MULCH SURFACE COLOR AFFECTS ACCUMULATION OF EPICUTICULAR WAX ON DEVELOPING LEAVES

Abstract— Leaf waxes are important to plant growth because they impede water loss and may influence entry of light. Leaf wax quantity and composition were studied in Capsicum annuum plants in trickle-irrigated field plots covered with white, black or red plastic mulches. The quantity of reflected blue light (BL) was greatest over white and about the same over black versus red surfaces; and reflected far-red to red ratios (FR/R) were about the same over white versus black and higher over red. The greatest quantity of total epicuticular wax developed on leaves of plants grown over white mulch (443 μg/cm²) while plants grown over black and red mulches had 229 and 227 μg/cm², respectively. When individual lipid classes were expressed as percentages of the totals, esters constituted the highest percentages over white and black surfaces while secondary free fatty alcohols dominated over red. The higher ester content of epicuticular wax on plants grown over black (versus red) was almost exactly equalled by increased contents of free fatty alcohols and free fatty acids in the epicuticular wax of plants grown over red mulch. We conclude that the total wax concentration on leaves of field-grown plants was influenced by quantity of BL, and the percentage of individual components was influenced by the FR/R ratio.     

SPECTRAL ALBEDO MEASUREMENTS IN THE UV and VISIBLE REGION OVER DIFFERENT TYPES OF SURFACES

Abstract— The spectral albedo of the earth's surface, i.e. the ratio between spectral irradiance reflected by the ground to all directions and global irradiance, was measured by a spectroradiometer in the UV and visible region from 290 nm to 800 nm with a spectral resolution of 1.5 nm at steps of 2 nm in the UV (290–400 nm) and 10 nm in the visible (400–800 nm) region. The measurements were performed over bare fertile soil, sand at the beach, concrete (autobahn) and snow as well as over different types of vegetation (grass, oats, rye, sugar-beet, stubble). As the albedo increases with increasing wavelengths for most types of surfaces considered, it is smaller in the UV than in the visible region. In the UVB region (λ < 315 nm) the measured albedo is as small as 0.016-0.017 over vegetation, 0.04-0.05 over bare fertile soil, 0.07-0.10 over concrete ("autobahn") and 0.62-0.76% over polluted snow with a small wavelength dependence. A somewhat higher albedo occurs in the UVA region (315 < λ < 400 nm) with values ranging from 0.02 over vegetation to 0.05 to 0.08 over bare soil. The albedo over dry bright sand, which is typically found at the beach, is significantly higher (0.14 at 300 nm to 0.24 at 400 nm) than over other snow-free surfaces, thus leading to an enhanced dose of biologically effective radiation at the beach.     

丙烷在金属铁表面还原NO的实验研究

在程序控温电加热水平陶瓷管反应器、N2气氛和模拟烟气气氛以及300~1 100℃时,对丙烷在金属铁表面还原NO的特性进行了实验研究,并且与相同条件下甲烷在金属铁表面脱硝的效率进行了对比。结果表明,丙烷在金属铁表面能够高效地还原NO。N2气氛中在500~900℃,丙烷在金属铁表面的脱硝效率高于相同含量的甲烷脱硝效率,900℃以上丙烷在金属铁表面的脱硝效率超过95%,并且与甲烷的脱硝效率差别很小。模拟烟气条件下,当过量空气系数SR1小于1.0时,温度超过900℃后丙烷在金属铁表面还原NO的效率能够达到90%以上,且有、无燃尽的情况下,NO的还原率相差不大。在相同的条件下,丙烷在金属铁表面的脱硝效率高于相同条件下甲烷的脱硝效率。SO2对丙烷在金属铁表面还原NO的效率影响很小,可以忽略。     

前驱体分子结构对聚糠醇基碳膜微结构及气体分离性能的影响

分别以草酸(OA)和碘(I)两种催化剂合成聚糠醇(PFA)前驱体制备气体分离碳膜. 采用TG, FTIR和XRD对其微结构进行研究, 并通过纯组分气体的渗透实验对碳膜的分离性能进行了探讨. 研究结果表明, 在热解过程中, 两种结构的聚糠醇都是通过脱氧、重排、环化、芳构化等热分解和热缩聚反应逐渐转化为无定形的乱层碳结构, 但热分解反应过程明显不同, 所形成碳膜微结构的差异也很大. 草酸催化剂制备的聚糠醇碳膜的微晶Lc值比碘催化剂制备碳膜的大, 而d(002)和La值则比后者的小, 表明草酸催化剂制备的聚糠醇碳膜碳微晶片层数多、排列规则、结构缺陷和孔隙均小于碘催化剂制备的聚糠醇碳膜, 而且其气体分离选择性较高、渗透通量较小, 表明聚糠醇的分子结构对所制备碳膜的微结构及气体分离性能有很大影响.     

