175 Matching Results

Search Results

Advanced search parameters have been applied.

Conformational Analogs of Some Phytoactive Compounds

Description: In an effort to determine if there is a specific conformational structure which is most effective at the appropriate active physiological site, the synthesis of a group of sterically restricted analogs was undertaken. A portion of the polymethylene carbon skeleton of glutaric acid was replaced by selected aromatic carbons in benzenedicarboxylic acids to produce a series of ridged conformers, and the relative plant growth regulating properties of these derivatives were determined.
Date: August 1973
Creator: Skelton, Wm. Paul
Partner: UNT Libraries

BEST: Bilingual environmental science training: Kindergarten level

Description: This booklet is one of a series of bilingual guides to environmental-science learning activities for students to do at home. Lesson objectives, materials required, procedure, vocabulary, and subjects integrated into the lesson are described in English for each lesson. A bilingual glossary, alphabetized by English entries, with Spanish equivalents in both English and Spanish, follows the lesson descriptions, and is itself followed by a bibliography of English-language references. This booklet includes descriptions of six lessons covering the senses of touch and sight, the sense of smell, how to distinguish living and non-living things, cell structures, the skeletal system, and the significance of food groups. 8 figs.
Date: March 1, 1996
Partner: UNT Libraries Government Documents Department

Radiocarbon dating organic residues at the microgram level

Description: Relation between submilligram sample size and {sup 14}C activity for sample blanks (wood from Pliocene sediments) and a contemporary standard (oxalic acid) for catalytically reduced graphitic carbon was examined down to 20 micrograms. Mean age of the 1 mg wood sample blanks is now about 51.3 ka (0.168 pMC) while the mean for 20 microgram sample blanks is about 42.9 ka. So far, the lowest value for a 1-mg wood sample blank is about 60.5 ka (0.056 pMC). We have determined a mean {sup 14}C age of about 9.4 ka from a suite of 7 organic extracts from hair, bone, and matting from a mummified human skeleton from Spirit Cave, Nevada. These data indicate that the Spirit Cave human is the third, oldest directly-dated, human skeleton currently known from North America.
Date: January 1, 1997
Creator: Kirner, D. L.; Burky, R.; Taylor, R. E. & Southon, J. R.
Partner: UNT Libraries Government Documents Department

Final report-98-ERI-003 identification of population with lifetime 41Ca-labeled skeletons

Description: In 1997 we first postulated the existence of a special human population that had had their skeletons inadvertently isotopically adulterated in the past. We theorized that the population, and the necessary LLNL accelerator mass spectrometer (AMS) measurement technology, would prove a significant resource in the fight to combat osteoporosis. This LDRD project was to establish such. The project was significantly successful in its initial year, but was not renewed for another and the research is now ended at LLNL. We proposed a three-year program to (1) confirm the magnitude and extent of historical 41 Ca dosing, (2) exactly characterize the long-term 41 Ca signal by comparing it with conventional measurements of skeletal health, and (3) demonstrate the utility of the historically labeled population in evaluating an actual potential therapy for osteoporosis. However, rather than investigate historical records to learn the identity of those inadvertently dosed, find them, and if possible enroll them into a new protocol, this project was to be particularly efficient by making use of a multiyear archive of samples from original, inadvertent 41 Ca-dosing experiments at Creighton University in Omaha, Nebraska. Because the subjects had been dosed in conventional studies of calcium kinetics, much important correlating historical data would also be available for comparison. Measurements of contemporary urine samples specifically provided for this project by selected identified subjects would follow. We discovered a second archive at the University of Texas Southwestern Medical Center. This is potentially a better source of material as the samples were generated in numerous historical evaluations of actual osteoporosis therapies in which 41 Ca-impure radiotracers were used. The therapies might now powerfully be retrospectively evaluated, both to contribute to our understanding of the therapies and to highlight the potential of the use of 41 Ca tracer and LLNL measurement.
Date: February 25, 1999
Creator: Freeman, S P
Partner: UNT Libraries Government Documents Department

