Scholars@Duke
Leonard D. Spicer

Leonard D. Spicer

University Distinguished Service Professor Emeritus of Radiology
Radiology
spicer@biochem.duke.edu
Box 3711 Med Ctr, Durham, NC 27710
235 Nanaline H Duke, Durham, NC 27708

Selected Publications

Leveraging Fungal and Human Calcineurin-Inhibitor Structures, Biophysical Data, and Dynamics To Design Selective and Nonimmunosuppressive FK506 Analogs.

Journal Article mBio · December 21, 2021 Calcineurin is a critical enzyme in fungal pathogenesis and antifungal drug tolerance and, therefore, an attractive antifungal target. Current clinically accessible calcineurin inhibitors, such as FK506, are immunosuppressive to humans, so exploiting calci ... Full text Open Access Link to item Cite

Salmonella Typhi Vi capsule prime-boost vaccination induces convergent and functional antibody responses.

Journal Article Sci Immunol · October 29, 2021 Vaccine development to prevent Salmonella Typhi infections has accelerated over the past decade, resulting in licensure of new vaccines, which use the Vi polysaccharide (Vi PS) of the bacterium conjugated to an unrelated carrier protein as the active compo ... Full text Open Access Link to item Cite

FKBP12 dimerization mutations effect FK506 binding and differentially alter calcineurin inhibition in the human pathogen Aspergillus fumigatus.

Journal Article Biochem Biophys Res Commun · May 21, 2020 The 12-kDa FK506-binding protein (FKBP12) is the target of the commonly used immunosuppressive drug FK506. The FKBP12-FK506 complex binds to calcineurin and inhibits its activity, leading to immunosuppression and preventing organ transplant rejection. Our ... Full text Open Access Link to item Cite

Leveraging Fungal Calcineurin-Inhibitor Structures, Biophysics and Dynamics to Design Selective and Non-Immunosuppressive FK506 Analogs

Journal Article · 2020 Calcineurin is a critical enzyme in fungal pathogenesis and antifungal drug tolerance and, therefore, an attractive antifungal target. Current clinically-accessible calcineurin inhibitors, such as FK506, are immunosuppressive to humans, so exploiting calci ... Full text Open Access Cite

Harnessing calcineurin-FK506-FKBP12 crystal structures from invasive fungal pathogens to develop antifungal agents.

Journal Article Nat Commun · September 19, 2019 Calcineurin is important for fungal virulence and a potential antifungal target, but compounds targeting calcineurin, such as FK506, are immunosuppressive. Here we report the crystal structures of calcineurin catalytic (CnA) and regulatory (CnB) subunits c ... Full text Open Access Link to item Cite

15N, 13C and 1H resonance assignments of FKBP12 proteins from the pathogenic fungi Mucor circinelloides and Aspergillus fumigatus.

Journal Article Biomol NMR Assign · April 2019 Invasive fungal infections are a leading cause of death in immunocompromised patients and remain difficult to treat since fungal pathogens, like mammals, are eukaryotes and share many orthologous proteins. As a result, current antifungal drugs have limited ... Full text Open Access Link to item Cite

Structures of Pathogenic Fungal FKBP12s Reveal Possible Self-Catalysis Function.

Journal Article mBio · April 26, 2016 UNLABELLED: Invasive fungal infections remain difficult to treat and require novel targeting strategies. The 12-kDa FK506-binding protein (FKBP12) is a ubiquitously expressed peptidyl-prolyl isomerase with considerable homology between fungal pathogens and ... Full text Link to item Cite

Structure of an HIV-1-neutralizing antibody target, the lipid-bound gp41 envelope membrane proximal region trimer.

Journal Article Proc Natl Acad Sci U S A · January 28, 2014 The membrane proximal external region (MPER) of HIV-1 glycoprotein (gp) 41 is involved in viral-host cell membrane fusion. It contains short amino acid sequences that are binding sites for the HIV-1 broadly neutralizing antibodies 2F5, 4E10, and 10E8, maki ... Full text Link to item Cite

Identification of autoantigens recognized by the 2F5 and 4E10 broadly neutralizing HIV-1 antibodies.

Journal Article J Exp Med · February 11, 2013 Many human monoclonal antibodies that neutralize multiple clades of HIV-1 are polyreactive and bind avidly to mammalian autoantigens. Indeed, the generation of neutralizing antibodies to the 2F5 and 4E10 epitopes of HIV-1 gp41 in man may be proscribed by i ... Full text Open Access Link to item Cite

In-cell NMR spectroscopy in Escherichia coli.

