Bis(1-adamantyl)(2-morpholinophenyl)phosphine (Mor-DalPhos)

(ligand employed in transition metal-catalyzed reactions) Alternate Name: di(1-adamantyl)-2-morpholinophenylphosphine. Physical Data: mp 219–224 °C. Solubility: soluble in most polar organic solvents. Form Supplied in: White to pale yellow powder or crystals. Also commercially available as preformed Au-ligand complexes such as (MeCN)(Mor-Dalphos)Au(I) SbF_6 and [Mor-Dalphos]Au(I)Cl. Analysis of Reagent Purity: NMR, Elemental Analysis. Preparative Method: Pd-catalyzed cross-coupling of N-(2-bromophenyl)morpholine and diadamantyl phosphine. Handling, Storage, and Precautions: the phosphine is not particularly sensitive to air or moisture although precautions, such as storage under inert atmosphere in a cool place, should be taken during long-term storage. Bis(1-adamantyl)(2-morpholinophenyl)phosphine (Mor-DalPhos) is a phosphine ligand that has been employed in Pd-catalyzed cross-coupling reactions and Au-catalyzed hydroamination and [3+2] annulations. This ligand, when combined with an appropriate Pd-source, is particularly effective for promoting selective monoarylation processes between aryl electrophiles and nucleophiles such as ammonia, hydrazine, and acetone

Surfzone-Beach-Dune interactions: Flow and Sediment Transport across the Intertidal Beach and Backshore

The original wave-beach-dune model stated that in the medium to long term, modal dissipative beaches display maximum onshore wave driven sediment transport, maximum aeolian transport off beaches, the largest foredune heights and volumes, and the largest Holocene dunefields. Modal reflective beaches display the opposite, while modal intermediate beaches display a trend in these from relatively high to relatively low sediment transport, foredune volumes, and Holocene barrier volumes with a trend from dissipative to reflective. New CFD modelling of flow and sediment transport over three modal beach types presented here shows that the original conceptual ideas and field data regarding aeolian sediment transport are correct. Dissipative beaches show the greatest long term potential for sediment delivery to the backshore whilst reflective beaches display the least, with a trend from relatively high to low in the intermediate beach state range

The biology of the Dhufish, Glaucosoma hebraicum, in offshore waters on the lower west coast of Australia

