Molecular modelling of saccharide-lipid interactions

Certain saccharides, including trehalose, sucrose and glucose, stabilize lipid bilayers against dehydration. It has been suggested that these saccharides replace waters of hydration as the system is dried, thereby maintaining the headgroups at their hydrated spacing. The lipid acyl chains consequently have sufficient free volume to remain in the liquid crystallines state, and the processes that disrupt membrane integrity are inhibited. Initial molecular graphic investigations of a model trehalose/DMPC system supported this idea (Chandrasekhar, I. and Gaber, B.P. (1988) J. Biomol. Stereodyn, 5, 1163–1171). We have extended these studies to glucose and sucrose. A set of AMBER potential parameters has been established that reproduce simple saccharide conformations, including the anomeric effect. Extensive energy minimizations have been conducted on all three systems. The saccharide-lipid interaction energies become less stable in the order trehalose

Relatório de atividades : 2009

Acima do título: Relatório de atividades : 2009 : 53ª Legislatura : 3ª Sessão Legislativa.

板壳断裂力学

本书阐明了板壳断裂理论的基础。论证了Reissner型板壳断裂理论的科学性、经典板壳断裂理论的缺陷及在一定范围内仍具有的实用价值；介绍了作者所创意的研究Reissner型板壳断裂纹尖端场的方法等。

目录

Cartas enviadas por Misael Bañuelos a Justo Garate entre 1928 y 1930

3 cartas (mecanografiadas) ; entre 225x165 mm y 215x275 mm

Nuclear reactions leading to energy levels of Ar37 and K37

In view of recent interest in the Cl³⁷ (ʋ solar’^e-)Ar³⁷ reaction cross section, information on some aspects of mass 37 nuclei has been obtained using the K³⁹ (d, ∝) Ar³⁷ and Cl³⁵ (He³, p) Ar³⁷ reactions. Ar³⁷ levels have been found at 0, 1.41, 1.62, 2.22, 2.50, 2.80, 3.17, 3.27, 3.53, 3.61, 3.71, (3.75), (3.90), 3.94, 4.02, (4.21), 4.28, 4.32, 4.40, 4.45, 4.58, 4.63, 4.74, 4.89, 4.98, 5.05, 5.10, 5.13, 5.21, 5.35, 5.41, 5.44, 5.54, 5.58, 5.67, 5.77, and 5.85 MeV (the underlined values correspond to previously tabulated levels). The nuclear temperature calculated from the Ar³⁷ level density is 1.4 MeV. Angular distributions of the lowest six levels with the K³⁹ (d, ∝) Ar³⁷ reaction at E_d = 10 MeV indicate a dominant direct interaction mechanism and the inapplicability of the 2I + 1 rule of the statistical model. Comparison of the spectra obtained with the K³⁹ (d, ∝) Ar³⁷ and Cl³⁵ (He³, p) Ar³⁷ reactions leads to the suggestion that the 5.13-MeV level is the T = 3/2 Cl³⁷ ground state analog. The ground state Q-value of the Ca⁴⁰ (p, ∝) K³⁷ reaction has been measured: -5179 ± 9 keV. This value implies a K³⁷ mass excess of -24804 ± 10 keV. Description of a NMR magnetometer and a sixteen-detector array used in conjunction with a 61-cm double-focusing magnetic spectrometer are included in appendices.

利用耳石日轮技术研究长江中游草鱼幼鱼的孵化期及生长

根据耳石日轮对2004年采自洞庭湖和新滩口江段的草鱼幼鱼进行日龄(D)鉴定,孵化时间推算以及生长的研究。草鱼幼鱼所有样品体长(BL,mm)生长方程为BL=-53.4195+3.1650D,体重(W,g)生长方程为W=0.9816 e0.0633D,体长体重相关方程为W=0.00001BL3.1003。孵化时间最早为5月14日,最晚为7月11日,主要集中在5月下旬和6月份。研究发现三峡大坝在139m水位运行后长江中游仍有草鱼产卵,最早繁殖时间稍晚于历史记录。