Journal Article Methods Mol Biol · 2012 Featured Publication A living cell is a complex system that contains many biological macromolecules and small molecules necessary for survival, in a relatively small volume. It is within this crowded and complex cellular environment that proteins function making in-cell studie ... Full text Link to item Cite

The MetJ regulon in gammaproteobacteria determined by comparative genomics methods.

Journal Article BMC Genomics · November 14, 2011 Featured Publication BACKGROUND: Whole-genome sequencing of bacteria has proceeded at an exponential pace but annotation validation has lagged behind. For instance, the MetJ regulon, which controls methionine biosynthesis and transport, has been studied almost exclusively in E ... Full text Link to item Cite

Crystal structure of a non-neutralizing antibody to the HIV-1 gp41 membrane-proximal external region.

Journal Article Nat Struct Mol Biol · December 2010 The monoclonal antibody 13H11 shares part of its epitope in the HIV-1 gp41 membrane-proximal external region (MPER) with the rare, broadly neutralizing human antibody 2F5. Although 13H11 partially cross-blocked 2F5 binding, 13H11 is non-neutralizing and do ... Full text Link to item Cite

Binding of MetJ repressor to specific and nonspecific DNA and effect of S-adenosylmethionine on these interactions.

Journal Article Biochemistry · April 20, 2010 Featured Publication We have used analytical ultracentrifugation to characterize the binding of the methionine repressor protein, MetJ, to synthetic oligonucleotides containing zero to five specific recognition sites, called metboxes. For all lengths of DNA studied, MetJ binds ... Full text Open Access Link to item Cite

MetJ repressor interactions with DNA probed by in-cell NMR.

Journal Article Proc Natl Acad Sci U S A · March 31, 2009 Featured Publication Atomic level characterization of proteins and other macromolecules in the living cell is challenging. Recent advances in NMR instrumentation and methods, however, have enabled in-cell studies with prospects for multidimensional spectral characterization of ... Full text Link to item Cite

Structural basis for the differential regulation of DNA by the methionine repressor MetJ.

Journal Article J Biol Chem · November 10, 2006 Featured Publication The Met regulon in Escherichia coli encodes several proteins responsible for the biosynthesis of methionine. Regulation of the expression of most of these proteins is governed by the methionine repressor protein MetJ and its co-repressor, the methionine de ... Full text Link to item Cite

Multidimensional NMR spectroscopy for protein characterization and assignment inside cells.

Journal Article J Am Chem Soc · August 10, 2005 Featured Publication High-field, heteronuclear NMR spectroscopy of biological macromolecules in native cellular environments is limited by the low concentrations present and the long data acquisition times needed for the experiments. Successful 1D and 2D heteronuclear NMR data ... Full text Link to item Cite

DNA-XPA interactions: a (31)P NMR and molecular modeling study of dCCAATAACC association with the minimal DNA-binding domain (M98-F219) of the nucleotide excision repair protein XPA.

Journal Article Nucleic Acids Res · June 15, 2001 Featured Publication Recent NMR-based, chemical shift mapping experiments with the minimal DNA-binding domain of XPA (XPA-MBD: M98-F219) suggest that a basic cleft located in the loop-rich subdomain plays a role in DNA-binding. Here, XPA-DNA interactions are further characteri ... Full text Link to item Cite

Human nucleotide excision repair protein XPA: NMR spectroscopic studies of an XPA fragment containing the ERCC1-binding region and the minimal DNA-binding domain (M59-F219).

Journal Article Mutat Res · June 5, 2001 XPA is a central protein component of nucleotide excision repair (NER), a ubiquitous, multi-component cellular pathway responsible for the removal and repair of many structurally distinct DNA lesions from the eukaryotic genome. The solution structure of th ... Full text Link to item Cite

Interactions of human nucleotide excision repair protein XPA with DNA and RPA70 Delta C327: chemical shift mapping and 15N NMR relaxation studies.

Journal Article Biochemistry · November 16, 1999 Featured Publication Human XPA is an essential component in the multienzyme nucleotide excision repair (NER) pathway. The solution structure of the minimal DNA binding domain of XPA (XPA-MBD: M98-F219) was recently determined [Buchko et al. (1998) Nucleic Acids Res. 26, 2779-2 ... Full text Link to item Cite

Nuclear magnetic resonance analysis of solution conformations in C4-V3 hybrid peptides derived from human immunodeficiency virus (HIV) type 1 gp120: relation to specificity of peptide-induced anti-HIV neutralizing antibodies.

