showing 36 of ~574560 from 574555 documents
Comparative study of different approaches for the flow injection-fourier transform infrared determination of toluene in gasolines.
1994
Abstract A single channel flow injection manifold has been employed to carry out the direct determination of toluene in gasolines by FT—IR without any sample pretreatment and by using different strategies. Toluene can be directly determined by measuring the absorbance at 728 cm −1 , using a base line established between 835 and 575 cm −1 ; and in this case a limit of detection of 0.01% (v/v) can be obtained with a dynamic range up to 2% (v/v). In some cases it could be convenient to determine toluene by derivative flow-injection FT—IR in order to avoid matrix interferences in the analysis of some types of gasolines. Carrying out the first order derivative FI—FT—IR measurements on the 728 cm…
Intra- and extracerebral blood flow changes and flushing after intravenous injection of human corticotropin-releasing hormone
1994
To study facial flush after systemic administration of human corticotropin-releasing hormone (hCRH) we injected 100 micrograms hCRH intravenously to ten healthy young men. The increase in facial temperature was measured by infrared camera. A significant increase in facial temperature of 1.39 degrees C +/- 0.3 was found within 7 min in all patients, which lasted up to 60 min, although facial flushing was visible in only 50% (5/10) of the probands. In a second experiment 100 micrograms hCRH was then administered to seven other healthy young men. Intra- and extracerebral blood flow velocity changes in the medial cerebral artery (MCA) and external carotid artery (ECA) were measured after hCRH a…
Competing proton and neutron alignments in neutron-deficient Xe-nuclei
1994
Abstract High-spin structures of the neutron-deficient 117,118,120 Xe isotopes have been studied by in-beam γ-ray spectroscopic techniques. The final nuclei have been identified by means of charged-particle detectors. Collective rotational bands based on the neutron d 5 2 , g 7 2 and h 11 2 configurations have been identified in 117 Xe. In the even 118 Xe and 120 Xe nuclei several new side bands were observed and the previously known bands were extended. The present level schemes include two positive-parity bands constructed to high spin in 118 Xe, whereas in 120 Xe three such bands were observed. In order to explain these bands, both proton and neutron ( h 11 2 ) 2 alignments, as well as t…
Comparison between complete and simplified methods for determining the microwave noise parameters of HEMTs
1994
Modem automatic noise parameter measuring systems are based on measurements of some values of F(rs ) for different values of IГs (more than four, for redundancy) realized by adjusting an admittance transformer (tuner) inserted between the noise source and the TUT mput . Such values are then manipulated by means of proper data processing techniques using eqn.( 1) [ 11. This measuring procedure is hereafter referred to as standard to point out that the old `Standards on methods of measuring noise in linear twoports´ published by the IRE Subcommittee on noise in 1960 is considered obsolete by all the experimenters.
NADPH-diaphorase activity of nitric oxide synthase in the olfactory bulb: co-factor specificity and characterization regarding the interrelation to N…
1994
The neuronal form of the enzyme nitric oxide synthase (nNOS) synthesizes the messenger molecule nitric oxide (NO). In addition to NO formation, nNOS exhibits a so-called NADPH-diaphorase (NADPH-d) activity. This study focused on the characterization of NADPH-d activity with regard to NO formation in the rat olfactory bulb. In this area of the brain pronounced staining is localized in discrete populations of neuronal somata and in olfactory glomeruli. Diaphorase staining combined with demonstration of nNOS by polyclonal antibodies revealed that NADPH-d activity of neuron somata is associated with nNOS immunoreactivity. It is concluded that neuron somata exhibit NADPH-d activity of nNOS. NAD…
Involvement of neuronal processes and nitric oxide in the inhibition by endotoxin of pentagastrin-stimulated sastric acid secretion
1994
Administration of E. coli endotoxin (1 mg kg-1, i.v.) abolished the acid response induced by the i.v. infusion of pentagastrin (8 micrograms kg-1 h-1) in the continuously perfused stomach of the anaesthetized rat. Local serosal application of tetrodotoxin (36 ng per rat) completely restored acid responses to pentagastrin in endotoxin-treated rats. However, pretreatment with atropine (0.5 mg kg-1, s.c.), capsaicin (20, 30, and 50 mg kg-1, s.c. 2 weeks before the study) or guanethidine (16 mg kg-1, s.c. 3 and 16h before) did not influence the inhibitory effects of endotoxin. Continuous i.v. infusion with NG-nitro arginine methyl ester (L-NAME, 10 mg kg-1 h-1) restored the secretory responses …
