207 research outputs found
Investigation of radiation effects in water solutions during exposure with laser or LEDs light
Abstract only.The installation for gamma-, X-ray and neutron registration in water solutions (600 ml LiOH, or NaOH, or Na2CO3) during exposure with red light (λ=645+/-20 nm) of laser or light-emission devises (LEDs) was created. The laser light power was 5 mW and the LEDs - from 600 mW up to 10 W. Neutrons were measured with help of tow 3He counters, placed in paraphine barrel. Small neutron emission (up to 100 neutrons) has been registered in the form of series of short (ms) bursts during some minutes. Tritium production has also been detected in water solution probes. The gamma-ray and X-ray radiation measured by NaI scintillation detector & Geiger counters was not detected. Received results are discussed
Evaluating the Developed Model of Experimental Rhinitis in Laboratory Rats: Pre-Clinical Experimental Randomized Study
Background. Among the damaging factors affecting the mucociliary system of the nasal cavity, surgical wound is of particular relevance in the practice of an otorhinolaryngologist. The clinical assessment of regeneration of the mucociliary system is associated with certain diffi culties, since the intravital morphological examination of the nasal mucosa in patients is traumatic. Therefore, the development of animal models of experimental rhinitis is considered to be highly relevant in order to study the dynamics of mucociliary pathomorphological changes and assess the epithelium regeneration.Objectives. To evaluate the developed model of experimental rhinitis in laboratory rats by studying clinical, morphological and biochemical changes in the infl ammatory process.Methods. The experimental rhinitis model was developed and tested on 60 mature male Wistar rats. All animals were randomized into two groups: experimental group #1 (n = 30) — rats in which experimental rhinitis modeling was performed and group #2 (n = 30) — control, intact animals. In the course of the experiment, the authors examined the content of CRP in blood, evaluated the differential blood cell count, and studied a morphology of the nasal septum mucosa in 2, 5, 10 days after the injury to assess the dynamics of the infl ammatory process in rats of both groups. Statistical analysis of the study results was carried out by means of Statistica 8.0 (StatSoft Inc., USA).Results. After injury, the rats from group #1 developed acute rhinitis, which was clinically manifested by the release of mucous or mucopurulent secretion from the nostrils, sneezing and scratching the nose. An increase in CRP, band and segmented neutrophils, and a decrease in lymphocytes were observed in blood of the rats from group #1 in comparison with the control group. Microscopic analysis of changes in the nasal septum mucosa showed that the acute phase of exudative infl ammation developed on the second day: vascular congestion, edema, neutrophilic infl ammatory infi ltration of the submucosal membrane were observed against the background of foci of epithelial necrosis. The proportion of lymphocytes and macrophages in the infl ammatory infi ltrate increased by the fi fth day, initial signs of restoration of epithelial tissue — the formation of an undifferentiated regenerating epithelium — appeared by the tenth day.Conclusion. The results of the study show that an adequate experimental model of acute rhinitis in laboratory animals have been obtained. An acute infl ammatory process is characterized by clinical manifestations and changes in blood parameters. Particular destructive and reparative-proliferative changes develop in the mucous membrane of the nasal septum of experimental animals as a result of a surgical wound
Work functions, ionization potentials, and in-between: Scaling relations based on the image charge model
We revisit a model in which the ionization energy of a metal particle is
associated with the work done by the image charge force in moving the electron
from infinity to a small cut-off distance just outside the surface. We show
that this model can be compactly, and productively, employed to study the size
dependence of electron removal energies over the range encompassing bulk
surfaces, finite clusters, and individual atoms. It accounts in a
straightforward manner for the empirically known correlation between the atomic
ionization potential (IP) and the metal work function (WF), IP/WF2. We
formulate simple expressions for the model parameters, requiring only a single
property (the atomic polarizability or the nearest neighbor distance) as input.
Without any additional adjustable parameters, the model yields both the IP and
the WF within 10% for all metallic elements, as well as matches the size
evolution of the ionization potentials of finite metal clusters for a large
fraction of the experimental data. The parametrization takes advantage of a
remarkably constant numerical correlation between the nearest-neighbor distance
in a crystal, the cube root of the atomic polarizability, and the image force
cutoff length. The paper also includes an analytical derivation of the relation
of the outer radius of a cluster of close-packed spheres to its geometric
structure.Comment: Original submission: 8 pages with 7 figures incorporated in the text.
