Thermocapillary Convection Instability in Shallow Annular Pools by Linear Stability Analysis

The thermocapillary convection instability in shallow annular pools with Prandtl numbers (Pr) from 0.011 to 57.9, differentially heated at the outer wall and cooled at the inner wall, is investigated numerically. The critical Marangoni numbers (Ma _c ), critical azimuthal wave numbers (m _c ) and critical phase velocities (ω _c ) for the incipience of oscillatory flow are determined by linear stability analysis. The results indicate that the Ma _c increases steeply with increase of Pr number when Pr≤15.9, while it increases slightly with increase of Pr between Pr=23.9 and 57.9. The m _c and ω _c decrease with increase of Pr number.     

Dynamic energy release rate evaluation of rapid crack propagation in discrete element analysis

A non-associated/associated flow rule coupled with an anisotropic/isotropic quadratic yield function is presented to describe the mechanical responses of two distinct X65 pipeline steels. The first as a product of the cold-rolling forming (UOE) process also known as seam weld pipes and the second as a result of high temperature piercing process called seamless tube manufacturing. The experimental settings consist of a wide range of sample types, whose geometric characteristics represent different state of stresses and loading modes. For low to intermediate stress triaxiality levels, flat specimens are extracted at different material orientations along with notched round bar samples for high stress triaxialities. The results indicate that despite the existing differences in plasticity between materials due to anisotropy induced processes, material failure can be characterized by an isotropic weighting function based on the modified Mohr–Coulomb (MMC) criterion. The non-associated flow rule allows for inclusion of strain directional dependence in the definition of equivalent plastic strain by means of scalar anisotropy (Lankford) coefficients and thus keeping the original capabilities of the MMC model.     

Core–shell porphyrin·multi-walled carbon nanotube hybrids linked by multiple hydrogen bonds: nanostructure and electronic communication

In this paper, multiple hydrogen bonding interaction of ureidopyrimidinone (UPM) was employed as the linking bridge for the formation of a novel porphyrin·multi-walled carbon nanotube (MWNT) hybrid, which was then used to fabricate a layer-by-layer (LbL) film composed of porphyrin-UPM·MWNT-UPM. Both in the assembled hybrid and the LbL film, porphyrin was closely attached to the surface of the MWNT under the strong multiple hydrogen bonding interaction, forming the core–shell structure. In addition, strong electronic communication was observed between porphyrin and MWNT. The hydrogen bonding association behavior between porphyrin-UPM and MWNT-UPM was attentively analyzed by UV–Vis spectra, fluorescent spectra and transmission electron microscope experiments. It was found that the hydrogen bonding interactions were crucial for the formation of the supramolecular hybrid and the LbL film as well as the occurrence of interfacial electronic communication. This result indicated that the introduction of strong noncovalent bonding interaction between donor and acceptor is an appropriate way to control the material structure and facilitate the interfacial electronic communication in the hybrids which lay the groundwork for their application in electrochemical sensors or photovoltaic devices.     

Reduction toxicity of Amphotericin B through loading into a novel nanoformulation of anionic linear globular dendrimer for improve treatment of leishmania major

Amphotericin B (A) as an antileishmanial drug has limited clinical application owing to severe side-effects and low-water solubility. This is the first study reported using Anionic Linear Globular Dendrimer (ALGD) as A carrier for the increase of A solubility rate, decrease its toxicity, and improve its therapeutic effects. ALGD was synthesized and A was loaded into nanoparticles for the first time with the drug-loading efficiency of 82%. Drug loading was confirmed using characterization methods. The drug solubility rate was increased by 478-folds. The results of the study showed that the A toxicity was significantly decreased by 95% in vitro and in vivo environments, which was confirmed by pathology findings and enzymatic evaluation. Furthermore, the nanodrug caused that mortality rate was reached to zero. Moreover, the nanodrug was as potent as the free drug and glucantime (GUL) in reducing the parasite burden and parasite number. These findings indicated the potency of ALGD to decrease the drug side-effects, increase the drug solubility rate, and improve the drug efficacy. Moreover, the nanoformulation was a non-toxic and cost-effective formulation. The conformity between in vitro and in vivo results suggested that the A-loaded ALGD could be considered as a promising candidate in reducing the side-effects of A in leishmaniasis treatment.

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Flow forming of thin-walled precision shells

Flow forming is an innovative form of cold and chipless metal forming process, used for the production of high precision, thin-walled, net-shaped cylindrical components. During this process, the length of a thick walled tube, commonly known as a preform, is increased with a simultaneous decrease in the thickness of the preform without any change in the internal diameter. Forming of the preform is carried out with the help of one or more rollers over a rotating mandrel. By a pre-determined amount of thickness reduction in one or more number of forming passes, the work material is plastically deformed in the radial direction by compression and made to flow in an axial direction. The desired geometry of the workpiece is achieved when the outer diameter and the wall of the preform are decreased, and the available material volume is forced to flow longitudinally over the mandrel. Over the last three and a half decades the flow forming technology has undergone several remarkable advancements. The versatility of the process makes it possible to produce a wide variety of axi-symmetric, nearer to the net-shape tubular parts with a complex profile using minimum tooling changes. In this review article, process details of flow forming have been elaborated. The current state-of-the-art process has been described, and future developments regarding research and industrial applications are also reviewed.     

