(4aR, 8aS, 9aR, 10aS)-8a, 9a-Difluoro-1,4,4a, 5,8,8a, 9,9a, 10,10a-decahydroanthracene-4a, 10a-diol hemihydrate

The title compound, C(14)H(18)F(2)O(2)center dot 0.5H(2)O, a hemihydrate of a C(s)-symmetric unsaturated difluorodiol, crystallizes in the centrosymmetric space group P2/m (Z = 4). The asymmetric unit contains two crystallographically independent difluorodiol half-molecules, occupying the mirror planes at (x, 0, z) and (x, 1/2, z), and half a molecule of water, lying on the twofold axis at (0, y, 0). Four difluorodiol molecules self-assemble around each solvent water molecule via O-H center dot center dot center dot O hydrogen bonds in a near tetrahedral symmetry to generate a cylindrical column-like architecture.

(1S*,3S*,8S*,10S*)-10-Fluoro-15-oxatetracyclo[6.6.1.0(1,10).0( 3,8)]pentadeca-5,12-dien-3-ol

The title compound, C(14)H(17)FO(2), was obtained from anti-4a, 9a:8a,10a-diepoxy-1,4,4a,5,8,8a, 9,9a, 10,10a-decahydroanthracene via tandem hydrogen-fluoride-mediated epoxide ring-opening and transannular oxacyclization. With the two cyclohexene rings folded towards the oxygen bridge, the title tetracyclic fluoroalcohol molecule displays a conformation reminiscent of a pagoda. The crystal packing is effected via intermolecular O-H center dot center dot center dot O hydrogen bonds, which link the molecules into a zigzag chain along the b axis.

N-(2-Amino-3,5-dibromobenzyl)-N-methylcyclohexan-1-aminium p-toluenesulfonate

The title compound, C(14)H(21)Br(2)N(2)(+)center dot C(7)H(7)O(3)S, features a salt of protonated bromhexine, a pharmaceutical used in the treatment of respiratory disorders, and the p-toluenesulfonate anion. The crystal packing is stabilized by intermolecular N-H center dot center dot center dot O, N-H center dot center dot center dot Br and C-H center dot center dot center dot O hydrogen bonds.

Structural characterization of backbone-expanded helices in hybrid peptides: (αγ) n and (αβ) n sequences with unconstrained β and γ homologues of L-Val

Learning your αβγ's: The diversity of hydrogen-bonding patterns in backbone-expanded hybrid helices is shown by crystal-structure determination of several oligomeric peptides (see scheme; C=gray; H=white; O=red; N=blue). C 12 helices were observed in the αγ peptide series for n=2-8. In comparison, the αα peptide and αβ peptide sequences show C 10 and mixed C 14/C 15 helices, respectively. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel tetranuclear distorted open-cubane copper complex containing oximate bridges: Synthesis, crystal structure, DNA binding and cleavage activity

The synthesis, molecular structure, DNA binding and nuclease activity of Cu4O4 open-cubane tetranuclear copper(II) complex with 3-2-(ethyl amino)ethyl]imino]-2-butanoneoxime (HL) are reported for the first time. The neutral tetranuclear Cu4L4(ClO4)(4)] complex crystallizes in tetragonal space group P (4) over bar2(1)c with the unit cell parameters; a = 13.798(4) angstrom, b = 13.798(4) angstrom, c = 14.119(6) angstrom, V = 2688(16) angstrom(3), Z = 8, R = 0.0636. Symmetrically equivalent copper atoms exhibit a CuN3O3 elongated distorted octahedral coordination environment, with three nitrogen atoms of the L ligand and one oxime-oxygen atom of second L ligand at equatorial positions, one oxime-oxygen atom of the third L ligand and perchlorate oxygen at axial positions. The complex shows quasireversible cyclic voltammetric response at 0.805 V (Delta E-p = 277 mV) at 100 mV s (1) in DMF for the Cu(II)/Cu(I) redox couple. The binding study of the complex with calf-thymus DNA has been investigated using absorption spectrophotometry. The complex shows strong nuclease activity on stranded pBR 322 plasmid DNA in the presence of hydrogen peroxide and marginal nuclease activity in the presence of reducing agent (dithiothreitol). (C) 2012 Elsevier B. V. All rights reserved.

Origin of grand minima in Sunspot cycles

One of the most striking aspects of the 11-year sunspot cycle is that there have been times in the past when some cycles went missing, a most well-known example of this being the Maunder minimum during 1645-1715. Analyses of cosmogenic isotopes (C-14 and Be-10) indicated that there were about 27 grand minima in the last 11 000 yrs, implying that about 2.7% of the solar cycles had conditions appropriate for forcing the Sun into grand minima. We address the question of how grand minima are produced and specifically calculate the frequency of occurrence of grand minima from a theoretical dynamo model. We assume that fluctuations in the poloidal field generation mechanism and in the meridional circulation produce irregularities of sunspot cycles. Taking these fluctuations to be Gaussian and estimating the values of important parameters from the data of the last 28 solar cycles, we show from our flux transport dynamo model that about 1-4% of the sunspot cycles may have conditions suitable for inducing grand minima.

