Carbohydrates as chiral templates: asymmetric ugi-synthesis of alpha-amino acids using galactosylamines as the chiral matrices

1988

Abstract In the presence of Lewis acid catalysts O-acetyl- (1) and O-pivaloyl- (2) protected β-D-galactopyranosylamines react with aldehydes, isocyanides and carboxylic acids in Ugi-four-component-condensations to give the corresponding N-galactosyl-amino acid amide derivatives 3,5 in almost quantitative yields. Zinc chloride is the most effective Lewis acid catalyst. At 0°C or even at room temperature the (2R,β-D)-diastereomers of the amino acid derivatives 3,5 are formed with high diastereoselectivity. If the sterically more demanding O-pivaloyl galactosylamine 2 is used at -78°C to -25°C the stereoselectivity often exeeds 20:1 favouring the (2R,β-D) diastereomers 5. After one recrystalli…

Diskussion zu den Referaten Eberbach, Hirsch und Eser

1988

Lempp: Herr Hirsch hat mich am Schlus sehr direkt angesprochen, und ich mochte auch sehr direkt antworten. Er hat die Regelungsnotwendigkeit und die Gefahr des Misbrauchs fur den Fall einer fehlenden Regelung betont.

Reversal of asymmetric induction in stereoselective strecker synthesis on galactosyl amine as the chiral matrix

1988

Abstract The reversal of the direction of asymmetric induction in Lewis acid catalyzed Strecker synthesis using the 2,3,4,6-tetra-O-pivaloyl-β-D-galactopyranosyl amine 1 is described. In isopropanol or tetrahydrofuran 1 had given ( R )-diastereomers of the corresponding α-amino nitriles preferably. However, in chloroform in the presence of heterogeneous zinc chloride the same auxiliary alternatively leads to an excess of the ( S )-diastereomers.

Monte Carlo Simulations of Polymer Systems

1988

The impact of Monte Carlo “computer experiments” in polymer physics is described, emphasizing three examples taken from the author’s research group. The first example is a test of the classical Flory—Huggins theory for polymer mixtures, including a discussion of cricital phenomena. Also “technical aspects” of such simulations (“grand-canonical” ensemble, finite—size scaling, etc.) are explained briefly. The second example refers to configurational statistics and dynamics of chains confined to cylindrical tubes; the third example deals with the adsorption of polymers at walls. These simulations check scaling concepts developed along the lines of de Gennes.

Pathophysiology of Tumors in Hyperthermia

1988

The response of tumor cells to hyperthermia is critically influenced by a number of pathophysiological factors both in vitro and in vivo. The most relevant factors in this context are tumor blood flow, tissue oxygenation, the energy status, and the pH distribution, which in turn define the cellular microenvironment.

Condotta di singoli organi e condotta dell’apparato statale in tema di colpa nell’illecito internazionale

1988

In questo scritto si dimostra che l'elemento della colpa nell'illecito internazionale (inteso come "colpevolezza") è difficilmente compatibile con la struttura complessa dell'organizzazione dello Stato contemporaneo. La dimostrazione è essenzialmente condotta con riferimento alla giurisprudenza della Corte di giustizia delle comunità europee in tema di violazione dei trattati o di regolamenti da parte degli Stati. Viene altresì sottolineato che un tale risultato è in linea con l'evanescenza delle cause di invalidità dei trattati concernenti la volontà di singoli organi partecipanti al processo di stipulazione. The idea is advanced that state fault - understood as an essential precondition f…

Una nota sull’Emporos di Filemone

1988

Ho cercato di dimostrare,contrariamente a quanto sostengono alcuni studiosi, che protagonista della commedia greca,così come avviene nel Mercator di Plauto è Carino e non Demifone.

Displasia espondiloepifisaria tarda : presentación familiar

1988

Los autores presentan un caso de Displasia Espondiloepifisaria Tarda, de presentación familiar y afectando sólo a las mujeres. Se revisa las principales manifestaciones clínicas y radiográficas. El estudio citogenético revela que se trata de una forma de transmisión diferente a la considerada clásica por la mayoría de autores.

Quiste óseo esencial : comparación del tratamiento quirúrgico con la inyección intraquística de corticoides

1988

The results obtained from the study of seventeen cases of unicameral bone cyst surgically treated are compared with the results in sixteen cases treated with intracyst corticosteroid injection. However, although there is a great proportion of the healed cysts injected, the healing is more secure with surgery. The cyst activity is the most important factor in bad results with surgical treatment, but not in final results obtained in a cyst treated with intracyst corticosteroid injection. It is recommended to control the distribution of the corticosteroid inside the cyst on previous injection of radiographic contrast.