Cancer from internal emitters

Description: Irradiation from internal emitters, or internally deposited radionuclides, is an important component of radiation exposures encountered in the workplace, home, or general environment. Long-term studies of human populations exposed to various internal emitters by different routes of exposure are producing critical information for the protection of workers and members of the general public. The purpose of this report is to examine recent developments and discuss their potential importance for understanding lifetime cancer risks from internal emitters. The major populations of persons being studied for lifetime health effects from internally deposited radionuclides are well known: Lung cancer in underground miners who inhaled Rn progeny, liver cancer from persons injected with the Th-containing radiographic contrast medium Thorotrast, bone cancer from occupational or medical intakes of {sup 226}Ra or medical injections of {sup 224}Ra, and thyroid cancer from exposures to iodine radionuclides in the environment or for medical purposes.
Date: October 1, 1995
Creator: Boecker, B.B. & Griffith, W.C. Jr.
Partner: UNT Libraries Government Documents Department

Radiocarbon Based Ages and Growth Rates: Hawaiian Deep Sea Corals

Description: The radial growth rates and ages of three different groups of Hawaiian deep-sea 'corals' were determined using radiocarbon measurements. Specimens of Corallium secundum, Gerardia sp., and Leiopathes glaberrima, were collected from 450 {+-} 40 m at the Makapuu deep-sea coral bed using a submersible (PISCES V). Specimens of Antipathes dichotoma were collected at 50 m off Lahaina, Maui. The primary source of carbon to the calcitic C. secundum skeleton is in situ dissolved inorganic carbon (DIC). Using bomb {sup 14}C time markers we calculate radial growth rates of {approx} 170 {micro}m y{sup -1} and ages of 68-75 years on specimens as tall as 28 cm of C. secundum. Gerardia sp., A. dichotoma, and L. glaberrima have proteinaceous skeletons and labile particulate organic carbon (POC) is their primary source of architectural carbon. Using {sup 14}C we calculate a radial growth rate of 15 {micro}m y{sup -1} and an age of 807 {+-} 30 years for a live collected Gerardia sp., showing that these organisms are extremely long lived. Inner and outer {sup 14}C measurements on four sub-fossil Gerardia spp. samples produce similar growth rate estimates (range 14-45 {micro}m y{sup -1}) and ages (range 450-2742 years) as observed for the live collected sample. Similarly, with a growth rate of < 10 {micro}m y{sup -1} and an age of {approx}2377 years, L. glaberrima at the Makapuu coral bed, is also extremely long lived. In contrast, the shallow-collected A. dichotoma samples yield growth rates ranging from 130 to 1,140 {micro}m y{sup -1}. These results show that Hawaiian deep-sea corals grow more slowly and are older than previously thought.
Date: January 13, 2006
Creator: Roark, E B; Guilderson, T P; Dunbar, R B & Ingram, B L
Partner: UNT Libraries Government Documents Department

Communication Between the Cell Membrane and the Nucleus: Role of Protein Compartmentalization

Description: Understanding how the information is conveyed from outside to inside the cell is a critical challenge for all biologists involved in signal transduction. The flow of information initiated by cell-cell and cell-extracellular matrix contacts is mediated by the formation of adhesion complexes involving multiple proteins. Inside adhesion complexes, connective membrane skeleton (CMS) proteins are signal transducers that bind to adhesion molecules, organize the cytoskeleton, and initiate biochemical cascades. Adhesion complex-mediated signal transduction ultimately directs the formation of supramolecular structures in the cell nucleus, as illustrated by the establishment of multi complexes of DNA-bound transcription factors, and the redistribution of nuclear structural proteins to form nuclear subdomains. Recently, several CMS proteins have been observed to travel to the cell nucleus, suggesting a distinctive role for these proteins in signal transduction. This review focuses on the nuclear translocation of structural signal transducers of the membrane skeleton and also extends our analysis to possible translocation of resident nuclear proteins to the membrane skeleton. This leads us to envision the communication between spatially distant cellular compartments (i.e., membrane skeleton and cell nucleus) as a bidirectional flow of information (a dynamic reciprocity) based on subtle multilevel structural and biochemical equilibria. At one level, it is mediated by the interaction between structural signal transducers and their binding partners, at another level it may be mediated by the balance and integration of signal transducers in different cellular compartments.
Date: October 21, 1998
Creator: Lelievre, Sophie A & Bissell, Mina J
Partner: UNT Libraries Government Documents Department

Human calcium metabolism including bone resorption measured with {sup 41}Ca tracer

Description: Accelerator mass spectrometry is so sensitive to small quantities of {sup 41}Ca that it might be used as a tracer in the study of human calcium kinetics to generate unique kinds of data. In contrast with the use of other Ca isotopic tracers, {sup 41}Ca tracer can be so administered that the tracer movements between the various body pools achieve a quasi steady state. Resorbing bone may thus be directly measured. We have tested such a protocol against a conventional stable isotope experiment with good agreement.
Date: August 1, 1996
Creator: Freeman, S.P.H.T.; King, J.C.; Vieira, N.E.; Woodhouse, L.R. & Yergey, A.L.
Partner: UNT Libraries Government Documents Department