Bulk mass flow in a vibratory finisher: mechanisms and effect of process parameters

Vibratory finishing is a widely-used manufacturing process in which a vibrating container filled with granular media becomes fluidized. The resulting bulk flow entrains workpieces and exposes their surfaces to the impacts resulting from the small-scale media vibrations. The bulk flow is responsible for entrainment and mixing, while the media vibration does work on the surfaces. The selection of machine vibration parameters is commonly based on experience due to the difficulty in predicting the fluidized bed behavior. In this work, a discrete element method was used to investigate how the bulk flow in an actual tub finisher filled with steel balls depends on the tub motion parameters through a parametric study. The underlying mechanisms that create and drive the bulk flow were identified by examining the relationships between the bulk flow rates and the wall forces. Finally, the connection between the wall motion and the wall forces was investigated. The tub frequency was the most effective control parameter and there was an optimal phase difference between the horizontal and vertical vibrations to maximize bulk flow. The relationship between the media packing at the walls and the tangential forces between the walls and the media explained the formation and speed of the bulk flow. Lastly, it was shown that the tangential wall forces, unlike the normal forces, cannot be obtained from the known wall motion alone since they also depend on the media velocities relative to the walls.     

Stabilising and Trimming 3D Woven Fabrics for Composite Preforming Applications

The work presented here focusses on the developments in the stabilising and trimming of 3D woven preforms. Dry fibre preforms are notoriously difficult to trim; once a fabric is cut, it loses its edge stability and consequently the fabric frays. The result is an unstable fabric which can easily be displaced/ distorted prior to composite manufacturing. In this work, three stabilisation and three trimming techniques were investigated. Of the stabilisation techniques these included powder binder, thermoplastic binder yarn (activated to give fabric stabilization); and polyester stitching. The stabilised fabrics were trimmed to near-net-shape using different trimming techniques. The trimming techniques investigated were laser, clicker press and ultrasonic knife. Each stabilisation method was trialled with each trimming method to assess the most suitable combination. The assessment of quality and suitability was made by observing the level of stabilisation, amount of fraying fibres, quality of the cut, ease of application and repeatability of the process. This paper details the assessments made for each combination alongside practical application conclusions. The key findings were; cutting by means of a laser is capable of sealing the fabric edges, producing high edge quality. Stitching as a method of stabilising is not sufficient in preventing fibres from moving during the cutting process, hence producing an unclean cut.     

The Reception and Sources of Berenice Abbott's Paris Portrait Style, 1925–1929

This study focuses on the photographs that first brought Berenice Abbott critical acclaim: her Paris portraits from the late 1920s. As a body of work, these images – along with what Abbott had to say about them and the critical attention they generated at the time – provide a rich resource for the study of three interconnected topics: the avant-garde critical climate of Europe in the late 1920s, the American expatriate experience in Paris during this same time and Abbott's nascent photographic values and aesthetic, which helped to inform not only her portraits but also her later, better-known photographs of New York City. The paper first defines the divergent critical responses to Abbott's portrait work in the late 1920s – focusing especially on the published criticism by Florent Fels and Pierre Mac Orlan that helped to secure Abbott's international reputation as a leading modern photographer. It then turns to Abbott's expatriate experience in order to examine the ideas and individuals that she identified as most important to her photographic practice. Specifically the paper explains Abbott's desire to create an alternative approach to photography from the one used by Man Ray, her awareness of the classical style associated with Pablo Picasso and her admiration for the aesthetic theories of Leo Stein.     

Overall gloss evaluation in the presence of multiple cues to surface glossiness

Human observers use the information offered by various visual cues when evaluating the glossiness of a surface. Several studies have demonstrated the effect of each single cue to glossiness, but little has been reported on how multiple cues are integrated for the perception of surface gloss. This paper reports on a psychophysical study with real stimuli that are different regarding multiple visual gloss criteria. Four samples were presented to 15 observers under different conditions of illumination in a light booth, resulting in a series of 16 stimuli. Through pairwise comparisons, an overall gloss scale was derived, from which it could be concluded that both differences in the distinctness of the reflected image and differences in luminance affect gloss perception. However, an investigation of the observers' strategy to evaluate gloss indicated a dichotomy among observers. One group of observers used the distinctness-of-image as a principal cue to glossiness, while the second group evaluated gloss primarily from differences in luminance of both the specular highlight and the diffuse background. It could therefore be questioned whether surface gloss can be characterized with one single quantity, or that a set of quantities is necessary to describe the gloss differences between objects.