Transition paths between phases IV, III and II of ammonium nitrate predicted from X-ray powder diffractometer and differential scanning calorimeter d…
1994
Abstract Ammonium nitrate solid phase transition paths between phases IV, III and II were explained and predicted on the basis of X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC) data by applying partial least-squares regression (PLS) and principal component analysis (PCA). The samples were clustered according to their different transition paths with the PLS and PCA models, and the transition paths were predicted with PLS component clusters. The best PLS clusters were formed by a few first components. Prediction of the transition path with the PLS clusters made a semiquantitative prediction of the transition energy possible. In PCA, principal components 6 and 11, w…
Organ xenografting between rodents: an evolutionary perspective
1994
Rejection times of heart xenografts in several donor-recipient combinations including the guinea pig, rat, hamster, and mouse are examined in light of the paleontological history of rodents and the resulting phylogenetic distances between taxa. This multidisciplinary review at the molecular, chromosomal and morphological levels suggests that xenograft rejection time is inversely proportional to the time divergence or phylogenetic distance, and that the binomial terminology concordant/discordant does not reflect the amplitude of phylogenetic distances.
Theoretical study of the stabilization of cubic-phaseZrO2by impurities
1994
We have performed a thermodynamical analysis of the phase diagrams for ${\mathrm{ZrO}}_{2}$-CaO and ${\mathrm{ZrO}}_{2}$-MgO solid solutions which has demonstrated that differential heats of mixing are important parameters determining the stabilization of the cubic phase of ${\mathrm{ZrO}}_{2}$ by impurities. It is shown that the differential heats of mixing in the cubic phase of these systems should be lower than in the tetragonal phase. To understand this effect we have studied the electronic and geometrical structures of the pure and doped ${\mathrm{ZrO}}_{2}$ crystals. Three computational techniques were employed: the ab initio Hartree-Fock pseudopotential method is used to study the at…
Immunocytochemical typification of mesothelial cells in effusions: in vivo and in vitro models.
1994
We have performed immunocytochemical, immunoelectron microscopy, Western blot, and culture techniques using monoclonal antibodies against cytokeratin, vimentin, and desmin on 17 benign and 20 malignant effusions of pleural and ascitic origin. Triple coexpression of these three antigens was observed in benign reactive mesothelial cells as well as in one case of mesothelioma. All metastatic adenocarcinoma cells were consistently negative to desmin and positive to cytokeratin and vimentin. Present results were helpful to distinguish reactive and malignant mesothelioma from metastatic carcinoma cells in effusions.
Effect of ethanol on membrane fluidity of protoplasts fromSaccharomyces cerevisiae andKloeckera apiculata grown with or without ethanol, measured by …
1994
Direct measurements of membrane fluidity by fluorescence anisotropy of protoplasts fromKloeckera apiculata andSaccharomyces cerevisiae, a low and a high ethanol tolerant strain respectively, are presented. The comparison of the behaviour of the two strains grown with or without ethanol enabled us to demonstrate the existing relationship between ethanol tolerance and membrane fluidity.
Photoelectropoling of azobenzene chromophores in molecular films
1994
The photoinduced reorientation and photoelectropoling processes were investigated in molecular films of aliphatically substituted azobenzenes. While polarized illumination leads to a conversion of isotropic samples into anisotropic ones, upon application of external electric fields even macroscopically polar materials are created. The macroscopic polarity can be reversed under suitable experimental conditions. Order parameters as a function of the poling field were determined by Stark spectroscopy. Using atomic force microscopy it is shown that the structure of the sample is well defined on a microscopic length scale, whereas on a macroscopic length scale it is not.
Induction of a recall deficit by rapid-rate transcranial magnetic stimulation
1994
We used rapid-rate, repetitive transcranial magnetic stimulation (rTMS) for the noninvasive study of verbal recall. Five right-handed normal subjects were studied. Recall followed immediately after presentation of a 12-word list. Focal rTMS was applied with a figure eight coil in trains of 500 ms duration to F7, F8, T5, T6, P3, P4, or O1, O2 at latencies of 0, 250, 500, or 1000 ms during word list presentation. Recall was consistently significantly diminished only after left mid-temporal and bilateral dorsofrontal rTMS at both 0 and 250 ms latencies. We conclude that rTMS may be useful as a non-invasive tool for the study of verbal memory processes.
