showing 36 of ~574560 from 574555 documents
Synthesis and magnetic properties of bis(μ-hydroxo)bis[(2,2 ′-bipyridyl)copper(II)] squarate. Crystal structure of bis(μ-hydroxo)bis[(2,2′-bipyridyl)…
1990
Abstract The compound [Cu2(bipy)2(OH)2](C4O4)·5.5H2O, where bipy and C4O42− correspond to 2,2′-bipyridyl and squarate (dianion of 3,4-dihydroxy-3-cyclo- butene-1,3-dione) respectively, has been synthesized. Its magnetic properties have been investigated in the 2–300 K temperature range. The ground state is a spin-triplet state, with a singlet-triplet separation of 145 cm−1. The EPR powder spectrum confirms the nature of the ground state. Well-formed single crystals of the tetrahydrate, [Cu2(bipy)2(OH)2](C4O4)·4H2O, were grown from aqueous solutions and characterized by X-ray diffraction. The system is triclinic, space group P 1 , with a = 9.022(2), b = 9.040(2), c = 8.409(2) A, α = 103.51(2…
ACUTE INFANTILE SPINAL MUSCULAR ATROPHY
1990
Biopsy as well as autopsy studies of a child who died 8 weeks after birth from the acute infantile form of spinal muscular atrophy revealed classical morphological changes, including degeneration and loss of motoneurons in the spinal cord, loss of large myelinated fibres in anterior roots and neurogenic atrophy in muscle. New ultrastructural findings include massive muscle cell elimination by apoptosis with the formation of membrane-bound muscle cell fragments, apoptotic bodies. In addition, numerous immature muscle fibres were observed. The morphological findings raise the possibility that in a severely growth-retarded muscle, the process of muscle cell apoptosis removes the peripheral tar…
Isolation and culture of grape vine cv. Chardonnay leaf protoplasts
1990
Experimental conditions were established that resulted in high yields and good viability of the protoplasts obtained from leaves of Vitis vinifera, cv. Chardonnay regenerated in vitro by somatic embryogenesis. The effect of factors of the culture medium and various environmental conditions upon the frequency of cell division has been examined, and a method of culture is described by which protoplasts were induced to begin division. Most protoplasts obtained in this way regenerated cell walls within the first few days and cell division occurred after 10 days of culture in a liquid medium. Some cells have divided two or even three times. Nevertheless, the cells did not continue dividing beyon…
Therapeutic Perspectives in Psychoneuroendocrinimmunology(PNEI): Potential Role of Phosphatidylserine in Neuroendocrine-Immune Communications
1990
(1990). Therapeutic Perspectives in Psychoneuroendocrinimmunology(PNEI): Potential Role of Phosphatidylserine in Neuroendocrine-Immune Communications. International Journal of Neuroscience: Vol. 51, No. 3-4, pp. 299-301.
Reduction of glutathione content by 12-O-tetradecanoylphorbol-13-acetate in confluent, but not in sparse cultures of human diploid fibroblasts.
1990
Treatment of confluent cultures of human diploid fibroblasts with 12-O-tetradecanoylphorbol-13-acetate (TPA) (10(-7) M) resulted in a 70% reduction of the glutathione (GSH) content, compared with untreated controls. The effect, which was dose-dependent, was observed 8 h after the beginning of the treatment could be followed for up to 72 h. On the other hand, GSH reduction was specific for confluent cultures, as the level of glutathione remained unchanged by TPA treatment of sparse cultures. The addition of immobilized plasma membrane proteins to sparsely seeded cells has been shown previously to induce cellular reactions which are characteristic for confluent cultures. It was shown that TPA…
Changes in the Level of Peptidase Activities in Pea Ovaries during Senescence and Fruit Set Induced by Gibberellic Acid
1990
The activities and changes in the levels of exopeptidase and endopeptidase activities were characterized in unpollinated ovaries of Pisum sativum L. cv Alaska during senescence and early fruit development induced by gibberellic acid (GA3). Two aminopeptidases and one iminopeptidase were electrophoretically separated. These peptidases were sensitive to inhibitors of sulfhydryl proteases. Carboxypeptidase activity was inhibited by phenylmethyl sulfonyl fluoride. An azocasein-degrading endopeptidase, sensitive to thiol protease inhibitors, was also found. An increase in the specific activity of aminopeptidase during both fruit development and ovary senescence was observed. In contrast, the spe…
Nitrous oxide--no laughing matter?