Error Estimates and Automatic Adaptive Mesh Refinement for the Metal Forming FEM Analysis

1988

The Authors propose a new technique which enables a estimation of the error inherent with the FEM analysis of metal forming processes. The aim is to evaluate the zones where the error is higher in order to proceed to a refinement of the mesh in such zones, and to obtain a smaller value of the global error. Moreover, to simplify the analyst work in the progressive refinement of the mesh, it has been prepared a software able to read the drawing created by a CAD program and to generate, automatically, all the geometrical and topological data necessary to perform the analysis on Personal Computer. The automatic renumbering of the elements in the refined mesh has been performed with the aim to r…

Prebiotic Evolution and the Origin of Life: Chemical and Biochemical Aspects

1988

Evolution, as the term is used here, signifies any development or change adapting to the environment. Chemical evolution connotes changes of chemical substances, it thus signifies that changes occur fundamentally in the molecules. Frequently “chemical evolution” is used synonymously for “abiotic” or “prebiotic formation” of organic molecules in a cosmic system, usually on the prebiotic (or primitive) Earth. It is then assumed that the organic molecules were formed from the constituents of the primitive atmosphere, hydrosphere, and — in part — lithospere.

New adsorbents for thymidylate synthase affinity chromatography

1988

New affinity adsorbents, intended for chromatography of thymidylate synthase (EC 2.1.1.45) from different sources, consisting of p-[N-[(2-amino-4-hydroxy-6-quinazolinyl)-methyl]-N-2-propynylamino]benzoyl-γ-[α-(3-carboxypropylamino)]glutamyl-glutamyl immobilized either on macroporous copolymer of acrylonitrile and n-butyl acrylate or on macroporous polymer of acrylonitrile itself, both crosslinked with divinylbenzene and having aminoethyl groups, were obtained. Both adsorbents were found to be effective in dUMP-dependent binding of thymidylate synthase from regenerating rat liver.

El arco romano de Cabanes (Castellón)

1988

Se estudia un arco romano cerca de Cabanés (Castellón), conocido a través de dibujos del siglo XVIII, pero que ha sido objeto de poca atención con posterioridad. Se propone una posible reconstrucción y se realizan algunas consideraciones acerca de su fecha y función. El estudio del tipo del monumento, su ubicación y la comparación con otros arcos similares, principalmente en el norte de África, nos permite proponer una fecha en torno a finales del siglo II o comienzos del III d. c., y una función como arco honorario-funerario.

Trait anxiety and parental child-rearing behavior: Support as a moderator variable?

1988

Abstract Based on central assumptions of the social support literature and on formulations concerning the construction of competence and consequence expectancies, a model for the interaction of maternal and paternal child-rearing behavior in the development of children's trait anxiety is presented. Hypotheses concerning this model are tested empirically; 160 boys and 169 girls (aged 12–14 years) responded to the “Erziehungsstil-Inventar” (“Child-Rearing Inventory”), which serves as a measure of child-rearing styles as perceived by the child, as well as to a German adaptation of the “State-Trait Anxiety Inventory for Children”. General relations between the variables were analyzed by means o…

A laser ion source for trace analysis

1988

A laser ion source has been set up which is based on resonant stepwise excitation and ionization of atomic vapor confined in an ionization chamber. Using a pulsed copper vapor/dye laser system with a high repetition rate (6.5 kHz) one expects high efficiency and high selectivity for this new type of ion source. First test experiments with lead are reported.

Carcinoma of the lung, stage III. Experience with the new TNM-AJCC classification.

1988

The records of 228 patients who underwent surgery for primary lung cancer in 1970–1986 were reviewed. In 115 cases (94 men, 21 women) the disease was in stage III according to the 1978 classification of the American Joint Committee on Cancer (AJCC). These 115 cases were retrospectively reassessed, using a recently proposed new TNM classification with subdivision of stage III into IIIa, in which the patients may benefit from surgery, and IIIb, in which surgery is not advisable. Stage IIIa disease was present at operation in 87 cases and stage IIIb in 28. Actuarial analysis of survival rates showed that the new subclassification permits identification of those stage III patients who may benef…

Ultrastructural studies of the retina in infantile neuronal ceroid-lipofuscinosis.