Journal Article J Virol · January 1999 Immunogenic peptides containing epitopes of the gp120 C4 and V3 regions from human immunodeficiency virus strains MN and EV91 have been studied by nuclear magnetic resonance and molecular modeling and used as immunogens in rhesus monkeys. The results, comb ... Full text Link to item Cite

Strategies for NMR assignment and global fold determinations using perdeuterated proteins

Journal Article Techniques in Protein Chemistry · December 1, 1997 Full text Cite

Nmr investigation of a microtubule binding region peptide from human tau (τ) protein

Journal Article Protein and Peptide Letters · December 1, 1997 Solution NMR studies of τD1, an 18-residue microtubule binding peptide from domain 1 of human tau protein, are reported. Using 2D 1H NMR (TOCSY, NOESY and ROESY) at 5 and 37°C, we assigned the resonances of almost all protons of τD1 at pH 4.2,5.8 and 7.3. ... Cite

Characterizing the use of perdeuteration in NMR studies of large proteins: 13C, 15N and 1H assignments of human carbonic anhydrase II.

Journal Article J Mol Biol · December 20, 1996 Featured Publication Perdeuteration of all non-exchangeable proton sites can significantly increase the size of proteins and protein complexes for which NMR resonance assignments and structural studies are possible. Backbone 1H, 15N, 13CO, 13C alpha and 13C beta chemical shift ... Full text Link to item Cite

NMR studies of structure, hydrogen exchange, and main-chain dynamics in a disrupted-core mutant of thioredoxin.

Journal Article Protein Sci · December 1996 Featured Publication Core-packing mutants of proteins often approach molten globule states, and hence may have attributes of folding intermediates. We have studied a core-packing mutant of thioredoxin, L78K, in which a leucine residue is substituted by lysine, using 15N hetero ... Full text Link to item Cite

Conformational preferences of a chimeric peptide HIV-1 immunogen from the C4-V3 domains of gp120 envelope protein of HIV-1 CAN0A based on solution NMR: comparison to a related immunogenic peptide from HIV-1 RF.

Journal Article Biochemistry · April 23, 1996 Featured Publication A critical problem to overcome on HIV vaccine design is the variability among HIV strains. One strategy to solve this problem is the construction of multicomponent immunogens reflective of common HIV motifs. Currently, it is not known if these motifs shoul ... Full text Link to item Cite

Improved excitation pulse bandwidths using shaped pulses, with application to heteronuclear half filters in macromolecular NMR.

Journal Article J Magn Reson B · July 1995 The advantageous use of sinc-shaped pulses in heteronuclear half filters is explored for studying biological macromolecules. The typical square, or hard, pulse used in half-filter pulse sequences for heteronuclear excitation results in suboptimal suppressi ... Full text Link to item Cite

High-level 2H/13C/15N labeling of proteins for NMR studies.

Journal Article J Biomol NMR · June 1995 The protein human carbonic anhydrase II (HCA II) has been isotopically labeled with 2H, 13C and 15N for high-resolution NMR assignment studies and pulse sequence development. To increase the sensitivity of several key 1H/13C/15N triple-resonance correlatio ... Full text Link to item Cite

NMR-STUDIES OF H-2/C-13/N-15-LABELED HCA-II

Conference JOURNAL OF CELLULAR BIOCHEMISTRY · April 2, 1995 Link to item Cite

Thermodynamic evaluation of binding interactions in the methionine repressor system of Escherichia coli using isothermal titration calorimetry.

Journal Article Biochemistry · March 14, 1995 The binding interactions of the methionine repressor protein, MetJ, from Escherichia coli with its cognate, metbox DNA sequence and corepressor S-adenosylmethionine were examined using calorimetric methods. A detailed thermodynamic characterization of this ... Full text Link to item Cite

Heteronuclear gradient-enhanced NMR for the study of 20–30kDa proteins: Application to human carbonic anhydrase II

Journal Article Techniques in Protein Chemistry · January 1, 1995 Human carbonic anhydrase (HCA) is ubiquitous in living systems with seven different mammalian isozymes (CAI to CAVII), and HCAII is one of the largest monomeric proteins currently, being studied by NMR, making it a good system on which to demonstrate the a ... Full text Cite

Use of 1HN- 1HN NOEs to Determine Protein Global Folds in Perdeuterated Proteins

Journal Article Journal of the American Chemical Society · January 1, 1995 Full text Cite

NMR-derived solution conformations of a hybrid synthetic peptide containing multiple epitopes of envelope protein gp120 from the RF strain of human immunodeficiency virus.