1990
Thermodynamics of electrokinetic processes—II. systems with different kinds of electrodes
1990
Abstract In this work Haase's Formulation of Electrokinetic Processes is applied to special systems: those working with two different electrodes and those where gaseous phases are formed. Phenomenological equations are always written in terms of directly observable variables. The extrinsic character of Haase's Formulation is clearly shown. Some special results on streaming current in dielectric liquids are explained.
Comparison of BT-PABA test and fecal chymotrypsin measurements in normal subjects and diabetic patients
1990
A N-benzoil-L-tyrosil-PABA test on 6h urine collection, a plasma PABA assay 2 h after administration and a fecal chymotrypsin assay were performed on 66 patients (36 controls and 30 type 2 diabetic patients on insulin therapy). All patients were hospitalized and without gastrointestinal and renal disease. The mean values of plasmatic PABA and fecal chymotrypsin were significantly lower in the diabetic group than in the controls (p less than 0.025 and p less than 0.01, respectively), although they remained within normal range. But this was not the case for PABA urinary excretion values. This may indicate a slower but more protracted PABA absorption during the third or fourth hour with the re…
Analysis of the infrared Fourier transform spectrum of the Dyad of 116SnH4
1990
Abstract The FTIR spectrum of monoisotopic 116SnH4 has been recorded with the Bruker 120 HR interferometer at Giessen, West Germany, in the ν 2 ν 4 range extending from 600 to 850 cm−1. The resolution (FWHM) was 2.1 × 10−3 cm−1. The Dyad ν 2 ν 4 (0100, 0001) was analyzed using a sixth-order Hamiltonian. The analysis of infrared transitions enabled us to determine 10 ground state parameters, 9 ν2 parameters, 17 ν4 parameters, and 18 interaction parameters. Of 3800 calculated transitions assigned to observed lines, 1183 unblended lines have been selected for the data refinement. For J ≤ 19, the value of the standard deviation is of the order of magnitude of the estimated experimental accuracy…
Compensating isothermal calorimeter to investigate the vulcanization of factice
1990
Abstract Sulphur factice is produced from a mixture of a vegetable oil and sulphur for linkage. To start vulcanization, the mixture is heated to temperatures betueen 130 and 150 °C. Within hours or days the temperature increases to about 160 °C and the product solidifies. To investigate the production process and to optimize the reaction, the temperature development was simulated in laboratory-scale experiments and the heat released was measured. In order to investigate the reaction kinetics of the entire vulcanization process, the calorimeter must a11ow the measurement of the mixture in liquid and solid state. The developed compensating calorimeter consists of a hot plate equipped with thi…
Unconventional optically active solids in san jose
1990
Synthesis and reactivity of cristobalite obtained from the SiO2-V2O5 system
1990
On etudie par diffraction RX l'evolution des phases cristallines lors de la cuisson a 650-1250 o C de compositions du systeme ZrO 2 −V 2 O 5 −SiO 2 et la reactivite de la cristobalite preparee avec la phase ZrO 2 monoclinique
Fluorescence induction kinetics as a tool to detect a chlororespiratory activity in the prasinophycean alga, Mantoniella squamata
1990
Abstract Pulse-modulated fluorescence measuring systems were used to study the fluorescence induction kinetics of the primitive prasinophycean alga, Mantoniella squamata . DCMU-treated cells show a very strong non-photochemical quenching which is insensitive to uncouplers and can not be attributed to state transitions or photoinhibition. In order to analyze the origin for this quenching, different inhibitors of the photosynthetic electron flow were applied. It was found that DCCD, an inhibitor of the ATP-synthase as well as of the cytochrome- c oxidase, enhances the fluorescence quenching, whereas antimycin A, which blocks the cyclic electron flow around PS I, stimulates it. The effect of b…
Crystal and molecular structure of 2,3,6,7-tetramethoxy-9-trichloromethyl-10-carboxymethyl-9,10-dihydroanthracene
1990
Cl3O6C21H21,Mr=475.75, orthorhombic,P212121,a=21.895(3),b=12.101(2), andc=8.237(2) A,V=2182.4(7) A3,Dx=1.45 g cm−3 forZ=4, λ(MoKα)=0.71069 Aμ=3.99 cm−1,F(000) 984, room temperature,R=0.035 for 1877 observed reflections. The molecule exhibits a folded conformation: the dihedral angle between the benzene rings is 28.3(1)°. The central ring is characterized by acis diaxal configuration of hydrogen atoms in the 9, 10 positions, confirming the 13-C NMR results.
