Search

Laser Powder Bed Fusion (L-PBF), also known as Selective Laser MeltingTM (SLMTM), allows additive manufacture of lower hybrid current drive (LHCD) Radio Frequency (RF) launchers from a new material, Glenn Research Copper 84 (GRCop-84), a Cr2Nb (8 at. % Cr, 4 at. % Nb) precipitation hardened alloy, in configurations unachievable with conventional machining. The resolution and geometric limitations are tested to explore the limitations of L-PBF printing of GRCop-84. Printing holes in the vertical and horizontal direction are examined to determine the minimum cooling channel diameter. Internal stress limits the minimum thickness of vertical walls and septa to 1 mm, thinner walls warp during printing. Roughness is minimized on vertical surfaces and increases on both upper and lower surfaces as angle increases. Accuracy within 40 μm is typical on well supported structures.

Laser Powder Bed Fusion (LPBF) of Glenn Research Copper 84 (GRCop-84), a Cr2Nb (8 at. % Cr, 4 at. % Nb) precipitation hardened alloy, produces a fully dense high conductivity alloy with a yield strength of 500 MPa and ultimate tensile strength (UTS) of 740 MPa, superior to other competing copper alloys, and 20% elongation at fracture for material stressed perpendicular to the build direction. The high thermal stability of the Cr2Nb precipitate in the copper matrix reduces coarsening and maintains a 300 MPa yield, 520 MPa UTS and 26% elongation after a 900 °C, 5-h heat treatment, while a 3 h 450 °C heat treatment increases yield to 810 MPa, UTS to 970 MPa with 9% elongation at fracture, for samples stressed perpendicular to the build direction. Tensile strength anisotropy based on print direction was attributed to internal stress and columnar grain formation. Void nucleation during tensile fracture was initiated by brittle fracture of precipitate particles within the copper matrix. Fracture cusps contain matching precipitate fragment geometry on opposing sides located near the cusp center in at least 80% of fracture cusps. An optimal precipitate size of 100 nm is predicted for maximum tensile strength from precipitates on fracture surfaces, while tensile testing with varying heat treatments shows maximum strength with 100 nm and smaller precipitates. Cr2Nb precipitates are shown to transition between polycrystalline and monocrystalline structures at high temperature.

Recent advances in selective laser melting (SLM) 3D printing technology allows additive manufacture of lower hybrid current drive (LHCD) RF launchers from a new material, Glenn Research Copper 84 (GRCop-84), a Cr2Nb (8 at. % Cr, 4 at. % Nb) precipitation hardened alloy, in configurations unachievable with conventional machining. Rough surfaces in additive manufactured components are a limiting factor in RF structures. Surface roughness increases RF losses and impedes conditioning by trapping gas and contaminants that induce arcing by evolving from the surface at high power. SLM printed GRCop-84 is post-processed with mass finishing to reduce surface roughness. Wet blasting, vibratory finishing, and chemical etching remove adhered powder grains from SLM printed GRCop-84. Profilometry and scanning electron microscopy were used to quantify resulting surface quality. Chemical etching is examined to remove zinc contamination from wire electrical discharge machining slag prior to vacuum use. Etch rates in SLM printed GRCop-84 are anisotropic, and etch times should be limited to prevent pitting corresponding to the laser hatch pattern. Vibratory mass finishing and mechanical polishing produced surfaces suitable for low RF loss. Use of chemo-mechanical finishing is recommended for the interior of SLM printed structures.

Recent advances in selective laser melting (SLM) 3D printing technology allow additive manufacture of lower hybrid current drive (LHCD) RF launchers from a new material, Glenn Research Copper 84 (GRCop-84), a Cr2Nb (8 at. % Cr, 4 at. % Nb) precipitation hardened alloy, in configurations unachievable with conventional machining. Tensile strength and thermal conductivity are compared to other competing high conductivity copper alloys for fusion use. Swelling and conductivity at 100 DPA when exposed to the Hanford Fast Flux Test Facility neutron spectrum is predicted in the 1–2 % and 65−70% IACS range, respectively, by comparison to copper alloys with similar precipitate and grain size. Self-similar ion irradiation of a GRCop-84 target at 430 °C to 20 DPA resulted in no noticeable void formation in FIB cross sections or TEM lamella.