Minutoexcipula tuckerae gen. et sp.nov., a new lichenicolous deuteromycete on Pertusaria texana in the United States
1994
The new deuteromycete genus and species Minutoexcipula tuckerae is described and illustrated from five collections on Pertusaria texana made in Louisiana. It is characterized by the formation of black convex sporodochia-like conidiomata which also have a well-differentiated exciple. The branched conidiophores bear proliferating holoblastic conidiogenous cells with distinct annellations, and the singly borne conidia are brown and 1-septate. The separation of the genus from Lichenopuccinia, Milospium, Monodictys, Sclerococcum, and Trimmatostroma is discussed. Notes on other brown-spored deuteromycetes known on Pertusaria are also included, together with a key to the nine currently known speci…
Nonlinear dynamical aspects of the human sleep EEG.
1994
This article deals with the application of methods from the theory of nonlinear dynamical systems to EEG signals. Theoretical background, mathematical concepts and algorithms for the calculation of "non-linear parameters" are reviewed and influences of the structure of reconstructed data sets on the calculations are pointed out. We present results for the estimation of the correlation dimension D2 and the principal Lyapunov-exponent lambda 1 for sleep EEG data respectively from 10 and 15 healthy subjects corresponding to different sleep stages. Essentially, we found a statistically significant decrease of both D2 and lambda 1 as sleep moves towards slow wave stages. The values for REM sleep…
Neuromuscular performance of lower limbs during voluntary and reflex activity in power- and endurance-trained athletes.
1994
Neural, mechanical and muscle factors influence muscle force production. This study was, therefore, designed to compare possible differences in the function of the neuromuscular system among differently adapted subjects. A group of 11 power-trained athletes and 10 endurance-trained athletes volunteered as subjects for this study. Maximal voluntary isometric force and the rate of force production of the knee extensor and the plantar flexor muscles were measured. In addition, basic reflex function was measured in the two experimental conditions. The power athletes produced higher voluntary forces (P<0.01-0.001) with higher rates for force production (P<0.001) by both muscle groups measured. U…
Measurement of vibrational line profiles inH2–rare-gas mixtures: Determination of the speed dependence of the line shift
1994
High-resolution inverse Raman experiments for ${\mathrm{H}}_{2}$ diluted in Ar have revealed unusual Q-line profile features at various concentrations which have been interpreted in terms of speed-changing collisions. A more general approach including both speed- and phase-changing collisions has led to an alternative interpretation of these features. In order to further analyze the role of these various collisional mechanisms, new experiments have been performed. Pure ${\mathrm{H}}_{2}$ and ${\mathrm{H}}_{2}$ perturbed by Ne, Ar, and Xe have been investigated at various temperatures between 295 and 800 K.
Was ist neu in der kardiopulmonalen Reanimation?