A distance metric on binary trees using lattice-theoretic measures
1990
A so called height function which is a strictly antitone supervaluation is defined on binary trees. Via lattice-theoretic results and using the height function, we can define a distance metric on binary trees of size n which can be computed in expected time O(n 3/2 )
Nephrosis in two siblings with infantile sialic acid storage disease
1990
The diagnosis of infantile sialic acid storage disease (ISSD) was established in two siblings on the basis of typical clinical signs and the biochemical findings of hyperexcretion and intracellular storage of free sialic acid. A severe, steroid resistant nephrosis occurred in both siblings. The activities of lysosomal enzymes, including sialidase, were normal. A combined detection method for sialic acids with Limax flavus agglutinin labelling and phosphotungstic acid staining showed severely alterated sialic acid components in epithelial kidney cells and indicate a causal relationship between the nephrosis and the underlying biochemical defect. Further observations of ISSD patients with ren…
false
1990
New monomers are described for the synthesis of rod-like poly(1,4-phenyleneethynylene)s with long flexible aliphatic side chains. By palladium catalyzed polycondensation soluble polymers with melting points around 100°C could be obtained. The molecular weight was estimated by GPC, VPO and elemental analysis: GPC showed a multimodale distribution with Pn = 9–15. NMR spectra were found to be in agreement with the assumed polymer structure, but signals of the acetylenic carbons could not be detected. A broad, structureless absorption with a maximum at λ = 410 nm is seen in the UV-VIS-spectra. The thermal decomposition of the substituted PPE's starts at about 400°C and is comparable to that of …
Comparative clinical trial of ceftazidime and imipenem/cilastatin in patients with severe nosocomial pneumonias and septicaemias.
1990
The efficacy and safety of ceftazidime and imipenem in patients with severe infections was compared in a randomized multi-centre trial. Patients on assisted respiration with clinical signs of pneumonia or septicaemia who had been in hospital for at least 3 days were studied. Twenty-one patients were treated with ceftazidime, 24 with imipenem. The mean duration of treatment was 9 days in both groups. At the end of the trial 17 patients (81%) of the ceftazidime group and 16 patients (67%) in the imipenem group were clinically cured or showed marked improvement. The bacteriological results showed an eradication of the causative pathogens in 17 of 21 cases in the ceftazidime group and 13 of 19 …
Protection effect of endurance training against reoxygenation-induced injuries in rat heart
1990
Endurance training by swimming (219-229 h) resulted in a significant protection against hypoxia/reoxygenation-induced injuries in Langendorff-perfused rat hearts. The protection was manifested as improved flow characteristics and a smaller release of creatine kinase into the perfusate. The concentration of thiobarbituric acid reactive substances (TBARS) was lower in the trained than in the respective control hearts. The trained hearts also showed a lower reoxygenation-induced increase in TBARS. The myocardium of the right ventricle and that of the left subepimyocardium were the most affected by reoxygenation. The swimming program induced a decrease in the activities of catalase and glutath…
Infrared linear dichroism spectroscopy by a double modulation technique
1990
A linear IR dichroism experiment has been devised using a FTIR instrument in combination with a photoelastic modulator. Based on the Mueller-Stokes calculus, a method to directly obtain the absorbance spectra Av parallel and Av perpendicular from the modulated interferogram is developped, which allows the sensitive evaluation of the dichroic ratio. The photoelastic modulator, in combination with a FTIR instrument, offers high sensitivity, high speed, excellent signal to noise ratio and a broad spectral range from 3300 to 850 cm-1. First experimental results obstained from SBS block copolymer are reported.
Upper bounds for the zeros of ultraspherical polynomials
1990
AbstractFor k = 1, 2, …, [n2] let xnk(λ) denote the Kth positive zero in decreasing order of the ultraspherical polynomial Pn(λ)(x). We establish upper bounds for xnk(λ). All the bounds become exact when λ = 0 and, in some cases (see case (iii) of Theorem 3.1), also when λ = 1. As a consequence of our results, we obtain for the largest zero xn1(λ)0.. We point out that our results remain useful for large values of λ. Numerical examples show that our upper bounds are quite sharp.