1988

A 9-year-old boy who had died of infantile neuronal ceroid-lipofuscinosis had experienced retina-derived visual failure. Ophthalmologically and morphologically, his retina was severely atrophic and scarred by a dense fibrillary gliosis while photoreceptor cells had completely disappeared, cells of the bipolar layer had decreased in number and had become atrophic beyond cytologic recognition. Retinal pigment epithelial cells had undergone either atrophy or proliferation. Disease-specific granular lipopigments had accumulated in perikarya and processes of remaining cells and were infrequently associated with melanin within huge melanolipofuscin bodies and RPE cells of sessile and migrating na…

Water and energy balance: water consumption by crops

1988

ISBN 2-7380-0006-1 17 ref.; National audience

Computertomographie und Kernspintomographie der Hirngeschwülste

1988

Unser Krankengut umfast 8516 Patienten mit Hirntumoren und Hirnmetastasen, die an den Neurochirurgischen bzw. Neuroradiologischen Kliniken und Abteilungen Berlin, Mainz und Munchen von 1975 bis 1986 und an der Neurochirurgischen Klinik des Zentralklinikums Augsburg von 1983 bis 1986 computertomographisch untersucht wurden. In Tabelle 5 finden sich alle Tumoren mit einem Anteil von uber 1% am Gesamtkrankengut, das zu 98% bioptisch (offene Operation, stereotaktische Biopsie, Sektion) geklart ist. In Tabelle 6 wurden die seltenen intrakraniellen Tumoren weiter differenziert, wobei wir Tumoren mit einer Haufigkeit von maximal 1% als selten ansehen. Die Haufigkeiten der einzelnen Tumorarten korr…

The Proton-Neutron Interaction in Neutron-Rich A ≃ 100 Nuclei

1988

The possible factors responsible for the sudden onset of nuclear deformation in neutron-rich A≅100 nuclei are reviewed from the systematics of subshell occupation numbers for neutron and proton orbitals. The agreement between our results from a Nilsson model with existing selfconsistent HFB calculations strengthens the role of a cumulative neutron-proton interaction, but does not substantiate the conjecture concerning a selective involvement of the πg9/2-νg7/2 spin-orbit-partner orbitals in producing deformation as das suggested in earlier work.

A Bottleneck Model of Imaging Systems for Digital Angiocardiography

1988

Some ten years ago, the performance of real-time digital subtraction angiocardiography was demonstrated for the first time [1]. Subtraction became in the years after 1980 nearly synonymous with digital angiography [2–4]. This image enhancement technique was certainly very efficient in paving the way for the digital approach to imaging. Relatively simple processors and memory structures could perform subtraction methods with some degree of success. However, even in that early stage, it was clear to many of those involved in the technical developments and in early clinical evaluations that subtraction was only one of many features that would motivate the change from traditional film technique…

Enfermedad de Perthes : factores epidemiológicos y etiopatogénicos

1988

A critical study of 25 cases of Perthes' disease diagnosed between 1975 and 1985 was made at the hospitals of N. ª S.ª de la Candelaria and Clínico Universitario of Canarias. A control group of 22 children from the paediatric out-patient clinics was made. Epidemiological and etiopathogenic studies were carried out, being more frequent in boys, in rural areas and the lower classes. The incidence of associated abnormalities was a 20%, being the youngest children of the family. Amongst the previous history they found a high incidence of traumatic and transient synovitis and alterations in the growth and development. They did not find a family bistory of Pertbes' disease present in this study.

Injerto óseo en la osteocondritis disecante de rodilla

1988

The authors report their experience in the surgical treatment of osteochondritis dissecans using a personal technique of periostial-bone autograph in 4 cases operated.

Laxitud crónica de ligamento lateral externo de tobillo : plastia de Castaing modificada

1988

Twenty cases of chronic laxitude of the external Iigament of the ankle, using the Castaing's technique for surgery, are reviewed. The authors describe the procedure abd show the excellent results obtained from the usage of this technique.

Comparative Investigation on the Nutrient Composition of Healthy and Injured Spruces of Different Locations

1988

Investigations on the content of cations (Ca2+, K+, Mg2+ and Mn2+) were carried out in spruce trees at two exemplary locations in the Taunus montains (Konigstein) and in the Hunsruck mountains (Hattgenstein) in the course of the vegetation period in 1985 and 1986.

La revitalización comercial reciente de la algarroba del País Valenciano

1988

Este artículo constituye un estudio de la comercialización y transformación industrial de la algarroba, cultivo donde contrasta su regresión espacial y la revitalización comercial reciente. En este sentido examinaremos los diferentes canales de comercialización que protagonizan el comercio de la algarroba y los diferentes factores que han originado el alza de los precios en los últimos años., haciendo hincapié en el movimiento cooperativista, pieza clave de esta situación y que, al parecer, ha supuesto una ralentización de la regresión de la superficie del algarrobal valenciano. Dentro de ese compás de espera en el que se encuentra al algarrobal es conveniente estudiar cuáles serán los efec…

Determination of trace elements by resonant ionization mass spectrometry (RIMS)