在超临界正己烷介质中的F-T合成反应行为

在固定床反应器中,以正己烷为超临界介质,研究了三种Co催化剂（浸渍、喷雾干燥、双模催化剂）上的F-T合成反应行为。在相同的Co质量分数下,喷雾干燥催化剂和双模催化剂的活性接近,都高于浸渍催化剂。在喷雾干燥催化剂上CO的转化率显著高于浸渍催化剂。喷雾干燥催化剂F-T产物中具有高的低碳选择性和低的1-烯烃质量分数,然而在相近的CO转化率下,喷雾干燥和浸渍催化剂具有类似的1-烯烃质量分数。对于浸渍催化剂,当Co质量分数从5％增加到15％,CO转化率从8.3％增加到43.6％。含Co5％的催化剂比质量分数为10％、15％、20％催化剂的甲烷选择性低2.0%～3.0%,但产物中1-烯烃的质量分数明显要高。     

Sequence recognition and self-sorting of a dipeptide by cucurbit[6]uril and cucurbit[7]uril

Cucurbit[7]uril forms very strong complex with zwitterionic dipeptide Phe-Gly with affinity exceeding 10(7) M(-1) and effectively recognizes peptide sequence of Phe-Gly over Gly-Phe as well as Tyr-Gly over Gly-Tyr and Trp-Gly over Gly-Trp with relative affinities of 23 000, 18 000 and 2000, respectively.     

The chemical nature of surface point defects on MoO3(010): adsorption of hydrogen and methyl.

We report density functional theory calculations using the Adaptive Coordinate Real-space Electronic Structure (ACRES) method of the terminal oxygen vacancy on the (010) surface of MoO3, within a (2 x 2) ordered array of vacancies on the surface. Analysis of the electronic structure of this surface shows that there are unoccupied dangling d(xz) and d(z)2 orbitals perpendicular to the surface that are created by the removal of terminal oxygen. The Mo-oxygen bonds surrounding the vacancy contract; however, the overall morphology of the surface is not drastically distorted. The vacancies alter the chemical character of the surface, as shown by studies of hydrogen and methyl binding. On both the "perfect" and vacancy surfaces, hydrogen was most strongly adsorbed over the terminal oxygen and most weakly bound over the symmetric bridging oxygen. Hydrogen is bound over the Mo atom, with a slightly smaller binding energy than hydrogen over the asymmetric bridging oxygen. The most favorable binding site for methyl on the vacancy surface is over the Mo atom exposed by removal of a terminal oxygen, whereas methyl bound to terminal oxygen is most stable on the perfect surface. There is no local minimum for adsorption over the symmetric bridging oxygen; instead, a methyl placed over this site moves toward the terminal oxygen vacancy. Analysis of the bonding shows that methyl is bound more strongly than hydrogen over the Mo atom because the C 2p orbital has better overlap with the Mo d(z)2 orbital than the hydrogen 1s. In addition, the steric repulsion observed for methyl over the perfect MoO3(010) surface is more easily relieved with the presence of the terminal oxygen vacancy.     

Methanol synthesis from CO2-H2 and from CO-H2 under atmospheric pressure over Pd and Cu catalysts

Under atmospheric pressure, methanol was produced from CO₂–H₂ over Pd/ZnO and from CO–H₂ over Pd/MgO catalyst. Similar support effects were observed over Cu catalysts.     

十氢萘在分子筛催化剂上的开环反应研究

在小型固定流化床(FFB)装置中研究了Y分子筛与ZSM-5分子筛催化剂上的十氢萘裂化开环反应性能,考察了温度和剂油比对Y分子筛开环反应催化性能的影响。结果表明,十氢萘在分子筛催化剂上通过环烷环开环反应生成丙烷、丙烯、丁烷、丁烯、甲基戊烷和环戊烷、环己烷等非芳烃以及苯、C_1~4烷基取代苯等单环芳烃,并通过脱氢缩合反应生成四氢萘、萘、甲基萘和菲、芘等多环芳烃甚至焦炭等。由于扩散和吸附性能的影响,ZSM-5分子筛催化剂的裂化开环反应选择性比Y分子筛催化剂的高,因此,十氢萘环烷环开环与脱氢缩合反应的相对比例(NRO/DHC)在ZSM-5分子筛催化剂上较高。在Y分子筛催化剂上,温度为450~550 ℃、剂油比为3~9,反应温度升高或者剂油比增加,双分子氢转移以及脱氢缩合反应增强,从而导致环烷环开环产物选择性降低。     