Biomimetic thin film deposition

Description: Biological mineral deposition for the formation of bone, mollusk shell and other hard tissues provides materials scientists with illustrative materials processing strategies. This presentation will review the key features of biomineralization and how these features can be of technical importance. We have adapted existing knowledge of biomineralization to develop a unique method of depositing inorganic thin films and coating. Our approach to thin film deposition is to modify substrate surfaces to imitate the proteins found in nature that are responsible for controlling mineral deposition. These biomimetic surfaces control the nucleation and growth of the mineral from a supersaturated aqueous solution. This has many processing advantages including simple processing equipment, environmentally benign reagents, uniform coating of highly complex shapes, and enhanced adherence of coating. Many different types of metal oxide, hydroxide, sulfide and phosphate materials with useful mechanical, optical, electronic and biomedical properties can be deposited.
Date: September 1, 1995
Creator: Rieke, P.R.; Graff, G.E.; Campbell, A.A.; Bunker, B.C.; Baskaran, S.; Song, L. et al.
Partner: UNT Libraries Government Documents Department

An Integrated Multi-component Processing and Interpretation Framework for 3D Borehole Seismic Data

Description: This report covers the October 2003 until March 2004 time period. Work has continued successfully on several tasks 1 through 7. Most of these tasks have been executed independently. Due to availability of manpower during that time period we progressed steadily and completed some of the tasks, while others are still on going. We achieved the goals that we had set up in the task schedule. Reviewing the results of this work period indicates that our plan is on schedule and we did not encounter any unforeseen problems. The work plan will continue as projected. Several independent tasks pursuant the statement of project objectives have been executed simultaneously and are still on-going. This report summarizes the selection, test processing and test flow generation of a relevant 3D borehole seismic high-resolution test dataset. This multi-component data set is suitable for future use in this project due to data quality and unique acquisition characteristics. This report shows initial processing results that supported the data selection scheduled for Task 1. Use of real data is augmented by the creating a 3D layered synthetic geologic model in which multi-component 3D borehole seismic data were generated using 3D ray tracing. A gridded surface representation of the reflection interfaces as well as fully populated velocity grids were generated and archived. The model consists of a moderately dipping geologic setting with horizon undulations. A realistic velocity variation is used in between the three layers. Acquisition was simulated from a set of equidistant source locations at the surface of the model, while a close to vertical VSP well was used to capture the wave field data. The source pattern was close to a staggered grid pattern. Multi-component particle displacements were recorded every 50 ft down with an array length of 4,000 ft. P-P as well as P-S reflections ...
Date: April 1, 2004
Creator: Karrenbach, M.
Partner: UNT Libraries Government Documents Department

Tolerance to Sr{sup 89} and radium

Description: Problems in extrapolation of the rate of tumor formation by strontium 89 from animal to man are addressed. Focus of this paper is on variability of latency period between different animals.
Date: July 22, 1946
Creator: Brues, A.M.
Partner: UNT Libraries Government Documents Department

Stress and flow in fractured porous media

Description: The purpose of the present study is to develop a method for simultaneous solution of stress and flow in a deformable fractured isotropic porous medium saturated with a single phase slightly compressible fluid. The system defined as such can be under the effect of body forces, boundary loads, initial stress, and influenced by some fluid pressure disturbance. The method involves application of the theory of elasticity for plane strain systems, Darcy's law for porous medium, and Biot's constitutive equations for the mixture of fluid and solid skeleton. The resulting initial boundary value problem is then numerically formulated into finite element equations using the calculus of variations. A computer program has been developed by modifying existing programs to consider interactions between fractures and porous medium when both flow and stress fields are coupled. The program is capable of handling problems in rock masses where fractures extend from one boundary to another, intersect each other, or are isolated in the porous medium. The fractures may have random orientations and the rock matrix can be permeable or impermeable. The region under investigation may be two dimensional or axially symmetric. Solutions can be obtained for either a steady-state flow field under static equilibrium or a non-steady flow field in conjunction with quasi-static equilibrium conditions.
Date: January 1, 1978
Creator: Ayatollahi, Mohammad Sadegh
Partner: UNT Libraries Government Documents Department