Samples of Dhufish, Glaucosoma hebraicum, were collected in each month between May 1996 and May 1997 from the catches of commercial and recreational wetline fishers and commercial trawlers. These catches were taken in the offshore waters of Western Australia near Geraldton (ca 28°S) and Perth (ca 33°S). Comparisons were made between the number of circuli on scales and the number of translucent zones on sectioned otoliths, and between the number of translucent zones on sectioned and whole otoliths. The number of circuli on scales was often either greater or less than the number of translucent zones on sectioned otoliths of the same fish. The number of translucent zones observed on whole otoliths were the same as on sectioned otoliths for fish with otoliths that have up to six translucent zones. However, the prevalence of underestimates, when using whole as opposed to sectioned otoliths, subsequently increased progressively as the number of translucent zones increased. The mean monthly marginal increments for sectioned otoliths showed a pronounced decline in spring and then a progressive rise during summer and mid-autumn, before levelling off in winter. These trends provide strong evidence that the translucent zones on the otoliths of G. hebraicum are formed annually and that their numbers in sectioned otoliths can be used to age this species. The von Bertalanffy growth parameters, L∞, K and t0, derived for the growth curves of G.hebraicum from length-at-age data were 1038, 0.108 and -0.172, respectively, for females and 1087, 0.109 and -0.219, respectively, for males. Males grew slightly faster than females, attaining total lengths of 234, 448, 688, 832 and 921mm after 2, 5, 10, 15 and 20 years, compared with 212,405, 626, 792 and 865mm for females at the same corresponding ages. Females and males reached the legal minimum (total) length (LML) for capture of 500mm at ca seven and six years, respectively. The maximum ages recorded for females and males were 29 and 35 years, respectively, and the maximum lengths for females and males were 976 and 1120mm, respectively. Although the growth curves of both females and males of G. hebraicum caught in waters near Geraldton were shown by a maximum likelihood ratio test to differ from those of fish caught in waters near Perth, the differences in the von Bertalanffy growth parameters for fish in these two regions were not pronounced. Macroscopic and microscopic examination of gonads showed that female and male G. hebraicum first reach sexual maturity at total lengths of between 250 to 300mm and 350 to 400mm, respectively. Sexual maturity was first attained by females and males at the end of their fifth and eighth years of life, respectively. Histological sections showed that some mature ovaries contained post-ovulatory follicles as well as granular and hydrated oocytes during the spawning period. This provides strong evidence that this species is a multiple spawner. On the basis of the monthly trends exhibited by gonadosomatic indices, gonad maturity stages and different stages in oocyte development, G. hebraicum is considered to breed between December and April, with spawning reaching a peak in late January/early February. For this reason, G. hebraicum was accorded a birth date of the first of February. The nematode parasite Philometra_sp. was found to infect the gonads of G. hebraicum. Preliminary studies have shown that the prevalence of infection is far higher in females than males, and that it increases with fish size and age. At the completion of spawning, this parasite can occupy 50% of the volume of the ovary. Thus, since philometrid worms are known to feed on blood, it is possible that the parasite has a deleterious effect on the reproduction of G. hebraicum. However, histological sections of ovaries failed to reveal visible signs of egg destruction by the parasite, and nor were there any signs of disruption of normal gonadal development of G. hebraicum. Observations of the life cycle stages of Philometra sp. throughout the year indicate that the life cycle of the parasite is closely synchronised with the pattern of reproductive development of its host. No fish were infected under the size at which sexual maturity is first reached and there was evidence that infection by the parasite occurs when G. hebraicum aggregates during the spawning period, when older, infected fish meet younger, uninfected fish. Since female and male G. hebraicum reach first sexual maturity at total lengths of between 250 to 300mm and 350 to 400mm, respectively, this means that the majority of both female and male G. hebraicum have had the opportunity to spawn at least once before they reach the LMLof 500mm. However because almost all Dhufish caught in waters >30m die upon release after capture, this species is subject to fishing mortality before they reach the LML. Therefore, in terms of fisheries management, there would be little value in maintaining a legal size limit for this species. Future management strategies for maintaining stocks of this recreationally and commercially important and heavily-fished species could include reducing fishing pressure in heavily-fished areas and closing from fishing certain areas of known high population density of G. hebraicum. However, for conservation purposes, further research is needed to determine locations of high population densities of Dhufish that could be restricted from fishing, and the migratory patterns of this species. Future studies involve the collection of a greater number of small G. hebraicum (i.e. <300mm), to provide more points for the commencement of the growth curve, more data for determining marginal increment trends in fish with otoliths containing one or two translucent zones, a more precise estimate of the size and age at which females and males reach sexual maturity, and the habitats of these small fish. An histological study of spermatogenesis would improve and consolidate the reproductive data already obtained for males and provide additional information for aiding the aquaculture studies presently being carried out on this species. Further investigations of Philometra sp. infection in G. hebraicum, including a comparison of the fecundity of parasitised fish and unparasitised fish, may provide information on the effects of this parasite on the reproduction of Dhufish

The western blue groper (Achoerodus gouldii), a protogynous hermaphroditic labrid with exceptional longevity, late maturity, slow growth, and both late maturation and sex change

The western blue groper (Achoerodus gouldii) is shown to be a temperate protogynous hermaphrodite, which spawns between early winter and mid-spring. Because A. gouldii changes body color at about the time of sex change, its color can be used as a proxy for sex for estimating the size and age at sex change and for estimating growth when it is not possible to use gonads for determining the sex of this fish. The following characteristics make A. gouldii highly susceptible to overfishing: 1) exceptional longevity, with a maximum age (70 years) that is by far the greatest yet estimated for a labrid; 2) slow growth for the first 15 years and little subsequent growth by females; and 3) late maturation at a large total length (TL50 = 653 mm) and old age (~17 years) and 4) late sex change at an even greater total length (TL50 = 821 mm) and age (~35 years). The TL50 at maturity and particularly at sex change exceeded the minimum legal total length (500 mm) of A. gouldii and the lengths of many recreationally and commercially caught fish. Many of these characteristics are found in certain deep-water fishes that are likewise considered susceptible to overfishing. Indeed, although fishing effort for A. gouldii in Western Australia is not particularly high, per-recruit analyses indicate that this species is already close to or fully exploited

Specialized Testing of Asphalt Cements from Various ADOT&PF Paving Projects

The Alaska Department of Transportation and Public Facilities (ADOT&PF) sampled five different asphalt cements for specialized testing at Queen’s University in Kingston, Ontario. This report documents and discusses the findings. The tested asphalts were: PG 58-34, PG 52-40D, PG 52-40N, PG 58-28, and PG 64-28. Testing results showed that grade losses according to Ontario’s LS-308 Extended Bending Beam Rheometer (EBBR) ranged from 3.4°C to 6.3°C. Losses according to Ontario’s LS-228 Modified Pressure Aging Vessel (PAV) ranged from 0°C to 7.3°C. Grade losses of 3°C and higher are significant in terms of their ability to reduce pavement life cycles. Double-edge-notched tension (DENT) tests according to Ontario’s LS-299 DENT protocol were done on PAV residues. The critical crack tip opening displacement (CTOD) was determined and, at 15°C, it varied from a low of 19 mm for the PG 58-28 to a high of 175 mm for the PG 58-34. The PG 58- 40D showed a CTOD of 139 mm, contrasting with the low polymer PG 52-40N at only 36 mm, a nearly four-fold difference. All the results obtained from this specialized testing effort suggest that these materials will provide significant differences in performance. This report provides recommendations on how to obtain better value for money by implementing a few simple changes to the ADOT&PF asphalt cement specifications