The cannabinoid 1 (CB1) allosteric modulator, 5-chloro-3-ethyl-1H-indole-2-carboxylic acid [2-(4-piperidin-1-yl-phenyl)-ethyl]-amide) (ORG27569), has the paradoxical effect of increasing the equilibrium binding of [3H](−)-3-[2-hydroxyl-4-(1,1-dimethylheptyl)phenyl]-4-[3-hydroxylpropyl]cyclohexan-1-ol (CP55,940, an orthosteric agonist) while at the same time decreasing its efficacy (in G protein-mediated signaling). ORG27569 also decreases basal signaling, acting as an inverse agonist for the G protein-mediated signaling pathway. In ligand displacement assays, ORG27569 can displace the CB1 antagonist/inverse agonist, N-(piperidiny-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide(SR141716A). The goal of this work was to identify the binding site of ORG27569 at CB1. To this end, we used computation, synthesis, mutation, and functional studies to identify the ORG27569-binding site in the CB1 TMH3-6-7 region. This site is consistent with the results of K3.28192A, F3.36200A, W5.43279A, W6.48356A, and F3.25189A mutation studies, which revealed the ORG27569-binding site overlaps with our previously determined binding site of SR141716A but extends extracellularly. Additionally, we identified a key electrostatic interaction between the ORG27569 piperidine ring nitrogen and K3.28192 that is important for ORG27569 to act as an inverse agonist. At this allosteric site, ORG27569 promotes an intermediate conformation of the CB1 receptor, explaining ORG27569's ability to increase equilibrium binding of CP55,940. This site also explains ORG27569's ability to antagonize the efficacy of CP55,940 in three complementary ways. 1) ORG27569 sterically blocks movements of the second extracellular loop that have been linked to receptor activation. 2) ORG27569 sterically blocks a key electrostatic interaction between the third extracellular loop residue Lys-373 and D2.63176. 3) ORG27569 packs against TMH6, sterically hindering movements of this helix that have been shown to be important for receptor activation.

Over the past five years the number of internet sites advertising "legal highs" has literally exploded, as have user reports of experiences (both pleasurable and frightening) with these substances and the number of emergency room visits by users. Although the majority of these "legal highs" have been described as bath salts and herbal extracts, most contain neither plant derived compounds nor components of personal hygiene products. So-called "bath salts" largely contain synthetic analogs of the natural compound Khat; spice-related materials, claimed to be "legal marijuana," are mostly synthetic analogs of cannabinoid receptor ligands that were developed as research tools. This review describes the emergence and properties of these two groups of "legal highs" from a medicinal chemist's perspective.

An iterative method of estimating permittivity and window thickness with high precision is developed for half wavelength resonant waveguide windows for use in a lower hybrid launcher for DIII-D. The high Q factor of half-wavelength windows results in extreme sensitivity of return loss on small deviations in permittivity. Permittivity and loss tangent measurements of Morgan AL-995 99.5% aluminum oxide ceramic using a waveguide resonant cavity per ASTM D2520-13 determine variation of permittivity with frequency. Measurement of window resonant frequency in conjunction with the slope of permittivity from waveguide cavity measurements determine required thickness of a resonant window within 5 MHz of the desired resonant frequency. Methods to improve measurement accuracy of resonant peaks on a vector network analyzer are discussed. A sensitivity study to dimensional variations in window or sample rod geometry, and shift in resonant frequency due to RF heating of the window material is conducted.

The development of an easy and inexpensive immunoassay to measure the limited quantities of endogenous cannabinoids found in the body would be beneficial for both cannabinoid researchers and clinicians. This report describes the hapten design and carrier molecule strategy that we used to generate a panel of monoclonal antibodies (mAB) to the endogenous cannabinoid anandamide (N-arachidonylethanolamide, AEA). We designed and successfully prepared a hapten, N-arachidonyl-7-amino-6-hydroxy-heptanoic acid (AHA), which retained the basic characteristic features of anandamide--the carboxamide, the hydroxyl and the lipophilic arachidonyl moiety with its skipped double bond system, while still allowing attachment to protein. In addition, a secondary alcohol structure was added to reduce the potential for biological hydrolysis of the hapten. Because of the diverse responses obtained after coupling this hapten to four different carriers, we determined that the type of carrier molecule used was particularly important for generating anti-anandamide antibodies. Described in this report are the characteristics of a panel of 11 mAB, generated from four separate fusions, with a range of relative affinities and cross reactivities. Excellent selectivity for anandamide vs. two other endogenous cannabinoids and arachidonic acid was achieved this strategy (cross-reactivities5%). In addition, at least one mAB maintained specificity for anandamide compared to two very closely related fatty acid amide molecules. However, the IC50 values in a standard enzyme-linked immunosorbent assay (ELISA) format (ca. 2-3 microM) indicate that improvement in antibody affinities or assay format will be required for an immunoassay to measure endogenous levels. Such work is underway.

A mild method for the cleavage of an acetal to afford a rearrangement sensitive diol using B-chlorocatecholborane was developed for the synthesis of the endogenous cannabinoid neurochemical messenger 2-arachidonoylglycerol. The tendency for rearrangement of 2-arachidonoylglycerol to the corresponding 1-arachidonoylglycerol was precluded with this reagent. Features of the partial recyclization to an isomeric acetal provide mechanistic detail.