Structural characterization of folded and extended conformations in peptides containing gamma amino acids with proteinogenic side chains: crystal structures of gamma(n), (alpha gamma)(n) and gamma gamma delta gamma sequences

The crystal structures of nine peptides containing gamma(4)Val and gamma(4)Leu are described. The short sequences Boc-gamma(4)(R)Val](2)-OMe 1, Boc-gamma(4)(R)Val](3)-NHMe 2 and Boc-gamma(4)(S)Val-gamma(4)(R)Val-OMe 3 adopt extended apolar, sheet like structures. The tetrapeptide Boc-gamma(4)(R)Val](4)-OMe 4 adopts an extended conformation, in contrast to the folded C-14 helical structure determined previously for Boc-gamma(4)(R)Leu](4)-OMe. The hybrid alpha gamma sequence Boc-Ala-gamma(4)(R)Leu](2)-OMe 5 adopts an S-shaped structure devoid of intramolecular hydrogen bonds, with both alpha residues adopting local helical conformations. In sharp contrast, the tetrapeptides Boc-Aib-gamma(4)(S)Leu](2)-OMe 6 and Boc-Leu-gamma(4)(R)Leu](2)-OMe 7 adopt folded structures stabilized by two successive C-12 hydrogen bonds. gamma(4)Val residues have also been incorporated into the strand segments of a crystalline octapeptide, Boc-Leu-gamma(4)(R)Val-Val-(D)Pro-Gly-Leu-gamma(4)(R)Val-Val-OMe 8. The gamma gamma delta gamma tetrapeptide containing gamma(4)Val and delta(5)Leu residues adopts an extended sheet like structure. The hydrogen bonding pattern at gamma residues corresponds to an apolar sheet, while a polar sheet is observed at the lone delta residue. The transition between folded and extended structures at gamma residues involves a change of the torsion angle from the gauche to the trans conformation about the C-beta-C-alpha bond.

Diagnóstico sobre la producción y comercialización de los productos lacteos en el municipio de San Pedro de Lóvago, Chontales, Nicaragua

El trabajo fue realizado en la época de verano en el municipio de San pedro de Lóvago, Chontales donde se encuestó el 10% de los productores. La población total del municipio es de 7,125 habitantes, donde la mayoría viven en zonas rurales; la principal base de subsistencia es la ganadería siendo su principal fuente de trabajo.Es un municipio con alto potencial en su producción de leche y ocupando el segundo lugar en el departamento de chontales, cuenta con 46269 cabezas de ganado en todo el municipio con un rendimiento promedio de cuatro litros de leche por vaca y su explotación es de doble propósito, pastoreo directo y extensivo. Las prácticas de manejo, sanidad, alimentación y reproducción siguen siendo las mismas de manera tradicional. Aun no existe en la mayoría de los productores interés al cambio, los resultados muestran que la producción total de leche diaria en el municipio durante el verano es de 10,393.25 galones a diario y en invierno es de 12,000 galones aproximados. Los productores que mas elaboran en el municipio son: queso mosarela, queso moralique, cuajadas, crema, queso palmito y quesillos. El precio de la leche varia según la épocas del año siendo en verano el mejor precio pagado (C$ 14.00 por galón) debido a que existe una poca producción de leche en caso contrario en invierno que es cuando se produce el "golpe de leche" y el precio llega alcanzar hasta (C$ 4.00 por galón). La parmalat es la única empresa que recolecta leche en las cooperativas: Manantial con 1,400 galones a diario y la cooperativa San pedro con 1,104.25 galones a diario para un total de 2,504.25 en verano y 5,008.5 galones en invierno, la cual mantiene durante todo el año el precio estable por galón de C$ 12.00. La comercialización se empieza desde el productor hasta el consumidor final a través de una cadena de intermediarios. La mayor pate de los productos van destinados a la capital (80%) y otra parte se exportan a El Salvador (20%) de manera directa. La producción anual de carne en el municipio es alrededor de 3,000 kilogramos siendo los principales acopiadores o centro de venta de. novíllo de modalidad canal caliente y en pie. El matadero MASESA con un 30% de la producción total, el matadero Nandaime con 20%, el matadero CARNIC con un 10%, los corrales de tipitapa 30% y los matarifes con el 10% restante de cabezas d ganado bovino.

