice leaves were exposed to O^0.3 for 3 h. The depression of stomatal conductance (g _s) observed under O^0.1 was accelerated by C⁸⁰⁰, and that under O^0.3 did not change because the decline under O^0.3 was too large. Excluding the stomatal effect, the mesophyll P _N was suppressed only by O^0.3, but was substantially ameliorated when C⁸⁰⁰ was combined. Ozone fumigation boosted the R _D value, whereas C⁸⁰⁰ suppressed it. An appreciable reduction of ascorbic acid occurred when the leaves were fumigated with O^0.3, but the reduction was partially ameliorated by C⁸⁰⁰. The degree of visible leaf symptoms coincided with the effect of the interaction between O₃ and CO₂ on P _N. The amelioration of O₃ injury by elevated CO₂ was largely attributed to the restriction of O₃ intake by the leaves with stomatal closure, and partly to the maintenance of the scavenge system for reactive oxygen species that entered the leaf mesophyll, as well as the promotion of the P _N.     

Effects of the interaction between ozone and carbon dioxide on gas exchange,photosystem II and antioxidants in rice leaves

To understand the interactive effects of O₃ and CO₂ on rice leaves; gas exchange, chlorophyll (Chl) fluorescence, ascorbic acid and glutathione were examined under acute (5 h), combined exposures of O₃ (0, 0.1, or 0.3 cm³ m⁻³, expressed as O₀, O_0.1, or O_0.3, respectively), and CO₂ (400 or 800 cm³ m⁻³, expressed as C⁴⁰⁰ or C⁸⁰⁰, respectively) in natural-light gas-exposure chambers. The net photosynthetic rate (P _N), maximum (F_v/F_m) and operating (F_q′/F_m′) quantum efficiencies of photosystem II (PSII) in young (8^th) leaves decreased during O₃ exposure. However, these were ameliorated by C⁸⁰⁰ and fully recovered within 3 d in clean air (O⁰ + C⁴⁰⁰) except for the O^0.3 + C⁴⁰⁰ plants. The maximum PSII efficiency at 1,500 μmol m⁻² s⁻¹ PPFD (F_v′/F_m′) for the O^0.3 + C₄₀₀ plants decreased for all measurement times, likely because leaves with severely inhibited P _N also had a severely damaged PSII. The P _N of the flag (16^th) leaves at heading decreased under O₃ exposure, but the decline was smaller and the recovery was faster than that of the 8^th leaves. The F_q′/F_m′ of the flag leaves in the O^0.3 + C⁴⁰⁰ and O^0.3 + C⁸⁰⁰ plants decreased just after gas exposure, but the F_v/F_m was not affected. These effects indicate that elevated CO₂ interactively ameliorated the inhibition of photosynthesis induced by O₃ exposure. However, changes in antioxidant levels did not explain the above interaction.     

Rapid Biomass Quality Determination of Corn Stover Using Near-Infrared Reflectance Spectroscopy

Near-infrared reflectance spectroscopy (NIRS) has been used extensively in the forage industry for rapid measurement of forage constituents and could be useful for determining quality of biomass feedstocks at the point of delivery. In previous work, we developed an assay that partitions feedstock carbohydrates based on their availability to be converted to fermentable sugars, including non-structural carbohydrates (C _N), biochemically available carbohydrates (C _B) with an associated first-order availability rate constant (k _B), and unavailable carbohydrates (C _U ). Additional quality parameters measured included neutral detergent lignin (NDL), total available carbohydrates (C _A), and total carbohydrates (C _T). We evaluated the variability of biomass quality parameters in a set of corn stover samples and developed calibration equations for determining parameter values using NIRS. Fifty-two corn stover samples harvested in Iowa and Wisconsin in 2005 and 2006 were analyzed using a high-throughput assay for determining feedstock quality for biochemical conversion. Non-structural carbohydrates ranged from 84 to 155?g?kg^?1 dry matter (DM); C _B ranged from 354 to 557?g?kg^?1 DM; k _B ranged from 0.199 to 0.330?h^?1; C _A ranged from 463 to 699?g?kg^?1 DM, and NDL ranged from 32 to 74?g?kg^?1 DM. Significant differences (P?<?0.0001) among samples were observed for all parameters, except k _B. Near-infrared reflectance spectroscopy calibration equations were developed for C _N, C _B, C _A, C _U , C _T, and NDL. It was not possible to generate a meaningful calibration equation for k _B. There is significant variability within the corn stover population for several key quality-related carbohydrate and lignin constituents which can be predicted reliably using NIRS.     

Lanthanide- and aromatic solvent-induced shift effects on proton resonances in C-4-methylated steroids and tetracyclic triterpenoids

Lanthanide-induced shifts (LIS) with Eu (dpm)₃ and aromatic solvent induced shifts (ASIS) with C₄H₄, C₅H₅N₁ and C₆F₆ of PMR signals were examined for a series of C-4-methylated steroids and tetracyclic triterpenoids having a hydroxyl, carbonyl or acetoxyl group at position C-3. The magnitude and/or direction of the LIS (or ASIS) of corresponding protons were extensively influenced by the nature of the C-3-functional groups. The possible geometries of Eu (dpm)₃-substrate complexes were also discussed on the basis of the LIS data. The above two techniques in the PMR spectroscopy provided the confirmatory evidence for the structural and stereochemical determination of steroids and triterpenoids.