Journal Article Biochemistry · March 1, 1994 Solution conformations of a 40-residue hybrid peptide containing T-helper epitopes and B-cell determinants from envelope glycoprotein gp120 of human immunodeficiency virus (HIV) have been investigated with NMR. Peptides of this general design are highly im ... Full text Link to item Cite

NMR Methods Used to Derive Solution Conformations in Peptides

Conference · January 1, 1994 This chapter discusses nuclear magnetic resonance (NMR) methods used to derive solution conformations in peptides. Two-dimensional proton NMR spectroscopy provides an important tool for identifying preferred conformers in otherwise unstructured peptides. T ... Full text Cite

Proton NMR of Escherichia coli sulfite reductase: studies of the heme protein subunit with added ligands.

Journal Article Biochemistry · August 31, 1993 The heme protein subunit of sulfite reductase (SiR-HP; M(r) 64,000) from Escherichia coli as isolated contains the isobacteriochlorin siroheme exchange-coupled to a [4Fe-4S] cluster in the 2+ oxidation state. SiR-HP in the presence of a suitable electron d ... Full text Link to item Cite

Proton NMR of Escherichia coli sulfite reductase: the unligated hemeprotein subunit.

Journal Article Biochemistry · March 23, 1993 The isolated hemeprotein subunit of sulfite reductase (SiR-HP) from Escherichia coli consists of a high spin ferric isobacteriochlorin (siroheme) coupled to a diamagnetic [4Fe-4S]2+ cluster. When supplied with an artificial electron donor, such as methyl v ... Full text Link to item Cite

HETERONUCLEAR EDITED STUDIES OF THE ESCHERICHIA-COLI METHIONINE REPRESSOR SYSTEM

Conference JOURNAL OF CELLULAR BIOCHEMISTRY · February 8, 1993 Link to item Cite

Phosphorus 31 magnetic resonance spectroscopy of perifused human placental villi under varying oxygen concentrations.

Journal Article Am J Obstet Gynecol · January 1993 OBJECTIVE: Initial phosphorus magnetic resonance spectroscopy observations on the oxygen metabolism of placental villi from normal term pregnancies are described. STUDY DESIGN: Villi were suspended in medium and perifused within a custom-designed 30 mm nuc ... Full text Link to item Cite

Catalyst type and concentration dependence in catalytic transfer hydrogenolysis of α,β-Unsaturated Carbonyls And Nitriles Via Ammonium Formate

Journal Article Synthetic Communications · September 1, 1992 The catalytic reduction of a variety of α. β-unsaturated compounds into saturated analogs in the presence of other reducible moieties is described using ammonium formate as a hydrogen source. The rate dependence on the concentration of Pd-C catalyst as wel ... Full text Cite

Temperature and solvent dependent catalytic transfer hydrogenolysis in aromatic aldehydes and ketones via ammonium formate

Journal Article Synthetic Communications · September 1, 1992 Temperature control and solvent specification are used to reduce aromatic aldehydes and ketones to intermediate alcohols rather than methylene derivatives using HCO2NH4as a catalytic hydrogen transfer agent. A mechanism for the catalytic reduction is propo ... Full text Cite

Comparative analysis of normal and growth-retarded placentas with phosphorus nuclear magnetic resonance spectroscopy.

Journal Article Am J Obstet Gynecol · August 1992 OBJECTIVE: Phosphorus 31 magnetic resonance spectroscopy studies were carried out on placentas from normal vaginal and elective cesarean deliveries without antenatal complications and from pregnancies complicated by intrauterine growth retardation of unkno ... Full text Link to item Cite

A refocused and optimized HNCA: increased sensitivity and resolution in large macromolecules.

Journal Article J Biomol NMR · March 1992 A 3D optimized, refocused HNCA experiment is described. It is demonstrated to yield a dramatic increase in sensitivity when applied to [13C, 15N]-labeled human carbonic anhydrase II, a 29-kDa protein. The reasons for the gain in sensitivity are discussed, ... Full text Link to item Cite

Characterization of a microcarrier cell culture system for 23Na MR spectroscopy studies.

Journal Article NMR Biomed · October 1991 A MR spectroscopy method is described for the simultaneous discrimination and observation of sodium from the three compartments created by an intact cell monolayer. Results are reported for Madin Darby Canine Kidney (MDCK) cells, an epithelial-like continu ... Full text Link to item Cite

Uniform 13C isotope labeling of proteins with sodium acetate for NMR studies: application to human carbonic anhydrase II.

Journal Article Biochemistry · May 7, 1991 Uniform double labeling of proteins for NMR studies can be prohibitively expensive, even with an efficient expression and purification scheme, due largely to the high cost of [13C6, 99%]glucose. We demonstrate here that uniformly (greater than 95%) 13C and ... Full text Link to item Cite

Phosphorus 31 magnetic resonance spectroscopy of human placenta and quantitation with perchloric acid extracts.