2-Arachidonylglycerol (2-Ara-Gl) was synthesized via the intermediacy of its 1,3-phenylboronic acid ester. The boronate ester is easily stable enough to enable chromatographic resolution from the corresponding 1-Ara-Gl boronate ester on normal phase elution yet immediately and completely hydrolyzes to 2-Ara-Gl and phenylboronic acid, without isomerization, by simple solution in aqueous-organic solvents. The phenylboronate ester of this 2-acylglycerol has the added advantage of being markedly more stable to both isomerization and oxidation upon storage than the labile 2-Ara-Gl.

A selective ligand for the dopamine transporter 3β-(4-iodophenyl)tropan-2β-carboxylic acid isopropyl ester (RTI-121) has been labeled with iodine-125 by electrophilic radioiododestannylation. The [ 125 I]RTI-121 was obtained in good yield (86 ± 7%, n = 3) with high radiochemical purity (>99%) and specific radioactivity (1210–1950 mCi/μmol). After i.v. administration of [ 125 I]RTI-121 to mice, the rank order of regional brain tissue radioactivity (striatum > olfactory tubercles ⪢> cortex, hippocampus, thalamus, hypothalamus, cerebellum) was consistent with dopamine transporter labeling. Specific in vivo binding in striatum and olfactory tubercles was saturable, and was blocked by the dopamine transporter ligands GBR 12,909 and (±)-nomifensine. By contrast, binding was not reduced by paroxetine, a serotonin transporter inhibitor, or desipramine, a norepinephrine transporter inhibitor. A variety of additional drugs having high affinities for recognition sites other than the neuronal dopamine transporter also had no effect. The [ 125 I]RTI-121 binding in striatum and olfactory tubercles was inhibited by d -amphetamine in dose-dependent fashion. Nonmetabolized radioligand represents 85% of the signal observed in extracts of whole mouse brain. Thus, [ 125 I]RTI-121 is readily prepared, and is a useful tracer for dopamine transporter studies in vivo .

Cannabidiol CBD, a non-psychoactive constituent of marihuana, has been reported to possess essentially no affinity for cannabinoid CB1 receptor binding sites in the brain. Our hypothesis concerning CBD's lack of affinity for the cannabinoid CB1 receptor is that CBD is not capable of clearing a region of steric interference at the CB1 receptor and thereby not able to bind to this receptor. We have previously characterized this region of steric interference at the CB1 receptor [P.H. Reggio, A.M. Panu, S. Miles J. Med. Chem. 36, 1761-1771 (1993)] in three dimensions using the Active Analog Approach. We report here a conformational analysis of CBD which, in turn, led to the design of a new analog, desoxy-CBD. Modeling results for desoxy-CBD predict that this compound is capable of clearing the region of steric interference by expending 3.64 kcal/mol of energy in contrast to the 12.39 kcal/mol expenditure required by CBD. Desoxy-CBD was synthesized by condensation of 3-pentylphenol with p-mentha-2,8-dien-1-ol mediated by DMF-dineopental acetal. Desoxy-CBD was found to behave as a partial agonist in the mouse vas deferens assay, an assay which is reported to detect the presence of cannabinoid receptors. The compound produced a concentration related inhibition of electrically-evoked contractions of the mouse vas deferens, possessing an IC50 of 30.9 nM in this assay. Taken together, these results support the hypothesis of the existence of a region of steric interference at the CB1 receptor. While the energy expenditure to clear this region was too high for the parent compound, CBD, the removal of the C6' hydroxyl of CBD produced a molecule (desoxy-CBD) able to clear this region and produce activity, albeit at a reduced level.

Nickel boride smoothly reduces aryl nitro compounds to the corresponding anilines in the presence of iodo and ortho carboalkoxy groups in contrast to the problematic reductions by other methods.

Trimethylsilyl bromide (TMSBr) in the presence of catalytic ZnI2 induces facile substitution of allylic acetates to the bromides with or without rearrangement as governed by product stability. This was applied to the preparation of a key intermediate employed in the synthesis of important cannabinoid metabolites.