1994
A strong consensus was reached for several changes in the guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC) in the 1992 conference on CPR and ECC held by the Emergency Cardiac Care Committee of the American Heart Association. These new recommendations, together with differing recommendations of the European Resuscitation Council, are described. An unresponsive person with spontaneous respirations should be placed in the recovery position if no cervical trauma is suspected. Compared with endotracheal intubation, other airway-protecting devices such as combination esophageal-tracheal tubes are of minor acceptance. During ventilation, the time for filling the …
Immunohistochemical Detection of Hormone Receptors in Breast Carcinomas (ER-ICA, PgR-ICA): Prognostic Usefulness and Comparison with the Biochemical …
1994
In a prospective study conducted since 1983, the hormone-receptor status of primary breast carcinomas was investigated using immunohistochemical (ER-ICA, PgR-ICA) and biochemical (DCC) methods. The degree of immunohistochemical staining was evaluated according to the immunoreactive score (IRS) devised by Remmele and Stegner [Frauenarzt 28, 41-43 (1987)]. The findings obtained using the biochemical radioactive-ligand-binding assay (cutoff level, 20 fmol/mg) and those obtained using qualitative immunohistochemical methods were in agreement in 72.5% (ER-ICA) and 72.2% (PgR-ICA) of cases. For the 789 cases of primary breast carcinoma examined, postoperative data were available for a mean follow…
The spatial dynamics of atmospheric pollution in Latvia and the Baltic Republics, as measured in mosses, topsoil and precipitation
1994
Atmospheric pollution in the Baltic countries of Estonia, Latvia, and Lithuania has been mapped using measurements of pollutant concentrations in mosses, topsoil and precipitation. Air masses from western Europe deposit industrial pollutants in the Baltic region and concentrations depend on meteorological conditions. Superimposed on this background is the pattern of deposits from local sources. Large areas receive neutral to basic precipitation due to cement industries and fly ash emissions from fossil fuel combustion. The burning of oil-shale in NE Estonia results in precipitation with pH values over 7.0, and high concentrations of V, Fe, and Cd. Heavy metal concentrations in the topsoil a…
Synthesis of (±)-(E)-2,6-dimethyl-6-hydroxyocta-2,7-dienoic acid and the corresponding amide (“acacialactam”)
1994
Abstract The total synthesis of the title compounds in racemic form is described. Linalool was used as the starting material and transformed into the target molecules in 6 steps. The synthetic amide displays spectral properties identical to those reported for the natural compound acacialactam, indicating that the structure proposed for the latter compound is not correct.
On 𝓕-subnormal subgroups and Frattini-like subgroups of a finite group
1994
Throughout the paper we consider only finite groups.J. C. Beidleman and H. Smith [3] have proposed the following question: “If G is a group and Ha subnormal subgroup of G containing Φ(G), the Frattini subgroup of G, such that H/Φ(G)is supersoluble, is H necessarily supersoluble? “In this paper, we give not only an affirmative answer to this question but also we see that the above result still holds if supersoluble is replaced by any saturated formation containing the class of all nilpotent groups.
Light Induced Modifications of Langmuir-Blodgett-Multilayer Assemblies Containing Amphotropic Azocopolymer
1994
Abstract Photochromic LB-multilayers of amphotropic copolymers having rod-like azobenzene moieties as side groups which exhibit thermotropic liquid crystalline behaviour in the bulk have been characterized by UV-VIS spectroscopy as well as by angular dependent and energy dispersive SAXS. Upon irradiation with UV-light the initial optical in-plane anisotropy and the vertical layered structure of LB-films can be destroyed. A new layered structure can be rebuilt on irradiation with visible light or by annealing. Using linearly polarized light for the irradiation an optical anisotropy (POA) has been induced or reversibly modified by a photoselection process.
Immobilization of enzymes by multilayer microcapsules
1994
A method is described to obtain a new type of microcapsules for immobilization of enzymes or living cells. The wall of these capsules consists of several layers of poly(ethyleneimine) and poly(acrylic acid). The idea is that diverging properties of the whole assembly can be better controlled when the membrane is built up by several consecutive steps, each being optimized with respect to a special property, for example, permeability or mechanical strength. The encapsulation of acidic phosphatase and the cleavage of p-nitrophenyl phosphate was used as a model system. The charged capsules were characterized by their enzymatic activity, as a function of membrane composition (number and sequence…
Effects of inhomogeneities of cross-links on a microphase separation of polymer mixtures
1994
We generalize de Gennes' theory of the microphase separation of cross-linked polymer mixtures to take into account the spatial fluctuations of the elasticity constant c, preventing the mixture from complete segregation. Within a mean-field analysis we found that the spatial fluctuations of c(r), which are assumed to obey the Poisson distribution, enlarge the size of the domains. The latter is obtained to be temperature dependent.