Journal Article Am J Obstet Gynecol · January 1991 Phosphorus 31 magnetic resonance spectroscopic studies of fresh placental tissue are reported that indicate resonances for adenosine triphosphate, inorganic phosphate, sugar phosphates-phosphomonoesters, and phosphodiesters. Perchloric acid extract methods ... Full text Link to item Cite

NMR-SPECTROSCOPY OF THE MET REPRESSOR PROTEIN AND ITS COMPLEX WITH S-ADENOSYLMETHIONINE

Conference ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY · April 22, 1990 Link to item Cite

Use of gel filtration in the preparation of biological fluids for magnetic resonance spectroscopy.

Journal Article Magn Reson Med · March 1990 Analysis of biological fluids by proton magnetic resonance spectroscopy is often complicated by dynamic range problems created from the large water resonance. Gel filtration chromatography is found to be a simple and nondestructive method for exchanging D2 ... Full text Link to item Cite

REGIOSELECTIVE AND CHEMOSELECTIVE N-METHYLATION OF PRIMARY AND SECONDARY-AMINES VIA CARBON-DIOXIDE

Conference ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY · September 10, 1989 Link to item Cite

Synthesis of the labeled D1 receptor antagonist SCH 23390 using [11C]carbon dioxide.

Journal Article Int J Rad Appl Instrum A · 1989 A new synthesis is described for the production of the positron emitting radiopharmaceutical R-(+)-7-chloro-8-hydroxy-2,3,4,5-tetrahydro-3-N-[11C]methyl-1-phenyl-1H- 3-benzazepine (SCH 23390, 2a). This novel method involves reductive carboxylation, in whic ... Full text Link to item Cite

Synthesis of 11C-labeled chlorpromazine directly from [11C]carbon dioxide.

Journal Article Int J Rad Appl Instrum A · 1989 Radiolabeled chlorpromazine was prepared by carboxylation of the N-trimethylsilyl derivative of norchlorpromazine with [11C]carbon dioxide, followed by in situ lithium aluminum hydride reduction. Radiochemical yields of 22-24% and radiochemical purities in ... Full text Link to item Cite

Direct incorporation of [11C]carbon dioxide for labeling bioactive molecules. An application to [11C] labeled tamoxifen

Journal Article Journal of Labelled Compounds and Radiopharmaceuticals · January 1, 1989 A one‐pot synthesis of [11C] labeled tamoxifen has been developed via reductive carboxylation. In this approach, [11C]CO2 is reacted with the N‐trimethylsilyl derivative of desmethyltamoxifen, followed by in situ sodium bis (2‐methoxyethoxy)aluminum hydrid ... Full text Cite

Regio- and Chemoselective N-C Bond Formation Via Carbon Dioxide: A New Source of the Methyl Group Applications to N-Methylated Secondary and Tertiary Amines

Journal Article Synthetic Communications · January 1, 1989 Reductive carboxylation of a variety of secondary and primary amines to the corresponding N-methylated amines in the presence of various functional groups such as chlorosubstituents, carbon-carbon double bonds and phenolic hydroxyls is described. © 1989, T ... Full text Cite

P-31 NMR-SPECTROSCOPY OF HUMAN-PLACENTA

Conference INVESTIGATIVE RADIOLOGY · September 1, 1988 Link to item Cite

SYNTHESIS OF [C-11] LABELED TAMOXIFEN VIA REDUCTIVE CARBOXYLATION

Conference JOURNAL OF NUCLEAR MEDICINE · July 1, 1988 Link to item Cite

Reduction of aldehydes and ketones to methylen derivatives using ammonium formate as a catalytic hydrogen transfer agent

Journal Article Tetrahedron Letters · January 1, 1988 Various aromatic aldehydes and ketones were reduced to the corresponding hydrocarbons using ammonium formate as the hydrogen source. © 1988. ... Full text Cite

Laser Initiated Hot Chemistry with Catalysts

Journal Article Radiochimica Acta · January 1, 1988 Full text Cite

Debenzylation Of N-Benzylamino Derivatives By Catalytic Transfer Hydrogenation With Ammonium Formate1, 2

Journal Article Synthetic Communications · March 1, 1987 A method for deprotection of several N-benzyl derivatives of amines to the corresponding amino derivatives with ammonium formate and 10% Pd-C is reported. © 1987, Taylor & Francis Group, LLC. All rights reserved. ... Full text Cite

Magnetic field effects on surgical ligation clips.