铜、汞、镉、六六六和对硫磷对食蚊鱼生长的影响

对2日龄的食蚊鱼仔鱼的急性毒性,96小时LC_(50)是:铜,0.28毫克/升;汞,0.58亳克/升;镉,10.2毫克/升;六六六(丙体),0.53毫克/升;对硫磷,0.3毫克/升。依据20天的生长数据求得的铜、镉和对硫磷的最大允许毒物浓度分别是0.015—0.030、0.005—0.010和0.0015—0.0030毫克/升,相应的应用系数分别为0.05—0.1、0.0005—0.0009和0.005—0.01。

on a class of pseudorandom sequences from elliptic curves over finite fields

Following the idea of Xing et al., we investigate a general method for constructing families of pseudorandom sequences with low correlation and large linear complexity from elliptic curves over finite fields in this correspondence. With the help of the tool of exponential sums on elliptic curves, we study their periods, linear complexities, linear complexity profiles, distributions of r-patterns, periodic correlation, partial period distributions, and aperiodic correlation in detail. The results show that they have nice randomness.

Development of a self-thermal insulation miniature combustor

A novel miniature cylindrical combustor, whose chamber wall is made of porous material, has been designed and experimented for reducing heat loss and enhancing flame stability. The combustor has the function of reducing wall heat loss, extending residence time and avoiding radical chemical quenching with a self-thermal insulation concept in which heat loss reduction is obtained by the opposite flow directions between thermal energy transfer and mass flow. The methane/air mixture flames formed in the chamber are blue and tubular in shape. Between the flames and the porous wall, there is a thin unburned film that plays a significant role in reducing the flames' heat loss and keeping the flames stable. The porous wall temperature was 150-400 degrees C when the temperatures of the flames and exhaust gas were more than 1200 degrees C. When the equivalence ratio phi < 1.0, the methane conversion ratio was above 95%; the combustion efficiency was near 90%; and the overall sidewall heat loss was less than 15% in the 1.53 cm(3) chamber. Moreover, its combustion efficiency is stable in a wider combustion load (input power) range.