Two New Eudesmanolides from Artemisia caerulescens subsp. gargantae.
1990
T cell receptor gene rearrangements of T lymphocytes infiltrating the liver in chronic active hepatitis B and primary biliary cirrhosis (PBC): Oligoc…
1990
Immunological events are involved in the pathophysiology of chronic active hepatitis as indicated from the accumulation of T lymphocytes at the site of tissue damage. We generated T cell clones from liver biopsies of 3 patients with chronic active hepatitis B and 2 patients with primary biliary cirrhosis. These T cell clones (n = 84) were analyzed by means of T cell receptor (TcR) beta gene rearrangements to determine whether the infiltrate consists of a polyclonal or oligoclonal T cell population. The vast majority (62 of 64) of T cell clones from three different patients with chronic active hepatitis B showed no identical rearrangements of the TcR beta chain genes. In marked contrast, in …
Hepatic expression patterns of the large and middle hepatitis B virus surface proteins in viremic and nonviremic chronic hepatitis B.
1990
The envelope of hepatitis B virus consists of large, middle, and small hepatitis B surface proteins. Recent data from in vitro studies suggest that intracellular expression and distribution of the three polypeptides may be variable. These observations in artificial expression systems prompted this analysis of the occurrence and distribution of the three hepatitis B surface proteins in the liver tissue of substantial viremic (hepatitis B virus DNA- and hepatitis B e antigen-positive) and low-viremic or nonviremic (hepatitis B virus DNA-negative, anti-hepatitis B e antigen-positive) carriers by specific monoclonal antibodies against large, middle, and small proteins. Patients with an active f…
Pathogenesis of Paraneoplastic Follicular Hyperkeratotic Spicules in Multiple Myeloma
1990
• We describe a 62-year-old man with multiple myeloma who developed horny spicules on his face, particularly on his nose. IgG-λ monoclonal gammopathy was detected, and the serum dysprotein was shown to be a cryoglobulin, which forms a cryogel at low temperatures. Light and electron microscopic and immunohistochemical examinations showed an intercellular precipitation and massive accumulation of the IgG dysprotein and cryoglobulin between the keratinocytes of the upper epidermis and the infundibular epithelium. The follicles were dilated and filled with parakeratotic cells, the protein deposits between them and a rudimentary hair thus resulting in the clinically visible symptoms of horny spi…
Long-term observation of endocrine ophthalmopathy and retrospective appraisal of therapeutic measures.
1990
The course of endocrine ophthalmopathy was investigated on the basis of clinical and biochemical parameters and in relation to different therapeutic strategies. A retrospective appraisal was made of 297 patients (44 +/- 14 yr, 249 women) with inclusion of anamnestic and clinical data as well as the results of computer tomography. At the beginning of therapy, 253 patients were hyperthyroid, 36 were euthyroid and eight were hypothyroid. The HLA typing carried out in 89 patients showed the phenotypes B8 and DR3 in 32% and 42% of the cases, respectively. Raised microsomal antibodies were present in 56% of the patients and there were raised thyroglobulin antibodies in 19%. Sixty-three % of the p…
Study of the micro-phase separation in LC-polymers with paired mesogens
1990
Differential scanning calorimetry and miscibility investigations were used to study the micro-phase separation of liquid-crystalline dimesogenic side-group polysiloxanes. Diluted co-polysiloxanes exhibit two glass transition temperatures and an unusual miscibility behavior. The observed biphasic character is compared with that of certain amphiphilic systems.
HyperShell: An expert system shell in a hypermedia environment—application in medical audiology
1990
HyperShell is an expert system shell developed in a hypermedia environment. Several artificial intelligence techniques such as frames and semantic networks are used in an original interpretation to enhance the interaction between the user and the program. The typical navigation tools of hypermedia such as clickable buttons and text search are extended to the semantic structure of HyperShell, creating a set of new tools. Examples from a medical expert system (Audex HM) developed in HyperShell are described.
Strong-field high-frequency approximation to the multiphoton ionization of hydrogen
1990
The strong-field multiphoton ionization of atoms is considered and a theoretical approach dealing nonperturbatively with the radiation field formulated. The general computational scheme is the conventional perturbation theory, but the intermediate states are dressed by the field. We present in detail a method to dress the continuum states and to study the dipole transitions within the continuum. In the high-frequency domain, the proposed procedure rapidly converges over a wide range of field intensity and offers an interesting framework for calculating ionization rates for arbitrary numbers of absorbed (above-threshold) photons and field polarization.