Journal Article Magn Reson Imaging · 1987 Magnetic forces exerted on surgical clips and the magnetic resonance imaging distortion they create in phantoms and rabbits at magnetic field strengths of 1.5 Tesla were investigated. Results are reported for both ligation and aneurysm clips manufactured f ... Full text Link to item Cite

Rapid debenzylation of N-benzylamino derivatives to amino-derivatives using ammonium formate as catalytic hydrogen transfer agent

Journal Article Tetrahedron Letters · January 1, 1987 Various N-benzyl derivatives of amino acids and amines were deprotected to the corresponding free amino acids and amines using ammonium formate as the hydrogen source. © 1987. ... Full text Cite

Promoting public understanding

Journal Article Chemical and Engineering News · December 1, 1986 Cite

139 SALT DEPENDENCIES ON LANTHANIDE INDUCED 23Na AND 7Li NMR SHIFTS

Journal Article Investigative Radiology · September 1986 Full text Cite

NA-23 NMR - APPLICATION TO EYE TISSUE

Conference INVESTIGATIVE RADIOLOGY · September 1, 1986 Link to item Cite

NMR studies of combined lanthanide shift and relaxation agents for differential characterization of 23Na in a two-compartment model system.

Journal Article Magn Reson Med · April 1986 Spin relaxation and chemical shifts by lanthanide chelate complexes are used to distinguish 23Na signals in a simulated two-compartment model. Both effects are significant in EDTA, DTPA, and TPP complexes of Gd and in the TPP complex of Dy. The simultaneou ... Full text Link to item Cite

Computed tomographic evaluation of surgical clip artifact: tissue phantom and experimental animal assessment.

Journal Article Comput Radiol · 1986 Surgical clips in postoperative patients create streak artifact on computed tomographic (CT) studies which often significantly degrade image quality. We have evaluated three types of surgical clips: tantalum, stainless steel, and titanium in a phantom and ... Full text Link to item Cite

FT-IR study of nitric oxide chemisorbed on Rh/Al2O3

Journal Article Journal of Physical Chemistry · 1985 Chemisorption of NO on Rh/Al2O3 surfaces has been examined by FT-IR. The spectra are assigned to two forms of Rh(NO) as well as the Rh(NO)2 species. Apparent interconversion of the linear nitrosyl and dinitrosyl complexes is readily observed at room temper ... Cite

FT-IR study of nitric oxide chemisorbed on Rh/Al2O3

Journal Article Journal of Physical Chemistry · January 1, 1985 Chemisorption of NO on Rh/Al2O3 surfaces has been examined by FT-IR. The spectra are assigned to two forms of Rh(NO) as well as the Rh(NO)2 species. Apparent interconversion of the linear nitrosyl and dinitrosyl complexes is readily observed at room temper ... Full text Cite

Ruminal and postruminal utilization of protein from feed grains by beef steers.

Journal Article Proceedings of the annual meeting - American Society of Animal Science. Western Section. · January 1983 Cite

Starch digestion of sorghum grain, barley and corn based diets by beef steers.

Journal Article Proceedings of the annual meeting - American Society of Animal Science. Western Section. · January 1982 Cite

The Reaction between Sulfur Dioxide and Hexamethyldisilazane. 2. Oxygen Atom Transfer from Sulfur Dioxide

Journal Article Inorganic Chemistry · January 1, 1982 The new reaction between sulfur dioxide and hexamethyldisilazane, which forms ((CH3)3Si)2O, (CH3)3SiNSO, and NH4(CH3)3SiOSO2, is characterized. In this reaction oxygen is transferred to silicon and sulfur from sulfur dioxide, but Si-N bonding is still part ... Full text Cite

The Reaction between Sulfur Dioxide and Hexamethyldisilazane. 3. The Characterization of Ammonium (Trimethylsilyl )sulfite

Journal Article Journal of the American Chemical Society · January 1, 1981 The reaction between ((CH3)3Si)2NH and S02 results in the formation of an ionic solid with empirical formula NH4(CH3)3SiOSO2 which readily “sublimes” at ambient temperature. Although (trimethylsilyl)ammonium bisulfite is a logical choice for a molecular fo ... Full text Cite

Formation of 1, 1, 1-trimethyl-N-sulfinylsilanamine from the direct reaction of sulfur dioxide with hexamethyldisilazane

Journal Article Inorganic Chemistry · January 1, 1980 The direct, facilq reaction between sulfur dioxide and the common silylating agent hexamethyldisilazane (HMDS) resulting in the formation of 1, 1, 1-trimethyl-N-sulfinylsilanamine, (CH3)3 Si—N=S=0 (1), has not previously been reported, although sulfur diox ... Full text Cite

Evaluation of Aeschynomene haylage supplemented with energy and protein for beef cattle.