落叶松人工林养分循环与养分利用效率研究

通过对抚顺市温道林场20、53和69年生长白落叶松（Larix olgensis）人工林生物量和营养元素的积累与分配、养分利用效率和养分再吸收效率、养分生物循环的研究，探讨了长白落叶松生长发育不同阶段的养分生态学特征；对东北林业大学帽儿山实验林场17年生兴安落叶松（Larix gmelinii）人工林进行5年的施肥（NH4NO3，15 g•m-2•a-1），研究了施肥对人工林养分生物循环的影响。结果表明： （1）20、53和69年生单株落叶松生物量分别为33.14 kg•tree-1、311.42 kg•tree-1和408.46 kg•tree-1，随林龄的增长而增加。各器官生物量的分配格局为：树干>根>树枝>树皮>针叶。树干生物量的分配比例为50.16%~69.20%，随林龄的增长比例增大，而其他器官生物量的分配比例则逐渐减小。20、53和69年生单株落叶松净生产力分别为3.04 kg•tree-1•a-1、9.68 kg•tree-1•a-1和10.21 kg•tree-1•a-1，随林龄的增长而增大。针叶和树干的净生产力最大，分别占整株林木净生产力的40.07%~47.93%和27.32%~40.97%，并且随林龄的增长而增大。树枝、树皮和根的净生产力则表现出随林龄的增长呈抛物线状。 （2）20、53和69年生单株落叶松N、P、K、Ca、Mg等5种营养元素的总贮量分别为308.14 g•tree-1、2021.01 g•tree-1和2485.24 g•tree-1，随林龄的增长而增加。5种营养元素的贮量大小为：Ca>N>K>Mg>P。树干养分贮量的分配比例为19.74%~34.23%，随林龄的增长呈抛物线状。针叶、树枝和树皮的养分贮量占整株林木养分贮量的比例为35.16%~45.59%，建议在采伐木材时实施去皮、打枝等措施，留下针叶、树枝和树皮在林地中，让其自然分解以使营养元素重新归还利用，对于维持林地的养分平衡和长期生产力具有积极作用。 （3）20、53和69年生单株落叶松年吸收养分量分别为35.31 g•tree-1•a-1、97.83 g•tree-1•a-1和100.08 g•tree-1•a-1，随林龄的增长而增加。5种营养元素的年吸收量大小为：Ca>N>K>Mg>P。落叶松的养分利用效率随林龄的增长而增大，但生长到一定年龄阶段后，其养分利用效率逐渐趋于稳定。落叶松的最佳采伐年龄应为养分利用效率保持稳定时的年龄，此时采伐单位干材所带走的林地养分量较少。不同营养元素的利用效率不同，P的利用效率最高，Mg、K次之，N、Ca最低。不同器官的养分利用效率不同，树干的养分利用效率最高，其次是根、树枝、树皮，针叶最低。随着林龄的增长，树干和根的养分利用效率增大，而树枝和树皮的养分利用效率减小。 （4）落叶松叶片的N再吸收效率为50.76%~55.11%，随林龄的增长表现出增大的趋势；P和K再吸收效率分别为64.38%~68.85%和87.85%~90.62%，随林龄的增长表现出减小的趋势。从养分利用效率和养分再吸收效率综合判断，本研究区落叶松生长可能受土壤N、P、K供应的限制，3种营养元素的限制作用大小为：K>P>N。 （5）落叶松人工林养分的年吸收量、年存留量和年归还量分别为51.94~78.35 kg•hm-2•a-1、17.77~29.43 kg•hm-2•a-1和34.18~48.92 kg•hm-2•a-1，均随林龄的增长而减少，这与林分密度逐渐减小有关。5种营养元素的年吸收量和年存留量大小均为：Ca>N>K>Mg>P，年归还量大小为：Ca>N>Mg>K>P。落叶松人工林的养分循环速率为0.624~0.658，随林龄的增长而增大。5种营养元素的循环速率以Mg、N最快，Ca、P次之，K最慢。K的循环速率较低，可能与研究区土壤K含量较低而表现出的K再吸收效率较高有关。 （6）施肥导致落叶松叶片N再吸收效率显著降低，而凋落叶片的N浓度显著增加，从而使凋落叶片的C/N比由80.29降低到60.29。施肥林地凋落叶片C/N比的降低使其分解速率加快，有利于其养分归还土壤，从而加快了系统的养分循环速率，提高了系统的养分利用率。因此，在人工林经营中，施肥不仅能提高林地生产力，而且对于维持林地养分循环具有积极作用。

KGR的理化和酶学性质及提高Vc二步发酵转化率的研究

本文对Vc二步发酵Gluconobacter oxydans胞内2—酮基—L—古龙酸还原酶的分离纯化过程的第3步进行了改进，提高了酶的提取收率和提纯倍数。分析表明KGR由两个分子量分别为32,000道尔顿和53,000道尔顿的亚基组成，等电点为3.6，酸性氨基酸占22%。本文还对稀土元素化合物对KGR酶活的抑制作用进行了研究。发现稀土元素化合物和路易士酸组成的添加剂能缩短Vc二步发酵的时间6hr，发酵转化率可提高10%以上。