1988

A resonant ionization mass spectrometer has been developed as an analytical tool for the detection of trace elements, especially of plutonium and other radionuclides. The sample, deposited on a rhenium filament, is evaporated by electrical heating and the atoms of the element under investigation are selectively ionized by laser light delivered from three dye lasers pumped by a copper vapour laser. The resulting photoions are detected in a time-of-flight spectrometer with a channelplate detector. For plutonium a mass resolution of M/δM=1500 was obtained and an overall detection efficiency of 4×10−6 was determined for stepwise excitation and ionization via autoionizing states. With a laser li…

Cheese

1988

Karyotypes in two species of the genusHippocampus (Pisces: Syngnatiformes)

1988

Diploid modal numbers of chromosomes 2n=48 forHippocampus ramulosus and 2n=44 forH. hippocampus, collected in the Gulf of Palermo in May 1985, are established. No sex-linked heteromorphic pairs are observed in the two species analyzed. The karyotype ofH. hippocampus seems to be a derived condition.

Band Structures in 96Zr and 98Zr Studied Through the High-Spin Beta Decays of the Y Parents

1988

The isotopes 96Zr and 98Zr are presently subject to intensive studies since their properties play a key role in the understanding of the rapid transition from spherical to deformed nuclear shapes at N ∼ 60. An interesting question is the strength of the subshell closures at Z = 38,40 and N = 56 and to which extent the structure of 96Zr, 98Zr and of their immediate neighbours is influenced by these shell effects. There is evidence, although limited, for closed- shell-or individual-particle character of these nuclei, but more information on the nature of the excited states, especially those with sizeable spins is desired. This is expected to help clarifying the situation with respect to the p…

Photoproduction of delta and Roper resonances in the cloudy bag model.

1988

The photoproduction of delta and Roper resonances has been calculated within the framework of the cloudy bag model. Two alternative formulations, the original pseudoscalar surface coupling and the pseudovector volume coupling of pions, have been used, and the results are compared. The helicity amplitudes are in fair agreement with experimental data, the prediction for the small ${E}_{1+}$/${M}_{1+}$ ratio for delta production is -1.8% for a bag radius of 1 fm and pseudovector coupling.

Intestinal transport in constipation and diarrhoea.

1988

Approximatively 10 liters of fluid enter the gastrointestinal tract with food and endogenous secretions, and only less than 100 ml or 1% leave it with the faeces. Minor changes of this equilibrium in the intestinal transport may cause diarrhoea or constipation. Functions of small and large intestine differ markedly in transport of electrolytes and water. The relatively leaky epithelium of the small intestine allows for rapid equilibrium of osmolality in both directions while the tight epithelium of the colon preserves electrolytes and water once they have been absorbed. It may compensate secretory diarrhoea of the small intestine for instance caused by bacterial toxins to a certain degree u…

Conclusion. L’action culturelle extérieure: Un moyen qui est une fin

1988

Multiple zircon growth within early Archaean tonalitic gneiss from the Ancient Gneiss Complex, Swaziland

1988

Abstract U Pb age determinations by ion microprobe reveal multiple episodes of zircon growth and recrystallization within a single sample of tonalitic gneiss from the Ancient Gneiss Complex. The oldest episode at3644 ± 4Ma(2σ) produced the dominant type of zircon, characteristically purplish-brown and massive in texture; this probably constitutes unaltered zircon precipitated from the original magma. Recrystallization accompanied (and obscured) by early Pb loss took place within the oldest grains at3504 ± 6Ma and3433 ± 8Ma. Whole new grains grew at these times also. We interpret the post-3644 Ma growth as due to episodic deformational and metamorphic events that transformed the tonalite plu…

In vitro Polymerization of ?-Carotene into Sporopollenin

1988

Postersitzung 10: Operative Techniken

1988

Abdominale Wunddehiszenzen treten postoperativ mit einer absoluten Haufigkeit von 1–3% auf und sind mit einer Mortalitat von bis zu 35% belastet. Die postoperative Festigkeit der Abdominalaponeurose beruht bis zum 7. postoperativen Tag allein auf dem chirurgischen Faden. Die Reisfestigkeit des Wundverschlusses steigt dann durch die Wundheilungsvorgange bis zum 21. Tag schnell an. Nach einem Vierteljahr ist eine endgultige Festigkeit erreicht [2, 4]. Die vordere Bauchwand weist durch den Faserverlauf der drei seitlichen Bauchmuskeln und der sie fortsetzenden Aponeurosen eine vorwiegend quere Struktur auf (Abb. 1, 2, 3). Die Zugfestigkeit der Abdominalaponeurosen ist in querer Richtung 3mal g…