Journal Article Proceedings of the annual meeting - American Society of Animal Science. Western Section. · January 1979 Cite

Application of multistep deactivation processes in the interpretation of intermodular energy transfer following chemical activation by kinetic techniques

Journal Article Journal of Physical Chemistry · January 1, 1979 Interpretation of vibrational energy transfer following kinetically controlled chemical activation is refined by incorporating multistep deactivation processes into the RRKM treatment of the excited molecule. The functional form of the initial primary prod ... Full text Cite

Calculation of the average energy of recoil hot reactions. Hot hydrogen replacement reactions in alkane systems moderated with noble gases

Journal Article Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics · December 1, 1978 The average energy of reaction for recoil hot species in a well scavenged system is defined explicitly and calculated for recoil tritium for hydrogen replacement reactions with cyclohexane and n-butane as a function of noble gas moderation. In general this ... Full text Cite

Irradiation of benzene with 14CH+ and 14CH3+ ions

Journal Article Journal of Physical Chemistry · January 1, 1978 Solid benzene at -196 °C was irradiated with 14CH+ and 14CH3+ ions at 10-eV kinetic energy. Yields were determined for the labeled hydrocarbon products: benzene, toluene, cycloheptatriene, diphenylmethane, biphenyl, and phenylcycloheptatriene. The radioact ... Full text Cite

Characterization of the unimolecular behavior of recoil hot reaction products in inert bath gases. Application to c-C4H7T

Journal Article The Journal of Chemical Physics · January 1, 1978 A model for the kinetically controlled, nuclear recoil, chemical activation process is further developed to characterize the generation of excited cyclobutane and its subsequent unimolecular behavior. This approach specifically accounts for the overall eff ... Full text Cite

Irradiation of benzene with 14CH+ and 14CH3+ ions

Journal Article Journal of Physical Chemistry · 1978 Solid benzene at -196 °C was irradiated with 14CH+ and 14CH3+ ions at 10-eV kinetic energy. Yields were determined for the labeled hydrocarbon products: benzene, toluene, cycloheptatriene, diphenylmethane, biphenyl, and phenylcycloheptatriene. The radioact ... Cite

Reactions of Recoil Generated Chlorine-38 Atoms with 2,3-Dichlorohexafluoro-2-butene. Cis/Trans Isomerization Accompanying Chlorine for Chlorine Replacement

Journal Article Journal of the American Chemical Society · January 1, 1978 Gas-phase reactions of nuclear recoil generated chlorine-38 atoms with 2,3-dichlorohexafluoro-2-butene (2,3-DCHF2B) result predominantly in chlorine for chlorine substitution. The reaction proceeds with geometrical isomerization, and the resulting cis-tran ... Full text Cite

Characterization of hot chlorine atom reactions with hydrogen

Journal Article Journal of Physical Chemistry · January 1, 1978 The reaction of nuclear recoil generated chlorine atoms with hydrogen to produce hydrogen chloride was studied in the presence of ethylene and iodine scavengers. The yield behavior is presented for this reaction over a relative average translational energy ... Full text Cite

Nuclear recoil chemical activation studies. Vibrational energy transfer from cyclobutane-t

Journal Article The Journal of Chemical Physics · January 1, 1977 A method is demonstrated for the determination of intermolecular energy transfer efficiencies in systems chemically activated by nuclear recoil reaction. Relative vibrational energy transfer efficiencies are determined for highly excited cyclobutane-t form ... Full text Cite

Potentiometric determination of solvation numbers and hydration constants for cations

Journal Article Journal of Physical Chemistry · January 1, 1977 A technique is developed for determining solvation numbers and hydration constants for metal ions. Stability constants are obtained that are essentially independent of the solution composition for a wide range of solvents. It is shown that two ROH molecule ... Full text Cite

Kinetics and mechanism of recoil chlorine atom reactions with ethylene

Journal Article Journal of Physical Chemistry · January 1, 1977 Addition and abstraction are the major reactions observed between nuclear recoil generated chlorine atoms and ethylene. The addition reaction is characterized, and its relative efficiency is determined for low energy chlorine in systems containing H2 and C ... Full text Cite

Energetics and Mechanism of the Recoil Tritium Replacement Reaction with Cyclohutane

Journal Article Radiochimica Acta · January 1, 1976 The energetics and mechanism of recoil hot tritium atom replacement reactions with cyclobutane are explored. Kinetic analysis of the pressure dependence for the total yields of hot replacement products is used to distinguish reactive processes. Results sho ... Full text Cite