The CB1 allosteric modulator, ORG27569, has the paradoxical effect of increasing the equilibrium binding of CP55,940 (an orthosteric agonist), while at the same time decreasing its efficacy. ORG27569 also acts as an inverse agonist. We have previously used computational methods, synthesis, mutation, and functional studies to identify ORG27569's binding site in the THM3/TMH6/TMH7 region (Shore et al., ICRS, 2012). In this site, ORG27569 promotes an active-like conformation of the CB1 receptor, explaining ORG27569's ability to increase CP55,940's equilibrium binding. This site explains ORG27569's ability to antagonize CP55,940's efficacy in three complimentary ways: 1) ORG27569 sterically blocks movements of the second extracellular loop that have been linked to receptor activation, 2) ORG27569 sterically blocks a key electrostatic interaction between the third extracellular loop residue K373 and D2.63(176), and 3) ORG27569 packs against TMH6, sterically hindering movements of TMH6 that the Farrens lab have shown to be important to receptor activation. Additionally, we identified a key interaction between ORG27569's piperidine ring nitrogen and K3.28(192) that is required for ORG27569 to act as an inverse agonist.Using our model of ORG27569 docked in our active state model (in the presence of CP55,940), we designed, synthesized, and functionally characterized 4 analogs of ORG27569 that were designed to test our model and have improved interactions with the receptor. The analogs were functionalized with 3 different goals: 1) to form electrostatic interactions with D6.58(366), 2) to form an aromatic stack with F3.25(189), or 3) to test packing with TMH6-7. Our strategy to form new interactions with D6.58(366) was the most successful, resulting in an analog that is more potent than ORG27569. Interestingly, none of the analogs acted as inverse agonists, suggesting the potential therapeutic promise of CB1's allosteric site.

The compound 9-beta-hydroxy-hexahydrocannabinol [(−)-9β-OH-HHC] was designed to fit a combined theoretical profile of an analgesic cannabinoid (equatorial alcohol at C-9, phenol at C-1 and a C-3 side chain) with reduced psychoactivity (axial C-9 substituent which protrudes into the α face). (−)-9β-OH-HHC was synthesized by the addition of methyl Grignard to 9-oxo-11-nor-HHC. Its α epimer was obtained by the regiospecific epoxide ring opening of 9α, 10α-epoxy-HHC acetate. (−)-9β-OH-HHC and (−)-9α-OH-HHC were each evaluated in a battery of tests in mice and were found to be 10–25 times less potent than (−)-trans-Δ9-tetrahydrocannabinol (Δ9-THC) in all tests including the tail flick test for antinociception (analgesia). Molecular mechanics calculations [MMP2(85)] revealed that, in the global minimum energy conformation of (−)-9β-OH-HHC, the axial methyl at C-9 protrudes into the α face of the molecule, while the axial hydroxyl at C-9 in (−)-9α-OH-HHC protrudes into this same face. These calculations also identified a higher energy carbocyclic ring (twist) conformer of each in which there is no protrusion of a C-9 substituent of the carbocyclic ring into the α face. The minimal activity of both compounds is attributed to these higher energy forms. It is concluded that protrusion of a C-9 substituent into the α-face of the molecule is associated with reduced cannabinoid analgesia, as well as with reduced cannabinoid psychopharmacological activity.

The lipid composition of a membrane fraction from bovine adrenal cortex was determined. This preparation has the capacity to bind adrenocorticotropic hormone and is enriched in adenylate cyclase and 5'-nucleotidase. The adrenal plasma membranes have a significantly higher lipid content (54.8%) than bovine liver plasma membranes and a surprisingly low proportion of this lipid is cholesterol (4.2%). The phospholipids comprise 76.4% of the total lipids and their composition if very similar to that of bovine liver membranes with the exception of sphingomyelin which comprises only 4.5% of the phospholipids in the adrenal preparation.

The treatment of hypertension with guanethidine is now in widespread use (1). Investigations of its biochemical and clinical pharmacology in hypertensive patients have been severely limited due to a lack of adequate analytical methodology for its measurement in plasma. The reported techniques for its estimation in biological fluids include spectrofluorimetric detection (2,3), radioisotopic dilution (4-6), and gas chromatography with electron capture (7) or multiple ion detection (8). The in vi?ro metabolic transformation of guanethidine in rabbit and pig liver homogenates as well as its excretion in rat and human urine have been studied (9,lO). A recent review discusses its metabolism (11). There are large variations in the dose (50-300 pg/kg) necessary for the sufficient control of blood pressure in different individuals as well as many side effects during administration of guanethidine. The cause of this variability has not been extensively investigated since the existing methods for its measurement are too insensitive (7) or are based upon expensive gas chromatographic-mass spectrometric instrumentation (8). We have developed a procedure based on a two-dimensional gas-liquid chromatograph (12,15) utilizing electroncapture detection for the analysis of guanethidine. The method consists of a twostep extraction of plasma followed by hydrolysis, derivatization, and dual gas chromatography. MATERIALS AND METHODS

The synthesis of (6aR, 10aR)-trans-3-[1′,3′-dithian-2′-yl]-6a,7,8,10a-tetrahydro-6,6,9- trimethyl-6H-dibenzo[b,d]pyran-l-ol t-butyldimethylsilyl ether ( 4b ) is reported. The use of this compound as a source of side chain derivatives of cannabinoids is illustrated by syntheses of 1′-,2′-,3′- and 4′-hydroxy-Δ9-THC, and 3-carboxy-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-1-o1 ( 6 ).