Crystallization and Si incorporation mechanisms of SAPO-34

In this study of the synthesis of SAPO-34 molecular sieves, XRD, SEM, XRF, IR and NMR techniques were applied to monitor the crystalloid, structure and composition changes of the samples in the whole crystallization process in order to get evidence for the crystallization as well as Si incorporation mechanism of SATO-34. XRD results revealed that the crystallization contained two stages. In the first 2.5 h (the earlier stage), high up to similar to80% of relative crystallinity could be achieved and the crystal size of SAPO-34 was almost the same as that of any longer time, indicating a fast crystallization feature of the synthesis. In this stage, IR revealed that the formation of SAPO-34 framework structure was accompanied by the diminution of hydroxyls, suggesting that crystal nuclei of SAPO-34 may arise from the structure rearrangement of the initial gel and the condensation of the hydroxyls. NMR results reveal that the template and the ageing period are crucial for the later crystallization of SAPO-34. Preliminary structure units similar to the framework of SAPO-34 have already formed before the crystallization began (0 h and low temperature). Evidence from IR, NMR, and XRF shows that the formation of the SAPO-34 may be a type of gel conversion mechanism, the solution support and the appropriate solution circumstance are two important parameters of the crystallization of SAPO-34. Meanwhile, NMR measurements demonstrated that about 80% of total Si atoms directly take part in the formation of the crystal nuclei as well as in the growth of the crystal grains in the earlier stage (<2.5 h). Evidence tends to support that Si incorporation is by direct participation mechanism rather than by the Si substitution mechanism for P in this stage (<2.5 h). In the later stage (>2.5 h), the relative content of Si increased slightly with a little decrease of Al and P. The increase of Si(4Al) and the appearance of the Si(3Al), Si(2Al), Si(1Al) and Si(OAl) in this stage suggest that substitution of the Si atoms for the phosphorus and for the phosphorus and aluminum pair takes place in the crystallization. The relationship among structure, acidity and crystallization process is established, which suggests a possibility to improve the acidity and catalytic properties by choosing a optimum crystallization time, thus controlling the number and distribution of Si in the framework of SAPO-34. (C) 2002 Elsevier Science Inc. All rights reserved.

温度、pH及干旱胁迫对沙地樟子松外生菌根菌生长影响

通过对采集于沙地樟子松人工林内的3种外生菌根真菌(牛肝菌Boletussp.、乳菇Lactariussp.、高环柄菇Macrolepiota procera)进行纯培养,在不同温度、pH值和PEG模拟干旱胁迫条件下,观测了外生菌根菌的生长发育状况。结果表明,3种外生菌根菌生物量在不同pH范围(3~7)内存在着显著差异(P<0.05);在低于5℃和高于37℃时,3种外生菌根菌均不能生长,其最适生长温度分别为:牛肝菌,25℃高环柄菇,25~28℃,乳菇,25~30℃;在低浓度PEG胁迫处理条件下(10%,-0.20MPa),3种外生菌根菌的生长均有所增加,当PEG胁迫达到30%(-1.53 MPa)时,3种外生菌根菌的生长均受到抑制。与上述结果比较,沙地樟子松人工林地土壤的实际pH值在外生菌根菌的最适生长范围内;林地最高气温值远远超过3种外生菌根菌的最适生长值的时间在每年的生长季都会出现;在极端干旱年份(如1996年),林地土壤的实际含水量在生长季节(5~9月)远远低于抑制外生菌根菌生长的土壤含水量,可能影响到外生菌根菌的生存。因此,可以推断,沙地樟子松人工林地的外生菌根菌的生长与发育,在干旱胁迫及高温作用下受到很大程度的影响,如果仅从微生物角度分析,外生菌根菌在干旱和高温条件下不能生长或已经死亡是导致沙地樟子松人工林衰退的一个原因。

Sol-gel-derived carbon ceramic electrode containing 9,10-phenanthrenequinone, and its electrocatalytic activity toward iodate

9,10-Phenanthrenequinone (PQ) supported on graphite powder by adsorption was dispersed in propyltrimethoxysilane-derived gels to yield a conductive composite which was used as electrode material to fabricate a PQ-modified carbon ceramic electrode. In this configuration, PQ acts as a catalyst, graphite powder guarantees conductivity by percolation, the silicate provides a rigid porous backbone, and the propyl groups endow hydrophobicity and thus limit the wetting region of the modified electrode. Square-wave voltammetry was exploited to investigate the pH-dependent electrochemical behavior of the composite electrode and an almost Nernstian response was obtained from pH 0.42 to 6.84. Because the chemically modified electrode can electrocatalyze the reduction of iodate in acidic aqueous solution (pH 2.45), it was used as an amperometric sensor for the determination of iodate in table salt. The advantages of the electrode are that it can be polished in the event of surface fouling, it is simple to prepare, has excellent chemical and mechanical stability, and the reproducibility of surface-renewal is good.