Preaxial Polydactyly in Sost/Sostdc1 Double Knockouts

Description: In the United States, {approx}5% are born with congenital birth defects due to abnormal function of cellular processes and interactions. Sclerosteosis, a rare autosomal recessive disease, causes hyperostosis of the axial and appendicular skeleton, and patients present radial deviation, digit syndactyly, nail dysplasia, and overall high bone mineral density. Sclerosteosis is due to a loss of function of sclerostin (Sost). Sost is a Wnt (abbrev.) antagonist; when mutated, nonfunctional Sost results in hyperactive osteoblast activity which leads to abnormal high bone mass. Previous studies have shown that Sost overexpression in transgenic mice causes reduced bone mineral density and a variety of limb phenotypes ranging from lost, fused, and split phalanges. Consistent with clinical manifestations of Sclerosteosis, Sost knockout mice exhibit increased generalized bone mineral density and syndactyly of the digits. Sostdc1 is a paralog of Sost that has also been described as an antagonist of Wnt signaling, in developing tooth buds. Unlike Sost knockouts, Sostdc1 null mice do not display any limb abnormalities. To determine if Sost and Sostdc1 have redundant functions during limb patterning, we examined Sost; Sostdc1 mice determined that they exhibit a novel preaxial polydactyly phenotype with a low penetrance. LacZ staining, skeletal preparations, and in situ hybridization experiments were used to help characterize this novel phenotype and understand how this phenotype develops. We find Sost and Sostdc1 to have complementary expression patterns during limb development, and the loss of their expression alters the transcription of several key limb regulators, such as Fgf8, Shh and Grem.
Date: July 29, 2011
Creator: Yee, C M; Collette, N M & Loots, G G
Partner: UNT Libraries Government Documents Department

Chemisorption On Nanoparticles: An Alternative Mechanism For Hydrogen Storage

Description: We present first principles, computational predictions of a porous, nano-structured semiconductor material that will reversibly store hydrogen for fuel cell applications. The material is competitive with current metal hydride storage materials, but contains only carbon and silicon, reducing both its cost and environmental impact. Additionally, unlike metal hydrides, the core skeleton structure of this material is unaltered when cycling from full hydrogen storage to full hydrogen depletion, removing engineering complications associated with expansion/contraction of the material.
Date: April 9, 2004
Creator: Williamson, A; Reboredo, F & Galli, G
Partner: UNT Libraries Government Documents Department

NMR clinical imaging and spectroscopy: Its impact on nuclear medicine

Description: This is a collection of four papers describing aspects of past and future use of nuclear magnetic resonance as a clinical diagnostic tool. The four papers are entitled (1) What Does NMR Offer that Nuclear Medicine Does Not? by Jerry W. Froelich, (2) Oncological Imaging: Now, Future and Impact Jerry W. Froelich, (3) Magnetic Resonance Spectroscopy/Spectroscopic Imaging and Nuclear Medicine: Past, Present and Future by H. Cecil Charles, and (4) MR Cardiology: Now, Future and Impact by Robert J. Herfkens.
Date: February 2, 1990
Partner: UNT Libraries Government Documents Department

Biomimetic lithography and deposition kinetics of iron oxyhydroxide thin films

Description: Heterogeneous nucleation and crystal growth on functionalized organic substrates is a critical step in biological hard tissue formation. Self assembled monolayers can be derivatized with various organic functional groups to mimic the ``nucleation proteins`` for induction of mineral growth. Studies of nucleation and growth on SAMs can provide a better understanding of biomineralization and can also form the basis of a superior thin film deposition process. We demonstrate that micron-scale, electron and ion beam, lithographic techniques can be used to pattern SAMs with functional organic groups that either inhibit or promote mineral deposition. Patterned films of iron oxyhydroxide were deposited on the areas patterned with nucleation sites. Studies of the deposition kinetic of these films show that indeed the surface induces heterogeneous nucleation and that film formation does not occur via absorption of polymers or colloidal material formed homogeneously in solution. The nucleus interfacial free energy was calculated to be 24 mJ/m2 on a SAM surface composed entirely of sulfonate groups.
Date: December 1, 1993
Creator: Rieke, P. C.; Wood, L. L.; Marsh, B. M.; Fryxell, G. E.; Engelhard, M. H.; Baer, D. R. et al.
Partner: UNT Libraries Government Documents Department