In Process Citation

Knowing the values of the equilibrium constants corresponding to the reactions N(2)O(4) right harpoon over left harpoon 2NO(2) and N(2)O(4) right harpoon over left harpoon NO(+) + NO(3)(-) in sulpholane, we have undertaken the electrochemical study of N(2)O(4) by means of linear and cyclic voltammetry at the platinum electrode. The N(2)O(4) species undergoes one oxidation step N(2)O(4) right harpoon over left harpoon 2NO(2) right harpoon over left harpoon 2NO(2)(+) + 2e and two reduction steps NO(2) + N(2)O(4) + e(-)right harpoon over left harpoon N(2)O(3) + NO(3)(-) (1st wave), followed by 3N(2)O(4) + 2e(-) right harpoon over left harpoon 2N(2)O(3) + 2NO(3)(-), N(2)O(4) + e(-) right harpoon over left harpoon NO + NO(3)(-), 2N(2)O(3) + e(-) right harpoon over left harpoon 3NO + NO(3)(-) (2nd wave). The redox properties of N(2)O(4) are complicated by trace quantities of water because of the formation of the electroactive species N(2)O(3), HNO(3) and HNO(2) according to N(2)O(4) + H(2)O right harpoon over left harpoon HNO(2) + HNO(3) and N(2)O(4) + HNO(2) right harpoon over left harpoon N(2)O(3) + HNO(3). The standard potentials of the couples concerned have been evaluated and are discussed. sont discutés et évalués.     

Asymmetric synthesis of N,O,O,O-tetra-acetyl d-lyxo-phytosphingosine, jaspine B (pachastrissamine), 2-epi-jaspine B, and deoxoprosophylline via lithium amide conjugate addition

The highly diastereoselective anti-aminohydroxylation of (E)-gamma-tri-iso-propylsilyloxy-alpha,beta-unsaturated esters, via conjugate addition of lithium (S)-N-benzyl-N-(alpha-methylbenzyl)amide and subsequent in situ enolate oxidation with (+)-(camphorsulfonyl)oxaziridine, has been used as the key step in the asymmetric synthesis of N,O,O,O-tetra-acetyl d-lyxo-phytosphingosine (20% yield over 7 steps), the anhydrophytosphingosine jaspine B (10% yield over 9 steps), 2-epi-jaspine B (14% yield over 9 steps), and the Prosopis alkaloid deoxoprosophylline (26% yield over 7 steps).     

Fourier — Transform Infrared Studies on Coke Formation Over Alumina Silica-Alumina and Zeolites

Results of the FT-IR studies have shown that the carbonaceous deposit formed over -Al₂O₃ has carboxylate character, while that formed over silica-alumina and HX zeolite is a mixture of the above and conventional (aromatic) coke. The deposit formed over HZSM-5 zeolite is composed mainly of conventional coke, however, species containing acetyl groups were also present. No carbonaceous deposit forms over A zeolite.     

Highly selective ammonia synthesis from nitrate with photocatalytically generated hydrogen on CuPd/TiO2

Body-centered-cubic type CuPd nanoalloys were synthesized by a chemical reduction method. Photocatalytic hydrogen evolution and nitrate reduction were simultaneously examined over CuPd nanoalloys deposited on TiO(2) (CuPd/TiO(2)). The efficiency of hydrogen evolution over CuPd/TiO(2) was better than that over Pd/TiO(2). As for nitrate reduction, ammonia was selectively (78%) produced with hydrogen generated photocatalytically over CuPd/TiO(2). The continuous generation of nascent hydrogen atoms on the surface of the CuPd nanoalloy, where Cu and Pd are homogeneously mixed, led to the high selectivity for ammonia.     