Exploring twisted bilayer graphene with nano-optics

Nano-optics studies the behaviour of light on the nanoscale. In particular, it probes the interaction of light with objects, often of nanometre-size, and reveals fine details of the material's optical properties. Optoelectronics is an integral part of optics and describes the interaction between light and electronics, such as the detection of light and subsequent conversion to an electrical signal. Understanding such mechanisms at the nanoscale is of importance for improving imaging and light-harvesting applications. In this Thesis, we apply near-field microscopy to study optics on the nanoscale. It probes optical properties using light interacting with the near-field electromagnetic field near the material's surface. Twisted bilayer graphene (TBG) is formed by stacking two layers of graphene - a one-atom-thick sheet of carbon atoms - with a small twist angle. This causes an interference pattern in the atomic lattice called a moiré pattern, which affects the electronic properties dramatically. The discovery of unconventional superconductivity in TBG in 2018 made it a thriving field of research. Adding to this, TBG revealed strongly correlating states and topological features, making it a host of tunable exotic phases that may shed light on the origins of unconventional superconductivity. These phenomena motivate us to study the optical properties of TBG on a nanoscale, which have received little attention thus far. In the first part of this Thesis, I describe spatially oscillating patterns within selected regions of TBG that we detected using near-field microscopy. We interpret them as a manifestation of plasmons --- electrons moving collectively in a wave-like pattern --- driven by interband transitions. We model these areas with a reduced interlayer coupling, which enhances the strength of interband transitions and explains the observed plasmon dispersion. After this, I discuss large-scale periodic features observed in minimally twisted bilayer graphene (¿ < 0.1 deg) by photocurent nanoscopy. For these small twist angles, the atoms rearrange in triangular domains separated by a network of domain walls. We find that the domain walls convert heat injected in the domains into a measurable current via the photothermoelectric effect. Our results uncover the sharp changes in electronic properties at the domain walls, which govern the optoelectronic response. I focus in the second part of the Thesis on the development of new experimental techniques, which enable nano-optical studies on exotic states of TBG and its relatives. I show that the semiconducting material WSe2 can be used as an ambipolar transparent top gate for infrared near-field experiments. This enables full control of the carrier density and transverse displacement field without blocking near-field access. Hereafter, I describe a commercial cryogenic near-field microscope with a base temperature of 10 K, which required modifications for reliable operation. I present an active damping system to oppose the vibrations in the system and enhance the mechanical stability. We further improve the AFM stability by changing the AFM excitation position. In the final two Chapters I examine the photoresponse of TBG at low temperature. We observe semi-periodic modulations across our sample, which we believe manifests a second-order superlattice arising from TBG aligned to the hBN substrate in combination with strain. In a different sample, we reveal a spatially inhomogeneous response from which we deduce a map of the local twist angle.La nano-óptica estudia el comportamiento de la luz en la nanoescala. En particular, mide la interacción de la luz con objetos, normalmente de tamaño nanométrico, y revela los detalles de las propiedades ópticas del material. La optoelectrónica es una parte integral de la óptica y describe la interacción entre la luz y la electrónica, como por ejemplo la detección de la luz y su sucesiva conversión a una señal eléctrica. Entender estos mecanismos en la nanoescala es de vital importancia para mejorar sus aplicaciones en imagen y en captación de luz. En esta Tesis, aplicamos la técnica de microscopía de campo-cercano para estudiar óptica en la nanoescala. Medimos las propiedades ópticas usando luz que interacciona con el campo electromagnético cercano a la superficie del material. Una bicapa de grafeno rotada (TBG por sus siglas en inglés) se forma al apilar dos capas de grafeno -una lámina de carbono de un solo átomo de grosor- con un pequeño ángulo entre ellas. Esto provoca un patrón de interferencia en la red atómica que se llama patrón moiré, que afecta las propiedades electrónicas dramáticamente. El descubrimiento de superconductividad no-convencional en TBG en el 2018 lo convirtió en un campo de investigación en auge. Además, el TBG ha revelado estados fuertemente correlacionados y características topológicas, convirtiéndolo en un portador de fases exóticas ajustable que podría arrojar luz sobre los orígenes de la superconductividad no-convencional. Estos fenómenos nos motivan a estudiar las propiedades ópticas del TBG en la nanoescala, que hasta ahora has recibido poca atención. En la primera parte de esta Tesis, describo patrones que oscilan espacialmente dentro de las regiones seleccionadas de TBG que detectamos usando microscopía de campo-cercano. Los interpretamos como la manifestación de plasmones -electrones moviéndose colectivamente en un patrón ondulatorio- promovidos por transiciones inter-banda. Modelamos estas áreas con un acoplamiento inter-capa, lo cual mejora la fuerza de las transiciones inter-banda y explica la dispersión plasmónica observada. Después de esto, hablo de características periódicas de gran escala observadas en bicapas de grafeno rotadas mínimamente (θ < 0.1°) usando nanoscopía de fotocorriente. Para estos pequeños ángulos, los átomos se reagrupan en dominios triangulares separados por una red de paredes de dominio, que gobiernan la respuesta optoelectrónica. En la segunda parte de la Tesis me concentro en el desarrollo de nuevas técnicas experimentales, que permiten estudios nano-ópticos en estados exóticos de TBG y familiares. Enseñaré que el material semiconductor WSe2 puede ser usado como una puerta superior para experimentos de campo-cercano en el infrarrojo. Esto permite un control completo de la densidad de portadores y del campo de desplazamiento eléctrico sin bloquear el acceso del campo-cercano. Sucesivamente, describo un sistema comercial de microscopía de campo-cercano con una temperatura base de 10 K, que requirió modificaciones para una operación fidedigna. Presento un sistema de amortiguación activa para contrarrestar vibraciones en el sistema y mejorar la estabilidad mecánica. Continuamos mejorando la estabilidad del AFM cambiando la posición de su excitación mecánica. En los dos capítulos finales examino la fotorespuesta del TBG a temperaturas bajas. Observamos modulaciones semi-periódicas en nuestra muestra, que creemos que manifiesta una super-red que proviene del TBG estando alineado con el substrato de hBN en combinación con deformación. En una muestra diferente, revelamos una respuesta espacial inhomogénea con la que deducimos un mapa del ángulo de rotación.Postprint (published version