BEST: Bilingual environmental science training: Grades 1--2

Description: This booklet is one of a series of bilingual guides to environmental-science learning activities for students to do at home. Lesson objectives, materials required, procedure, vocabulary, and subjects integrated into the lesson are described in English for each lesson. A bilingual glossary, alphabetized by English entries, with Spanish equivalents and definitions in both English and Spanish, follows the lesson descriptions, and is itself followed by a bibliography of English-language references. This booklet includes descriptions of ten lessons covering surface tension in water, the life cycle of plants, the protective function of the skeletal system, functions and behavior of the circulatory system and how to measure its activities, structure and functions of the digestive system, simple food chains, how that many foods come from different plant parts, importance of a good diet, distinguishing living and non-living things, and the benefits of composting. 8 figs.
Date: March 1, 1996
Partner: UNT Libraries Government Documents Department

Bone sarcoma in humans induced by radium: A threshold response?

Description: The radium 226 and radium 228 have induced malignancies in the skeleton (primarily bone sarcomas) of humans. They have also induced carcinomas in the paranasal sinuses and mastoid air cells. There is no evidence that any leukemias or any other solid cancers have been induced by internally deposited radium. This paper discuses a study conducted on the dial painter population. This study made a concerted effort to verify, for each of the measured radium cases, the published values of the skeletal dose and the initial intake of radium. These were derived from body content measurements made some 40 years after the radium intake. Corrections to the assumed radium retention function resulted in a considerable number of dose changes. These changes have changed the shape of the dose response function. It now appears that the induction of bone sarcomas is a threshold process.
Date: August 1996
Creator: Rowland, R. E.
Partner: UNT Libraries Government Documents Department

The Advancement of Public Awareness, Concerning TRU Waste Characterization, Using a Virtual Document

Description: Building public trust and confidence through openness is a goal of the DOE Carlsbad Field Office for the Waste Isolation Pilot Plant (WIPP). The objective of the virtual document described in this paper is to give the public an overview of the waste characterization steps, an understanding of how waste characterization instrumentation works, and the type and amount of data generated from a batch of drums. The document is intended to be published on a web page and/or distributed at public meetings on CDs. Users may gain as much information as they desire regarding the transuranic (TRU) waste characterization program, starting at the highest level requirements (drivers) and progressing to more and more detail regarding how the requirements are met. Included are links to: drivers (which include laws, permits and DOE Orders); various characterization steps required for transportation and disposal under WIPP's Hazardous Waste Facility Permit; physical/chemical basis for each characterization method; types of data produced; and quality assurance process that accompanies each measurement. Examples of each type of characterization method in use across the DOE complex are included. The original skeleton of the document was constructed in a PowerPoint presentation and included descriptions of each section of the waste characterization program. This original document had a brief overview of Acceptable Knowledge, Non-Destructive Examination, Non-Destructive Assay, Small Quantity sites, and the National Certification Team. A student intern was assigned the project of converting the document to a virtual format and to discuss each subject in depth. The resulting product is a fully functional virtual document that works in a web browser and functions like a web page. All documents that were referenced, linked to, or associated, are included on the virtual document's CD. WIPP has been engaged in a variety of Hazardous Waste Facility Permit modification activities. During the public ...
Date: February 28, 2002
Creator: West, T. B.; Burns, T. P.; Estill, W. G.; Riggs, M. J.; Taggart, D. P. & Punjak, W. A.
Partner: UNT Libraries Government Documents Department

Bone formation: The rules for fabricating a composite ceramic

Description: Bone, teeth and shells are complex composite ceramics which are fabricated at low temperature by living organisms. The detailed understanding of this fabrication process is required if we are to attempt to mimic this low temperature assembly process. The guiding principles and major components are outlined with the intent of establishing non-vital fabrication schemes to form a complex composite ceramic consisting of an organix matrix inorganic crystalline phase. 19 refs.
Date: January 1, 1990
Creator: Caplan, A.I. (Case Western Reserve Univ., Cleveland, OH (USA))
Partner: UNT Libraries Government Documents Department

Technical progress report on the metabolic studies of plutonium for month of August 1945

Description: This monthly report briefly describes ongoing studies including urinary and fecal excretion of Plutonium 238 by human subjects and by rats, exploring way to facilitate the removal of Plutonium 238 from rat bone, the absorption of Plutonium 238 by barley plants, and use of inert iodine to block absorption of Iodine-131 in the rat.
Date: December 31, 1945
Creator: Hamilton, J.G.
Partner: UNT Libraries Government Documents Department