甲烷在SrO-La2O3/CaO催化剂上的氧化偶联Ⅱ.反应动力学的研究

在２０％Ｌａ２Ｏ３／ＣａＯ（ＬＣ）催化剂中添加ＳｒＯ（添加ＳｒＯ的ＬＣ以ＳＬＣ表示）明显地提高了反应活性和Ｃ２选择性。反应动力学研究表明，ＬＣ和ＳＬＣ催化剂在甲烷氧化偶联反应中，在表观活化能和表观反应级数上存在很大的差异。ＬＣ催化剂在ＣＨ４转化以及Ｃ２和ＣＯｘ形成过程中，表观活化能大于ＳＬＣ催化剂，而ＳＬＣ催化剂的指前因子小于ＬＣ体系，两者存在着补偿形象。ＳＬＣ催化剂的反应速率常数比ｋｃ２／ｋＣＨ     

The thermodynamic parameters of solution of L-phenylalanine in water

The heat effects of solution of L-phenylalanine in water were measured over wide concentration and temperature ranges. The enthalpies of solution of L-phenylalanine were found to be independent of the content of the amino acid in solution over the concentration range studied. The standard enthalpies, heat capacities, and entropies of solution of the amino acid and the solubility of L-phenylalanine over the temperature range studied were calculated.     

Reaction of N-(2-hydroxyethyl) ethylenediamine over zeolite and chromite catalysts

N-(2-hydroxyethyl) ethylenediamine reaction was observed over zeolite catalysts giving rise to only dehydrocyclization and over chromite catalysts showing dehydrocyclization together with dehydrogenation. The major product changes from the cyclized compound piperazine to pyrazine when the reactant is switched from zeolite to chromite catalyst. This process stands as a model reaction for characterizing lone acid sites and adjacent acid-base sites over zeolite and chromite catalysts, respectively.IICT Communication No. 3175     

全氢菲在分子筛催化剂上环烷环开环反应的研究

在小型固定流化床(FFB)装置上考察了Y与ZSM-5分子筛催化剂以及Y分子筛催化剂上温度、剂油比对全氢菲裂化环烷环开环反应的影响。结果表明,全氢菲在分子筛催化剂上通过环烷环开环反应生成环己烷、十氢萘等单环或双环环烷烃;单环或双环环烷烃进一步侧链断裂生成2-甲基戊烷、甲基己烷等异构烷烃等,异构化生成二甲基环戊烷、甲乙基环戊烷等烷基环戊烷,氢转移生成苯、甲苯、二甲苯等烷基苯,进行深度氢转移反应生成萘、烷基萘等双环芳烃;另外,全氢菲也会通过脱氢缩合生成菲、芘等三环以上芳烃甚至焦炭等。由于扩散和吸附性能的影响,其裂化开环反应的选择性在Y分子筛催化剂上比在ZSM-5分子筛催化剂上高。因此,全氢菲环烷环开环与脱氢缩合反应的相对比例(s(NRO)/s(DHC))在Y分子筛催化剂上较高;在Y分子筛催化剂上,温度为475~550 ℃、剂油比为3.0~9.0,反应温度升高或者剂油比增加,双分子氢转移以及脱氢缩合反应增强,导致环烷环开环反应产物选择性降低。     

Pt/Al2O3和Pt-Cu/Al2O3催化CCl4氢化脱氯反应

制备了Al2O3负载Pt单金属催化剂和负载Pt-Cu双金属催化剂,比较了二者不同还原温度对其催化CCl4氢化脱氯反应性能的影响。 单金属Pt催化剂上主要生成CHCl3,而双金属Pt-Cu催化剂上产物随催化剂制备时的还原温度不同而异,当催化剂经400 ℃用H2还原后产物主要为CHCl3,而当催化剂经800 ℃用H2还原后产物主要为CCl2CCl2。 由于CCl4氢化反应是强放热反应,催化剂表面局部过热使得在反应中生成的C2等产物聚合结焦,覆盖了催化剂的活性中心,导致催化剂失活。 因此,通过加入甲醇作为稀释剂以带走部分反应热可提高催化剂的稳定性。 同时也降低了CHCl3的选择性,提高了CCl2CCl2的选择性。     

Ni催化剂上一氧化碳加氢反应机理研究

Ｎｉ催化剂上一氧化碳加氢反应机理研究胡云行，万惠霖，关玉德，林恒生（厦门大学化学系，固体表面物理化学国家重点实验室，厦门，３６１００５）（中国科学院山西煤炭化学研究所，太原）关键词脉冲法，一氧化碳，加氢，反应机理自本世纪初报道了一氧化碳加氢生成甲烷以...     

Dielectric spectroscopy at microwave frequencies

A method is described which is capable of measuring the dielectric properties of liquids as a continuous function of frequency over the range 10 MHz to 18 GHz; an evaluation is made of its performance over the frequency range up to 4.2 GHz. The method described has substantial advantages in ease of operation and evaluation of results over the conventional “spot” frequency and time-domain spectrometer techniques.