Evidence for S(1D) Atom Reactions Involving 34S(n,γ)35S Nuclear Recoil Generated Sulfur

Journal Article Journal of the American Chemical Society · August 1, 1975 Full text Cite

Energy transfer studies from excited cyclobutane chemically activated by nuclear recoil reaction

Journal Article Chemical Physics Letters · July 1, 1975 Relative vibrational energy transfer efficiencies are determined for cyclobutane-t chemically activated to an average energy of 5 eV by recoil tritium replacement reaction. The pressure and composition dependence of the stabilization-decomposition ratio in ... Full text Cite

Evidence for S(1D) atom reactions involving 34S(n,γ)35S nuclear recoil generated sulfur [11]

Journal Article Journal of the American Chemical Society · 1975 Cite

On the collision density in recoil hot atom systems. Effect of reactive events

Journal Article Chemical Physics Letters · February 1, 1973 Characteristics of the collisional distribution function for reactive hot atoms in nuclear recoil systems are examined and illustrated for the T + H2 system both unmoderated and moderated with argon. Reaction induced extrema are evident in the collision de ... Full text Cite

Deuterium Isotope Effect in Halogen Atom Reactions with Methane and Perdeuteriomethane at Energies above Thermal Thresholds

Journal Article Journal of the American Chemical Society · January 1, 1973 The origin of the isotope effect in the reaction of recoil chlorine atoms with methane and perdeuteriomethane was determined by diluting the systems with inert moderator to establish a unique steady-state collision distribution. The ratio of product yields ... Full text Cite

Effects of inelastic processes on the collision distribution in recoil systems

Journal Article The Journal of Chemical Physics · January 1, 1973 The collisional distribution function for recoil hot atom systems is examined to determine the influence of specific inelastic processes on the collision density over the reactive energy range. The inelastic processes considered result from collisional dis ... Full text Cite

The Reactive Isotope Effect in Nuclear Recoil 18F Reactions with CH4 and CD4 to Produce CH3F and CD3F

Journal Article Radiochimica Acta · January 1, 1972 The absolute yields of single replacement products CH318F and CD318F were determined in highly moderated systems for the reaction of 18F with CH4 and CD4 respectively. Carbon tetrafluoride moderator was used in dilutions of up to 98%. The ratio of yields i ... Full text Cite

Vibrational energy transfer in thermal methyl isocyanide isomerization. Relative cross sections in complex molecular systems

Journal Article Journal of Physical Chemistry · January 1, 1970 Relative energy transfer collision cross sections for several complex hydrocarbon and substituted hydrocarbon molecules have been determined in the methyl isocyanide thermal isomerization system. Particular interest was placed in the incremental cross sect ... Full text Cite

Energy transfer in thermal methyl isocyanide isomerization. A comprehensive investigation

Journal Article Journal of Physical Chemistry · January 1, 1970 The low-pressure thermal isomerization of methyl isocyanide has been studied at 280.5° in the presence of 109 different inert bath gases. Relative collisional activation-deactivation efficiencies β were measured. The attractive nature of the interaction is ... Full text Cite

Energy transfer in thermal methyl isocyanide isomerization. Relative cross sections of fluoroalkanes and nitriles

Journal Article Journal of Physical Chemistry · January 1, 1970 The inert gas effect on the thermal isomerization of methyl isocyanide at 280.5° by the members of the homologous series of n-perfluoroalkanes and n-nitriles has been studied up to C6 in both cases. Relative collision diameters of these molecules, appropri ... Full text Cite

Dipolar orientation effect in collisional energy transfer [2]

Journal Article Journal of Physical Chemistry · January 1, 1969 Full text Cite

Kinetic analysis of the reaction of hot chlorine atoms with alkanes; collisional dissociation of translationally excited products

Journal Article The Journal of Chemical Physics · January 1, 1969 The reactions with methane and ethane of hot chlorine atoms recoiling from the 40Ar (γ, p)39Cl nuclear reaction have been studied. Displacement reactions, analogous to those of hot hydrogen with alkanes, were found. In the case of methane, these gave CH339 ... Full text Cite

Systematics and Mechanism of Hot Halogen Reactions. Trends in Total Yield

Journal Article Journal of the American Chemical Society · January 1, 1968 Full text Cite

Systematics and Mechanism of Hot Halogen Reactions. Product Distribution

Journal Article Journal of the American Chemical Society · January 1, 1968 Full text Cite

STRUCTURE OF STREPTOLYDIGIN.

Journal Article Antimicrob Agents Chemother (Bethesda) · 1963 Link to item Cite