Diagnostico histopatologico de lesiones hepaticas en bovinos faenados en el rastro municipal de Esteli en el periodo de marzo a agosto de 2008

Con el presente trabajo se pretende conocer las lesiones de hígados bovinos decomisados (condenados) en el Rastro Municipal de Estelí del año 2008 y la realización de su diagnóstico histopatológico utilizando la técnica de tinción Hematoxilina. Eosina, además de ampliar los conocimientos de patología bovina en Nicaragua. El Rastro municipal está ubicado al norte de la ciudad en su periferia y en el actual límite del casco urbano. Los datos del presente estudio se obtuvieron de los registros de los animales faenados por mes y los datos de hígados decomisados (condena dos) se obtuvo de la inspección post-mortem del rastro municipal de Estelí lo cual es realizado por el médico veterinario oficial que depende de la alcaldía, dichos datos fueron recopilados en el período comprendido de marzo a agosto del año 2008. El presente estudio fue de tipo descriptivo donde se hicieron los análisis frecuenciales de las distintas variables evaluadas como categoría, clasificación macroscópica y microscópica, pérdidas económicas. Se encontró que de los 59 casos de hígados condenados representa el 4.16% de animales afectados por diversas patologías. Los resultados encontrados según categorías de los animales afectados fueron: 42 Vacas representaron el 71.18%, 16 Vaquillas el 27.11 % y e1 1.69% un Buey. A los cuales se le designó valor numérico 1-Vaquilla; 2-Vaca; 3-Buey. De los 59 bovinos afectados por Afecciones hepáticas, el 51% presentaron hepatitis, el 12% se refiere peri hepatitis, 10% a hepatitis telangiectasia, 5% a hepatitis pigmentación 3.4% hepatitis crónica, hepatitis absceso, peri hepatitis fibrinosa y absceso, y los rangos de 1.7% corresponden a hemorragia, adherencia, telangiectasia absceso, combina 1 y 9, (hepatitis focal crónica, degeneración, hiperplasia de canalículos biliares) 7 y 9 (degeneración, hemorragia, hiperplasia de canalículos biliares). Las pérdidas económicas por la cantidad hígados condenados fue de C$ 14, 160.00 córdobas que en dólares equivale a US$ 734.013.00 de acuerdo a la tasa de cambio del período estudiado.

The ontogeny of haematopoiesis in the marine teleost Leiostomus xanthurus and a comparison of the site of initial haematopoiesis with Opsanus tau

The ontogeny of haematopoiesis in the perciform fish, spot Leiostomus xanthurus, differed from that reported as the norm for fishes, as exemplified by the cypriniform zebrafish Danio rerio, and observed in the batrachoidiform oyster toadfish Opsanus tau. Erythropoiesis in spot was first evident in the head kidney of yolk-sac larvae 3 days after hatching (DAH). No embryonic intermediate cell mass (ICM) of primitive stem cells or blood islands on the yolk were apparent within embryos. Erythrocytes were first evident in circulation near the completion of yolk absorption, c. 5 DAH, when larvae were c. 20 mm notochord length (LN). Erythrocyte abundance increased rapidly with larval development for c. 14 to 16 DAH, then became highly variable following changes in cardiac chamber morphology and volume. Erythrocytic haemoglobin (Hb) was not detected within whole larvae until they were 12 DAH or c. 31 mm LN, well after yolk and oil-globule absorption. The Hb was not quantified until larvae were >47 DAH or >7 mm standard length. The delayed appearance of erythrocytes and Hb in spot was similar to that reported for other marine fishes with small embryos and larvae. In oyster toadfish, a marine teleost that exhibits large embryos and larvae, the ICM and Hb were first evident in two bilateral slips of erythropoietic tissue in the embryos, c. 5 days after fertilization. Soon thereafter, erythrocytes were evident in the heart, and peripheral and vitelline circulation. Initial haematopoiesis in oyster toadfish conformed with that described for zebrafish. While the genes that code for the development of haematopoiesis are conserved among vertebrates, gene expression lacks phylogenetic pattern among fishes and appears to conform more closely with phenotypic expression related to physiological and ecological influences of overall body size and environmental oxygen availability.

Spin dynamics of pulsed nuclear magnetic double resonance in solids

In the first part of this thesis, experiments utilizing an NMR phase interferometric concept are presented. The spinor character of two-level systems is explicitly demonstrated by using this concept. Following this is the presentation of an experiment which uses this same idea to measure relaxation times of off-diagonal density matrix elements corresponding to magnetic-dipole-forbidden transitions in a ^(13)C-^1H, AX spin system. The theoretical background for these experiments and the spin dynamics of the interferometry are discussed also.