EFFECT OF MICROENCAPSULATION ON OXYGEN DISTRIBUTION IN ISLETS ORGANS
1994
In islet transplantation, limitation of oxygen supply may restrict graft function, particularly when encapsulated tissue is used. Therefore, oxygen tensions (PO2) in isolated islet organs (Brockmann bodies) of Osphronemus gorami were measured. In a thermostatically (37 degrees C) controlled measuring chamber, PO2 values were recorded at subsequent microelectrode positions on a radial track toward the center of the organ. In 2 independent groups, we studied the effect of fluid convection (n = 12) and microencapsulation (n = 12). In both groups, sigmoidal PO2 profiles were found, which permit differentiation in an oxygen-depleted zone surrounding the surface, a steep decline inside the tissue…
Towards a standardized definition of educational expenditure
1994
Statistical reports and studies, division des statistiques, UnescoRéférence interne : 94041
Assembly of the Major and the Minor Capsid Protein of Human Papillomavirus Type 33 into Virus-like Particles and Tubular Structures in Insect Cells
1994
Native virions of human papillomaviruses (HPV) can be isolated from genital lesions only in very limited amounts. Recent studies have shown that virus-like particles can be obtained by expression of the capsid proteins using vaccinia virus recombinants or the baculovirus system. We now present the first detailed characterization of virus-like particles of a human papillomavirus associated with malignant genital lesions, HPV-33, produced in high yield using the baculovirus expression system. Assembly of the major capsid protein L1 alone or together with the minor capsid protein L2 has been obtained. Both spherical virus-like particles of 50-60 nm diameter and tubular structures of either 25-…
Emergency angioplasty of totally occluded left main coronary artery in acute myocardial infarction and unstable angina pectoris--institutional experi…
1994
Acute occlusion of the left main coronary artery (LMCA) is a rare angiographic finding. We report five patients with acute myocardial infarction (AMI) and one patient with unstable angina, in whom reperfusion was achieved or attempted with percutaneous transluminal coronary angioplasty (PTCA). All patients had a long history of stable angina pectoris. The indication for emergency PTCA was cardiogenic shock in the five patients with MI. PTCA was successful in five of six patients. Three patients with reperfusion survived, three died. All survivors underwent coronary artery bypass grafting (CABG) and were still alive at 23 months, 3 and 8 years respectively in NYHA functional class II or III.…
Evolution de la place des émotions dans la recherche en comportement du consommateur : un état de l'art
1994
International audience
Inhibition of anti-GD3-ganglioside antibody-induced proliferation of human CD8+ T cells by CD16+ natural killer cells
1994
The ganglioside GD3 has been described as a membrane component of human T cells which is involved in T cell growth. In the present study the activating function of GD3 for human CD4+ and CD8+ T cells was analyzed by five different monoclonal antibodies (mAb) directed against the GD3 molecule. Three mAb U5, Z21 and R24 induced strong proliferation of peripheral blood mononuclear cells and purified CD8+ and CD4+ T cells of normal donors containing less than 5% CD16+ natural killer (NK) cells. In contrast to CD4+ T cells, CD8+ T cells proliferated only weakly in the presence of 15% CD16+ NK cells. The proliferative response of purified CD4+ and CD8+ T cells (< 5% NK cells) correlated with the …
Production of volatile compounds in model milk and cheese media by eight strains of Geotrichum candidum Link
1994
SummaryEight strains of Geotrichum candidum isolated from cheese were compared for aroma production. Twenty-four components, including alcohols, methyl ketones, fatty acids and esters, were identified by gas–liquid chromatography and gas chromatography–mass spectrometry of the volatile compounds produced by G. candidum cultures. Strains could be differentiated by their ability to produce dimethyldisulphide, phenol, phenylethanol and methyl ketones.
Solvent dependence of the νs(OD) bandshape in 2,6-dichlorophenol
1994
Abstract The infrared bandshape of νs(OD) of 2,6-dichlorophenol is measured in a series of solvents of increasing polarity, and is quantitatively analysed. The bandshape is described in terms of band indices, moments, correlation functions and correlation times. A distinct solvent dependence of bandshape and relaxation parameters has been found. The changes of the νs(OD) bandshape with increasing solvent polarity are compared in detail with those obtained earlier for analogous solvents for νs(OH) of 2,6-dichlorophenol. The overall behaviour of the spectral and relaxation parameters is similar, but the changes are less distinct for the weaker OD ⋯ Cl bond.
Synthetic studies toward natural furanosesquiterpenoids from santonin. Synthesis of (+)-1,2-dihydrotubipofuran
1994
Abstract Santonin (1) was converted into (+)-1,2-dihydrotubipofuran (13) via a synthetic pathway involving a very easy preparation of 7,11-ene-8,12-olide and 8,12-furan moieties and A-ring elaboration on the eudesmane framework.