Revised submission (added one more paragraph about alloy work functions): 18
double spaced pages + 8 separate figures. Accepted for publication in PR
MRI sensing based on the displacement of paramagnetic ions from chelated complexes
We introduce a mechanism for ion sensing by MRI in which analytes compete with paramagnetic ions for binding to polydentate chelating agents. Displacement of the paramagnetic ions results in alteration of solvent interaction parameters and consequent changes in relaxivity and MRI contrast. The MRI changes can be tuned by the choice of chelator. As an example, we show that calcium-dependent displacement of Mn[superscript 2+] ions bound to EGTA and BAPTA results in a T[subscript 1]-weighted MRI signal increase, whereas displacement from calmodulin results in a signal decrease. The changes are ion selective and can be explained using relaxivity theory. The ratio of T[subscript 2] to T[subscript 1] relaxivity is also calcium-dependent, indicating the feasibility of “ratiometric” analyte detection, independent of the probe concentration. Measurement of paramagnetic ion displacement effects could be used to determine analyte ion concentrations with spatial resolution in opaque specimens.National Institutes of Health (U.S.) (grant DP2-OD2441)National Institutes of Health (U.S.) (grant R01-GM65519)McGovern Institute for Brain Research at MIT. Neurotechnology (MINT) Progra
Conference of Soviet and American Jurists on the Law of the Sea and the Protection of the Marine Environment
Included in the papers for the Conference of Soviet and American Jurists on the Law of the Sea and the Protection of the Marine Environment:
Introduction by Milton Katz and Richard R. Baxter, p. 1
Freedom of Scientific Research in the World Ocean by A.F. Vysotsky, p. 7
The International Law of Scientific Research in the Oceans by Richard R. Baxter, p. 27
Responsibility and Liability for Harm to the Marine Environment by Robert E. Stein, p. 41
Liability for Marine Environment Pollution Damage in Contemporary International Sea Law by A. L. Makovsky, p. 59
Protection of the Marine Environment from Pollution by Richard A. Frank, p. 73
The Freedom of Navigation and the Problem of Pollution of the Marine Environment by V. A. Kiselev, p. 93
The Freedom of Navigation Under International Law by William E. Butler, p. 107
International Fisheries Management Without Global Agreement: United States Policies and Their Impact on the Soviet Union by H. Gary Knight, p. 119
Some Biological Background for International Legal Acts on Rational Utilization of the Living Resources of the World Ocean by P. A. Moiseev, p. 143
An International Regime for the Seabed Beyond National Jurisdiction by Thomas M. Franck, p. 151
Settlement of Disputes Under the Law of Ocean Use, with Particular Reference to Environmental Protection by John Lawrence Hargrove, p. 18
Seasonal variations in pore water and sediment geochemistry of littoral lake sediments (Asylum Lake, MI, USA)
BACKGROUND: Seasonal changes in pore water and sediment redox geochemistry have been observed in many near-surface sediments. Such changes have the potential to strongly influence trace metal distribution and thus create seasonal fluctuations in metal mobility and bioavailability. RESULTS: Seasonal trends in pore water and sediment geochemistry are assessed in the upper 50 cm of littoral kettle lake sediments. Pore waters are always redox stratified, with the least compressed redox stratification observed during fall and the most compressed redox stratification observed during summer. A 2-step sequential sediment extraction yields much more Fe in the first step, targeted at amorphous Fe(III) (hydr)oxides (AEF), then in the second step, which targets Fe(II) monosulfides. Fe extracted in the second step is relatively invariant with depth or season. In contrast, AEF decreases with sediment depth, and is seasonally variable, in agreement with changes in redox stratification inferred from pore water profiles. A 5-step Tessier extraction scheme was used to assess metal association with operationally-defined exchangeable, carbonate, iron and manganese oxide (FMO), organic/sulfide and microwave-digestible residual fractions in cores collected during winter and spring. Distribution of metals in these two seasons is similar. Co, As, Cd, and U concentrations approach detection limits. Fe, Cu and Pb are mostly associated with the organics/sulfides fraction. Cr and Zn are mostly associated with FMO. Mn is primarily associated with carbonates, and Co is nearly equally distributed between the FMO and organics/sulfide fractions. CONCLUSION: This study clearly demonstrates that near-surface lake sediment pore water redox stratification and associated solid phase geochemistry vary significantly with season. This has important ramifications for seasonal changes in the bioavailability and mobility of trace elements. Without rate measurements, it is not possible to quantify the contribution of various processes to natural organic matter degradation. However, the pore water and solid phase data suggest that iron reduction and sulfate reduction are the dominant pathways in the upper 50 cm of these sediments
Variant of the <i>FLNC</i> gene nucleotide sequence in a family with different phenotypic manifestations of left ventricular non-compaction
Left ventricular non-compaction is a heterogeneous heart disease with various phenotypic and clinical manifestations. The article presents the results of clinical, instrumental and molecular genetic investigations of a family with diagnosed left ventricular non-compaction (LVNC) with different clinical and phenotypic manifestations. As a result of a molecular genetic testing, all family members with the LVNC phenotype were found to have a likely pathogenic variant in the FLNC gene. Variants in this gene are associated with a number of cardiomyopathies: dilated, hypertrophic, and restrictive. In the international scientific literature, isolated clinical cases of LVNC development with variants of the FLNC gene nucleotide sequence are presented. In our work, we present a case report of LVNC with a variety of clinical manifestations within the same family
Human Tumor Cell Proliferation Evaluated Using Manganese-Enhanced MRI
Tumor cell proliferation can depend on calcium entry across the cell membrane. As a first step toward the development of a non-invasive test of the extent of tumor cell proliferation in vivo, we tested the hypothesis that tumor cell uptake of a calcium surrogate, Mn(2+) [measured with manganese-enhanced MRI (MEMRI)], is linked to proliferation rate in vitro.Proliferation rates were determined in vitro in three different human tumor cell lines: C918 and OCM-1 human uveal melanomas and PC-3 prostate carcinoma. Cells growing at different average proliferation rates were exposed to 1 mM MnCl(2) for one hour and then thoroughly washed. MEMRI R(1) values (longitudinal relaxation rates), which have a positive linear relationship with Mn(2+) concentration, were then determined from cell pellets. Cell cycle distributions were determined using propidium iodide staining and flow cytometry. All three lines showed Mn(2+)-induced increases in R(1) compared to cells not exposed to Mn(2+). C918 and PC-3 cells each showed a significant, positive correlation between MEMRI R(1) values and proliferation rate (p≤0.005), while OCM-1 cells showed no significant correlation. Preliminary, general modeling of these positive relationships suggested that pellet R(1) for the PC-3 cells, but not for the C918 cells, could be adequately described by simply accounting for changes in the distribution of the cell cycle-dependent subpopulations in the pellet.These data clearly demonstrate the tumor-cell dependent nature of the relationship between proliferation and calcium influx, and underscore the usefulness of MEMRI as a non-invasive method for investigating this link. MEMRI is applicable to study tumors in vivo, and the present results raise the possibility of evaluating proliferation parameters of some tumor types in vivo using MEMRI
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