Thoracic research scholarship 1988: pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension at the University of California…
1990
At the University of California, San Diego pulmonary thromboendarterectomy (PTE) has emerged as an effective measure in the treatment of chronic thromboembolic pulmonary hypertension. Unresolved emboli become organized by incorporation into the vascular wall and may form strictures, webs, bands and/or membranous occlusions and cause pulmonary hypertension refractory to medical treatment. When pulmonary vascular resistance exceeds 300 dyn.sec.cm-5 and the vascular wall changes are located to begin at or proximal to the lobar artery level, surgery is indicated. The operation is performed using cardiopulmonary bypass, deep hypothermia and periods of circulatory arrest. The dissection of each s…
Multiple Objective Analysis of Input-Output Models for Emergency Management
1990
This paper shows how a visual, interactive, dynamic multiple objective linear programming decision support system can effectively be used for analyzing input-output models. We have applied our approach to studying the quantitative effects of economic or political crises to the Finnish economy. Examples of such crises are nuclear power plant accidents, trade embargoes, and international conflicts. An input-output model of the Finnish economy with 17 industries (sectors) is employed. Our system has been implemented on a microcomputer and is being used by the National Board of Economic Defense. Several typical case situations are discussed.
13C and17O NMR study of methoxy groups in chlorinated Di- and trimethoxybenzenes
1990
13C and 17O NMR data [chemical shifts and 1J(CH) values] for the methoxy groups in isomeric 1,2-, 1,3- and 1,4-dimethoxybenzenes, 1,2,3-trimethoxybenzenes and most of their chlorinated derivatives and some related brominated compounds were measured for CDCl3 solutions. The 17O NMR chemical shifts show up to 60 ppm dispersion. Comparison between the compounds with and without adjacent chlorine atoms (2,6-di- and 2,4,6-tri-substitution) also showed a clear methoxy carbon chemical shift change. The number and position of the chlorine atoms in the aromatic ring give small but observable effects on the 17O NMR chemical shifts of the methoxy group if it is coplanar with the aromatic plane. Simila…
Surface and virulence properties of environmental Vibrio cholerae non-O1 from Albufera Lake (Valencia, Spain).
1990
A total of 140 environmental Vibrio cholerae non-O1 isolates, together with several culture collection strains from both environmental and clinical sources, were studied in relation to hemagglutination, surface hydrophobicity, and the enzymatic, hemolytic, cytotoxic, and enterotoxic activities of their extracellular products. A total of 78 and 62% of the strains produced hemagglutinins and exohemagglutinins, respectively. Four different hemagglutinating and two exohemagglutinating activities were found by using eight sugars in the inhibition assays. Cell-bound mannose-sensitive hemagglutination was detected mainly in chicken blood, whereas fucose-sensitive hemagglutination was recorded only…
The complexity of graph languages generated by hyperedge replacement
1990
Although in many ways, hyperedge replacement graph grammars (HRGs) are, among all graph generating mechanisms, what context-free Chomsky grammars are in the realm of string rewriting, their parsing problem is known to be, in general, NP-complete. In this paper, the main difficulty in HRG parsing is analysed and some conditions on either grammar or input graphs are developed under which parsing can be done in polynomial time. For some of the cases, the parsing problem is shown to be log-space reducible to context-free string parsing.
Alloying-induced transition from local-moment to itinerant heavy fermion magnetism in Ce(Cu1−xNix)2Ge2
1990
Abstract A monotonous increase of the Kondo temperature in Ce(Cu1−xNix)2Ge2 from 7 (x = 0) to 30 K (x = 1) is accompanied by drastic changes of ground state properties: for x⩽0.2, a modulated magnetic structure (q01 = (0.28, 0.28, 0.54)) involving Kondo-reduced local Ce moments ( μ s = 0.74μ B Ce for x = 0) forms below TN1(x). TN1 = 4. 1 K for CeCu2Ge2 is strongly depressed upon increasing x. At x ≲ 0.2, a different modulation develops below TN2(x) which becomes maximum (≃4 K) for x = 0.5. Since this is characterized by a very small value of q02 (=(0, 0, 0.13) at x = 0.5) and a gradually decreasing ordered moment (reaching μs ≲ 0.2μB/Ce for x ⩾0.65), we ascribe it to “heavy fermion band mag…