Detailed studies of IPHAS sources - III. The highly extinguished bipolar planetary nebula IPHASX J191104.8+060845

We present the first detailed study of the bipolar planetary nebula (PN) IPHASX J191104.8+060845 (PN G 040.6−01.5) discovered as part of the Isaac Newton Telescope Photometric Hα Survey of the Northern Galactic plane (IPHAS). We present Nordic Optical Telescope (NOT) narrow-band images to unveil its true morphology. This PN consists of a main cavity with two newly uncovered extended low-surface brightness lobes located towards the NW and SE directions. Using near-IR WISE images we unveiled the presence of a barrel like structure, which surrounds the main cavity, which would explain the dark lane towards the equatorial regions. We also use Gran Telescopio de Canarias (GTC) spectra to study the physical properties of this PN. We emphasise the potential of old PNe detected in IPHAS to study the final stages of the evolution of the circumstellar medium around solar-like stars.

Numerical Simulation during Short-Shot Water-Assisted Injection Molding Based on the Overflow Cavity for Short-Glass Fiber-Reinforced Polypropylene

Compared with water penetration condition of short-shot water-assisted injection molding with or without overflow cavity, it can be known from theory and common knowledge that short-shot water-assisted injection molding with overflow cavity has many advantages, such as it can save materials and energy. Then, the effects of melt short shot size, water injection delay time, melt temperature and water injection pressure on the penetration of water after penetration, and the orientation distribution of short fibers during water-assisted injection molding of the overflow cavity short-shot method were studied. It is found that the melt short shot size had the greatest influence on it, followed by water injection pressure, water injection delay time, and finally, melt temperature. With the increase of the melt short shot size, the thickness of the residual wall of the whole main cavity becomes thinner, the orientation of short fiber along the melt flow direction becomes higher, and the degree of fiber orientation changes becomes lower. In the front half of the main cavity, with the decrease of water injection pressure, the delay time of water injection, and the melt temperature, in the front part of the main cavity, the residual wall thickness becomes thinner, the fiber orientation along the melt flow direction becomes lower, and the fiber orientation changes degree becomes higher; in the latter half of the main cavity, the influence of the water penetration and the orientation distribution of short fibers along the melt flow direction are not significant.

Hidden IR structures in NGC 40: signpost of an ancient born-again event

We present the analysis of infrared (IR) observations of the planetary nebula NGC 40 together with spectral analysis of its [WC]-type central star HD 826. Spitzer IRS observations were used to produce spectral maps centred at polycyclic aromatic hydrocarbons (PAH) bands and ionic transitions to compare their spatial distribution. The ionic lines show a clumpy distribution of material around the main cavity of NGC 40, with the emission from [Ar ii] being the most extended, whilst the PAHs show a rather smooth spatial distribution. Analysis of ratio maps shows the presence of a toroidal structure mainly seen in PAH emission, but also detected in a Herschel PACS 70 $\mu$m image. We argue that the toroidal structure absorbs the UV flux from HD 826, preventing the nebula to exhibit lines of high-excitation levels as suggested by previous authors. We discuss the origin of this structure and the results from the spectral analysis of HD 826 under the scenario of a late thermal pulse.

Thermodynamically driven oxidation-induced Kirkendall effect in octahedron-shaped cobalt oxide nanocrystals

Cobalt oxide nanooctahedra with a main cavity or cracks branching out due to a Kirkendall effect, stem from the synthetic process, the intermediate stages of rearrangement and the final thermodynamically-driven oxidation at the surface.

Cavitation Flow Structure and Unsteady Pressure Pulsation Around a Hydrofoil

The present work is an original study of the flow induced vibration, cavitation structures and cavitation induced pressure pulsation characteristics around a typical hydrofoil named 791, which is widely applied in the axial flow pump. From the vibration experiment of the hydrofoil at various operating conditions, it is clear that at low frequency band, with Reynolds number increasing, vibration energy first experiences a stable slightly increasing tendency, and then decreases rapidly, finally rises steeply again. Besides, according to the results of several positive incidence angles, it is observed that vibration energy usually achieves a local minimum level at a certain positive incidence angle falling into the range of 2° to 4°. Based on results obtained from the detached eddy simulation (DES) turbulent model, full developing process of cavitation stages including, incipient cavitation, sheet cavitation and cloud cavitation could be captured and easily identified. It is found that pressure spectra in accordance with different cavitation stages show great discrepancy. In the stage of incipient cavitation and cloud cavitation, predominant components in pressure spectra are caused by the cyclical evolution of the main cavity and the periodic variation of the small vacuoles shedding at the span-wise outer edge of the hydrofoil. However, in sheet cavitation stage, the pronounced excitation frequencies are generated by cyclical evolution of the main cavity and cavity shedding from both sides of the U-shaped cavitation structure. Pressure pulsation amplitude is pretty small at the cavity stable adhesion region. But the amplitude of vacuoles shedding from the hydrofoil is much larger than main cavity adhesion region at these three stages.