Formation of Precessing Jets by Tilted Black-hole Discs in 3D General Relativistic MHD Simulations

Gas falling into a black hole (BH) from large distances is unaware of BH spin direction, and misalignment between the accretion disc and BH spin is expected to be common. However, the physics of tilted discs (e.g., angular momentum transport and jet formation) is poorly understood. Using our new GPU-accelerated code H-AMR, we performed 3D general relativistic magnetohydrodynamic simulations of tilted thick accretion discs around rapidly spinning BHs, at the highest resolution to date. We explored the limit where disc thermal pressure dominates magnetic pressure, and showed for the first time that, for different magnetic field strengths on the BH, these flows launch magnetized relativistic jets propagating along the rotation axis of the tilted disc (rather than of the BH). If strong large-scale magnetic flux reaches the BH, it bends the inner few gravitational radii of the disc and jets into partial alignment with the BH spin. On longer time scales, the simulated disc-jet system as a whole undergoes Lense-Thirring precession and approaches alignment, demonstrating for the first time that jets can be used as probes of disc precession. When the disc turbulence is well-resolved, our isolated discs spread out, causing both the alignment and precession to slow down.Comment: MNRAS Letters, accepted. Animations available at https://www.youtube.com/playlist?list=PL39mDr1uU6a5RYZdXLAjKE1C_GAJkQJN

A Phase Lag between Disk and Corona in GRMHD Simulations of Precessing Tilted Accretion Disks

In the course of its evolution, a black hole (BH) accretes gas from a wide range of directions. Given a random accretion event, the typical angular momentum of an accretion disc would be tilted by $\sim$60$^\circ$ relative to the BH spin. Misalignment causes the disc to precess at a rate that increases with BH spin and tilt angle. We present the first general-relativistic magnetohydrodynamic (GRMHD) simulations spanning a full precession period of highly tilted (60$^\circ$), moderately thin ($h/r=0.1$) accretion discs around a rapidly spinning ($a\simeq0.9$) BH. While the disc and jets precess in phase, we find that the corona, sandwiched between the two, lags behind by $\gtrsim 10^{\circ}$. For spectral models of BH accretion, the implication is that hard non-thermal (corona) emission lags behind the softer (disc) emission, thus potentially explaining some properties of the hard energy lags seen in Type-C low frequency quasi-periodic oscillations in X-Ray binaries. While strong jets are unaffected by this disc-corona lag, weak jets stall when encountering the lagging corona at distances $r \sim 100$ black hole radii. This interaction may quench large-scale jet formation.Comment: 5 pages, 4 figures, submitted to MNRAS, see YouTube playlist for 3D renderings: https://www.youtube.com/playlist?list=PLDO1oeU33GwmwOV_Hp9s7572JdU8JPSS