The second part of this thesis deals with NMR dipolar modulated chemical shift spectroscopy, with which internuclear bond lengths and bond angles with respect to the chemical shift principal axis frame are determined from polycrystalline samples. Experiments using benzene and calcium formate verify the validity of the technique in heteronuclear (^(13)C-^1H) systems. Similar experiments on powdered trichloroacetic acid confirm the validity in homonuclear (^1H- ^1H) systems. The theory and spin dynamics are explored in detail, and the effects of a number of multiple pulse sequences are discussed.

The last part deals with an experiment measuring the ^(13)C chemical shift tensor in K_2Pt(CN)_4Br_(0.3) • 3H_2O, a one-dimensional conductor. The ^(13)C spectra are strongly affected by ^(14)N quadrupolar interactions via the ^(13)C - ^(14)N dipolar interaction. Single crystal rotation spectra are shown.

An appendix discussing the design, construction, and performance of a single-coil double resonance NMR sample probe is included.

外源草酸对采后果实的保鲜效应及其生理机理研究

本文以桃(Prunus persica L. cv. Bayuecui.)栽培种‘八月脆’和芒果（Mangifera indica L.）栽培种‘圣心’为材料，研究外源草酸对采后果实的生理生化效应及其作用机理，为果实贮藏保鲜提供新方法。采后桃果实用1、5 mM的草酸溶液浸果10 min，以浸水10 min为对照，然后在常温下贮藏，测定果实在贮藏期间对草酸处理的一些生理生化反应。芒果经采后杀菌剂（post- P）、采后草酸（post-OA）、采前＋采后草酸（pre-OA + post-OA）、采前Ca ＋ 采后草酸处理（pre-Ca + post-OA）处理，以采后浸水为对照，然后分别将果实在常温(25 C)、低温（14 C）和控制性气调（3% CO2 + 2% O2 ，14 ± 1 C）下贮藏，测定草酸处理对芒果的成熟进程、病情发展及其相关生理指标的影响。研究结果表明如下： 1．与对照相比，草酸处理的桃果实在贮藏期间果实的电解质渗漏量和呼吸速率降低、果实硬度高、果实的抗氧化酶（超氧化物岐化酶、SOD;过氧化物酶，POD;过氧化氢酶、CAT;抗坏血酸过氧化物酶、APX）和多酚氧化酶（PPO）活性提高、脂氧合酶（LOX）活性降低。同时，在贮藏后期，果实的活性氧自由基（ROS）产量（超氧阴离子、O2.;过氧化氢、H2O2)和丙二醛（MDA）含量降低。草酸的这些生理效应有利于保持膜的完整性和延缓桃果实的成熟;草酸诱导POD、SOD、PPO活性可能有助于提高采后果实的抗病性。 2．外源5、10 mM浓度的草酸（pH值中和或不中和）对芒果炭疽病原菌（Colletotrichum gloeosporioides）孢子萌发和菌丝生长均表现出显著的抑制作用。这种作用不仅与草酸降低培养基（PDA）的pH值相关，而且与草酸独特的化学特性相关。 3．在常温、低温和控制性气调贮藏下，采后草酸、采前 + 采后草酸、采前Ca + 采后草酸处理均能有效减缓芒果果实的软化速率，延缓芒果的成熟进程，降低芒果的病情指数，同时改善芒果成熟时的表皮着色，对果实完全后熟时的可溶性固形物（SSC）、可滴定酸（TA）含量、果肉口感均没有产生负面的影响。 4．草酸处理增强芒果细胞膜的稳定性，诱导提高芒果抗氧化酶活性，特别是提高果皮SOD、APX活性，降低LOX活性，以及降低果皮O2.、H2O2 和果肉H2O2含量，抑制采后果实的乙烯生物合成。这些生理生化效应与延缓芒果的成熟衰老和提高果实的抗病性相关。 5． 采后草酸、采前 + 采后草酸和采前Ca + 采后草酸处理表现出高效低廉、无毒无副作用、易操作等优点，是芒果采后贮藏保鲜的可供选、具有实际应用前景的新方法。

细菌视紫红质的构象模拟和视黄醛的顺反异构模型

在细菌视紫红质构象模拟的基础上提出了一个视黄醛顺反异构模型。该模型中视黄醛的C~(13)—C~(14)与Lys—216的C~(δ)—C~(ε) 处于一直线上, 这样, 顺反异构只涉及视黄醛C~(15)和Lys—216的N~(ζ)绕此直线为轴的旋转。理论计算表明, 这是一种空间障碍最小的模型, 并能通过Asp—96和Asp—212传递质子。图3表2参10

直链烷基苯磺酸盐在模拟水生态系统中转化和归宿的研究

用~(14)C标记直链烷基苯磺酸盐,(~(14)C-LAS),研究了在由塘泥、水草、鱼、螺蛳和溞构成的室内模拟水生态系统中,LAS的降解规律、在水生生物体内的积累分布及其与在水中降解之间的相互关系.