R433 – The Anterior Epitympanum

Problem Early studies report detailed microscopic anatomy of the anterior epitympanum, yet none describe its anatomy from an endoscopic point of view. Methods Thirty-five temporal bones were dissected, and the anatomic details were studied utilizing an operating microscope and otoendoscopes with 0o, 30o and 70o angles and 2.7 and 3 mm diameters. Results Marked variation in the size and shape of the anterior epitympanum was observed. The recess was found in all of the 35 bones. In 43% of the specimens, the main cavity was above the tensor tympanic fold, it was best endoscopically approached via the posterior transmastoid approach. But in 49% of the specimens, because the recess was divided into two cavities by the tensor tympanic fold, it necessitated both the transmastoid and the transcanal routes to endoscopically approach it. While in 8% of specimens, it was mainly endoscopically approached via the transcanal approach, as the recess was contiguous with the eustachian tube. Conclusion The shape of the anterior epitympanum is influenced by the relation between the cavities above and below the tensor tympanic fold. The incorporation of otoendoscopes helps in more exposure of its different types with less aggressive approaches. Significance Review the added value of intra-operative use of otoendoscopes to approach the different areas of the anterior epitympanic region.

The Leading Edge Cavitation Dynamics

In the present paper, we present an experimental investigation of the onset and detachment of a leading edge cavitation over a 2-D and 3-D hydrofoils. An insight of the flow field in the vicinity of the main cavity detachment is reached with the help of a miniature sensor fitted in a NACA009 hydrofoil suction side close to the leading edge stagnation point. Owing to theses experiments, we have demonstrated how the water may withstand negative pressure as low as −0.8 bar without any visible cavitation. As soon as the leading edge cavitation takes place, the pressure upstream to the cavity detachment rises significantly but remains negative while the measured pressure in the cavity is almost equal to the vapor pressure. This result confirms the assumption already stated by former studies according to which the liquid is in tension just upstream to the detachment point. Furthermore, flow visualization clearly shows that a well developed leading edge cavitation turns into bubble cavitation in a continuous way when the surrounding pressure is gradually increased. Owing to those results, we have introduced a physical model of the cavitation detachment in which, no laminar separation of the boundary layer is required to ensure its mechanical equilibrium as already stated by former studies. The nuclei in the vicinity of the blade surface explode as they cross the liquid-vapor interface, which is not a material surface. The main cavity is thus continuously fed with exploding bubbles at its detachment location. The negative pressure measured upstream to the cavity detachment may thus be explained by the dynamic delay of exploding nuclei due to inertia.

Synthetic site-directed ligands

Complexes of nucleotides, peptides and arom atic hapten-like compounds with immunoglobulin fragments were studied by X-ray analysis. Alter tri- or hexanucleotides of deoxythymidylate were diffused into triclinic crystals of a Fab (BV04- 01) with specificity for single-stranded DNA, extensive changes were detected throughout the structure of the protein. The Fab co-crystallized with a tri- or pentanucleotide in a different space group (monoclinic), an observation sometimes correlated with alterations in the structure of the ‘native’ protein. Structural analyses of the co-crystals are in progress for direct comparisons with the unliganded Fab. In crystals of a human (Meg) Bence-Jones dimer, synthetic opioid peptides, chemotactic peptides or dinitrophenyl (DNP) derivatives could be diffused into a large conical binding cavity. The conformations of both the ligand and the protein were usually altered during the binding process. At the base of the cavity tyrosine residues could be displaced like trap-doors to permit entry of some opioid peptides and DNP compounds into a deep binding pocket. In co-crystals of the dimer and bis(DNP)lysine, two ligand molecules were bound in tandem, one in the main cavity and the second in the deep pocket. One ligand adopted an extended conformation, with the ε-DNP ring near the floor of the main cavity and the α-DNP group in solvent outside the binding site. There were no significant conformational changes in the protein. In contrast, the second ligand was very compact, with both DNP rings immersed in the deep pocket, and the binding site was expanded to accommodate the oversized ligand. Peptides designed to be specific for the main cavity were incrementally constructed from minimal binding units by M. Geysen, G. Trippick, S. Rodda and their colleagues. A pentapeptide optimized for binding by this method was diffused into a crystal of the dimer and found by Fourier difference analysis to lodge exclusively in the main cavity as predicted. Binding regions in the BV04-01 Fab and the Meg dimer were markedly different in size and shape. The Fab had a groove-type site, in which a layer of sidechains acted like a false floor over regions analogous to the cavity and deep pocket of the Bence-Jones dimer.

Sound Pressure in Insert Earphone Couplers and Real Ears

It is known that sound pressure, measured in couplers via a probe-tube microphone, often shows a pressure vs frequency response that drops sharply at a single frequency. In this study sound pressure was theoretically determined at various locations within a hard-walled cylindrical cavity, driven by a constant-volume velocity source with circular symmetry. At each location in the volume, a transfer impedance was defined as the ratio of pressure to inlet-volume velocity. In the region around the inlet, the transfer impedance passes through zero as it changes from negative to positive reactance with increasing frequency. Two hard-walled cavity examples were examined in detail (1) the main cavity of a 2-cm 3 HA-2 coupler, and (2) a cavity having dimensions approximately equal to the occluded ear canal between an earmold tip and the eardrum. Contours of constant minimum sound pressure vs frequency are given for these two cylindrical volumes with experimental verification. Implications for probe microphone calibration and measurement of sound pressure in ears are discussed.